METHOD OF BUILDING A 3D FUNCTIONAL OPTICAL MATERIAL LAYER STACKING STRUCTURE
Embodiments herein describe a sub-micron 3D diffractive optics element and a method for forming the sub-micron 3D diffractive optics element. In a first embodiment, a method is provided for forming a sub-micron 3D diffractive optics element on a film stack disposed on a substrate without planarization. The method includes forming a hardmask on a top surface of a film stack. Forming a mask material on a portion of the top surface and a portion of the hardmask. Etching the top surface. Trimming the mask. Etching the top surface again. Trimming the mask a second time. Etching the top surface yet again and then stripping the mask material.
This application claims is a continuation application U.S. Pat. No. 11,187,836, issued on Nov. 30, 2021, which claims benefit of U.S. Provisional Application Ser. No. 62/639,475, filed Mar. 6, 2018 (Attorney Docket No. APPM/44014928 USL), of which both are incorporated by reference in their entirety.
BACKGROUND OF THE DISCLOSURE Field of the InventionThe embodiments herein generally relate to a process for forming 3D optical stackable structures.
Description of the Background ArtThe 3D optical structures are used to produce complex optical devices. For example, the 3D optical structures may be used to generate 3D holograms with light. However, the quality of the 3D optics is highly dependent on increasing the density, and reducing the size of the 3D patterns on a stackable layer structure used for 3D optics. Creating a conventional 3D optical structure involves the formation of a 3-dimensional (3D) patternable and stackable layer structure with resist over a substrate. The substrate has a first layer of material deposited thereon and a resist is patterned for a first layer. The structure is then filled with a metal prior to planarizing with a chemical mechanical polisher. These operations are repeated over and over again for each layer to produce a plurality of different vertical heights in the structure. However, the current structures still yield structures of greater than a micron scale which results in a resolution that is undesirable for some 3D optical applications such as holograms.
While the problems and benefits of multiple patterning in terms of resolution, depth of focus and lithographic defect sensitivity are understood, there is additional desire to control the process budget and increase and maintain yield. Additionally, it is not easy to create this kind of structure since the application of subsequent material level(s) can dissolve or destroy the previously patterned material.
Therefore, there is a need for an improved method for creating a high density 3D multi-patterned structure on a substrate.
SUMMARY OF THE INVENTIONEmbodiments herein describe a sub-micron 3D optical material structure and a method for forming the sub-micron 3D optical material structure. In a first embodiment, a method is provided for forming a sub-micron 3D optical material structure on a substrate without planarization, the method begins by depositing a material stack to be patterned on a substrate; depositing and patterning a thick mask material on a portion of the material stack, etching the material stack down one level; trimming a side portion of the thick mask material; etching the material stack down one more level, repeating trim and etch operations above ‘n’ times, and stripping the thick mask material from the material stack.
In a second embodiment, a method is provided for forming a sub-micron 3D optical material structure on a substrate without planarization, the method begins by coating a substrate with a first layer of a material, exposing the specified material with a lithography method to produce a first pattern, curing the exposed specified material if needed, coating the substrate with a second layer of the material, exposing the specified material with a lithography method to produce a second pattern, curing the exposed specified material if needed, repeating the operations for coating, exposing and curing above ‘n’ times for n layers of the material having n patterns exposed therein, and developing the exposed and cured regions of n patterns on n layers simultaneously.
In a third embodiment, a sub-micron asymmetrical 3D optical material structure is provided. The asymmetrical 3D optical material structure has a substrate having a top surface, a first functional material level formed on the top surface of the substrate. The first function material level further has a plurality of first unit pieces of material, each first unit piece of material having a height, a width and a length, all of which are less than about a micron. The asymmetrical 3D optical material structure further has a second functional material level formed on the first top surface of the first functional material level. The second function material level further has a plurality of second unit pieces of material, wherein each second unit piece of material is disposed on one of the first unit pieces and each second unit piece of material having a height, a width and a length, substantially similar to that of the first unit piece of material. The asymmetrical 3D optical material structure further has a third functional material level formed on the second top surface of the second functional material level, wherein the third function material level further has a plurality of third unit piece of material, wherein each third unit piece of material is disposed on one of the second unit piece of material and each third unit piece of material having a third height, a third width and a length, substantially similar to that of the second unit piece of material.
In a fourth embodiment, a sub-micron symmetrical 3D optical material structure is provided. The sub-micron symmetrical 3D optical material structure has a substrate having a top surface, a film stack disposed on the top surface of the substrate having an upper surface, a first functional material level formed on the upper surface of the film stack having a first width and a first upper surface, a second functional material level formed on the first upper surface of the first functional material level having a second width, and a third functional material level formed on the second upper surface of the second functional material level having a third width wherein the first width is greater than the second width which is greater than the third width and the first width, second width and third width form a profile symmetric about a center of the 3D optical material structure.
In a fifth embodiment, a method is provided for fabricating a sub-micron 3D diffractive optics element. The method begins by depositing an optical material stack to be patterned into a diffractive optics element on a substrate. The method then deposits and patterns a mask material on a portion of the material stack. The method continues by etching the material stack down one level. The method then directionally etch one or more side portions of the mask material laterally by a desired distance and etches vertically the material stack down vertically a 2nd level. The method finishes by stripping the mask material.
So that the manner in which the above recited features of the embodiments herein are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings.
To facilitate understanding of the embodiments, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.
It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
DETAILED DESCRIPTIONDiffractive optical elements have been in use since the 19th century. In recent years, advancement in optics research enabled light manipulation using sub-wavelength and sub-micron diffractive optics, in both simulation and low volume fabrication. These nano-antennae can change the phase, amplitude, and polarization of light. Meta-surfaces based on Pancharatnam-Berry effect or other posts are one embodiment, made of high-aspect-ratio dielectric pillars. Mie or Huygens resonators, made with nano-discs are another embodiment and plasmonics resonance might be another. However, the feature dimensions required by resonators are challenging to achieve at scale, whether through stringent deposition, patterning, etching or other semiconductor-based methods. Moreover, the efficiency of plasmonics optical elements is limited, so it could only cater to some applications.
Multi-level diffractive optics elements benefit from manipulating the scalar properties of light through features that could be larger than the wavelength. If the features involve dimensions that are over 1 um, they can be fabricated using greyscale lithography, either with direct or indirect writing tools. Yet, greyscale lithography is limited in its resolution and shrinking the x, y and z features could enable higher field-of-view, larger numerical aperture and others.
One approach to fabrication of sub-micron multi-level diffractive optics is taking the multiple patterning, in which every layer is separately deposited, patterned and etched. Another approach takes a metal damascene route for multiple level fabrications. This approach of multiple patterning demonstrates both benefits and challenges in terms of resolution, depth of focus and lithographic defect sensitivity. It is also additional beneficial to control the process budget and increase and maintain yield. This work describes a method for creating a high-density, sub-micron multi-level patterned structure on a substrate.
Functional layer(s) modification makes the previous layer(s) more robust to withstand subsequent layer processing which enables 3D layer stacking optical structures. Embodiments here aim to reduce the material processing interaction when processing multiple patterned layers to form 3D patterned optical structures for engineered optics application. Embodiments are illustrated below to show the fabrication techniques for the 3D layer stacking optical structures. In one embodiment, one or more radiation curable functional leave-on material levels form the 3D patterned structure. In another embodiment, one or more radiation curable functional organic polymer, inorganic, or organic/inorganic hybrid material level form 3D patterned structures. In yet another embodiment, radiation hardening is provided for a previous material level (additional polymer cross linking) to improve the robustness of the previous material and to provide “skin” protection against subsequent material level processing and patterning. In yet another embodiment, a surface treatment process, such as atomic layer deposition (ALD), is used between patterned layers to provide a barrier layer to minimize interaction of subsequent layers with previous layer(s). In yet another embodiment, an impregnation technique (can be dry, wet or vapor treatment) is used to improve the robustness of the previous material level(s). In yet another embodiment, a doping technique, or ion implantation technique, is used to improve the robustness of the previous material level(s). In yet another embodiment, alternating material level pairs (layer of material A and layer of material B) are used to reduce material interaction during processing. For example, material A may be a sol-gel base material and material B can be a polymer based material. In yet another embodiment, sol-gel material levels are used to build up 3D structures such that cured sol-gel layers forming SiOx are robust enough to withstand material interaction with subsequent sol-gel layer processing. Advantageously, previous patterned layers are protected and are able to endure subsequent layer processing and patterning.
Additional embodiments are directed to the formation of symmetrical 3D optical stacking structures. The symmetrical 3D optical stacking structures utilize a resist trim process to generate sub-micron scale features. Further embodiments take the symmetrical approach and add a hardmask to make the symmetrical feature one sided, such as a Fresnel lens. In yet further embodiments, directional etch is utilized to form completely customizable and/or asymmetrical sub-micron 3D optical structures.
The embodiments briefly discussed above advantageously provide reduced operations for generating the structures while enabling the construction of sub-micron scale 3D optical structures. The methods disclosed below enable highly sophisticated customizable 3D optical structures to be quickly formed in a cost effective manner on a sub-micron scale. For example, the 3D features may be formed at a scale with a height such as between about 20 nm to about 1 micron, such as about 500 nm or 200 nm. The 3D optical structures may be formed on a diffractive optics element structure, i.e., a sheet of material with sub-wavelength thickness with subwavelength-scaled patterns in the horizontal dimensions. The diffractive optics element structure may have gratings and other single level structures, symmetrically stepped structures and stepped structures with one or more sides with no steps.
The structures disclosed herein are completely customizable for forming features which may appear at the Nano scale to display symmetry or asymmetry about a central axis, a step structure, or a portion thereof any possibly 3D feature. It should be appreciated that the scale of said features, although 3D at the Nano scale, may be used to form a flat lens at a scale visible to an unaided human eye. Furthermore, although the figures for the discussion below all illustrate square structures, it should be appreciated that the methods disclosed herein could be used to make elliptical cross-section pillars having different major and minor axis, a circular pillar or any other polygon shape for forming pillars of differing heights in the 3D optical stacking structures.
The coating tool 110 is configured to apply a layer of material onto a substrate. The coating tool 110 may use a spray coating technique for applying a substantially even layer of material. Alternately, the coating tool 110 may use a spin coating technique for applying a substantially even layer of material. In yet other alternatives, the coating tool 110 may be a chemical vapor deposition chamber or a plasma vapor deposition chamber, an atomic layer deposition chamber, or other suitable device suitable to apply a thin film, such as few micro meters or nanometers, of material to the substrate.
The photo exposure tool 120 may be a lithography tool which provides light energy to alter the resist to form a pattern therein. The photo exposure tool 120 may use a digital mask to form the patterns on the resist for forming features thereon.
The baking/curing tool 130 may use temperature or other energy to change the material composition of an outer surface or entire layer of the material deposited on the substrate. The baking/curing tool 130 may remove moisture, or volatiles, i.e., solvents, or catalyzes a reaction to alter the material for suitability or compatibility of subsequently materials subsequently applied on to the baked, i.e., cured, layer of material.
The development tool 140 dissolves the layers of resist on the substrate to reveal the structure of the pattern created thereon. After development, the substrate contains the 3D optical material stacking structures for creating devices thereon the substrate. The 3D optical material stacking structure may be formed by using one of the several methods discussed below.
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It should be appreciated that the layers may continue to be stacked well beyond three layers. Each layer merely needs to be chemically compatible with the surface treatment provided at the lower layer. The operations outlines above may be repeated any number of times to produce a complex and highly sophisticated 3D optical structure as illustrated in
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It should be appreciated that the layers may continue to be stacked well beyond three layers. Each layer merely needs to be chemically compatible with an adjacent layer with the treatment changing the material composition to facilitate the compatibility. The operations outlined above may be repeated any number of times to produce a complex and highly sophisticated 3D optical structure as illustrated in
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It should be appreciated that by alternating material A and material B, the number of levels may continue to be stacked well beyond three levels. Each level chemically compatible with an adjacent layer to facilitate rapid building of the 3D structure with a minimum number of operations. For example, repeated cycles of deposit, etch, and planarization at each level is unnecessary. The operations outlined above may be repeated any number of times to produce a complex and highly sophisticated 3D optical structure as illustrated in
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It should be appreciated that additional sol-gel levels of silicon oxide material may continue to be stacked well beyond the three levels discussed above. The sol-gel material levels are used to build up 3D structures such that cured sol-gel levels (forming SiOx) are robust enough to withstand material interaction with subsequent sol-gel levels. Each level is chemically compatible with an underlying level to facilitate rapid building of the levels for the 3D structure with a minimum number of operations. The operations outlined above may be repeated any number of times to produce a complex and highly sophisticated 3D optical structure as illustrated in
The fifth method 600 begins at block 610 by coating a substrate 701 with a first resist layer 711 of a material. The material may be a resist layer. The substrate 701 is acquired and a SiO2 layer is grown thereon in preparation of the first layer of material in step 705 shown in
The first layer of material, the first resist layer 711, is applied to the substrate 701 at block 710 in
At block 620, the first resist layer 711 is exposed with a lithography method to produce a first pattern. At block 630, the exposed the first resist layer 711 may be cured if needed. Block 715 shown in
At block 640, the substrate is coating with a second resist layer 721 of the material. The second resist layer 721 is shown at block 720 in
At block 650, the second resist layer 721 is exposed with a lithography method to produce a second pattern. At block 660, the exposed the second resist layer 721 may be cured if needed. An exposure and baking process 729 is shown block 725 shown in
At block 670, the blocks 640 through blocks 660 may be repeated ‘n’ times for n layers of the resist material having n patterns exposed therein. N is an integer corresponding to the number of levels for the sub-micron 3D optical structure. For example, the sub-micron 3D optical structure may have N equal to 4, 8, 16, 32 layers/levels, or maybe more.
In one purely illustrative example, N may be equal to 4 corresponding to 4 layers of resist. This is shown at block 730,
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It should be appreciated that the aforementioned steps of spin coating a resist and exposing the resist through a mask and backing to form the cured materials can be repeated to form multiple layers and complex 3D structures.
At block 680, the exposed and cured regions of the n patterns on n layers are simultaneously developed. Block 750 shown in
The conventional approach for building 3D functional optical material structure on a substrate may involve a multitude of operations which may include operations for SiO2 thermal oxide growth, Cu physical vapor deposition (PVD) deposition, Cu electrochemical plating (ECP), and lithography. Each layer repeatedly performing the steps for Cu ECP, Chemical Mechanical polishing (CMP), stop on resist and lithography prior to removing the resist. The fifth method 600 can build the same 3D functional optical material level structure in as little as ten process steps. Therefore, the fifth method 600, illustrated above, provides savings of time and resources for building a 3D pattern suitable for generating the 3D functional optical structure resulting in significant savings in time, material and factory resources.
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As shown above, a multitude of layers may be stacked to form 3D structure 800 having four (4), eight (8), sixteen (16), thirty two (32) or more layers of material. Each layer having structures at a sub-micron scale. At step 850 as shown in
In addition to the methods disclosed above for forming fully customizable 3D optical structure at the sub-micron level, methods below describe alternative methods for forming similarly sized symmetrical 3D structures.
The method 900 starts at block 910, wherein an optical material stack, i.e., film stack 1008, to be patterned into a diffractive optics element is deposited on a substrate 1001. The substrate 1001 may be a single optical material. The depositing material may be used to make a master for forming an 3D optical structure wherein the master is transposed from the final 3D optical structure. The film stack 1008 may be a resist material for forming features in the substrate below or the film stack 1008 may be a plurality of materials suitable to form the final 3D optical features.
At block 915, a “blocking layer”, such as hardmask 1171 in
Resuming with block 920, a mask material 1080 is deposited and patterned on a portion of the film stack 1008. In
At block 930, the film stack 1008 is etched down one level. The film stack 1008 is shown in
At block 940, a side portion of the mask material 1080 is trim etched laterally by a desired distance. The desired distance for the trim etch may correspond to a lateral step size, for example, first layer top portion 1027.
At block 950, a second vertical etch is performed on the mask material 1080 and optical material, i.e., film stack 1008, vertically down a 2nd level.
At block 955, a second trim etching is performed to form a desired second lateral step size. The sequence of steps may be repeated. At block 960, the trim operation (block 940) and etch operation (block 950) are repeated ‘N’ times to form the desired stair-step structure where not optionally blocked by the blocking layer at block 915. N is an integer corresponding to the number of levels for the sub-micron 3D optical structure. For example, the sub-micron 3D optical structure may have N equal to the number of levels for the sub-micron 3D optical structure. The sub-micron 3D optical structure may have 4, 8, 16 32 or more levels.
In one purely illustrative example, N is equal to 3 corresponding to 3 levels of etch and trim. At block 1050 shown in
At block 1060 shown in
At block 970, the mask material 1080 is stripped from the film stack 1008. The optional blocking material is stripped as well if it is present. At step 1070 shown in
At block 980, a mask material may optionally be added to cover selected stepped regions, and etching down the originally blocked area to a lower step level. This operation is described with respect to block 1140 shown in
Resuming with block 990, the 3D optical structure 1099 may optionally be used as a master for imprinting the inverse shape in an optical material or stack. The 3D optical structure 1000 is shown symmetrical but may incorporate a stepped structure through the use of the optional blocked material. It should be appreciated that the steps may be irregular as will be further discussed below with respect to
As will be disclosed now with respect to method 1100, the embodiment of method 1000 disclosed in
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Block 1510 additionally includes a mask material 1509 is deposited and patterned on a top surface 1511 of the film stack 1508. The mask material 1509 has an upper surface 1588, a bottom surface 1589, a right side surface 1581 and a left side surface 1582. It should be appreciated that the mask material 1509 may be any shape having any number of sides surfaces and the following operations may be performed on one or more of the individual side surfaces. For simplicity, the following discussion will be with respect to the right side surface 1581 and the left side surface 1582. Additionally, the discussion shall utilize a right side 1591 and a left side 1592 of the 3D functional optical material level structure 1500. The mask material 1509 may be a photo resist or other suitable mask material. The formation of the mask material 1509 may be performed in a series of steps which deposit, expose, and remove unwanted mask material 1509.
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At block 1540, shown in
The sequence of steps above may be repeated any number of times to produce the desired structure. For example, the trim operation at block 1530 and etch operation at block 1540 are repeated ‘N’ times to form the desired stair-step structure having optional flat sections disposed throughout the structure. N is an integer corresponding to the number of levels for the sub-micron 3D optical structure. For example, the sub-micron 3D optical structure may have N equal to the number of levels for the sub-micron 3D optical structure. The sub-micron 3D optical structure may have 4, 8, 16 32 or more levels.
In one purely illustrative example, N is equal to 3 corresponding to 3 levels of etch and trim. At block 1550, shown in
At block 1560 shown in
At block 1570 shown in
At block 1580 shown in
At block 1590 shown in
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At block 1610 shown in
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At block 1625 shown in
At block 1630 shown in
At block 1635 shown in
At block 1640, the step 1625 for depositing optical material on an underlying layer, the step 1630 for exposing the optical material to form a pattern therein, and the step 1635 for optionally baking the patterned optical material are repeating for N levels to produce a multi-level 3D functional optical material level structure. The 3D functional optical material level structure has N levels such as 4 levels, 8 levels, 16 levels, 32 levels, or maybe more.
At block 1645, shown in
At block 1650, the master left behind from the development step above is used for imprinting the inverse shape in an optical material or stack. Thus, the optical material may be repeatedly and accurately used to form a plurality of 3D functional optical material level structures.
Advantageously, the methods described above provide techniques having reduced steps for building sub-micron devices. The techniques require fewer operations (such as planarization) saving raw materials, machine operational costs, and time. The 3D optical devices may be symmetrical or asymmetrical and are formed from units having dimensions between about 20 nm to about 1 micron, such as about 200 nm in each of the coordinate directions, such as in an X, Y and Z direction. The 3D optical devices therefore can be made small enough to be utilized for creating high resolution holographic images from small devices.
In addition to the examples described above, some additional non-limiting examples may be described as follows:
EXAMPLE 1.1A method for forming a sub-micron asymmetrical 3D optical material structure on a substrate without planarization, the method comprising:
forming a plurality of first functional material levels on a top surface of a substrate at a depth of less than one micron;
treating a first outer surface of the first functional material levels, the first outer surface having a first top surface;
forming a plurality of second functional material levels on the first top surface for one or more of the first functional material levels only and at a depth of less than one micron;
treating a second outer surface of the second functional material levels, the second outer surface having a second top surface; and
forming a plurality of third functional material levels on the second top surface for one or more of the second functional material levels only and at a depth of less than one micron.
EXAMPLE 1.2The method of example 1.1 wherein forming the first functional material level may not have a second third functional material level formed thereon.
EXAMPLE 1.3The method of example 1.2 wherein the first, second and third functional material levels result in pillars of various heights on the substrate.
EXAMPLE 1.4The method of example 1.2 wherein the second third functional material level and the third functional material are not formed directly on the top surface of the substrate.
EXAMPLE 1.5The method of example 1.1 wherein the depth for each of the first, second and third functional material levels is about 200 nm.
EXAMPLE 1.6The method of example 1.1 wherein treating the first and second functional material levels further comprises at least one of:
forming an atomic deposition layer;
doping or ion implantation; and
radiation hardening.
EXAMPLE 1.7The method of example 1.6 wherein treating the first and second functional material level changes the composition of the first outer surface and the second outer surface respectively such that a solvent or other chemical of a functional material level overlaid thereon will not attack the first and second functional material level.
EXAMPLE 1.8The method of example 1.1 further comprising:
imprinting the inverse shape of the sub-micron asymmetrical 3D optical material structure in an optical material or stack.
EXAMPLE 2.1A method for forming a sub-micron asymmetrical 3D optical material structure on a substrate without planarization, the method comprising:
forming a first functional material level on a top surface of a substrate at a depth of less than one micron;
impregnating the first functional material level to form a first treated functional material level, the first treated functional material level having a first top surface;
forming a second functional material level on the first top surface for one or more of the first treated functional material level only and at a depth of less than one micron;
impregnating the second functional material level to form a second treated functional material level, the second treated functional material level having a second top surface; and
forming a third functional material level on the second top surface for one or more of the second treated functional material level only and at a depth of less than one micron.
EXAMPLE 2.2The method of example 2.1 wherein the first functional material level may not have a second third functional material level formed thereon.
EXAMPLE 2.3The method of example 2.2 wherein forming the first, second and third functional material levels result in pillars of various heights on the substrate.
EXAMPLE 2.4The method of example 2.2 wherein the second third functional material level and the third functional material are not formed directly on the top surface of the substrate.
EXAMPLE 2.5The method of example 2.1 wherein impregnating the first and second functional material levels further comprises:
baking or electron volt implantation to alter the structure of the first, second and third functional material levels.
EXAMPLE 2.6The method of example 2.5 wherein impregnating the first and second functional material levels treatment alters the structure of the first and second functional material levels to a more robust material substantially chemically inert to a subsequent layer which may be disposed thereon.
EXAMPLE 2.7The method of example 2.1 further comprising:
imprinting the inverse shape of the sub-micron asymmetrical 3D optical material structure in an optical material or stack.
EXAMPLE 3.1A method for forming a sub-micron asymmetrical 3D optical material structure on a substrate without planarization, the method comprising:
forming a first functional material level on a top surface of a substrate at a depth of less than one micron, the first functional material level having a first top surface and being of a first material;
forming a second functional material level on the first top surface of the first functional material level at a depth of less than one micron, the second functional material level having a second top surface and being of a second material compatible for stacking on the first material; and
forming a third functional material level on the second top surface of the second functional material level at a depth of less than one micron, the third functional material level being of the first material compatible for stacking on the second material.
EXAMPLE 3.2The method of example 3.1 wherein the first functional material level may not have a second third functional material level formed thereon.
EXAMPLE 3.3The method of example 3.2 wherein forming the first, second and third functional material levels result in pillars of various heights on the substrate.
EXAMPLE 3.4The method of example 3.2 wherein the second third functional material level and the third functional material are not formed directly on the top surface of the substrate.
EXAMPLE 3.5The method of example 3.1 wherein the first functional material level may be a sol-gel base material and the first functional material level may be a polymer based material.
EXAMPLE 3.6The method of example 3.5 wherein the third functional material is of a sol-gel base material.
EXAMPLE 3.7The method of example 3.1 wherein the first functional material, the second functional material and the third functional material have a height of between about 20 nm to about 1 micron.
EXAMPLE 3.8The method of example 3.7 wherein the height is about 200 nm.
EXAMPLE 3.9The method of example 3.1 further comprising: imprinting the inverse shape of the sub-micron asymmetrical 3D optical material structure in an optical material or stack.
EXAMPLE 4.1A method for forming a sub-micron asymmetrical 3D optical material structure from sol-gel on a substrate without planarization, the method comprising:
forming a first functional material level on a top surface of a substrate at a depth of less than one micron, the first functional material level having a first top surface and being of a sol-gel material;
forming a second functional material level on the first top surface of the first functional material level at a depth of less than one micron, the second functional material level having a second top surface and being of the sol-gel material; and
forming a third functional material level on the second top surface of the second functional material level at a depth of less than one micron, the third functional material level being of the sol-gel material.
EXAMPLE 4.2The method of example 4.1 further comprising:
curing the sol-gel material of the first functional material level to form a compatible polymer that is robust enough to allow the colloidal solution of the second functional material level to be placed thereon.
EXAMPLE 4.3The method of example 4.2 wherein the compatible polymer is SiOx.
EXAMPLE 4.4The method of example 4.1 wherein forming a first functional material level comprises:
depositing the sol-gel material by spin coating.
EXAMPLE 4.4The method of example 4.1 wherein the first functional material, the second functional material and the third functional material have a height of between about 20 nm to about 1 micron.
EXAMPLE 4.5The method of example 4.4 wherein the height is about 200 nm.
EXAMPLE 4.6The method of example 4.1 wherein the first functional material level may not have a second third functional material level formed thereon.
EXAMPLE 4.7The method of example 4.6 wherein forming the first, second and third functional material levels result in pillars of various heights on the substrate.
EXAMPLE 4.8The method of example 4.1 further comprising:
imprinting the inverse shape of the sub-micron asymmetrical 3D optical material structure in an optical material or stack.
EXAMPLE 5.1A method for forming a sub-micron symmetrical 3D optical material structure into a film stack disposed on a substrate without planarization, the method comprising:
forming a mask material on to a top surface of the film stack, the mask material having a plurality of sides;
etching the top surface of the film stack a depth of less than one micron revealing a second top surface and forming a first material level under the mask material;
trimming the sides of the mask material by less than one micron to reveal a second side surface of the mask material and a first upper surface of the first material level;
etching the second top surface of the film stack and the first upper surface of the first material level by a depth of less than one micron forming a second material level under the first material level and revealing a third top surface for the film stack and a second upper surface for the second material level;
trimming the second sides of the mask material by less than one micron to reveal a third side surface of the mask material and the first upper surface of the first material level;
etching the third top surface of the film stack, the first upper surface of the first material level and the second upper surface of the second material level all by a depth of less than one micron forming a third material level under the second material level and revealing a fourth top surface for the film stack and a third upper surface for the third material level; and
stripping the mask material from the film stack to reveal a step 3D optical material structure.
EXAMPLE 5.2The method of example 5.1 wherein the depth of the etch is about 200 nm.
EXAMPLE 5.3The method of example 5.1 wherein trimming the second sides of the mask material a desired distance corresponding to a lateral step size.
EXAMPLE 5.4The method of example 5.3 wherein the lateral step size is substantially similar to the depth.
EXAMPLE 5.5The method of example 5.3 further comprising:
directional etching the mask material.
EXAMPLE 5.6The method of example 5.1 wherein the second top surface is closer to the mask material than the third top surface.
EXAMPLE 5.7The method of example 5.1 further comprising:
depositing a blocking layer resistant to etch of the other materials; and
patterning the blocking layer with lithography.
EXAMPLE 5.8The method of example 5.7 wherein response to the patterning of the blocking material, the method further comprises:
developing the blocking layer and removing un-patterned material.
EXAMPLE 5.9The method of example 5.7 further comprising:
striping the blocking layer.
EXAMPLE 5.10The method of example 5.1 further comprising:
skipping the trimming of the sides of the mask material for one or more etching operations.
EXAMPLE 5.11The method of example 5.1 further comprising:
imprinting the inverse shape of the step 3D optical material structure in an optical material or stack.
EXAMPLE 6.1A method for forming a sub-micron one sided symmetrical 3D optical material structure into a film stack disposed on a substrate without planarization, the method comprising:
forming a hardmask on a top surface of the film stack;
forming a mask material on to a portion of the top surface of the film stack and a portion of the hardmask, the mask material having a plurality of sides;
etching the top surface of the film stack a depth of less than one micron revealing a second top surface and forming a first material level under the mask material;
trimming the sides of the mask material by less than one micron to reveal a second side surface of the mask material and a first upper surface of the first material level;
etching the second top surface of the film stack and the first upper surface of the first material level by a depth of less than one micron forming a second material level under the first material level and revealing a third top surface for the film stack and a second upper surface for the second material level;
trimming the second sides of the mask material by less than one micron to reveal a third side surface of the mask material and the first upper surface of the first material level;
etching the third top surface of the film stack, the first upper surface of the first material level and the second upper surface of the second material level all by a depth of less than one micron forming a third material level under the second material level and revealing a fourth top surface for the film stack and a third upper surface for the third material level; and
stripping the mask material from the film stack to reveal the sub-micron symmetrical 3D optical material structure.
EXAMPLE 6.2The method of example 6.1 further comprising:
removing the hardmask;
forming a second mask material a step 3D optical material structure and the fourth top surface of the film stack;
etching the top surface of the film stack to the depth of the fourth top surface; and
stripping the second mask material from the film stack to reveal a sub-micron one sided symmetrical 3D optical material structure.
EXAMPLE 6.3The method of example 6.1 further comprising:
imprinting the inverse shape of the one sided symmetrical 3D optical material structure in an optical material or stack.
EXAMPLE 6.4The method of example 6.1 wherein the depth of the etch is about 200 nm.
EXAMPLE 6.5The method of example 6.1 wherein trimming the second sides of the mask material a desired distance corresponding to a lateral step size.
EXAMPLE 6.6The method of example 6.5 wherein the lateral step size is substantially similar to the depth.
EXAMPLE 6.7The method of example 6.5 further comprising:
directional etching the mask material.
EXAMPLE 6.8The method of example 6.1 wherein the second top surface is closer to the mask material than the third top surface.
EXAMPLE 6.9The method of example 6.1 further comprising:
skipping the trimming of the sides of the mask material for one or more etching operations.
EXAMPLE 6.10The method of example 6.1 further comprising:
imprinting the inverse shape of the 3D optical material structure in an optical material or stack.
EXAMPLE 7.1A sub-micron 3D optical material structure on a diffractive optics element, the 3D optical material structure comprising:
a substrate having a top surface;
a first material level formed on the top surface of the substrate, wherein the first material level has a first top surface and comprises:
-
- a plurality of first unit pieces of material, each first unit piece of material having a height, a width and a length, all of which are less than about one micron;
a second material level formed on the first top surface of the first material level, wherein the second material level has a second top surface and comprises:
-
- a plurality of second unit pieces of material, wherein each second unit piece of material is disposed on one of the first unit pieces of material and each second unit piece of material having a second height, a second width and a second length, substantially similar to the height, the width and the length of the first unit piece of material; and
a third material level formed on the second top surface of the second material level, wherein the third material level comprises:
-
- a plurality of third unit piece of material, wherein each third unit piece of material is disposed on one of the second unit piece of material and each third unit piece of material having a third height, a third width and a third length, substantially similar to that of the second unit piece of material.
The 3D optical material structure of example 7.1 wherein the first material level further comprises:
a plurality of first vias, wherein the first vias are devoid of any of the plurality of first unit pieces.
EXAMPLE 7.3The 3D optical material structure of example 7.2 wherein each via of the plurality of first vias is substantially similar in size to that of the first unit piece.
EXAMPLE 7.4The 3D optical material structure of example 7.2 wherein each second unit piece is disposed on a first unit piece and not on or in any of the plurality of first vias.
EXAMPLE 7.5The 3D optical material structure of example 7.2 wherein the second material level further comprises:
a plurality of second vias, wherein the second vias are devoid of any of the plurality of second unit pieces and disposed on the plurality of first vias.
EXAMPLE 7.6The 3D optical material structure of example 7.5 wherein one or more of the plurality of second vias is additionally disposed on one or more of the first unit pieces.
EXAMPLE 7.7The 3D optical material structure of example 7.6 wherein a multitude of layers are be stacked to form the 3D optical material structure having four (4), eight (8), sixteen (16), thirty two (32) or more layers of material.
EXAMPLE 8.1A sub-micron 3D optical material structure on a diffractive optics element, the 3D optical material structure comprising:
a substrate having a top surface;
a film stack disposed on the top surface of the substrate having an upper surface;
a first material level formed on the upper surface of the film stack having a first width and a first upper surface;
a second material level formed on the first upper surface of the first material level having a second width and a second upper surface; and
a third material level formed on the second upper surface of the second material level having a third width wherein the first width is greater than the second width which is greater than the third width, and wherein the first width, the second width and the third width form a profile symmetric about a center of the 3D optical material structure.
EXAMPLE 8.2The 3D optical material structure of example 8.1 wherein a depth of the first material level, the second material level and the third material level is between about 20 nm to about 1 micron.
EXAMPLE 8.3The 3D optical material structure of example 8.1 wherein a depth of the first material level, the second material level and the third material level is about 200 nm.
EXAMPLE 8.3The 3D optical material structure of example 8.1 further comprising:
a void in the second material level having no material therein disposed on the first material level and where the third material level spans the void when disposed on top thereof.
EXAMPLE 8.4The 3D optical material structure of example 8.1 wherein a size of a width, length and height for each material level forming the 3D optical material structure is a function of the thickness of material spun on to the first, second and third material level and a feature size in the pattern used in one or more lithography operations.
EXAMPLE 8.5The 3D optical material structure of example 8.1 further comprising:
a blocking layer disposed on one or more of the first, second and third material level configured to prevent the formation of subsequent material levels above the blocking layer.
EXAMPLE 9.1A method of fabricating a sub-micron 3D optical diffractive optics element, the method comprising:
A) depositing an optical material stack to be patterned into a diffractive optics element on a substrate;
B) depositing and patterning a mask material on a portion of the material stack;
C) etching the material stack down one level;
D) directionally etch one or more side portions of the mask material laterally by a desired distance;
E) vertically etching the material stack down vertically a 2nd level;
F) repeating D and E; and
G) stripping the mask material.
EXAMPLE 9.2The method of example 9.1 further comprising:
depositing a blocking layer that is resistant to etch of the other materials may and patterned with lithography to a blocked area; and
adding a mask material covering a selected stepped regions and etching down the originally blocked area to the to a lower step level.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, the embodiments described in clam 16 as illustrated in
Claims
1. A method for forming a sub-micron one sided symmetrical 3D optical material structure into a film stack disposed on a substrate without planarization, the method comprising:
- forming a hardmask on a top surface of the film stack;
- forming a mask material onto a portion of the top surface of the film stack and a portion of the hardmask, the mask material having a plurality of sides;
- etching the top surface of the film stack a depth of less than one micron revealing a second top surface and forming a first material level under the mask material;
- trimming the sides of the mask material by less than one micron to reveal a second side surface of the mask material and a first upper surface of the first material level;
- etching the second top surface of the film stack and the first upper surface of the first material level by a depth of less than one micron forming a second material level under the first material level and revealing a third top surface for the film stack and a second upper surface for the second material level;
- trimming the second sides of the mask material by less than one micron to reveal a third side surface of the mask material and the first upper surface of the first material level;
- etching the third top surface of the film stack, the first upper surface of the first material level and the second upper surface of the second material level all by a depth of less than one micron forming a third material level under the second material level and revealing a fourth top surface for the film stack and a third upper surface for the third material level; and
- stripping the mask material from the film stack to reveal the sub-micron symmetrical 3D optical material structure.
2. The method of claim 1 further comprising:
- removing the hardmask;
- forming a second mask material on the sub-micron symmetrical 3D optical material structure and the fourth top surface of the film stack;
- etching the top surface of the film stack to the depth of the fourth top surface; and
- stripping the second mask material from the film stack to reveal a sub-micron one sided symmetrical 3D optical material structure.
3. The method of claim 1 further comprising:
- imprinting the inverse shape of the one sided symmetrical 3D optical material structure in an optical material or stack.
4. The method of claim 1 wherein the depth of the etch is about 200 nm.
5. The method of claim 1 wherein trimming the second sides of the mask material a desired distance corresponding to a lateral step size.
6. The method of claim 5 wherein the lateral step size is the same as the depth.
7. The method of claim 5 further comprising:
- directional etching the mask material.
8. The method of claim 1 wherein the second top surface is closer to the mask material than the third top surface.
9. The method of claim 1 further comprising:
- skipping the trimming of one or more of the sides of the mask material for one or more etching operations.
10. The method of claim 1 further comprising:
- imprinting the inverse shape of the 3D optical material structure in an optical material or stack.
11. A sub-micron 3D optical material structure on a diffractive optics element, the 3D optical material structure comprising:
- a substrate having a top surface;
- a first material level formed on the top surface of the substrate, wherein the first material level has a first top surface and comprises: a plurality of first unit pieces of material, each first unit piece of material having a height, a width and a length, all of which are less than about one micron;
- a second material level formed on the first top surface of the first material level, wherein the second material level has a second top surface and comprises: a plurality of second unit pieces of material, wherein each second unit piece of material is disposed on one of the first unit pieces of material and each second unit piece of material having a second height, a second width and a second length, comparable to the height, the width and the length of the first unit piece of material; and
- a third material level formed on the second top surface of the second material level, wherein the third material level comprises: a plurality of third unit piece of material, wherein each third unit piece of material is disposed on one of the second unit piece of material and each third unit piece of material having a third height, a third width and a third length, comparable to that of the second unit piece of material.
12. The 3D optical material structure of claim 11 wherein the first material level further comprises:
- a plurality of first vias, wherein the first vias are devoid of any of the plurality of first unit pieces.
13. The 3D optical material structure of claim 12 wherein each via of the plurality of first vias is substantially similar in size to that of the first unit piece.
14. The 3D optical material structure of claim 12 wherein each second unit piece is disposed on a first unit piece and not on or in any of the plurality of first vias.
15. The 3D optical material structure of claim 12 wherein the second material level further comprises:
- a plurality of second vias, wherein the second vias are devoid of any of the plurality of second unit pieces and disposed on the plurality of first vias.
16. The 3D optical material structure of claim 15 wherein one or more of the plurality of second vias is additionally disposed on one or more of the first unit pieces.
17. The 3D optical material structure of claim 16 wherein a multitude of layers are be stacked to form the 3D optical material structure having four (4), eight (8), sixteen (16), thirty two (32) or more layers of material.
18. A method of fabricating a sub-micron 3D optical diffractive optics element, the method comprising:
- A) depositing an optical material stack to be patterned into a diffractive optics element on a substrate;
- B) depositing and patterning a mask material on a portion of the material stack;
- C) etching the material stack down one level;
- D) directionally etch one or more side portions of the mask material laterally by a desired distance;
- E) vertically etching the material stack down vertically a 2nd level;
- F) repeating D and E; and
- G) stripping the mask material.
19. The method of claim 18 further comprising:
- depositing a blocking layer that is resistant to etch to a blocked area and patterned with lithography a non-blocked area;
- removing the blocking layer; and
- adding a mask material covering the non-blocked area and etching down the optical material stack to a lower step level.
Type: Application
Filed: Nov 24, 2021
Publication Date: Mar 17, 2022
Inventors: Michael Yu-tak YOUNG (Cupertino, CA), Ludovic GODET (Sunnyvale, CA), Robert Jan VISSER (Menlo Park, CA), Naamah ARGAMAN (San Jose, CA), Christopher Dennis BENCHER (Santa Clara, CA), Wayne MCMILLAN (San Jose, CA)
Application Number: 17/456,507