Semiconductor film, semiconductor device, and method of manufacturing the same

• US 20030089909A1
• Filed: 10/08/2002
• Published: 05/15/2003
• Est. Priority Date: 10/09/2001
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.), Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Matsuo, Takuya, Miyairi, Hidekazu, Shiga, Aiko, Makita, Naoki, Nomura, Katsumi
• Granted Patent: US 6,777,713 B2
• Time in Patent Office: Days
• US Class Current: 257/59
• CPC Class Codes: G02F 1/1362 Active matrix addressed cells G02F1/134336, G02F1/134363 take precedence
• CPC Class Codes: H01L 21/0237 Materials
• CPC Class Codes: H01L 21/02488 Insulating materials
• CPC Class Codes: H01L 21/02532 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/02667 Crystallisation or recrystallisation of non-monocrystalline semiconductor materials, e.g. regrowth
• CPC Class Codes: H01L 21/02672 using crystallisation enhancing elements
• CPC Class Codes: H01L 21/02686 Pulsed laser beam
• CPC Class Codes: H01L 27/12 the substrate being other than a semiconductor body, e.g. an insulating body
• CPC Class Codes: H01L 27/1277 using a crystallisation promoting species, e.g. local introduction of Ni catalyst
• 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 29/78675 with normal-type structure, e.g. with top gate

Abstract

By adding a novel improvement to the technique disclosed in JP 8-78329 A, a manufacturing method in which film characteristics of a semiconductor film having a crystalline structure are improved is provided. In addition, a TFT having superior TFT characteristics, such as field effect mobility, which uses the semiconductor film as an active layer, and a method of manufacturing the TFT, are also provided. A metallic element which promotes the crystallization of silicon is added to a semiconductor film having an amorphous structure and an oxygen concentration within the film of less than 5×10¹⁸/cm³. The semiconductor film having an amorphous structure is then heat-treated, forming a semiconductor film having a crystalline structure. Subsequently, an oxide film on the surface is removed. Oxygen is introduced to the semiconductor film having a crystalline structure, and processing is performed such that the concentration of oxygen within the film is from 5×10¹⁸/cm³ to 1×10²¹/cm³. After removing an oxide film on the surface of the semiconductor film, the semiconductor film surface is leveled by irradiating laser light under an inert gas atmosphere or in a vacuum.

Claims

1. A semiconductor film, a surface of said semiconductor film having an irregular mesh pattern, wherein:

ridges having convex portions that extend out in a ridge shape diverge; and

at least one pathway that is not obstructed by the ridges is provided between two arbitrary points in a region containing level portions and concave portions sandwiched irregularly by the ridges.

2. A semiconductor film according to claim 1, wherein a metallic element is contained within the semiconductor film at a concentration of 1×

10¹⁶/cm³ to 5×

10¹⁸/cm³

3. A semiconductor film according to claim 2, wherein the metallic element is a metallic element for promoting crystallization of silicon, and is one element, or a plurality of elements, selected from the group consisting of Fe, Ni, Co, Ru, Rh, Pd, Os, Ir, Pt, Cu, and Au.

4. A semiconductor film according to any one of claims 1, wherein an average surface roughness (Ra value) of a surface of the semiconductor film is equal to or less than 2 nm.

5. A semiconductor device comprising a TFT having:

a semiconductor layer having a channel formation region, a drain region, and a source region;

a gate insulating film; and

a gate electrode,

wherein;

a surface of the semiconductor layer has an irregular mesh pattern;

ridges having convex portions that extend out in a ridge shape diverge; and

at least one pathway that is not obstructed by the ridges is provided between two arbitrary points in a region containing a level portion and a concave portion sandwiched irregularly by the ridges.

6. A semiconductor device according to claim 5, wherein a metallic element is contained within the semiconductor layer at a concentration of 1×

10¹⁶/cm³ to 5×

10¹⁸/cm³

7. A semiconductor device according to claim 6, wherein the metallic element is a metallic element for promoting crystallization of silicon, and is one element, or a plurality of elements, selected from the group consisting of Fe, Ni, Co, Ru, Rh, Pd, Os, Ir, Pt, Cu, and Au.

8. A semiconductor device according to any one of claims 5, wherein an average surface roughness (Ra value) of a surface of the semiconductor layer is equal to or less than 2 nm.

9. A method of manufacturing a semiconductor device, comprising:

a first step of forming a semiconductor film having an amorphous structure on an insulating surface;

a second step of adding a metallic element to the semiconductor film having an amorphous structure;

a third step of heat-treating the semiconductor film having an amorphous structure to form a semiconductor film having a crystalline structure, and then removing an oxide film from the crystalline semiconductor film surface;

a fourth step of introducing oxygen into the semiconductor film having a crystalline structure to make an oxygen concentration within the film from 5×

10¹⁸/cm³ to 1×

10²¹/cm³;

a fifth step of removing an oxide film on the surface of the semiconductor film having a crystalline structure; and

a sixth step of irradiating laser light under an inert gas atmosphere or in a vacuum to level the surface of the semiconductor film having a crystalline structure.

12. A method of manufacturing a semiconductor device according to any one of claims 9, wherein a concentration of oxygen within the semiconductor film having an amorphous structure and formed by the first step is less than 5×

10¹⁸/cm³.

15. A method of manufacturing a semiconductor device according to any one of claims 9, wherein the fourth step is a step of irradiating laser light under an inert gas atmosphere, or in a vacuum, after oxidizing the semiconductor surface having a crystalline structure by using ozone water, the laser light having an energy density which is lower than the energy density of the laser light used in the sixth step by 30 to 60 mJ/cm².

18. A method of manufacturing a semiconductor device according to any one of claims 9, wherein the fourth step is a step of irradiating laser light under an atmosphere containing oxygen or water molecules, the laser light having an energy density which is lower than the energy density of the laser light used in the sixth step by 30 to 60 mJ/cm².

21. A method of manufacturing a semiconductor device according to any one of claims 9, wherein the fourth step is a step of irradiating laser light under an inert gas atmosphere, or in a vacuum, after adding oxygen by ion doping or ion implantation so that the oxygen concentration within the semiconductor film having a crystalline structure is from 5×

10¹⁸/cm³ to 1×

10²¹/cm³, the laser light having an energy density which is lower than the energy density of the laser light used in the sixth step by 30 to 60 mJ/cm².

24. A method of manufacturing a semiconductor device according to any one of claims 9, wherein the metallic element in the above structure is a metallic element for promoting crystallization of silicon, and is one element, or a plurality of elements, selected from the group consisting of Fe, Ni, Co, Ru, Rh, Pd, Os, Ir, Pt, Cu, and Au.

10. A method of manufacturing a semiconductor device, comprising:

a first step of forming a semiconductor film having an amorphous structure on an insulating surface;

a second step of adding a metallic element to the semiconductor film having an amorphous structure;

a third step of heat-treating the semiconductor film having an amorphous structure to form a semiconductor film having a crystalline structure;

a fourth step of introducing oxygen into the semiconductor film having a crystalline structure to make the oxygen concentration within the film from 5×

10¹⁸/cm³ to 1×

10²¹/cm³;

a fifth step of removing an oxide film on the surface of the semiconductor film having a crystalline structure; and

a sixth step of irradiating laser light under an inert gas atmosphere or in a vacuum to level the surface of the semiconductor film having a crystalline structure.

13. A method of manufacturing a semiconductor device according to any one of claims 10, wherein a concentration of oxygen within the semiconductor film having an amorphous structure and formed by the first step is less than 5×

10¹⁸/cm³.

16. A method of manufacturing a semiconductor device according to any one of claims 10, wherein the fourth step is a step of irradiating laser light under an inert gas atmosphere, or in a vacuum, after oxidizing the semiconductor surface having a crystalline structure by using ozone water, the laser light having an energy density which is lower than the energy density of the laser light used in the sixth step by 30 to 60 mJ/cm².

19. A method of manufacturing a semiconductor device according to any one of claims 10, wherein the fourth step is a step of irradiating laser light under an atmosphere containing oxygen or water molecules, the laser light having an energy density which is lower than the energy density of the laser light used in the sixth step by 30 to 60 mJ/cm².

22. A method of manufacturing a semiconductor device according to any one of claims 10, wherein the fourth step is a step of irradiating laser light under an inert gas atmosphere, or in a vacuum, after adding oxygen by ion doping or ion implantation so that the oxygen concentration within the semiconductor film having a crystalline structure is from 5×

10¹⁸/cm³ to 1×

10²¹/cm³, the laser light having an energy density which is lower than the energy density of the laser light used in the sixth step by 30 to 60 mJ/cm².

25. A method of manufacturing a semiconductor device according to any one of claims 10, wherein the metallic element in the above structure is a metallic element for promoting crystallization of silicon, and is one element, or a plurality of elements, selected from the group consisting of Fe, Ni, Co, Ru, Rh, Pd, Os, Ir, Pt, Cu, and Au.

11. A method of manufacturing a semiconductor device, comprising:

a first step of forming a semiconductor film having an amorphous structure on an insulating surface;

a second step of adding a metallic element to the semiconductor film having an amorphous structure;

a third step of heat-treating the semiconductor film having an amorphous structure to form a semiconductor film having a crystalline structure, and then removing an oxide film from the crystalline semiconductor film surface;

a fourth step of introducing oxygen into the semiconductor film having a crystalline structure to make the oxygen concentration within the film from 5×

10¹⁸/cm³ to 1×

10²¹/cm³;

a fifth step of removing an oxide film on the surface of the semiconductor film having a crystalline structure;

a sixth step of irradiating laser light under an inert gas atmosphere or in a vacuum to level the surface of the semiconductor film having a crystalline structure; and

a seventh step of gettering the metallic element to remove the metallic element from, or reduce the concentration of the metallic element within, the semiconductor film having a crystalline structure.

14. A method of manufacturing a semiconductor device according to any one of claims 11, wherein a concentration of oxygen within the semiconductor film having an amorphous structure and formed by the first step is less than 5×

10¹⁸/cm³.

17. A method of manufacturing a semiconductor device according to any one of claims 11, wherein the fourth step is a step of irradiating laser light under an inert gas atmosphere, or in a vacuum, after oxidizing the semiconductor surface having a crystalline structure by using ozone water, the laser light having an energy density which is lower than the energy density of the laser light used in the sixth step by 30 to 60 mJ/cm².

20. A method of manufacturing a semiconductor device according to any one of claims 11, wherein the fourth step is a step of irradiating laser light under an atmosphere containing oxygen or water molecules, the laser light having an energy density which is lower than the energy density of the laser light used in the sixth step by 30 to 60 mJ/cm².

23. A method of manufacturing a semiconductor device according to any one of claims 11, wherein the fourth step is a step of irradiating laser light under an inert gas atmosphere, or in a vacuum, after adding oxygen by ion doping or ion implantation so that the oxygen concentration within the semiconductor film having a crystalline structure is from 5×

10¹⁸/cm³ to 1×

10²¹/cm³, the laser light having an energy density which is lower than the energy density of the laser light used in the sixth step by 30 to 60 mJ/cm².

26. A method of manufacturing a semiconductor device according to any one of claims 11, wherein the metallic element in the above structure is a metallic element for promoting crystallization of silicon, and is one element, or a plurality of elements, selected from the group consisting of Fe, Ni, Co, Ru, Rh, Pd, Os, Ir, Pt, Cu, and Au.