T-gate formation using modified damascene processing with two masks

• US 6,319,802 B1
• Filed: 07/20/2000
• Issued: 11/20/2001
• Est. Priority Date: 07/20/2000
• Status: Expired due to Term

• Current Assignee: GlobalFoundries, Inc.
• Original Assignee: Advanced Micro Devices, Inc.
• Inventors: Subramanian, Ramkumar, Singh, Bhanwar, Lyons, Christopher F., Plat, Marina
• Primary Examiner(s): Bowers, Charles
• Assistant Examiner(s): NGUYEN, THANH T
• Application Number:
  US09/620,145
• Time in Patent Office: 488 Days
• Field of Search: 438/585, 438/182-184, 438/574, 438/579, 438/299
• US Class Current: 438/585
• CPC Class Codes: H01L 21/28114 characterised by the sectional shape, e.g. T, inverted-T

Abstract

A method for fabricating a T-gate structure is provided. A structure is provided that has a silicon layer having a gate oxide layer, a protection layer over the gate oxide layer and a sacrificial layer over the protection layer. An opening is then formed in the sacrificial layer. A contact material is deposited over the sacrificial layer filling the opening with the contact material and forming a contact layer. Portions of the contact material outside a gate region are then removed. Finally, the sacrificial layer and portions of the protection layer and the gate oxide layer not forming a part of the T-gate structure are removed.

Claims

1. A method for fabricating a T-gate structure comprising the steps of:

providing a silicon layer having a gate oxide layer, a protection layer over the gate oxide layer and a sacrificial layer over the protection layer;

forming an opening in the sacrificial layer;

depositing a contact material over the sacrificial layer filling the opening with the contact material and forming a contact layer;

removing portions of the contact material outside a gate region; and

removing the sacrificial layer and portions of the protection layer and the gate oxide layer not forming a part of the T-gate structure.

2. The method of claim 1, the sacrificial layer including at least one of silicon oxide, silicon dioxide, silicon nitride (Si₃N₄), (SiN), silicon oxynitride, (SiO_xN_y), fluorinated silicon oxide (SiO_xN_y), and polyimide(s).

3. The method of claim 1, the step of depositing a contact material comprising the step of depositing with one of polysilicon, germanium, amorphous polysilicon and metal.

4. The method of claim 1, the step of forming an opening in the sacrificial layer comprising etching the sacrificial layer to form a first opening in a photoresist layer to expose the sacrificial layer and a second step of etching the exposed sacrificial layer to form the opening.

5. The method of claim 4, the first etching step being employed utilizing a dark field mask with a positive resist.

6. The method of claim 5, the step of removing portions of the contact material outside a gate region comprising performing an etch step employing a clear field mask.

7. The method of claim 4, the first etching step being employed utilizing a clear field mask with a negative resist.

8. The method of claim 7, the step of removing portions of the contact material outside a gate region comprising performing an etch step employing a dark field mask.

9. The method of claim 4, the first etch step being highly selective to the photoresist layer over the underlying sacrificial layer.

10. The method of claim 4, the second etch step being highly selective to the sacrificial layer over the photoresist layer and the underlying protection layer.

11. The method of claim 1, the step of removing portions of the sacrificial layer, the protection layer and the gate oxide layer not forming a part of the T-gate structure comprising performing a wet etch.

12. The method of claim 1, the step of removing portions of the sacrificial layer, the protection layer and the gate oxide layer not forming a part of the T-gate structure comprising performing a vertical plasma etch.

13. The method of claim 1, the protection layer being formed from one of polysilicon and germanium.

14. The method of claim 1, further including the step of forming the protection layer to have a thickness within the range of about 50 Å

to 150 Å

.

15. The method of claim 1, further including the step of forming the sacrificial layer to have a thickness within the range of about 400 Å

to 600 Å

.

16. A method for fabricating a T-gate structure comprising the steps of:

providing a silicon layer having a gate oxide layer, a protection layer over the gate oxide layer and a sacrificial layer over the protection layer, the protection layer being one of a polysilicon and a germanium material;

forming an opening in the sacrificial layer;

depositing a contact material over the sacrificial layer filling the opening with the contact material and forming a contact layer, the contact material being one of a polysilicon material and a germanium material;

removing portions of the contact material outside a gate region; and

removing the sacrificial layer and portions of the protection layer and the gate oxide layer not forming a part of the T-gate structure.

17. The method of claim 16, the sacrificial layer including at least one of silicon oxide, silicon dioxide, silicon nitride (Si₃N₄), (SiN), silicon oxynitride, (SiO_xN_y), fluorinated silicon oxide (SiO_xF_y), and polyimide(s).

18. The method of claim 16, further including the step of forming the protection layer to have a thickness within the range of about 50 Å

to 150 Å

.

19. The method of claim 16, further including the step of forming the sacrificial layer to have a thickness within the range of about 400 Å

to 600 Å

.

20. A method for fabricating a T-gate structure comprising the steps of:

providing a silicon layer having a gate oxide layer, a protection layer having a thickness within the range of about 50 Å

to 150 Å

over the gate oxide layer and a sacrificial layer having a thickness within the range of about 400 Å

to 600 Å

over the protection layer, the protection layer being formed from one of a polysilicon and germanium material;

etching an opening in the sacrificial layer;

depositing a polysilicon material over the sacrificial layer filling the opening with the polysilicon material and forming a polysilicon layer;

removing portions of the polysilicon material outside a gate region;

removing the sacrificial layer; and

etching portions of the protection layer and the gate oxide layer not forming a part of the T-gate structure using one of a wet etch and a vertical plasma etch.