# US 7,608,383 B2 · UV radiation blocking protective layers compatible with thick film pastes

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- Number: US 7,608,383 B2
- Document ID: US7608383B2
- Status: Granted
- Kind: B2
- Application number: 12/175,633
- Filed: 2008-07-18
- Published: 2008-11-06
- Granted: 2009-10-27
- Earliest claimed: 2005-02-03
- Assignees: E.I. du Pont de Nemours and Company
- Inventors: Young H. Kim; Gann Xu
- Web page: https://patentgrep.com/patent/US7608383B2

## CPC

- G03F 7/039: Macromolecular compounds which are photodegradable, e.g. positive electron resists (G03F7/075 takes precedence; macromolecular quinonediazides G03F7/023)
- G03F 7/0035: {Multiple processes, e.g. applying a further resist layer on an already in a previously step, processed pattern or textured surface}
- G03F 7/0045: {with organic non-macromolecular light-sensitive compounds not otherwise provided for, e.g. dissolution inhibitors}
- G03F 7/0392: {the macromolecular compound being present in a chemically amplified positive photoresist composition}
- G03F 7/091: {characterised by antireflection means or light filtering or absorbing means, e.g. anti-halation, contrast enhancement}
- G03F 7/2022: {Multi-step exposure, e.g. hybrid; backside exposure; blanket exposure, e.g. for image reversal; edge exposure, e.g. for edge bead removal; corrective exposure}
- G03F 7/40: Treatment after imagewise removal, e.g. baking
- G03F 7/002: {using materials containing microcapsules; Preparing or processing such materials, e.g. by pressure; Devices or apparatus specially designed therefor}
- G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G)

## Abstract

This invention relates to novel compositions comprising a protective polymer layer and a UV blocking agent. This is used in the fabrication of electronic devices using thick film pastes. The present invention is also an electronic device fabrication process using the compositions. The protective polymer layer is fabricated from materials, which are insoluble after irradiation in the ester-type solvents contained in the thick film paste. By appropriate selection of protective film polymers, the protective film can be compatible with the thick film paste and can be further used to shield portions of the thick film paste from UV irradiation.

## Claims

### Claim 1

A process for fabricating an electronic device that comprises a substrate, comprising:
(a) forming a protective layer on a first side of the substrate from a composition that comprises;
(i) a UV blocking agent selected from the group consisting of nitro benzoic acid, methoxy benzoic acid, nitro naphthalic acid, methoxy naphthalic acid, cinnamic acid and its derivatives, anthracene sulfonic acid and its derivatives, and carbon nanotubes; and
(ii) a polymer in which at least 50 mole percent of the monomers in the polymer comprise one or more of the structures (i), (ii) and (iii) described as follows:
where R1 is hydrogen or lower alkyl; R2 is a lower alkyl; and R3 is hydrogen or a lower alkyl, where the definition of lower alkyl includes alkyl groups having 1 to 6 linear or cyclic carbon atoms;
where R1 is hydrogen or lower alkyl; R2 is a lower alkyl; and R3 and R4 are independently hydrogen or a lower alkyl, where the definition of lower alkyl includes alkyl groups having 1 to 6 carbon atoms and the joining of R1 and R2, or R1 and either R3 or R4, or R2 and either R3 or R4 to form a 5-, 6-, or 7-membered ring; and
where R1 is hydrogen or lower alkyl; R2 is a lower alkyl; and R3 and R4 are independently hydrogen or a lower alkyl; where the definition of lower alkyl includes alkyl groups having 1 to 6 carbon atoms and the joining of R1 and R2, or R1 and either R3 or R4, or R2 and either R3 or R4 to form a 5-, 6-, or 7-membered ring; and where n is 0 to 4;
(b) irradiating the protective layer through a mask;
(c) heating the device;
(d) contacting the protective layer with a developing solution to remove the portions of the protective layer composition exposed to radiation in step (b), and thereby form a patterned protective layer;
(e) irradiating the patterned protective layer;
(f) heating the device;
(g) applying to the patterned protective layer a paste composition;
(h) irradiating the device from a second side of the substrate to form a pattern in the paste composition; and
(i) contacting the paste composition and the patterned protective layer with a developing solution to remove (I) the portions of the paste composition not exposed to radiation in step (h), and (II) the patterned protective layer.

### Claim 2 (depends on 1)

A process according to claim 1 wherein the composition comprises a polymer in which at least 60 mole percent of the monomers in the polymer comprise one or more of the structures (A), (B) and (C).

### Claim 3 (depends on 1)

A process according to claim 1 wherein the composition comprises a copolymer.

### Claim 4 (depends on 1)

A process according to claim 1 wherein the composition comprises a polymer comprising, as a polymerized unit, a monomer having a hydrophilic group.

### Claim 5 (depends on 1)

A process according to claim 1 wherein the composition comprises a UV blocking agent in an amount of about 1 to about 20 wt % based on the weight of the polymer.

### Claim 6 (depends on 1)

A process according to claim 1 wherein the UV blocking agent is selected from the group consisting of 2 hydroxyl aryl benzotriazole and its derivatives.

### Claim 7 (depends on 1)

A process according to claim 1 wherein the UV blocking agent is selected from the group consisting of 2 hydroxy benzophenone and its derivatives.

### Claim 8 (depends on 1)

A process according to claim 1 wherein the thick film paste composition comprises silver or carbon nanotubes or both.

### Claim 9 (depends on 1)

A process according to claim 1 wherein the substrate is transparent.

### Claim 10 (depends on 1)

A process according to claim 1 wherein the UV blocking agent comprises 3,5 dimethoxy,4-hydroxy cinnamic acid.