Semiconductor device and method of manufacturing the same

• US 20060081931A1
• Filed: 10/31/2005
• Published: 04/20/2006
• Est. Priority Date: 11/09/1998
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Adachi, Hiroki, Yamazaki, Shunpei
• Granted Patent: US 7,923,779 B2
• Time in Patent Office: Days
• US Class Current: 257/347
• CPC Class Codes: H01L 2029/7863 with an LDD consisting of more than one lightly doped zone or having a non-homogeneous dopant distribution, e.g. graded LDD
• CPC Class Codes: H01L 27/124 with a particular composition, shape or layout of the wiring layers specially adapted to the circuit arrangement, e.g. scanning lines in LCD pixel circuits wiring structures per se H01L23/52
• CPC Class Codes: H01L 29/42384 for thin film field effect transistors, e.g. characterised by the thickness or the shape of the insulator or the dimensions, the shape or the lay-out of the conductor
• CPC Class Codes: H01L 29/4908 for thin film semiconductor, e.g. gate of TFT
• CPC Class Codes: H01L 29/6675 Amorphous silicon or polysilicon transistors
• 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 29/78621 with LDD structure or an extension or an offset region or characterised by the doping profile
• CPC Class Codes: H01L 29/78627 with a significant overlap between the lightly doped drain and the gate electrode, e.g. GOLDD

Abstract

The present invention relates to a semiconductor device including a circuit composed of thin film transistors having a novel GOLD (Gate-Overlapped LDD (Lightly Doped Drain)) structure. The thin film transistor comprises a first gate electrode and a second electrode being in contact with the first gate electrode and a gate insulating film. Further, the LDD is formed by using the first gate electrode as a mask, and source and drain regions are formed by using the second gate electrode as the mask. Then, the LDD overlapping with the second gate electrode is formed. This structure provides the thin film transistor with high reliability.

Claims

1-67. -67. (canceled)

68. A semiconductor element having a top gate type LDD structure located on a substrate, comprising:

a lower gate electrode;

an upper gate electrode, at least a side thereof on the source electrode side and the drain electrode side protruding from said lower gate electrode, and formed in close contact with said lower gate electrode; and

a semiconductor section having a channel area directly below said upper gate electrode and said lower gate electrode, an LDD area directly below a protruding portion of said upper electrode, and a source area and a drain area not covered with said upper gate electrode and said lower electrode;

said lower gate electrode comprises a low resistance metal material; and

said upper gate electrode comprises a high-density metal material having a density of at least 8 or a hydrogen adsorptive metal, and has a high masking ability of hydrogen ions injected during injection of impurities.

69. The semiconductor element of claim 68 wherein said lower gate electrode comprises a metal material having an electric specific resistance of up to 5 Ω

·

cm.

70. Gate type semiconductor element located on a substrate, having gate electrodes comprising an upper gate electrode and a lower gate electrode located one on top of the other in close contact with each other on a gate insulating film, wherein:

said lower gate electrode comprises a low-resistance metal material; and

said upper gate electrode comprises a high-density metal material having a density of at least 8 or a hydrogen adsorptive metal, and a high-masking electrode having a high masking ability of hydrogen ions injected during injection of impurities.

71. The semiconductor element of claim 70 wherein said lower gate electrode comprises a metal material having an electric specific resistance of up to 5 Ω

·

cm.