HYBRID-GUIDED BLOCK COPOLYMER ASSEMBLY
A method for nano-patterning includes imprinting features in a resist with an imprint mold to form one or more topographic surface patterns on the imprinted resist. A a block copolymer (“BCP”) material is deposited on the imprinted resist, wherein a molecular dimension L0 of the BCP material correlates by an integer multiple to a spacing dimension of the one or more topographic surface patterns on the imprinted resist. The deposited BCP is annealed and at least a portion of the annealed BCP is removed, forming a template having discrete domains.
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This disclosure relates generally to the use of block copolymers for high density patterning.BACKGROUND
Bit pattern media (BPM) has been extensively explored by the magnetic recording industry as one of several key solutions to expand perpendicular magnetic recording (PMR) technology in high density disk drives (HDDs). A typical BPM media consists of two repeating zones—a data zone and a servo zone. Data zones consist of homogenous dots to store data bits. Servo zones consist of dots with various patterns to describe a location and address of information in the data zone. In the servo zone, dots need be arranged into various pattern and spacings to encode information such as head position, timing, and tracking following information for a respective data zone.
The storage capacity of BPM is dependent upon the density of the magnetic islands, or “bits” on the media substrate surface. Current processes for achieving high density patterned media include imprint mold fabrication, nano-imprinting and pattern transfer into magnetic dots, and the like.
Self-assembling block copolymer (BCP) enables high-density lithographic bit patterning capability and is a promising material for BPM template fabrication. Directed self-assembly combines ‘top-down’ lithography (pre-registered pattern) and ‘bottom-up’ self-assembling materials like block copolymers. Directed self-assembly may generate ultra-high density homogenous patterns.SUMMARY
In an embodiment, a method for nan-opatterning includes imprinting features in a resist on a substrate with an imprint mold to form one or more topographic surface patterns on the resulting imprinted resist. A a block copolymer (“BCP”) material is deposited on the resulting imprinted resist, wherein a molecular dimension L0 of the BCP material correlates by an integer multiple to a spacing dimension of the one or more topographic surface patterns on the resulting imprinted resist. The deposited BCP is annealed and at least a portion of the annealed BCP is removed, forming a template having discrete domains.
Embodiments of this disclosure are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements, and in which:
A high density disk drive (HDD) 100 is a medium that has different regions besides the regions used for storing data (data zones 110). For example, as shown in
Referring back to
In this method, block copolymer self-assembly in the data zone 110 is guided with pre-patterned dots created with a template. The pre-patterned dots may create chemical/topographical contrast to anchor self-assembly location of polymer blocks and achieve the long range ordering for block copolymer assembly in the data zone.
In an embodiment, a method of self-assembling density multiplied block copolymers (BCP) structures in the data zone 110 includes coating a substrate with an imprint resist. A composition of the BCP is chosen to have a selected molecular weight and natural lattice constant L0, wherein the BCP composition includes a first polymer block (A) and a second polymer block (B). The resist is imprinted with an imprint template having imprint features in the data zone 110 spaced at a pitch distance Ls based on the selected composition of the BCP and satisfying the equation Ls=n×L0 , where n is an integer density multiplication factor=0, 1, 2, 3, etc. The imprint resist is cured, and additional process may be performed to prepare the substrate and imprint resist for coating with the BCP. The BCP is annealed to laterally segregate the BCP into self-assembled structures of the first polymer block A surrounded by the second polymer block B, the structures having a lateral spatial pitch of L0. Thus, the linear density of block A structures (e.g., pillars, spheres, and the like, depending on the choice of polymers) is n times the linear density of the template features imprinted in the resist. In a template having hexagonal close-packed (hcp) arrangement of the imprinted features, the areal density of self-assembled block A structures is n2 times that of the template.
In all embodiments described herein, annealing may be a thermal, chemical (including solvent), irradiative process, or the like.
In the servo zone 120, BCP self-assembly is mainly guided by pre-defined line patterns provided by the template. By controlling a thickness of the BCP spin-coated over the line patterns, the BCP assembles in grooves between the line ridges. By pre-defining a shape and spacing of the lines, self-assembly of BDP may be confined to servo zone formation.
Disclosed herein is a system and processes for incorporating hybrid-guided growth of BCPs in the BPM manufacturing process. Specifically, the processes described herein illustrate how BCPs may be used to form hybrid nano-patterns on a bit pattern media (BPM) substrate. An imprint technique may be used to guide the growth of BCP structures. As a result, embodiments of this disclosure may avoid the pattern defects and chemo-toxicity associated with e-beam lithography techniques. One having ordinary skill in the art will appreciate that different BCPs may be used, such as a cylindrical, lamellar or spherical BCP. In an embodiment, the BCP may have organic components, inorganic components, or a combination of organic and inorganic components. BCP selection may be based upon the size, molecular weight, or other features of the BCP constituent units that are described further below. While specific BCPs are selected for the particular application, the process disclosed herein is a generalized process. Other variations are discussed further below and are illustrated in the figures.
In the following examples, the BCP is comprised of at least two constituent units, structural units or “blocks”, herein termed “ block A” and “block B”, or “A block” and “B block”. The following examples describe removal of the A block; however, a person having ordinary skill in the art will appreciate that in an embodiment, the B block may be removed instead of the A block. Use of the singular “block A” or “block B” also includes use of plural “blocks A” and “blocks B.” As described above, block A and block B may be organic or inorganic, or block A may be organic, and block B inorganic, or block A may be inorganic and block B organic. In an embodiment, block A or block B comprises an organic polystyrene-block-polymethylmethacrylate (PS-b-PMMA), polystyrene-block-poly2-vinylpyridine, polystyrene-block-poly4-vinylpyridine, polystyrene-block-polyethyleneoxide, polystyrene-block-polyisoprene or polystyrene-block-butadiene. In an embodiment, block A or block B comprises an inorganic polystyrene-block-polydimethylsiloxane (PS-b-PDMS or, more compactly, PS-PDMS) or polystyrene-block-polyferrocenylsilane. A person having ordinary skill in the art will appreciate that the processes described herein may be varied accordingly depending upon the chemical characteristics of the BCP blocks. One will appreciate that selection of the BCP may also depend upon the target pattern to be created using the BCP. For example, the topographical pattern left by the imprinting described below may determine the selection of the BCP, since certain BCP blocks may correlate better with certain topographical pattern features and pattern dimensions. For example, PS-PDMS may be utilized to form spherical BCP structures.
In an aspect of the disclosure,
In the servo zone 120, BCP self-assembly is mainly guided by pre-defined lines 320 provided by the template. By controlling a thickness of the BCP coated over the lines 320, the BCP is not able to self-segregate during annealing in the space over the lines 320, but only assembles in grooves between the lines 320. By pre-defining a shape and spacing of the lines, self-assembly of BDP will be confined to desired servo zone 120 formation.
In the servo zone 120, the height of the ridge lines 330 and the thickness of the BCP coating over the lines 320 may be chosen to be too thin to permit formation of block A polymer on top of the lines 320. Instead, lateral segregation of A and B polymers may be restricted to the space between the ridge lines 320 according to Ls′=n′×L0, where n′ is an integer density multiplication factor=0, 1, 2, 3, etc. In the example shown, n′=2, but the spacing may be larger to accommodate n′ rows of block A polymer dots.
The remaining A polymer (e.g., spherical polymer) and B polymer and resist masked by the A polymer may serve as a mask. Referring to
A plan view of the template 316 is shown in
In another aspect of the disclosure,
As shown in
In an aspect of the disclosure, the PS and lines 420 (of resist) coating the substrate 415 may be thinned by an appropriate removal technique (e.g., dry etching) to expose the substrate 415 beneath the holes 440. The entire etched substrate 415, including the remaining resist and PS, may be coated with a masking layer, such as Cr, and the remaining resist and PS removed, leaving Cr dots where PMMA columns previously stood. The substrate 415 may be an etch processible material like quartz, silicon, or the like, which can be etched with the Cr dots serving as a mask. The etching then forms a high density template, as shown in
As previously mentioned, the processes illustrated in
The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more. A phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover: a; b; c; a and b; a and c; b and c; and a, b and c. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. §112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.”
1. A method comprising:
- imprinting features in a resist with an imprint mold to form one or more topographic surface patterns on the resulting imprinted resist;
- depositing a block copolymer (“BCP”) material on the imprinted resist, wherein a molecular dimension L0 of the BCP material correlates by an integer multiple to a spacing dimension of the one or more topographic surface pattern on the resulting imprinted resist;
- annealing the deposited BCP; and
- removing at least a portion of the annealed BCP to form a template having discrete domains is formed.
2. The method of claim 1, further comprising treating imprinted resist the imprinted resist to form a chemical surface pattern.
3. The method of claim 2, wherein the treating of the imprinted resist comprises exposing the imprinted resist to oxygen plasma.
4. The method of claim 1, further comprising transferring the imprinted resist onto the substrate.
5. The method of claim 1, wherein the imprinting of the resist comprises applying a UV imprinting process.
6. The method of claim 1, wherein the imprinting of the resist comprises applying a thermal imprinting process.
7. The method of claim 1, wherein the imprinting of the resist comprises applying an inking imprinting process.
8. The method of claim 1, wherein the BCP material is selected from the group consisting of polystyrene-block-polymethylmethacrylate (PS-b-PMMA), polystyrene-block-poly2-vinylpyridine, polystyrene-block-poly4-vinylpyridine, polystyrene-block-polyethyleneoxide, polystyrene-block-polyisoprene, polystyrene-block-butadiene, and mixtures thereof.
9. The method of claim 1, wherein the BCP material is selected from the group of BCP materials consisting of polystyrene-block-polydimethylsiloxane (PS-b-PDMS), polystyrene-block-polyferrocenylsilane, and mixtures thereof.
10. The method of claim 1, wherein the removing of at least a portion of the annealed BCP forms the template having pitch of 5-100 nm.
11. The method of claim 1, wherein the removing of at least a portion of the annealed BCP forms the template having a bit density of at least 1 Tdpsi.
12. The method of claim 1, wherein the removing of at least a portion of the annealed BCP forms the template having at least one of a long-ranged laterally ordered 1D array and a long-ranged laterally ordered 2D array.
13. The method of claim, wherein the one or more topographical surfaces comprises differing heights.
14. The method of claim 1, further comprising using the template to pattern a second resist.
15. The method of claim 1, further comprising using the template as a mask.
16. An apparatus manufactured by the method of claim 1.
Filed: Jan 31, 2011
Publication Date: Aug 2, 2012
Applicant: SEAGATE TECHNOLOGY LLC (SCOTTS VALLEY, CA)
Inventors: Yuan Xu (Fremont, CA), Kim Lee (Fremont, CA), Wei Hu (Chandler, AZ), Koichi Wago (Sunnyvale, CA), David Shiao-Min Kuo (Palo Alto, CA)
Application Number: 13/018,416
International Classification: B32B 3/00 (20060101); B05D 1/36 (20060101); B05D 3/06 (20060101); B05D 3/12 (20060101); B05D 3/00 (20060101); B05D 3/10 (20060101);