Thin film semiconductor device

Claim 2

A process for fabricating a thin film semicon­ductor device on a transparent substrate, wherein a photoresist is exposed with photolithographic­ally active light which passes through serial layers at least one of which has a light absorbing property comprising: depositing at least one thin film, light-permeable layer (20) which has a light absorbing property, depositing a transparent insulating layer (16, 18, 25) on each side of each of said light absorbing layers having a refractive index different from said substrate and a thickness dimension chosen so the wave components of said lithographically active light reflected at the interfaces of the completed structure interfere destructively to minimize the reflectance and to maximize the transmission of said lithographically active light.

Claim 3

A process for fabricating a thin film semicon­ductor device (10) on a transparent substrate (14), wherein a photoresist is exposed with lithographically active light that passes through serial layers of the semiconductor device at least one of which has a light absorbing property comprising: depositing a gate electrode (12) on said trans­parent substrate (14), depositing at least one transparent insulating layer (16, 18) over said substrate (14) and said gate (12) electrode with a refractive index different from said substrate and with a thickness dimension chosen so the wave components of said lithographically active light reflected at the interfaces of the completed structure interfere destructively to minimize the reflectance and to maximize the transmission of said lithographically active light, depositing a thin light-permeable semiconductor layer (20) over said transparent insulating layer (16, 18) which has a light absorbing property, applying a photoresist (30) over said semicon­ductor layer (20), and exposing said photoresist layer (30) by trans­mitted photolithographically active light through said substrate, said transparent insulating layers (16, 18) and said semiconductor layers (20).

Claim 4

A process for fabricating a thin film semicon­ductor device (10) on a transparent substrate (14), wherein a photoresist is exposed with lithographically active light that passes through serial layers of the semiconductor device at least one of which has a light absorbing property comprising: depositing a gate electrode (12) on said trans­parent substrate (14), depositing at least one transparent insulating layer (16, 18) over said substrate (14) and said gate (12) electrode with a refractive index different from said substrate and with a thickness dimension chosen so the wave components of said lithographically active light reflected at the interfaces of the completed structure interfere destructively to minimize the reflectance and to maximize the transmission of said lithographically active light, depositing a thin light-permeable semiconductor layer (20) over said transparent insulating layer (16, 18) which has a light absorbing property, applying a photoresist (30) over said semicon­ductor layer (20), and exposing said photoresist layer (30) by trans­mitted photolithographically active light through said substrate, said transparent insulating layers (16, 18) and said semiconductor layers (20).

Claim 5

A process for fabricating a thin film semicon­ductor device as recited in claim 2 which further comprises: depositing at least one transparent insulating layer (25) over said semiconductor layer (20) having a refractive index different from said photoresist (30) and with a thickness dimension chosen so the wave components of said litho­graphically active light reflected at the inter­faces of the completed structure interfere destructively to minimize the reflectance and to maximize the transmission of said lithographically active light.

Claim 6

A process for fabricating a thin film semicon­ductor device as recited in claim 2 or 3 comprising: depositing at least one transparent insulating layer (16, 18, 25) with a thickness dimension approximately equal to an odd multiple of one fourth of the wavelength of said lithographically active light divided by the refractive index of said layer to maximize the transmission of said lithographically active light.

Claim 7

A process for fabricating a thin film semicon­ductor device as recited in one of the preceding claims 2 to 4 wherein said transparent insulating layers are chosen from the group consisting of SiO₂ and Si₃N₄.

Claim 8

A process for fabricating a thin film semicon­ductor device as recited in one of the preceding claims 2 to 5 wherein said semiconductor layer is amorphous silicon.

Claim 9

A process for fabricating a thin film semicon­ductor device as recited in one of the preceding claims 2 to 6 wherein the substrate comprises glass.

Claim 10

A thin film transistor (10) comprising: a transparent substrate (14), preferably comprising glass, a gate electrode (12) formed on said substrate, at least one transparent insulating layer (16, 18), preferably chosen from the group consisting of SiO₂ and Si₃N₄, formed on said substrate (14) and gate electrode (12) having a refractive index different than said substrate and a thickness dimension chosen so the wave components of said lithographically active light reflected at the interfaces of the completed structure interfere destructively to minimize the reflectance and to maximize the transmission of said lithographically active light, an amorphous semiconductor layer (20), preferably amorphous silicon, formed on said transparent insulating layer (16, 18), and source and drain electrodes (22, 24) disposed on said semiconductor layer (20) and self-aligned with said gate electrode (12).

Claim 11

A thin film transistor (10) comprising: a transparent substrate (14), preferably comprising glass, a gate electrode (12) formed on said substrate, at least one transparent insulating layer (16, 18), preferably chosen from the group consisting of SiO₂ and Si₃N₄, formed on said substrate (14) and gate electrode (12) having a refractive index different than said substrate and a thickness dimension chosen so the wave components of said lithographically active light reflected at the interfaces of the completed structure interfere destructively to minimize the reflectance and to maximize the transmission of said lithographically active light, an amorphous semiconductor layer (20), preferably amorphous silicon, formed on said transparent insulating layer (16, 18), and source and drain electrodes (22, 24) disposed on said semiconductor layer (20) and self-aligned with said gate electrode (12).

Claim 12

A thin film transistor as recited in claim 8 which further comprises: a second amorphous semiconductor layer (26) disposed on said amorphous semiconductor layer (20) between said source (22) and drain (24) electrodes with a thickness dimension chosen so the wave components of said lithographically active light reflected at the interfaces of the completed structure interfere destructively to minimize the reflectance and to maximize the transmission of said lithographically active light.

Claim 13

A thin film transistor as recited in claim 8 or 9 which further comprises: at least one transparent insulating layer (25) disposed on said amorphous semiconductor layer (20) and between said source (22) and drain (24) electrodes having a refractive index different than said photoresist and a thickness dimension chosen so the wave components of said lithographically active light reflected at the interfaces of the completed structure interfere destructively to minimize the reflectance and to maximize the transmission of said lithographically active light.