Title: Crystallization and doping of amorphous silicon on low temperature plastic

Abstract

A method or process of crystallizing and doping amorphous silicon (a-Si) on a low-temperature plastic substrate using a short pulsed high energy source in a selected environment, without heat propagation and build-up in the substrate. The pulsed energy processing of the a-Si in a selected environment, such as BF3 and PF5, will form a doped micro-crystalline or poly-crystalline silicon (pc-Si) region or junction point with improved mobilities, lifetimes and drift and diffusion lengths and with reduced resistivity. The advantage of this method or process is that it provides for high energy materials processing on low cost, low temperature, transparent plastic substrates. Using pulsed laser processing a high (>900.degree. C.), localized processing temperature can be achieved in thin films, with little accompanying temperature rise in the substrate, since substrate temperatures do not exceed 180.degree. C. for more than a few microseconds. This method enables use of plastics incapable of withstanding sustained processing temperatures (higher than 180.degree. C.) but which are much lower cost, have high tolerance to ultraviolet light, have high strength and good transparency, compared to higher temperature plastics such as polyimide.

Inventors:

Kaschmitter, James L ^[1]; Truher, Joel B ^[2]; Weiner, Kurt H ^[3]; Sigmon, Thomas W ^[4]

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+ Show Inventor Affiliations

1. Pleasanton, CA
2. Palo Alto, CA
3. Campbell, CA
4. Beaverton, OR

Issue Date:

1994-01-01

Research Org.:

Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

OSTI Identifier:

869492

Patent Number(s):

5346850

Assignee:

Regents of University of California (Oakland, CA)

Patent Classifications (CPCs):

C - CHEMISTRY C30 - CRYSTAL GROWTH C30B - SINGLE-CRYSTAL-GROWTH

H - ELECTRICITY H01 - BASIC ELECTRIC ELEMENTS H01L - SEMICONDUCTOR DEVICES

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C - CHEMISTRY C30 - CRYSTAL GROWTH C30B - SINGLE-CRYSTAL-GROWTH

C30B1/023 - {from solids with amorphous structure}
C30B29/06 - Silicon

H - ELECTRICITY H01 - BASIC ELECTRIC ELEMENTS H01L - SEMICONDUCTOR DEVICES

H01L21/02422 - {Non-crystalline insulating materials, e.g. glass, polymers}
H01L21/02488 - {Insulating materials}
H01L21/02532 - {Silicon, silicon germanium, germanium}
H01L21/02595 - {polycrystalline}
H01L21/02667 - {Crystallisation or recrystallisation of non-monocrystalline semiconductor materials, e.g. regrowth}
H01L21/02686 - {Pulsed laser beam}
H01L21/02689 - {using particle beams}
H01L21/32155 - {Doping polycristalline - or amorphous silicon layers}
H01L29/78603 - {characterised by the insulating substrate or support

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DOE Contract Number:  

W-7405-ENG-48

Resource Type:

Patent

Country of Publication:

United States

Language:

English

Subject:

crystallization; doping; amorphous; silicon; temperature; plastic; method; process; crystallizing; a-si; low-temperature; substrate; pulsed; energy; source; selected; environment; heat; propagation; build-up; processing; bf3; pf5; form; doped; micro-crystalline; poly-crystalline; pc-si; region; junction; improved; mobilities; lifetimes; drift; diffusion; lengths; reduced; resistivity; advantage; provides; materials; cost; transparent; substrates; laser; 900; degree; localized; achieved; films; accompanying; rise; temperatures; exceed; 180; microseconds; enables; plastics; incapable; withstanding; sustained; tolerance; ultraviolet; light; strength; transparency; compared; polyimide; pulsed energy; plastic substrate; method enables; diffusion length; ultraviolet light; amorphous silicon; energy source; pulsed laser; crystalline silicon; processing temperatures; substrate temperature; plastic substrates; substrate temperatures; laser processing; processing temperature; rate temperature; temperature rise; temperature plastic; energy processing; violet light; low-temperature plastic; /438/