PILLAR-SUPPORTED ARRAY OF MICRO ELECTRON LENSES
One embodiment relates to a pillar-supported array of micro electron lenses. The micro-lens array includes a base layer on a substrate, the base layer including an array of base electrode pads and an insulating border surrounding the base electrode pads so as to electrically isolate the base electrode pads from each other. The micro-lens array further includes an array of lens holes aligned with the array of base electrode pads and one or more stacked electrode layers having openings aligned with the array of lens holes. The micro-lens array further includes one or more layers of insulating pillars, each layer of insulating pillars supporting a stacked electrode layer. Another embodiment relates to a method of fabricating a pillar-supported array of micro electron lenses. Other embodiments, aspects and features are also disclosed.
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The present application is a continuation of International Patent Application No. PCT/US2013/029444, filed Mar. 6, 2013, entitled “Pillar-Supported Array of Micro Electron Lenses”, the disclosure of which is hereby incorporated by reference. International Patent Application No. PCT/US2013/029444 claims the benefit of U.S. Provisional Patent Application No. 61/612,648, filed Mar. 19, 2012, entitled “Pillar Based Digital Pattern Generator (DPG) for Reflective Electron Beam Lithography (REBL),” the disclosure of which is hereby incorporated by reference.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENTThis invention was made with Government support under Agreement No. HR0011-07-9-0007 awarded by DARPA. The Government has certain rights in the invention.
BACKGROUND1. Technical Field
The present invention relates a dynamic pattern generator for use in electron beam lithography and other applications.
2. Description of the Background Art
A dynamic pattern generator (DPG) may be used for electron beam lithography or other applications. Independently-controllable voltages may be applied to pixels or a DPG. The voltages may determine whether each pixel is in an ON state or an OFF state. For example, the ON state may correspond to the reflection of incident electrons by the pixel, and the OFF state may correspond to the absorption or diffraction of the incident electrons by the pixel.
One embodiment relates to a pillar-supported array of micro electron lenses. The micro-lens array includes a base layer on a substrate, the base layer including an array of base electrode pads and an insulating border surrounding the base electrode pads so as to electrically isolate the base electrode pads from each other. The micro-lens array further includes an array of lens holes aligned with the array of base electrode pads and one or more stacked electrode layers having openings aligned with the array of lens holes. The micro-lens array further includes one or more layers of insulating pillars, each layer of insulating pillars supporting a stacked electrode layer.
Another embodiment relates to a method of fabricating a pillar-supported array of micro electron lenses. A base layer is formed on a substrate, the base layer including an array of base electrode pads separated by insulating material. A first stacked electrode layer is formed above the base layer. A first array of insulating pillars is formed, the first array of insulating pillars supporting the first stacked electrode layer above the base layer. An array of lens holes is formed, the lens holes being aligned to the array of base electrode pads.
Another embodiment relates to a device for dynamically patterning an electron beam. The device includes a base layer on a substrate. The base layer includes an array of base electrode pads to which individually-controllable voltages are applied. The device further includes an array of lens holes aligned with the array of base electrode pads, a plurality stacked electrode layers, and a plurality of layers of insulating pillars. Each stacked electrode layer includes an array of openings aligned with the array of lens holes. Each layer of insulating pillars supports one stacked electrode layer.
Other embodiments, aspects and feature are also disclosed.
DETAILED DESCRIPTIONApplicants have determined that one of the issues with previous DPG designs is that the charging of the insulators in the device reduces the efficiency of the DPG lenslets. To mitigate such insulator charging, a conformal conductive coating may be applied, but such a coating has been observed to degrade thermally and electrically over time.
The present disclosure provides a technique for overcoming the above-discussed issues. In accordance with an embodiment of the invention, a support structure is formed using relatively small pillars in the interstitial regions of the electron lenslets of a dynamic pattern generator. In such a support structure, the insulating material is advantageously located farther away from the electron beam while the stacked electrode layers are still supported. In contrast, previous designs have wells in which the lenslet insulators are flush or nearly flush with the electrode openings.
As shown in
The multiple stacked electrode layers (111, 112, 113, and 114) may be separated and supported by insulating pillars (121, 122, 123 and 124, respectively). Each stacked electrode layer may be titanium nitride, or another conductive material and may have a separately-controlled voltage applied to that layer. The insulating pillars may be silicon nitride or another insulating material.
Below the first (lowest) stacked electrode layer 111 is a base electrode layer 110. A planar view of the structure of the base electrode layer 110 is depicted in
The base electrode pads 202 may be formed using a different metal than that used to form the stacked electrodes (111-114) such that selective etching may be performed that etches the stacked electrodes but not the base electrode pads 202. For example, the base electrode pads 202 may be copper, and the stacked electrodes (111-114) may be aluminum or an aluminum alloy. The insulating regions 204 may be silicon nitride or silicon oxynitride, for example. While a 3×3 array of base electrode pads are depicted for purpose of simplicity, it is understood that a practical array will be much larger. As just one example, the array may be a 1024×128 array of base electrode pads.
Returning to
An exemplary implementation may have the following dimensions and applied voltages. However, it is expected that the dimensions and applied voltages will vary depending on the use for which the array 100 is intended.
In the exemplary implementation, each pixel opening 130 to a lens hole may be 1.4 microns across and each stacked electrode layer (111, 112, 113 and 114 may be 1.0 microns above the electrode layer beneath it. In other words, the first stacked electrode layer 111 may be 1.0 microns above the base electrode layer 110, the second stacked electrode layer 112 may be 1.0 microns above the first stacked electrode layer 111, and so on. In the exemplary implementation, the first and second stacked electrode layers (111 and 112) may both have an applied voltage of negative 2.5 volts (V), the third stacked electrode layer 113 may have an applied voltage of positive 15 V, and the fourth stacked electrode layer 114 may have an applied voltage of positive 0.5 V. Finally, each base electrode pad 202 in the base electrode layer 110 may have an applied voltage that may be switched individually between zero volts and negative 5 V, for example, in order to achieve the OFF and ON states, respectively.
In this exemplary implementation, the negative voltages applied to the first and second stacked electrode layers (111 and 112) may be used to focus the electrons as these electrode layers are near the bottom of each lens hole. The relatively strong positive voltage applied to the third stacked electrode layer 113 (which is just beneath the uppermost electrode) may be used to both focus the incoming electrons by drawing them into the lens hole and extract the reflected electrons by drawing them out of the lens hole. The relatively weak positive voltage applied to the fourth stacked electrode layer (the uppermost electrode in this embodiment) 114 may be used to both screen the insulating pillars from the incoming electron current and to deflect the incoming electrons with lower energy towards the inside of a nearest lens hole.
Note that, while
After depositing the first stacked conductive layer 314 per
After depositing the second stacked conductive layer 414 per
After depositing the third stacked conductive layer 514 per
The widest span d of the cross-section of each support pillar (e.g., the diameter if the pillar has a circular cross-section) may be less than one-half of the width W of the largest square (shown as a dashed square) which fits into the interstitial region between a 2×2 sub-array of four lens holes. As shown in the exemplary implementation depicted in
In accordance with an embodiment of the invention, the conformal coating may be a nanolaminate of alumina and a metal. For example, the conformal coating may be applied using atomic layer deposition (ALD), and the materials deposited may be alumina and molybdenum. Other conformal coatings that may be used include an ALD coating of ZnO and Al2O3, a carbon coating, and a diamond like carbon (DLC) coating.
The above-described diagrams are not necessarily to scale and are intended be illustrative and not limiting to a particular implementation. In the above description, numerous specific details are given to provide a thorough understanding of embodiments of the invention. However, the above description of illustrated embodiments of the invention is not intended to be exhaustive or to limit the invention to the precise forms disclosed. One skilled in the relevant art will recognize that the invention can be practiced without one or more of the specific details, or with other methods, components, etc. In other instances, well-known structures or operations are not shown or described in detail to avoid obscuring aspects of the invention. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize.
These modifications can be made to the invention in light of the above detailed description. The terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification and the claims. Rather, the scope of the invention is to be determined by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.
Claims
1. A pillar-supported array of micro electron lenses, the pillar-supported array comprising:
- a base layer on a substrate, the base layer including an array of base electrode pads;
- an insulating border surrounding each base electrode pads so as to electrically isolate the base electrode pads from each other;
- an array of lens holes aligned with the array of base electrode pads;
- a first stacked electrode layer having a first array of openings aligned with the array of lens holes; and
- a first layer of insulating pillars which support the first stacked electrode layer above the base layer.
2. The pillar-supported array of claim 1, further comprising:
- a second stacked electrode layer having openings aligned with the array of lens holes; and
- a second layer of insulating pillars which support the second stacked electrode layer above the first stacked electrode layer.
3. The pillar-supported array of claim 2, further comprising:
- a third stacked electrode layer having openings aligned with the array of lens holes; and
- a third layer of insulating pillars which support the third stacked electrode layer above the second stacked electrode layer.
4. The pillar-supported array of claim 3, further comprising:
- a fourth stacked electrode layer having openings aligned with the array of lens holes; and
- a fourth layer of insulating pillars which support the fourth stacked electrode layer above the third stacked electrode layer.
5. The pillar-supported array of claim 1, wherein there is at least one open space between each pair of adjacent lens holes.
6. The pillar-supported array of claim 5, wherein there are no sidewalls between each pair of adjacent lens holes.
7. The pillar-supported array of claim 5, wherein a widest span of an insulating pillar is less than one-half a width of a largest square that fits into an interstitial region between four of the openings.
8. The pillar-supported array of claim 1, wherein the insulating pillars are formed using a nitride or an oxynitride.
9. The pillar-supported array of claim 1 further comprising:
- a conformal coating over surfaces of the electrodes and insulating pillars.
10. The pillar-supported array of claim 9, wherein the conformal coating comprises a nanolaminate of alumina and a metal.
11. A method of fabricating a pillar-supported array of micro electron lenses, the method comprising:
- forming a base layer on a substrate, the base layer including an array of base electrode pads separated by insulating material;
- forming a first stacked electrode layer above the base layer;
- forming a first array of insulating pillars that support the first stacked electrode layer above the base layer; and
- forming an array of lens holes, the array of lens holes being aligned to the array of base electrode pads.
12. The method of claim 11 further comprising:
- forming a second stacked electrode layer above the first stacked electrode layer;
- forming a second array of insulating pillars that support the second stacked electrode layer above the first stacked electrode layer.
13. The method of claim 12 further comprising:
- forming a third stacked electrode layer above the second stacked electrode layer; and
- forming a third array of insulating pillars that support the third stacked electrode layer above the second stacked electrode layer.
14. The method of claim 13 further comprising:
- forming a fourth stacked electrode layer above the third stacked electrode layer; and
- forming a fourth array of insulating pillars that support the fourth stacked electrode layer above the third stacked electrode layer.
15. The method of claim 11, wherein forming the array of lens holes comprises:
- selectively etching a dielectric material while leaving the insulating pillars.
16. The method of claim 15, wherein the dielectric material comprises an oxide and the insulating pillars comprise a nitride or an oxynitride.
17. The method of claim 11 further comprising:
- depositing a conformal coating over surfaces of the electrodes and insulating pillars.
18. The method of claim 17, wherein depositing the conformal coating comprises atomic layer deposition of molybdenum and alumina
19. A device for dynamically patterning an electron beam, the device comprising:
- a base layer on a substrate, the base layer including an array of base electrode pads to which individually-controllable voltages are applied;
- an insulating border surrounding each base electrode pads so as to electrically isolate the base electrode pads from each other;
- an array of lens holes aligned with the array of base electrode pads;
- a plurality of stacked electrode layers, each stacked electrode layer having an array of openings aligned with the array of lens holes; and
- a plurality of layers of insulating pillars, each layer of insulating pillars supporting one stacked electrode layer.
20. The device of claim 19, further comprising:
- open spaces between each pair of adjacent lens holes.
Type: Application
Filed: Jun 5, 2014
Publication Date: Nov 26, 2015
Applicant: KLA-Tencor Corporation (Milpitas, CA)
Inventors: Alan D. BRODIE (Palo Alto, CA), Yehiel GOTKIS (Belmont, CA), Allen CARROLL (San Jose, CA), Leonid BARANOV (Sunnyvale, CA)
Application Number: 14/296,960