Semiconductor device and fabrication method thereof

• US 6,573,564 B2
• Filed: 05/10/2002
• Issued: 06/03/2003
• Est. Priority Date: 09/29/1997
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Koyama, Jun, Yamazaki, Shunpei, Satou, Yurika
• Primary Examiner(s): Nelms, David
• Assistant Examiner(s): Huynh, Andy
• Application Number:
  US10/141,821
• Publication Number:
  US 20020130363A1
• Time in Patent Office: 389 Days
• Field of Search: 257/353, 257/57, 257/348, 257/344, 257/458, 438/164, 438/149
• US Class Current: 257/353
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode
• CPC Class Codes: G02F 1/136227 Through-hole connection of the pixel electrode to the active element through an insulation layer
• CPC Class Codes: H01L 21/02532 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/02672 using crystallisation enhancing elements
• CPC Class Codes: H01L 21/02686 Pulsed laser beam
• CPC Class Codes: H01L 21/02691 Scanning of a beam
• CPC Class Codes: H01L 27/1255 integrated with passive devices, e.g. auxiliary capacitors
• CPC Class Codes: H01L 27/1277 using a crystallisation promoting species, e.g. local introduction of Ni catalyst
• 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 29/78618 characterised by the drain or the source properties, e.g. the doping structure, the composition, the sectional shape or the contact structure silicide contacts, electrodes in general H01L29/458

Abstract

To provide a semiconductor device having high mass production performance and high reliability and reproducibility by simple fabrication steps, in a constitution of a semiconductor device of a bottom gate type formed by a semiconductor layer having a crystal structure, source and drain regions are constituted by a laminated layer structure comprising a first conductive layer (n⁺ layer), a second conductive layer (n⁻ layer) having resistance higher than the first conductive layer and an intrinsic or a substantially intrinsic semiconductor layer (i layer) in which the n⁻ layer functions as an LDD region and the i layer functions as an offset region in a film thickness direction.

Claims

1. An electric device including a display device, said display device comprising:

a plurality of gate wirings;

a plurality of source wirings;

a plurality of pixels each being located at an intersection of each of the plurality of gate wirings and each of the plurality of source wirings;

at least a bottom gate type thin film transistor in each of the plurality of pixels;

at least a storage capacitor connected to a pixel electrode; and

a first crystalline semiconductor film of the thin film transistor, said first crystalline semiconductor film including a source region, a drain region and at least one channel forming region therein,

wherein each of the source region and the drain region in the first crystalline semiconductor film includes toward a gate insulating film,

at least a first conductive layer,

at least a second conductive layer having a higher resistance than the first conductive layer, and

at least a first semiconductor layer having a same conductive type as the channel forming region,

wherein a concentration profile of an impurity to give a conductivity to the first and the second conductive layers is varied continuously from the first conductive layer to the second conductive layer, and

wherein the storage capacitor comprises,

a first electrode comprising a same conductive film as the gate wiring,

a dielectric body in contact with the first electrode, and

a second electrode comprising a second semiconductor layer being in contact with the dielectric body and having a same conductive type as the channel forming region,

wherein the electric device is one selected from the group consisting of a mobile computer, a head mount display, a portable telephone, a video camera, a still camera, a personal computer, a rear type projector, and a front type projector.

2. The device according to claim 1,

wherein the second semiconductor layer is formed in the first crystalline semiconductor film of the thin film transistor.

3. The device according to claim 1,

wherein the second semiconductor layer includes a region having a film thickness same as a film thickness of the channel forming region.

4. The device according to claim 1,

wherein a film thickness of the second semiconductor layer is equal to a film thickness of the first semiconductor layer.

5. The device according to claim 1,

wherein an impurity selected from group 13 or group 15 to control a threshold voltage is added to the second semiconductor layer at a concentration in the range of 1×

10¹⁵-5×

10¹⁷ atoms/cm³.

6. The device according claim 1, further comprising:

a third semiconductor layer in contact with the second semiconductor layer; and

a fourth semiconductor layer in contact with the third semiconductor layer,

wherein a concentration profile of an impurity to give a conductivity from the fourth semiconductor layer to the third semiconductor layer is substantially equal to the concentration profile of the first and second conductive layers,

wherein the second, third and fourth semiconductor layers are formed in a second crystalline semiconductor film.

7. The device according to claim 6,

wherein the fourth semiconductor layer is connected to a drain electrode of the thin film transistor.

8. The device according to claim 6,

wherein the fourth semiconductor layer is connected to the pixel electrode.

9. The device according to claim 1,

wherein the impurity to give a conductivity to the first and second conductive layers is an element selected from group 13 or group 15.

10. The device according to claim 1,

wherein the first crystalline semiconductor film includes at least an element selected from the group consisting of Ni, Ge, Pt, Co, Fe, Au, Pd, Pb and Cu.

11. The device according to claim 10,

wherein a concentration of the element in the channel forming region is 5×

10¹⁷ atoms/cm³ or lower.

12. An electric device including a display device, said display device comprising:

a plurality of gate wirings;

a plurality of source wirings;

a plurality of pixels each being located at an intersection of each of the plurality of gate wirings and each of the plurality of source wirings;

at least a bottom gate type thin film transistor in each of the plurality of pixels;

at least a storage capacitor connected to a pixel electrode; and

a first crystalline semiconductor film of the thin film transistor, said first crystalline semiconductor film including a source region, a drain region, and at least one channel forming region therein,

wherein each of the source region and the drain region in the first crystalline semiconductor film includes toward a gate insulating film,

at least a first conductive layer,

at least a second conductive layer having a higher resistance than the first conductive layer, and

at least a first semiconductor layer having a same conductive type as the channel forming region,

wherein a concentration profile of an impurity to give a conductivity to the first and the second conductive layers is varied continuously from the first conductive layer to the second conductive layer, and

wherein the storage capacitor comprises,

a first electrode of the capacitor comprising a first conductive film common to the gate wiring,

a dielectric body in contact with the first electrode,

a second electrode being in contact with the dielectric body and comprising a second conductive film common to the source wiring,

wherein the electric device is one selected from the group consisting of a mobile computer, a head mount display, a portable telephone, a video camera, a still camera, a personal computer, a rear type projector, and a front type projector.

13. The device according to claim 12,

wherein the second electrode of the storage capacitor is integrally formed with a drain electrode of the thin film transistor.

14. The device according to claim 12,

wherein an impurity to give a conductivity to the first and the second conductive layers is an element selected from group 13 or group 15.

15. The device according to claim 12,

wherein an impurity selected from group 13 or group 15 to control the threshold voltage is added to at least the channel forming region at a concentration in the range of 1×

10¹⁵-5×

10¹⁷ atoms/cm³.

16. The device according to claim 12,

wherein the first crystalline semiconductor film includes at least an element selected from the group consisting of Ni, Ge, Pt, Co, Fe, Au, Pd, Pb and Cu.

17. The device according to claim 16,

wherein a concentration of the element in the channel forming region is 5×

10¹⁷ atoms/cm³ or lower.

18. An electric device including a display device, said display device comprising:

a plurality of gate wirings;

a plurality of source wirings;

a plurality of pixels each being located at an intersection of each of the plurality of gate wirings and each of the plurality of source wirings;

at least a bottom gate type thin film transistor in each of the plurality of pixels;

at least a storage capacitor connected to a pixel electrode; and

a first crystalline semiconductor film of the thin film transistor, said first crystalline semiconductor film including a source region, a drain region, and at least one channel forming region therein;

wherein each of the source region and the drain region in the first crystalline semiconductor film includes toward a gate insulating film,

at least a first conductive layer,

at least a second conductive layer having a higher resistance than the first conductive layer, and

at least a first semiconductor layer having a same conductive type as the channel forming region;

wherein a concentration profile of an impurity to give a conductivity to the first and the second conductive layers is varied continuously from the first conductive layer to the second conductive layer,

wherein the storage capacitor comprises,

a first electrode comprising a first conductive film common to the gate wiring,

a dielectric body in contact with the first electrode,

a second electrode being in contact with the dielectric body and being extended from the pixel electrode,

wherein the electric device is one selected from the group consisting of a mobile computer, a head mount display, a portable telephone, a video camera, a still camera, a personal computer, a rear type projector, and a front type projector.

19. The device according to claim 18,

wherein the impurity to give a conductivity to the first and the second conductive layers is an element selected from group 13 or group 15.

20. The device according to claim 18,

wherein an impurity selected from group 13 or group 15 to control the threshold voltage is added to at least the channel forming region at a concentration in the range of 1×

10¹⁵-5×

10¹⁷ atoms/cm³.

21. The device according to claim 18,

wherein the first crystalline semiconductor film of the thin film transistor includes at least an element selected from the group consisting of Ni, Ge, Pt, Co, Fe, Au, Pd, Pb and Cu.

22. The device according to claim 21,

wherein a concentration of the element in the channel forming region is 5×

10¹⁷ atoms/cm³ or lower.

23. An electric device including a display device, said display device comprising:

a plurality of gate wirings;

a plurality of source wirings;

a plurality of pixels each being located at an intersection of each of the plurality of gate wirings and each of the plurality of source wirings;

at least one thin film transistor in each of the plurality of pixels, said bottom gate type thin film transistor having a source region, a drain region, at least one channel forming region and a gate electrode adjacent to said channel forming region with a gate insulating film interposed therebetween;

at least a storage capacitor connected to a pixel electrode; and

wherein each of the source region and the drain region comprises,

at least a first conductive layer,

at least a second conductive layer having a higher resistance than the first conductive layer, and

at least a first semiconductor layer having a same conductive type as the channel forming region,

wherein a concentration profile of an impurity to give a conductivity to the first and the second conductive layers is varied continuously from the first conductive layer to the second conductive layer, and

wherein the storage capacitor comprises,

a first electrode comprising a same conductive film as the gate wiring,

a dielectric body in contact with the first electrode, and

a second electrode comprising a second semiconductor layer being in contact with the dielectric body and having a same conductive type as the channel forming region,

wherein the electric device is one selected from the group consisting of a mobile computer, a head mount display, a portable telephone, a video camera, a still camera, a personal computer, a rear type projector, and a front type projector.

24. The device according to claim 23,

wherein the second semiconductor layer includes a region having a film thickness same as a film thickness of the channel forming region.

25. The device according to claim 23,

wherein a film thickness of the second semiconductor layer is equal to a film thickness of the first semiconductor layer.

26. The device according to claim 23,

wherein an impurity selected from group 13 or group 15 to control a threshold voltage is added to the second semiconductor layer at a concentration in the range of 1×

10¹⁵-5×

10¹⁷ atoms/cm³.

27. The device according claim 23, further comprising:

a third semiconductor layer in contact with the second semiconductor layer; and

a fourth semiconductor layer in contact with the third semiconductor layer,

wherein a concentration profile of an impurity to give a conductivity from the fourth semiconductor layer to the third semiconductor layer is substantially equal to the concentration profile of the first and second conductive layers.

28. The device according to claim 27,

wherein the fourth semiconductor layer is connected to a drain electrode of the thin film transistor.

29. The device according to claim 27,

wherein the fourth semiconductor layer is connected to the pixel electrode.

30. The device according to claim 23,

wherein the impurity to give a conductivity to the first and second conductive layers is an element selected from group 13 or group 15.

31. An electric device including a display device, said display device comprising:

a plurality of gate wirings;

a plurality of source wirings;

a plurality of pixels each being located at an intersection of each of the plurality of gate wirings and each of the plurality of source wirings;

at least a bottom gate type thin film transistor in each of the plurality of pixels, said bottom gate type thin film transistor having a source region, a drain region, at least one channel forming region and a gate electrode adjacent to the channel forming region with a gate insulating film interposed therebetween;

at least a storage capacitor connected to a pixel electrode; and

wherein each of the source region and the drain region comprises,

at least a first conductive layer,

at least a second conductive layer having a higher resistance than the first conductive layer, and

at least a first semiconductor layer having a same conductive type as the channel forming region,

wherein a concentration profile of an impurity to give a conductivity to the first and the second conductive layers is varied continuously from the first conductive layer to the second conductive layer, and

wherein the storage capacitor comprises,

a first electrode of the capacitor comprising a first conductive film common to the gate wiring,

a dielectric body in contact with the first electrode,

a second electrode being in contact with the dielectric body and comprising a second conductive film common to the source wiring,

wherein the electric device is one selected from the group consisting of a mobile computer, a head mount display, a portable telephone, a video camera, a still camera, a personal computer, a rear type projector, and a front type projector.

32. The device according to claim 31,

wherein the second electrode of the storage capacitor is integrally formed with a drain electrode of the thin film transistor.

33. The device according to claim 31,

wherein an impurity to give a conductivity to the first and the second conductive layers is an element selected from group 13 or group 15.

34. The device according to claim 31,

wherein an impurity selected from group 13 or group 15 to control the threshold voltage is added to at least the channel forming region at a concentration in the range of 1×

10¹⁵-5×

10¹⁷ atoms/cm³.

35. An electric device including a display device, said display device comprising:

a plurality of gate wirings;

a plurality of source wirings;

a plurality of pixels each being located at an intersection of each of the plurality of gate wirings and each of the plurality of source wirings;

at least a bottom gate type thin film transistor in each of the plurality of pixels, said bottom gate type thin film transistor having a source region, a drain region, at least one channel forming region and a gate electrode adjacent to the channel forming region with a gate insulating film interposed therebetween;

at least a storage capacitor connected to a pixel electrode; and

wherein each of the source region and the drain region comprises,

at least a first conductive layer,

at least a second conductive layer having a higher resistance than the first conductive layer, and

at least a first semiconductor layer having a same conductive type as the channel forming region;

wherein a concentration profile of an impurity to give a conductivity to the first and the second conductive layers is varied continuously from the first conductive layer to the second conductive layer,

wherein the storage capacitor comprises,

a first electrode comprising a first conductive film common to the gate wiring,

a dielectric body in contact with the first electrode,

a second electrode being in contact with the dielectric body and being extended from the pixel electrode,

wherein the electric device is one selected from the group consisting of a mobile computer, a head mount display, a portable telephone, a video camera, a rear type projector, and a front type projector.

36. The device according to claim 35,

wherein the impurity to give a conductivity to the first and the second conductive layers is an element selected from group 13 or group 15.

37. The device according to claim 35,

wherein an impurity selected from group 13 or group 15 to control the threshold voltage is added to at least the channel forming region at a concentration in the range of 1×

10¹⁵-5×

10¹⁷ atoms/cm³.