Method of forming topcoat for patterning
Disclosed is a method for the fabrication of polymeric topcoat via initiated chemical vapor deposition (iCVD) or photoinitiated chemical vapor deposition (piCVD) in conjunction with directed self-assembly (DSA) of block copolymers to generate high resolution patterns. A topcoat deposited by iCVD or piCVD allows for conformal, ultra-thin, uniform, pinhole-free coatings. iCVD or piCVD topcoat enables the use of a diversity of block copolymer (BCP) materials for DSA and facilitates the direct and seamless integration of the topcoats for a pattern transfer process.
1. A method of forming a topcoat on a block copolymer film, comprising the steps of:
(a) providing a substrate;
(b) forming a lithographically defined physical or chemical pattern on the substrate;
(c) coating the substrate with the block copolymer film;
(d) heating or irradiating an initiator, thereby producing a gaseous free radical initiator; and
(e) contacting the block copolymer film with the gaseous free radical initiator and a gaseous monomer, thereby forming a cross-linked topcoat;
wherein the topcoat forms an interface displaying equal preference for both components of a block copolymer; and the thickness of the topcoat is less than about 10 nm.
2. The method of claim 1 , wherein the initiator is selected from the group consisting of a peroxide, an aryl ketone, and an azo compound.
3. The method of claim 1 , wherein the initiator is triethylamine.
4. The method of claim 1 , wherein the initiator is an aryl ketone.
5. The method of claim 1 , wherein the initiator is an azo compound selected from the group consisting of 4,4′-Azobis(4-cyanovaleric acid), 4,4′-Azobis(4-cyanovaleric acid), 1,1′-Azobis(cyclohexanecarbonitrile), 2,2′-Azobis(2-methylpropionamidine) dihydrochloride, 2,2′-Azobis(2-methylpropionitrile), and 2,2′-Azobis(2-methylpropionitrile).
6. The method of claim 1 , wherein the initiator is a peroxide selected from the group consisting of tert-butyl hydroperoxide, tert-butyl peracetate, cumene hydroperoxide, dicumyl peroxide, benzoyl peroxide, tert-amyl peroxide, tert-butyl peroxide, and tert-butyl peroxybenzoate.
7. The method of claim 1 , wherein the monomer is at least one of an acrylate, a siloxane, a silazane, and a vinyl compound.
8. The method of claim 7 , wherein the monomer is selected from the group consisting of methyl methacrylate, butyl acrylate, glycidal methacrylate, vinyl pyridine, divinylbenzene, stylene, trivinlytrimethylcyclotrisiloxane, tetravinyltetramethylcyclotetrasiloxane, trivinyltrimethylcyclotrisilazane, and tetravinyltetramethylcyclotetrasilazane.
9. The method of claim 1 , wherein the substrate is selected from the group consisting of silicon wafer, glass slide, quartz, polyurethane, polyorthoester, polyacrylonitrile, polyphenazine, polytetrafluoroethylene, polyamide resin, low density polyethylene (LDPE), high density polyethylene (HDPE), expanded polytetrafluoroethylene (e-PTFE), polyimide (PI), and polypropylene (PP).
10. The method of claim 1 , wherein the substrate is a silicon wafer.
11. The method of claim 1 , wherein the physical or chemical pattern is formed by photolithography or electron-beam lithography.
12. The method of claim 1 , wherein the block copolymer is selected from the group consisting of poly(styrene-block-methacrylate), poly(2-vinylpyridine)-block-polystyrene-block-poly(2-vinylpyridine), poly(styrene-block-ethylene oxide), and poly(styrene-block-dimethylsiloxane).
13. The method of claim 1 , wherein forming the topcoat comprises initiated chemical vapor deposition (iCVD) or photoinitiated chemical vapor deposition (piCVD) of the topcoat in a deposition chamber.
14. The method of claim 1 , wherein the topcoat is pinhole-free.
15. A method of forming a pattern on an article, comprising the steps of:
(a) providing an article, comprising a substrate, and a coating on the substrate, wherein the coating comprises a block copolymer film and a topcoat on the block copolymer formed by a method comprising the steps of:
(i) providing a substrate;
(ii) forming a lithographically defined physical or chemical pattern on the substrate;
(iii) coating the substrate with the block copolymer film;
(iv) heating or irradiating an initiator, thereby producing a gaseous free radical initiator;
(v) contacting the block copolymer film with the gaseous free radical initiator and a gaseous monomer, thereby forming a cross-linked topcoat;
wherein the topcoat forms an interface displaying equal preference for both components of a block copolymer; and the thickness of the topcoat is less than about 10 nm,
(b) coating the article with a resist;
(c) forming a resist pattern using lithography to form a mask;
(d) removing the topcoat from the masked article by a first reactive ion etching;
(e) removing the remaining polymer of the article by a second reactive ion etching; and
(f) etching the substrate by a third reactive ion etching,
thereby forming the pattern on the article.