Semiconductor device and method of fabricating same

• US 6,303,415 B1
• Filed: 06/10/1998
• Issued: 10/16/2001
• Est. Priority Date: 06/10/1997
• Status: Expired due to Term

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei
• Primary Examiner(s): Bowers, Charles
• Assistant Examiner(s): MENZ, LAURA MARY
• Application Number:
  US09/094,345
• Time in Patent Office: 1,224 Days
• Field of Search: 438/795, 438/40, 438/88, 438/248, 438/166, 438/165, 438/163, 438/164, 438/162, 438/160, 257/66, 257/65, 257/64, 257/70, 257/72
• US Class Current: 438/166
• CPC Class Codes: G02B 27/017 Head mounted
• CPC Class Codes: H01L 21/02532 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/02672 using crystallisation enhancing elements
• CPC Class Codes: H01L 21/3221 of silicon bodies, e.g. for gettering
• CPC Class Codes: H01L 27/1277 using a crystallisation promoting species, e.g. local introduction of Ni catalyst
• CPC Class Codes: H01L 27/1296 adapted to increase the uniformity of device parameters
• CPC Class Codes: H01L 29/4908 for thin film semiconductor, e.g. gate of TFT
• 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 29/66765 Lateral single gate single channel transistors with inverted structure, i.e. the channel layer is formed after the gate
• CPC Class Codes: H01L 29/78675 with normal-type structure, e.g. with top gate
• CPC Class Codes: H01L 29/78678 with inverted-type structure, e.g. with bottom 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
• CPC Class Codes: Y10S 257/902 FET with metal source region

Abstract

There are disclosed TFTs that have excellent characteristics and can be fabricated with a high yield. The TFTs are fabricated, using an active layer crystallized by making use of nickel. Gate electrodes are comprising tantalum. Phosphorus is introduced into source/drain regions. Then, a heat treatment is performed to getter nickel element in the active layer and to drive it into the source/drain regions. At the same time, the source/drain regions can be annealed out. The gate electrodes of tantalum can withstand this heat treatment.

Claims

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

forming a semiconductor film comprising crystalline silicon over a substrate, said semiconductor film containing a catalytic element for promoting crystallization of said semiconductor film;

forming an active layer of a thin film transistor by patterning said semiconductor film;

forming a gate electrode adjacent to said active layer with a gate insulating film interposed therebetween, said gate electrodes comprising tantalum;

introducing phosphorus into source and drain regions in said active layer; and

then

performing a heat treatment at a temperature of 550 to 700°

C. to getter said catalytic element in said active layers into the source and drain regions introduced with phosphorus, whereby a concentration of said element in said source and drain regions is higher than that in other regions in said active layer,

wherein said gate electrode has heat-resistance to the heat treatment.

2. The method according to claim 1, wherein a crystal growth of said semiconductor film is laterally and parallel to said substrate.

3. The method according to claim 1, wherein said catalytic element is nickel.

4. The method according to claim 1, wherein said catalytic element is selected from the group consisting of Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu, and Au.

5. The method according to claim 1, further comprising a step of irradiating laser for said source and drain regions after said heat treatment.

6. A method of fabricating a semiconductor device having at least a P-channel thin film transistor and at least an N-channel thin film transistor, comprising the steps of:

forming a semiconductor film comprising silicon over a substrate;

disposing an element for promoting crystallization of silicon in contact with said semiconductor film;

crystallizing said semiconductor film by a first heat treatment;

forming active layers of said P-channel and N-channel thin film transistors by patterning said semiconductor film;

forming a gate electrode adjacent to each of said active layers with a gate insulating film interposed therebetween;

introducing phosphorus into regions except for at least a region to be a channel region in each of said active layers; and

then

performing a second heat treatment at a temperature of 550 to 700°

C. to getter said element in said active layer from said region to be said channel region to said regions introduced with phosphorus,

wherein said gate electrode has heat-resistance to the second heat treatment, and

wherein said temperature of said second heat treatment is higher than that of said first heat treatment.

7. A method according to claim 6, wherein said gate electrode comprises tantalum.

9. A method according to claim 6, wherein said element is selected from the group consisting of Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu, and Au.

10. A method according to claim 6, further comprising a step of irradiating laser for said source and drain regions after said second heat treatment.

11. A method according to claim 6, wherein said device is an EL display device.

12. A method according to claim 6, wherein said device is one of a portable intelligent terminal, a head mounted display, a front-projection, a cellular mobile telephone, a portable video camera and a rear-projection.

8. A method according to clam 6, wherein said regions introduced with phosphorus are source and drain regions in said active layer.

13. A method of fabricating a semiconductor device comprising the steps of:

forming a semiconductor film comprising silicon over a substrate;

disposing an element for promoting crystallization of silicon in contact with a first region of said semiconductor film;

crystallizing said semiconductor film by a first heat treatment;

introducing phosphorus into a second region in the crystallized semiconductor film; and

then

performing a second heat treatment to getter said element to said second region,

forming an active layer of a thin film transistor by patterning said semiconductor film so a to exclude said first and second regions;

forming a gate electrode adjacent to said active layer with a gate insulating film interposed therebetween;

introducing phosphorus into regions except for at least a region to be a channel region in said active layer; and

then

performing a third heat treatment to getter said element from said region to be said channel region in said active layer to said regions introduced with phosphorus,

wherein said gate electrode has heat-resistance to the third heat treatment and

wherein said third heat treatment is performed at a higher temperature than said first heat treatment.

14. A method according to claim 13, wherein said gate electrode comprises tantalum.

15. A method according to claim 13, wherein said first and second regions are the same portion in the semiconductor film.

16. A method according to claim 13, wherein said third heat treatment is performed at a temperature of 550-700°

C.

17. A method according to claim 13, wherein said element is selected from the group consisting of Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu, and Au.

18. A method according to claim 13, further comprising a step of irradiating laser for said source and drain regions after said third heat treatment.

19. A method according to claim 13, wherein said device is an EL display device.

20. A method according to claim 13, wherein said device is one of a portable intelligent terminal, a head mounted display, a front-projection, a cellular mobile telephone, a portable video camera and a rear-projection.

21. A method of fabricating a semiconductor device comprising the steps of:

forming a semiconductor film comprising silicon over a substrate;

disposing an element for promoting crystallization of silicon in contact with said semiconductor film;

crystallizing said semiconductor film by a first heat treatment;

forming an active layer of a thin film transistor by patterning said semiconductor film;

forming a gate electrode adjacent to said active layer with a gate insulating film interposed therebetween, said gate electrode comprising tantalum;

introducing phosphorus into regions except for a region to be a channel region in said active layer; and

then

performing a second heat treatment at a temperature of 550 to 700°

C. to getter said catalytic element from said region to be the channel region into said regions except for the channel region in the active layer;

forming a first interlayer insulating film over said active layer and the gate electrode; and

forming a second interlayer insulating film comprising resinous material over said first interlayer insulating film.

22. A method according to claim 21, wherein said element is selected from the group consisting of Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu, and Au.

23. A method according to claim 21, further comprising a step of irradiating laser for said source and drain regions after said second heat treatment.

24. A method according to claim 21, wherein said first interlayer insulating film comprises silicon nitride.

25. A method according to claim 21, wherein said second interlayer insulating film comprises a material selected from the group consisting of acrylics, polyimide, polyamide, polyimidamide, and epoxies can be used.

26. A method according to claim 21, wherein said second interlayer insulating film is a multilayer film.

27. A method according to claim 21, wherein said device is an EL display device.

28. A method according to claim 21, wherein said device is one of a portable intelligent terminal, a head mounted display, a front-projection, a cellular mobile telephone, a portable video camera and a rear-projection.

29. A method according to claim 21 further comprising steps of:

introducing phosphorus into regions in the crystallized semiconductor film after said crystallizing; and

then

performing another heat treatment to getter said element to said regions in the crystallized semiconductor film before said forming the active layer,

wherein said active layer does not include the regions introduced with phosphorus.