Semiconductor device and process for producing semiconductor device

• US 6,555,420 B1
• Filed: 08/27/1999
• Issued: 04/29/2003
• Est. Priority Date: 08/31/1998
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei
• Primary Examiner(s): Zarabian, Amir
• Assistant Examiner(s): NOVACEK, CHRISTY L
• Application Number:
  US09/384,647
• Time in Patent Office: 1,341 Days
• Field of Search: 438/149, 438/158, 438/163, 438/164, 438/166
• US Class Current: 438/158
• CPC Class Codes: G02F 1/13454 Drivers integrated on the active matrix substrate G02F1/136277 takes precedence
• 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 27/1285 using control of the annealing or irradiation parameters, e.g. using different scanning direction or intensity for different transistors
• CPC Class Codes: H01L 27/1288 employing particular masking sequences or specially adapted masks, e.g. half-tone mask
• 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 29/78636 with supplementary region or layer for improving the flatness of the device

Abstract

In a TFT using a crystalline semiconductor film of a bottom gate type, a gate insulating film is flattened. On a substrate, an underlying film, a gate wiring and a gate insulating film are accumulated in this order. The gate insulating film includes a flattening film including an insulating organic resin film, such as BCB, polyimide and acrylic, and an insulating inorganic film. Because the surface of the gate insulating film is flattened by the flattening film, a flat amorphous semiconductor film can be formed on the surface thereof. Therefore, in the laser crystallization, since no difference in focal point of the laser light is formed among each position of the semiconductor film, crystallization can be uniformly conducted. Because the edge part of the gate wiring can be covered with the thick flattening film, implantation of an electron or a hole to the gate insulating film, and electrostatic breakage of the gate insulating film can be prevented.

Claims

1. A process for producing a semiconductor device comprising:

forming a gate wiring on an insulating surface;

forming a flattening film comprising an insulating organic resin to cover said gate wiring;

forming an insulating inorganic film in contact with said flattening film;

forming a semiconductor film having an amorphous component to cover said insulating inorganic film;

forming a protective film in contact with said semiconductor film having an amorphous component; and

crystallizing said semiconductor film having an amorphous component to form a crystalline semiconductor film,

wherein said insulating inorganic film, said semiconductor film having an amorphous component, and said protective film are formed continuously without opening to the air.

2. A process for producing a semiconductor device as claimed in claim 1, wherein said semiconductor device is incorporated into an electronic apparatus selected from the group consisting of a personal computer, a video camera, a mobile computer, a goggle-like display, a recording medium, a digital still camera, a front projection display and a rear projection display.

3. A process for producing a semiconductor device as claimed in claim 1, wherein said semiconductor device is one selected from a liquid crystal display device, an electroluminescence display deice and an image sensor.

4. A process for producing a semiconductor device as claimed in claim 1, wherein in said step of forming said flattening film, said flattening film is formed by a coating method.

5. A process for producing a semiconductor device as claimed in claim 1, wherein in said step of forming said flattening film, said flattening film is formed with benzocyclobutene or polyimide.

6. A process for producing a semiconductor device as claimed in claim 1, wherein after forming said flattening film comprising an insulating organic resin, said process further comprises baking said flattening film,

wherein baking said flattening film, forming said insulating inorganic film, forming said semiconductor film having an amorphous component, and forming said protective film are formed continuously without opening to the air.

7. A process for producing a semiconductor device as claimed in claim 1, wherein said step of forming said crystalline semiconductor film comprises a step of irradiating said semiconductor film having an amorphous component with laser light or high intensity light having a wavelength of 400 nm or less.

8. A process for producing a semiconductor device comprising a circuit comprising a thin film transistor formed on an insulating surface, said process comprising;

forming a gate wiring on an insulating surface;

forming a flattening film comprising an insulating organic resin to cover said gate wiring;

forming an insulating inorganic film in contact with said flattening film;

forming a semiconductor film having an amorphous component to cover said insulating inorganic film;

forming a protective film in contact with said semiconductor film having an amorphous component;

crystallizing said semiconductor film having an amorphous component to form a crystalline semiconductor film; and

adding an impurity to said crystalline semiconductor film through at least a part of said protective film, to form a source region and a drain region,

wherein said insulating inorganic film, said semiconductor film having an amorphous component, and said protective film are formed continuously without opening to the air.

9. A process for producing a semiconductor device as claimed in claim 8, wherein said semiconductor device is incorporated into an electronic apparatus selected from a group consisting of a personal computer, a video camera, a mobile computer, a goggle-like display, a recording medium, a digital still camera, a front projection display and a rear projection display.

10. A process for producing a semiconductor device as claimed in claim 8, wherein said semiconductor device is one selected from a liquid crystal display device, an electroluminescence display device and an image sensor.

11. A process for producing a semiconductor device as claimed in claim 9, wherein in said step of forming said flattening film, said flattening film is formed by a coating method.

12. A process for producing a semiconductor device as claimed in claim 8, wherein in said step of forming said flattening film, said flattening film is formed with benzocyclobutene or polyimide.

13. A process for producing a semiconductor device as claimed in claim 8, wherein after forming said flattening film comprising an insulating organic resin, said process further comprises baking said flattening film,

wherein baking said flattening film, forming said insulating inorganic film, forming said semiconductor film having an amorphous component, and forming said protective film are formed continuously without opening to the air.

14. A process for producing a semiconductor device as claimed in claim 9, wherein said step of forming said crystalline semiconductor film comprises a step of irradiating said semiconductor film having an amorphous component with laser light or high intensity light having a wavelength of 400 nm or less.

15. A process for producing a semiconductor device comprising a circuit comprising a thin film transistor formed on an insulating surface, said process comprising:

forming a gate wiring on an insulating surface;

forming a flattening film comprising an insulating organic resin to cover said gate wiring;

forming an insulating inorganic film in contact with said flattening film;

forming a semiconductor film having an amorphous component to cover said insulating inorganic film;

forming a protective film in contact with said semiconductor film having an amorphous component;

crystallizing said semiconductor film having an amorphous component to form a crystalline semiconductor film;

patterning said protective film into an island form;

patterning said crystalline semiconductor film into an island form; and

adding an impurity endowing a conductive type to said crystalline semiconductor film in an island form using said protective film in an island form as a mask,

wherein said insulating inorganic film, said semiconductor film having an amorphous component, and said protective film are formed continuously without opening to the air.

16. A process for producing a semiconductor device as claimed in claim 15, wherein said step of patterning said protective film into an island form comprising:

coating a positive photoresist to cover said protective film;

patterning said photoresist by exposing to light from a back surface of said insulating surface, using said gate wiring as a mask in order to form a first mask; and

patterning said protective film using said first mask.

17. A process for producing a semiconductor device as claimed in claim 15, wherein said step of adding said impurity comprising:

coating a positive photoresist to cover said protective film in an island form;

patterning said photoresist by exposing to light from a back surface of said insulating surface, using said gate wiring as a mask in order to form a first mask; and

adding said impurity to said crystalline semiconductor film in an island form using said first mask and said protective film as a mask,

wherein at a cross section in a direction of a channel length, a side surface of said first mask is positioned inside a side surface of said gate wiring.

18. A process for producing a semiconductor device as claimed in claim 15, wherein in said step of patterning said crystalline semiconductor film, said crystalline semiconductor film is patterned into the same pattern as in said protective film in an island form.

19. A process for producing a semiconductor device as claimed in claim 15, wherein said step of adding said impurity comprises:

forming a second mask comprising coating a positive photoresist to cover said protective film in an island form, and patterning said photoresist by exposing to light from a back surface of said insulating surface, using said gate wiring as a mask;

adding said impurity to said crystalline semiconductor film in an island form using said second mask;

forming a third mask comprising coating a positive photoresist to cover said protective film in an island form, and patterning said photoresist by exposing to light from a back surface of said insulating surface, using said gate wiring as a mask; and

adding said impurity to said crystalline semiconductor film in an island form using said third mask,

wherein at a cross section in a direction of a channel length, a side surface of said third mask is positioned inside a side surface of said gate wiring.

20. A process for producing a semiconductor device as claimed in claim 15, wherein in said step of forming said flattening film, said flattening film is formed by a coating method.

21. A process for producing a semiconductor device as claimed in claim 15, wherein in said step of forming said flattening film, said flattening film is formed with benzocyclobutene or polyimide.

22. A process for producing a semiconductor device as claimed in claim 15, wherein after forming said flattening film comprising an insulating organic resin, said process further comprises baking said flattening film,

wherein baking said flattening film, forming said insulating inorganic film, forming said semiconductor film having an amorphous component, and forming said protective film are formed continuously without opening to the air.

23. A process for producing a semiconductor device as claimed in claim 15, wherein said step of forming said crystalline semiconductor film comprises a step of irradiating said semiconductor film having an amorphous component with laser light or high intensity light having a wavelength of 400 nm or less.

24. A process for producing a semiconductor device comprising a circuit comprising a thin film transistor formed on an insulating surface, said process comprising:

forming a gate wiring on an insulating surface;

forming a flattening film comprising an insulating organic resin to cover said gate wiring;

forming an insulating inorganic film in contact with said flattening film;

forming a semiconductor film having an amorphous component to cover said insulating inorganic film;

forming a protective film in contact with said semiconductor film having an amorphous component;

crystallizing said semiconductor film having an amorphous component to form a crystalline semiconductor film;

patterning said protective film into an island form;

adding an impurity endowing a conductive type to said crystalline semiconductor film through at least a part of said protective film; and

patterning said crystalline semiconductor film into an island form;

wherein said insulating inorganic film, said semiconductor film having an amorphous component, and said protective film are formed continuously without opening to the air.

25. A process for producing a semiconductor device as claimed in claim 24, wherein said step of patterning said protective film comprising:

coating a positive photoresist to cover said protective film;

patterning said photoresist by exposing to light from a back surface of said insulating surface, using said gate wiring as a mask in order to form a first mask; and

patterning said protective film using said first mask.

26. A process for producing a semiconductor device as claimed in claim 24, wherein said step of adding said impurity comprising:

coating a positive photoresist to cover said protective film in an island form;

patterning said photoresist by exposing to light from a back surface of said insulating surface, using said gate wiring as a mask in order to form a first mask; and

adding said impurity to said crystalline semiconductor film in an island form using said first mask and said protective film as a mask,

wherein at a cross section in a direction of a channel length, a side surface of said first mask is positioned inside a side surface of said gate wiring.

27. A process for producing a semiconductor device as claimed in claim 24, wherein said semiconductor device is incorporated into an electronic apparatus selected from a group consisting of a personal computer, a video camera, a mobile computer, a goggle-like display, a recording a digital still camera, a front projection display and a rear projection display.

28. A process for producing a semiconductor device as claimed in claim 24, wherein said semiconductor device is one selected from a liquid crystal display device, an electroluminescence display device and an image sensor.

29. A process for producing a semiconductor device as claimed in claim 24, wherein in said step of forming said flattening film, said flattening film is formed by a coating method.

30. A process for producing a semiconductor device as claimed in claim 24, wherein in said step of forming said flattening film, said flattening film is formed with benzocyclobutene or polyimide.

31. A process for producing a semiconductor device as claimed in claim 24, wherein after forming said flattening film comprising an insulating organic resin, said process further comprises baking said flattening film,

wherein baking said flattening film, forming said insulating inorganic film, forming said semiconductor film having an amorphous component, and forming said protective film are formed continuously without opening to the air.

32. A process for producing a semiconductor device as claimed in claim 24, wherein said step of forming said crystalline semiconductor film comprises a step of irradiating said semiconductor film having an amorphous component with laser light or high intensity light having a wavelength of 400 nm or less.

33. A process for producing a semiconductor device comprising a circuit comprising a thin film transistor formed on an insulating surface, said process comprising:

forming a gate wiring on an insulating surface;

forming a flattening film comprising an insulating organic resin to cover said gate wiring;

forming an insulating inorganic film in contact with said flattening film;

forming a semiconductor film having an amorphous component to cover said insulating inorganic film;

forming a protective film in contact with said semiconductor film having an amorphous component;

crystallizing said semiconductor film having an amorphous component to form a crystalline semiconductor film;

adding an impurity endowing a conductive type to said crystalline semiconductor film through said protective film, to form a source region and a drain region; and

patterning said protective film into an island form; and

patterning said crystalline semiconductor film into an island form,

wherein said insulating inorganic film, said semiconductor film having an amorphous component, and said protective film are formed continuously without opening to the air.

34. A process for producing a semiconductor device as claimed in claim 33, wherein said step of adding said impurity comprising:

coating a positive photoresist to cover said protective film;

patterning said photoresist by exposing to light from a back surface of said insulating surface, using said gate wiring as a mask in order to form a first mask; and

adding said impurity to said crystalline semiconductor film in an island form using said first mask and said protective film as a mask,

coating a positive photoresist to cover said protective film;

patterning said photoresist by exposing to light from a back surface of said insulating surface, using said gate wiring as a mask in order to form a second mask; and

adding said impurity to said crystalline semiconductor film in an island form using said second mask,

wherein at a cross section in a direction of a channel length, a side surface of said second mask is positioned inside aside surface of said gate wiring.

35. A process for producing a semiconductor device as claimed in claim 33, wherein in said step of patterning said crystalline semiconductor film into an island form, said crystalline semiconductor film is patterned into the same pattern as in said protective film in an island form.

36. A process for producing a semiconductor device as claimed in claim 33, wherein said semiconductor device is incorporated into an electronic apparatus selected from a group consisting of a personal computer, a video camera, a mobile computer, a goggle-like display, a recording medium, a digital still camera, a front projection display and a rear projection display.

37. A process for producing a semiconductor device as claimed in claim 33, wherein said semiconductor device is one selected from a liquid crystal display device, an electroluminescence display device and an image sensor.

38. A process for producing a semiconductor device as claimed in claim 33, wherein in said step of forming said flattening film, said flattening film is formed by a coating method.

39. A process for producing a semiconductor device as claimed in claim 33, wherein in said step of forming said flattening film, said flattening film is formed with benzocyclobutene or polyimide.

40. A process for producing a semiconductor device as claimed in claim 33, wherein after forming said flattening film comprising an insulating organic resin, said process further comprises baking said flattening film,

wherein baking said flattening film, forming said insulating inorganic film, forming said semiconductor film having an amorphous component, and forming said protective film are formed continuously without opening to the air.

41. A process for producing a semiconductor device as claimed in claim 33, wherein said step of forming said crystalline semiconductor film comprises a step of irradiating said semiconductor film having an amorphous component with laser light or high intensity light having a wavelength of 400 nm or less.