# US 7,745,100 B2 · Polymers, methods of use thereof, and methods of decomposition thereof

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- Number: US 7,745,100 B2
- Document ID: US7745100B2
- Status: Granted
- Kind: B2
- Application number: 11/451,144
- Filed: 2006-06-12
- Published: 2007-02-08
- Granted: 2010-06-29
- Earliest claimed: 2003-10-16
- Assignees: Georgia Tech Research Corporation
- Inventors: Paul A. Kohl; SueAnn Bidstrup Allen; Xiaoqun Wu; Clifford Lee Henderson
- Web page: https://patentgrep.com/patent/US7745100B2

## CPC

- G03F 7/004: Photosensitive materials (G03F7/12, G03F7/14 take precedence)
- B81C 1/00103: {Structures having a predefined profile, e.g. sloped or rounded grooves}
- C08J 3/28: Treatment by wave energy or particle radiation
- G03F 7/40: Treatment after imagewise removal, e.g. baking
- B81B 2201/058: Microfluidics not provided for in B81B2201/051 - B81B2201/054
- B81B 2203/0338: Channels
- B81B 2203/0384: sloped profile
- B81C 2201/0108: Sacrificial polymer, ashing of organics
- C08K 5/0041: {Optical brightening agents, organic pigments}
- Y10T 428/24479: including variation in thickness
- 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)
- B81C: PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS (making microcapsules or microballoons B01J13/02; processes or apparatus specially adapted for the manufacture or treatment of piezoelectric, electrostrictive or magnetostrictive elements per se H10N30/01)
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- B81B: MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES (piezoelectric, electrostrictive or magnetostrictive elements per se H10N30/00, H10N35/00)
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

Polymers, methods of use thereof, and methods of decomposition thereof, are provided. One exemplary polymer, among others, includes, a photodefinable polymer having a sacrificial polymer and a photoinitiator.

## Claims

### Claim 1

A method for fabricating a structure, comprising:
disposing a photodefinable polymer onto a surface, wherein the photodefinable polymer includes a sacrificial polymer and a photoinitiator selected from a negative tone photoinitiator and a positive tone photoinitiator;
providing a gray scale photomask, wherein the gray scale photomask encodes optical density profiles defining three-dimensional structures having areas with non-rectangular cross-sections;
exposing the photodefinable polymer through the gray scale photomask to optical energy; and
removing portions of the photodefinable polymer to form the three-dimensional structures having areas with non-rectangular cross-sections;
disposing an overcoat layer onto the three-dimensional structures having areas with non-rectangular cross-sections; and
decomposing the photodefinable polymer, thermally, to form three-dimensional air-regions having non-rectangular cross-sections.

### Claim 2 (depends on 1)

The method of claim 1, wherein removing includes:
removing unexposed portions of the photodefinable polymer to form the three-dimensional structure.

### Claim 3 (depends on 1)

The method of claim 1, wherein removing includes:
removing exposed portions of the photodefinable polymer to form the three-dimensional structure.

### Claim 4 (depends on 1)

The method of claim 1, wherein decomposing includes:
maintaining a constant rate of decomposition as a function of time.

### Claim 5 (depends on 1)

The method of claim 1, wherein decomposing includes:
maintaining a constant rate of mass loss of the photodefinable polymer.

### Claim 6 (depends on 1)

The method of claim 1, wherein decomposing includes:
heating the structure according to the thermal decomposition profile expression
T
=
E
a
R
⁡
[
ln
⁢
A
⁡
(
1
-
rt
)
n
r
]
-
1
where R is the universal gas constant, t is time, n is the overall order of decomposition reaction, r is the desired polymer decomposition rate, A is the Arrhenius pre-exponential factor, and Ea is the activation energy of the decomposition reaction.

### Claim 7 (depends on 1)

The method of claim 1, wherein said areas with non-rectangular cross-sections of said three-dimensional structure are tapered cross-sections.

### Claim 8 (depends on 1)

The method of claim 1, wherein said three-dimensional air-regions having non-rectangular cross-sections are further defined by tapered corner regions.