Electrophotographic patterning of thin film circuits
First Claim
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1. A method for producing thin film transistors, comprising the steps of:
- electrophotographically printing a negative source-drain pattern on a clean substrate in the form of toner, thereby initiating the formation of a stack;
post-baking the toner;
depositing an electrical conductor on the above;
dissolving the toner with a solvent to lift off the portion of the conductor deposited on the toner;
depositing amorphous silicon on top of the stack;
depositing gate insulator on the top and passivation on the bottom of the stack;
depositing photoresist on top of the stack;
applying a negative gate toner pattern to the top of the stack;
exposing the photoresist to ultraviolet light;
developing the photoresist;
depositing an electrical conductor on the top of the stack;
lifting-off the conductor deposited over the toner and photoresist by exposing the stack to a stripper;
applying photoresist to the top of the stack;
applying to the top of the stack a positive toner pattern for contact hole opening and transistor separation;
exposing the photoresist to ultraviolet light;
developing the photoresist;
etching the exposed gate insulator and amorphous silicon; and
stripping the photoresist and toner to obtain the desired thin film transistors.
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Abstract
Amorphous silicon thin-film transistors on glass foil are made using exclusively electrophotographic printing for pattern formation, contact hole opening, and device isolation. Toner etch masks are applied by feeding the glass substrate through a laser printer or photocopier, or from laser-printed patterns on transfer paper. This all-printed patterning is a low-cost, large-area circuit processing technology, suitable for producing backplanes for active matrix liquid crystal displays.
182 Citations
34 Claims
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1. A method for producing thin film transistors, comprising the steps of:
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electrophotographically printing a negative source-drain pattern on a clean substrate in the form of toner, thereby initiating the formation of a stack; post-baking the toner; depositing an electrical conductor on the above; dissolving the toner with a solvent to lift off the portion of the conductor deposited on the toner; depositing amorphous silicon on top of the stack; depositing gate insulator on the top and passivation on the bottom of the stack; depositing photoresist on top of the stack; applying a negative gate toner pattern to the top of the stack; exposing the photoresist to ultraviolet light; developing the photoresist; depositing an electrical conductor on the top of the stack; lifting-off the conductor deposited over the toner and photoresist by exposing the stack to a stripper; applying photoresist to the top of the stack; applying to the top of the stack a positive toner pattern for contact hole opening and transistor separation; exposing the photoresist to ultraviolet light; developing the photoresist; etching the exposed gate insulator and amorphous silicon; and stripping the photoresist and toner to obtain the desired thin film transistors. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 19, 27, 28)
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17. A method for patterning a sheet material comprising the steps of:
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applying dry toner to said sheet material in a configuration forming a toner etch having a desired pattern; exposing said sheet material with said toner pattern to an etchant for a predetermined period of timer; and removing said toner from said patterned sheet material. - View Dependent Claims (18, 20, 21, 22, 23, 24, 25, 26, 29, 30, 31, 32, 33, 34)
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Specification