Semiconductor device

• US 7,910,929 B2
• Filed: 12/15/2008
• Issued: 03/22/2011
• Est. Priority Date: 12/18/2007
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Akimoto, Kengo, Takayama, Toru
• Primary Examiner(s): Dickey; Thomas L
• Application Number:
  US12/335,234
• Publication Number:
  US 20090152550A1
• Time in Patent Office: 827 Days
• Field of Search: 257/55, 257/65, 257/E29.151, 257/E51.005
• US Class Current: 257/65
• CPC Class Codes: H01L 21/02263 deposition from the gas or vapour phase
• CPC Class Codes: H01L 21/3105 After-treatment
• CPC Class Codes: H01L 21/31604 Deposition from a gas or vapour H01L21/31691, H01L21/31695 take precedence
• CPC Class Codes: H01L 21/32055 Deposition of semiconductive layers, e.g. poly - or amorphous silicon layers
• CPC Class Codes: H01L 29/41733 for thin film transistors with insulated gate
• CPC Class Codes: H01L 29/4908 for thin film semiconductor, e.g. gate of TFT
• CPC Class Codes: H01L 29/66765 Lateral single gate single channel transistors with inverted structure, i.e. the channel layer is formed after the gate
• CPC Class Codes: H01L 29/78696 characterised by the structure of the channel, e.g. multichannel, transverse or longitudinal shape, length or width, doping structure, or the overlap or alignment between the channel and the gate, the source or the drain, or the contacting structure of the channel H01L29/78612 takes precedence; transistors having a drain offset region or a lightly doped drain [LDD] H01L29/78621

Abstract

An object is to provide a semiconductor device including a microcrystalline semiconductor film with favorable quality and a method for manufacturing the semiconductor device. In a thin film transistor formed using a microcrystalline semiconductor film, yttria-stabilized zirconia having a fluorite structure is formed in the uppermost layer of a gate insulating film in order to improve quality of a microcrystalline semiconductor film to be formed in the initial stage of deposition. The microcrystalline semiconductor film is deposited on the yttria-stabilized zirconia, so that the microcrystalline semiconductor film around an interface with a base particularly has favorable crystallinity while by crystallinity of the base.

Claims

1. A semiconductor device comprising:

a substrate;

a gate electrode over the substrate;

a gate insulating film including an yttria-stabilized zirconia film over the gate electrode;

a semiconductor film over the gate insulating film; and

an amorphous semiconductor film,

wherein the semiconductor film is in contact with the yttria-stabilized zirconia film,

wherein the amorphous semiconductor film is located over the semiconductor film and in contact with the semiconductor film, and

wherein the amorphous semiconductor film has a depressed portion on a top surface.

2. The semiconductor device according to claim 1, wherein the gate insulating film includes one or a plurality of films selected from the group consisting of a silicon oxide film, a silicon nitride film, a silicon oxynitride film, and a silicon nitride oxide film.

3. The semiconductor device according to claim 1, wherein the semiconductor film is a microcrystalline semiconductor film.

4. The semiconductor device according to claim 3, wherein the microcrystalline semiconductor film is a microcrystalline silicon film.

5. The semiconductor device according to claim 3, wherein the microcrystalline semiconductor film contains germanium.

6. A semiconductor device comprising:

a substrate;

a gate electrode over the substrate;

a gate insulating film including an yttria-stabilized zirconia film over the gate electrode;

a first semiconductor film over the gate insulating film;

a second semiconductor film over the first semiconductor film, the second semiconductor film having a depressed portion on a top surface;

a third semiconductor film over the second semiconductor film without the depressed portion of the second semiconductor film; and

a conductive film over the third semiconductor film,

wherein the first semiconductor film is in contact with the yttria-stabilized zirconia film, and

wherein edge portions of the third semiconductor film are located at outside of edge portions of the conductive film.

7. The semiconductor device according to claim 6, wherein the gate insulating film includes one or a plurality of films selected from the group consisting of a silicon oxide film, a silicon nitride film, a silicon oxynitride film, and a silicon nitride oxide film.

8. The semiconductor device according to claim 6, wherein the first semiconductor film is a microcrystalline semiconductor film.

9. The semiconductor device according to claim 8, wherein the microcrystalline semiconductor film is a microcrystalline silicon film.

10. The semiconductor device according to claim 8, wherein the microcrystalline semiconductor film contains germanium.

11. The semiconductor device according to claim 6,

wherein edge portions of the second semiconductor film are located at outside of edge portions of the third semiconductor film.