Thin film semiconductor device with oxide film on insulating layer

• US 4,984,033 A
• Filed: 12/21/1988
• Issued: 01/08/1991
• Est. Priority Date: 04/02/1986
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Ishizu, Akira, Inoue, Yasuo, Nishimura, Tadashi
• Primary Examiner(s): Mintel, William
• Application Number:
  US07/287,146
• Time in Patent Office: 748 Days
• Field of Search: 357/17, 357/30 I, 357/30 H, 357/30 K, 357/30 L, 357/30 G, 357/23.7, 357/59 G, 357/2, 350/338, 350/336, 350/339 R, 350/342
• US Class Current: 257/98
• CPC Class Codes: H01L 21/0242 Crystalline insulating materials
• CPC Class Codes: H01L 21/02491 Conductive materials
• CPC Class Codes: H01L 21/02532 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 21/02639 Preparation of substrate for selective deposition
• CPC Class Codes: H01L 27/1214 comprising a plurality of TFTs formed on a non-semiconducting substrate, e.g. driving circuits for AMLCDs
• CPC Class Codes: H01L 27/1259 Multistep manufacturing methods
• CPC Class Codes: H01L 29/66757 Lateral single gate single channel transistors with non-inverted structure, i.e. the channel layer is formed before the gate
• CPC Class Codes: H01L 29/78633 with a light shield
• CPC Class Codes: Y10S 148/091 Laser beam processing of fets
• CPC Class Codes: Y10S 148/093 Laser beam treatment in general

Abstract

A thin film semiconductor device is formed by preparing a substrate, forming a pattern of metal thin film on the substrate, forming an insulating layer on the metal thin film, and forming a pattern of a semiconductor thin film active layer over the pattern of the metal thin film by laser CVD.

Claims

1. A thin film semiconductor device, the thin film semiconductor device having a gate, gate oxide, and source, gate, and drain electrodes, said device comprising:

a transparent substrate;

a light shielding layer formed on the substrate;

an insulating layer formed over said light shielding layer;

a semiconductor active layer formed over said insulating layer;

a gate oxide film formed on the semiconductor active layer;

a gate formed on the gate oxide film;

an oxide film formed directly on the insulating layer, the semiconductor active layer and the gate; and

a source electrode and a drain electrode formed on the oxide film and the semiconductor active layer, and a gate electrode formed on the oxide film and the gate.

2. A device according to claim 1, wherein said light shielding layer is formed of a metal film.

3. A device according to claim 1, wherein said insulating layer is formed of silicon oxide.

4. A device according to claim 1, wherein said semiconductor active layer is formed of crystallized silicon.

5. A device according to claim 1, wherein said light shielding layer has a certain pattern;

and said semiconductor active layer has a pattern identical to said certain pattern of the light shielding layer.

6. A device according to claim 5, wherein said semiconductor active layer is formed selectively over said light shielding layer by a laser CVD process.

7. A device according to claim 6, wherein, during the laser CVD process for forming the semiconductor active layer, a laser beam is scanned unselectively across the surface of the substrate.

8. A device according to claim 1, wherein the light shielding layer is formed of chrome.

9. A device according to claim 6, wherein the laser CVD process is conducted in an atmosphere of silane.

10. A device according to claim 6, wherein the laser CVD process uses an argon laser.

11. A device according to claim 6, wherein the laser CVD process is conducted in an atmosphere of silane.