SEMICONDUCTOR DEVICE AND MANUFACTURING METHOD THEREOF

• US 20090096024A1
• Filed: 10/15/2008
• Published: 04/16/2009
• Est. Priority Date: 10/16/2007
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: SATO, Yurika, SHINGU, Takashi, OHGARANE, Daisuke
• Granted Patent: US 8,053,289 B2
• Time in Patent Office: Days
• US Class Current: 257/347
• CPC Class Codes: H01L 29/458 for thin film silicon, e.g. source or drain electrode
• CPC Class Codes: H01L 29/66621 using etching to form a recess at the gate location etching of semiconductor bodies H01L21/302
• 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

Abstract

In a method for manufacturing a semiconductor device, a semiconductor film formed over an insulator is doped with an impurity element to a depth less than the thickness of the semiconductor film, thereby forming an impurity doped layer; a metal silicide layer is formed on the impurity doped layer; the metal silicide layer and the semiconductor film are etched to form a recessed portion; and a layer which is not doped with the impurity element and is located at the bottom of the recessed portion of the semiconductor film is thinned to make a channel formation region. Further, a gate electrode is formed in the recessed portion over the thinned non impurity doped layer, with an insulating film interposed therebetween.

Claims

1. A method for manufacturing a semiconductor device comprising the steps of:

forming a semiconductor film over an insulator, using a semiconductor material including silicon;

forming a metal suicide layer on an upper surface of the semiconductor film;

patterning the metal silicide layer and the semiconductor film by etching, thereby forming a recessed portion at a position corresponding to a channel formation region of the semiconductor device, and thinning a portion of the semiconductor film which is located at a bottom of the recessed portion to a desired thickness;

forming an insulating film to cover at least the thinned portion of the semiconductor film; and

forming a gate electrode over the thinned portion of the semiconductor film with the insulating film interposed therebetween.

2. A method for manufacturing a semiconductor device comprising the steps of:

forming a semiconductor film over an insulator, using a semiconductor material including silicon;

doping the semiconductor film with an impurity element to a depth less than a thickness of the semiconductor film, thereby forming an impurity doped layer and a non impurity doped layer under the impurity doped layer;

forming a metal silicide layer on an upper surface of the semiconductor film;

patterning the metal silicide layer and the semiconductor film by etching, thereby forming a recessed portion which reaches the non impurity doped layer at a position corresponding to a channel formation region of the semiconductor device, and thinning a portion of the semiconductor film which is located at a bottom of the recessed portion to a desired thickness;

forming an insulating film to cover at least the thinned portion of the semiconductor film; and

forming a gate electrode over the thinned portion of the semiconductor film with the insulating film interposed therebetween.

3. The method for manufacturing a semiconductor device according to claim 2, wherein the step of patterning the metal silicide layer and the semiconductor film by etching comprises the steps of:

exposing a portion of the semiconductor film by isotropically etching the metal suicide layer using a resist as a mask, which has an opening that is the same length as a length of the gate electrode in a channel length direction; and

etching the exposed portion of the semiconductor film anisotropically using the resist having the opening as a mask.

4. The method for manufacturing a semiconductor device according to claim 2, wherein the step of patterning the metal suicide layer and the semiconductor film by etching comprises the steps of:

forming a resist to cover the metal silicide layer;

exposing the resist to light and developing the resist using a half-tone mask, thereby forming a patterned resist which has an opening at a position corresponding to a channel formation region of the semiconductor device, a portion with a relatively small thickness at a portion adjacent to the opening, and a portion with a relatively large thickness at an outer side of and adjacent to the portion with a relatively small thickness; and

etching the metal silicide layer and the semiconductor film using the patterned resist.

5. The method for manufacturing a semiconductor device according to 2, further comprising the steps of:

forming a sidewall film to cover a surface of the patterned metal silicide layer and the patterned semiconductor film, and

etching the sidewall film, whereby a portion of the sidewall film which is along a side surface of the recessed portion remains as a sidewall and the thinned portion of the semiconductor film is exposed;

wherein the steps of forming the sidewall film and etching the sidewall film are carried out after the step of patterning the metal silicide layer and the semiconductor film by etching, and the step of forming the insulating film to cover the thinned portion of the semiconductor film is carried out after the step of etching the sidewall film.

6. The method for manufacturing a semiconductor device according to claim 5, wherein the step of forming the sidewall film comprises the steps of:

forming a first sidewall film comprising one of a first material and a second material wherein the first material is silicon oxynitride and the second material is one of silicon nitride and silicon nitride oxide, and

forming a second sidewall film over the first sidewall film, the second side wall film comprising the other of the first material and the second material;

wherein the step of etching the sidewall film comprises the steps of;

etching the second sidewall film so that a portion of the second sidewall film which is along the side surface of the recessed portion can remain, to make the remaining portion of the second sidewall film a sidewall, and

removing a portion of the first sidewall film which is not covered with the second sidewall film by etching, thereby exposing the thinned portion of the semiconductor film.

7. A method for manufacturing a semiconductor device comprising the steps of:

forming a semiconductor film over an insulator, using a semiconductor material including silicon;

forming a metal silicide layer on an upper surface of the semiconductor film;

patterning the metal silicide layer and the semiconductor film by etching, thereby forming a recessed portion at a position corresponding to a channel formation region of the semiconductor device, and thinning a portion of the semiconductor film which is located at a bottom of the recessed portion to a desired thickness;

forming an insulating film to cover at least the thinned portion of the semiconductor film;

forming a gate electrode over the thinned portion of the semiconductor film with the insulating film interposed therebetween; and

doping a portion of the semiconductor film which is located under the metal suicide layer with an impurity element through the metal silicide layer using the gate electrode as a mask.

8. The method for manufacturing a semiconductor device according to claim 7, wherein the step of patterning the metal silicide layer and the semiconductor film, by etching comprises the steps of:

exposing a portion of the semiconductor film by isotropically etching the metal silicide layer using a resist as a mask, which has an opening that is the same length as a length of the gate electrode in a channel length direction and

etching the exposed portion of the semiconductor film anisotropically using the resist having the opening as a mask.

9. The method for manufacturing a semiconductor device according to claim 7, wherein the step of patterning the metal silicide layer and the semiconductor film by etching comprises the steps of;

forming a resist to cover the metal silicide layer

exposing the resist to light and developing the resist using a half-tone mask, thereby forming a patterned resist which has an opening at a position corresponding to a channel formation region of the semiconductor device, a portion with a relatively small thickness at a portion adjacent to the opening, and a portion with a relatively large thickness at an outer side of and adjacent to the portion with a relatively small thickness; and

etching the metal silicide layer and the semiconductor film the patterned resist.

10. The method for manufacturing a semiconductor device according to claim 7, further comprising the steps of:

forming a sidewall film to cover a surface of the patterned metal suicide layer and the patterned semiconductor film, and etching the sidewall film, whereby a portion of the sidewall film which is along a side surface of the recessed portion remains as a sidewall and the thinned portion of the semiconductor film is exposed;

wherein the steps of forming the sidewall film and etching the sidewall film are carried out after the step of patterning the metal silicide layer and the semiconductor film by etching, and the step of forming the insulating film to cover the thinned portion of the semiconductor film is carried out after the step of etching the sidewall film.

11. The method for manufacturing a semiconductor device according to claim 10, wherein the step of forming the sidewall film comprises the steps of:

forming a first sidewall film comprising one of a first material and a second material wherein the first material is silicon oxynitride and the second material is one of silicon nitride and silicon nitride oxide, and forming a second sidewall film over the first sidewall film, the second side wall film comprising the other of the first material and the second material;

wherein the step of etching the sidewall film comprises the steps of;

etching the second sidewall film so that a portion of the second sidewall film which is along the side surface of the recessed portion can remain, to make the remaining portion of the second sidewall film a sidewall, and

removing a portion of the first sidewall film which is not covered with the second sidewall film by etching, thereby exposing the thinned portion of the semiconductor film.

12. A semiconductor device comprising:

a semiconductor film which is formed over an insulator, is provided with a recessed portion at a portion corresponding to a channel formation region of the semiconductor device, and includes a non impurity doped layer at least at a portion located at the bottom of the recessed portion;

an insulating film which covers at least the non impurity doped layer which is located at the bottom of the recessed portion;

a gate electrode which is formed over the non impurity doped layer which is located at the bottom of the recessed portion, with the insulating film interposed therebetween;

a pair of metal silicide layers which are formed on portions of the semiconductor film which are located adjacent to the recessed portion and form side surfaces of the recessed portion; and

a pair of impurity doped layers which are formed under and in contact with the pair of metal silicide layers and function as a source region and a drain region of the semiconductor device.

13. The semiconductor device according to claim 12, wherein a thickness of the non impurity doped layer which is located at the bottom of the recessed portion is smaller than a thickness of the pair of impurity doped layers which function as the source region and the drain region.

14. The semiconductor device according to claim 12, wherein a distance between the metal ailicide layer on the source region and the metal silicide layer on the drain region is longer than a distance between the source region and the drain region.

15. The semiconductor device according to any one a claim 12, further comprising a sidewall along the side surface of the recessed portion of the semiconductor film.