Structure and method to improve threshold voltage of MOSFETS including a high K dielectric

• US 8,173,531 B2
• Filed: 08/04/2009
• Issued: 05/08/2012
• Est. Priority Date: 08/04/2009
• Status: Expired due to Fees

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: International Business Machines Corporation
• Inventors: Fang, Sunfei, Greene, Brian J., Leobandung, Effendi, Liang, Qingqing, Maciejewski, Edward P., Wang, Yanfeng
• Primary Examiner(s): Fourson, III, George
• Application Number:
  US12/535,183
• Publication Number:
  US 20110031554A1
• Time in Patent Office: 1,008 Days
• Field of Search: 438/585, 438/775, 438/776, 257/E21.194
• US Class Current: 438/585
• CPC Class Codes: H01L 21/28247 passivation or protection of the electrode, e.g. using re-oxidation
• CPC Class Codes: H01L 21/823842 gate conductors with different gate conductor materials or different gate conductor implants, e.g. dual gate structures
• CPC Class Codes: H01L 21/823857 with a particular manufacturing method of the gate insulating layers, e.g. different gate insulating layer thicknesses, particular gate insulator materials or particular gate insulator implants
• CPC Class Codes: H01L 21/823864 with a particular manufacturing method of the gate sidewall spacers, e.g. double spacers, particular spacer material or shape
• CPC Class Codes: H01L 29/517 the insulating material comprising a metallic compound, e.g. metal oxide, metal silicate H01L29/518 takes precedence
• CPC Class Codes: H01L 29/6659 with both lightly doped source and drain extensions and source and drain self-aligned to the sides of the gate, e.g. lightly doped drain [LDD] MOSFET, double diffused drain [DDD] MOSFET
• CPC Class Codes: H01L 29/66636 with source or drain recessed by etching or first recessed by etching and then refilled

Abstract

A method of forming threshold voltage controlled semiconductor structures is provided in which a conformal nitride-containing liner is formed on at least exposed sidewalls of a patterned gate dielectric material having a dielectric constant of greater than silicon oxide. The conformal nitride-containing liner is a thin layer that is formed using a low temperature (less than 500° C.) nitridation process.

Claims

1. A method of fabricating a semiconductor structure comprising:

providing at least one patterned gate stack in at least one device region of a semiconductor substrate, said at least one patterned gate stack including from bottom to top, a patterned gate dielectric material having a dielectric constant of greater than silicon oxide and a patterned gate conductor;

forming an embedded semiconductor material having a different lattice constant than the semiconductor substrate within the semiconductor substrate at a footprint of the at least one patterned gate stack; and

forming a conformal nitride-containing liner on at least exposed sidewalls of the patterned gate dielectric material, wherein said forming the conformal nitride-containing liner comprises a thermal nitridation process that is performed at a temperature of less than 500°

C. in a nitrogen-containing ambient, wherein said embedded semiconductor material is formed prior to forming the conformal nitride-containing liner, and said conformal nitride-containing liner is present only on exposed sidewalls of the patterned gate dielectric material.

2. The method of claim 1 wherein said providing the at least one patterned gate stack includes providing a patterned threshold voltage adjusting layer between the patterned gate dielectric and the patterned gate conductor, wherein the patterned threshold voltage adjusting layer is a pFET threshold voltage adjusting material or an nFET threshold voltage material.

3. The method of claim 2 wherein said threshold voltage adjusting material is a pFET threshold voltage adjusting material, said pFET threshold adjusting material includes Al, Al₂O₃, Ge, GeO₂, Ta, Ta₂O₅, Ti, or TiO₂.

4. The method of claim 2 wherein said threshold voltage adjusting material is an nFET threshold voltage adjusting material, said nFET threshold adjusting material includes a rare earth metal-containing material or an alkaline earth metal-containing material.

5. A method of fabricating a semiconductor structure comprising:

providing at least one patterned gate stack in at least one device region of a semiconductor substrate, said at least one patterned gate stack including from bottom to top, a patterned gate dielectric material having a dielectric constant of greater than silicon oxide, a patterned nFET threshold voltage adjusting layer and a patterned gate conductor, wherein said wherein said patterned nFET threshold voltage adjusting layer is an nFET threshold adjusting material selected from the group consisting of a rare earth metal-containing material and an alkaline earth metal-containing material; and

forming a conformal nitride-containing liner on at least exposed sidewalls of the patterned gate dielectric material in both device regions, wherein said forming the conformal nitride-containing liner is performed at a temperature of less than 500°

C. in a nitrogen-containing ambient.

6. The method of claim 5 further comprising forming an embedded semiconductor material having a different lattice constant than the semiconductor substrate within the semiconductor substrate at a footprint of the at least one patterned gate stack, wherein said forming the embedded semiconductor material is performed before the forming the conformal nitride-containing liner or after forming the conformal nitride-containing liner.

7. The method of claim 6 wherein said embedded semiconductor material is formed prior to forming the conformal nitride-containing liner, and said conformal nitride-containing liner is present only on exposed sidewalls of the patterned gate dielectric material.

8. A method of fabricating a CMOS structure comprising:

providing a first patterned gate stack in a first device region of a semiconductor substrate, and a second patterned gate stack in a second device region of the semiconductor substrate, said first patterned gate stack including from bottom to top, a patterned gate dielectric material having a dielectric constant of greater than silicon oxide, and a patterned gate conductor and said second patterned gate stack including from bottom to top, a patterned gate dielectric material having a dielectric constant of greater than silicon oxide, and a patterned gate conductor;

forming an embedded semiconductor material having a different lattice constant than the semiconductor substrate within the semiconductor substrate at a footprint of the patterned gate stacks; and

forming a conformal nitride-containing liner on at least exposed sidewalls of the patterned gate dielectric material in both device regions, wherein said forming the conformal nitride-containing liner comprises a thermal nitridation process that is performed at a temperature of less than 500°

C. in a nitrogen-containing ambient, wherein said embedded semiconductor material is formed prior to forming the conformal nitride-containing liner, and said conformal nitride-containing liner is present only on exposed sidewalls of the patterned gate dielectric material.

9. The method of claim 8 further comprising providing a patterned first threshold voltage adjusting layer between the patterned gate dielectric and the patterned gate conductor in the first patterned gate stack, and a patterned second threshold voltage adjusting layer between the patterned gate dielectric and the patterned gate conductor in the second patterned gate stack, wherein said first patterned threshold voltage layer is either a pFET threshold voltage adjusting material or an nFET threshold voltage material, while the second patterned threshold voltage layer is the other of a pFET threshold voltage adjusting material or an nFET threshold voltage material not used as the first patterned threshold voltage layer.

10. The method of claim 9 wherein said pFET threshold adjusting material includes Al, Al₂O₃, Ge, GeO₂, Ta, Ta₂O₅, Ti, or TiO₂.

11. The method of claim 9 wherein said nFET threshold adjusting material includes

a rare earth metal-containing material or an alkaline earth metal-containing material.

12. A method of fabricating a CMOS structure comprising:

providing a first patterned gate stack in a first device region of a semiconductor substrate, and a second patterned gate stack in a second device region of the semiconductor substrate, said first patterned gate stack including from bottom to top, a patterned gate dielectric material having a dielectric constant of greater than silicon oxide, a patterned first threshold voltage adjusting layer, and a patterned gate conductor and said second patterned gate stack including from bottom to top, a patterned gate dielectric material having a dielectric constant of greater than silicon oxide, a patterned second threshold voltage adjusting layer and a patterned gate conductor, wherein said first patterned threshold voltage layer is either a pFET threshold voltage adjusting material or an nFET threshold voltage material, while the second patterned threshold voltage layer is the other of a pFET threshold voltage adjusting material or an nFET threshold voltage material not used as the first patterned threshold voltage layer and wherein said nFET threshold adjusting material includes a rare earth metal-containing material or an alkaline earth metal-containing material;

forming an embedded semiconductor material having a different lattice constant than the semiconductor substrate within the semiconductor substrate at a footprint of one of the patterned gate stacks;

selectively exposing a sidewall of said patterned gate dielectric material of each of said patterned gate stacks; and

forming a conformal nitride-containing liner on at least exposed sidewalls of the patterned gate dielectric material in both device regions, wherein said forming the conformal nitride-containing liner comprises a thermal nitridation process that is performed at a temperature of less than 500°

C. in a nitrogen-containing ambient.

13. The method of claim 12 wherein said pFET threshold adjusting material includes Al, Al₂O₃, Ge, GeO₂, Ta, Ta₂O₅, Ti, or TiO₂.

14. A method of fabricating a semiconductor structure comprising:

providing at least one patterned gate stack in at least one device region of a semiconductor substrate, said at least one patterned gate stack including from bottom to top, a patterned gate dielectric material having a dielectric constant of greater than silicon oxide and a patterned gate conductor;

forming an embedded semiconductor material having a different lattice constant than the semiconductor substrate within the semiconductor substrate at a footprint of the at least one patterned gate stack; and

forming a conformal nitride-containing liner on at least exposed sidewalls of the patterned gate dielectric material, wherein said forming the conformal nitride-containing liner is performed at a temperature of less than 500°

C. in a nitrogen-containing ambient, wherein said embedded semiconductor material is formed prior to forming the conformal nitride-containing liner, and said conformal nitride-containing liner is present only on exposed sidewalls of the patterned gate dielectric material.

15. A method of fabricating a CMOS structure comprising:

providing a first patterned gate stack in a first device region of a semiconductor substrate, and a second patterned gate stack in a second device region of the semiconductor substrate, said first patterned gate stack including from bottom to top, a patterned gate dielectric material having a dielectric constant of greater than silicon oxide, and a patterned gate conductor and said second patterned gate stack including from bottom to top, a patterned gate dielectric material having dielectric constant of greater than silicon oxide, and a patterned gate conductor, wherein a patterned first threshold voltage adjusting layer is located between the patterned gate dielectric and the patterned gate conductor in the first patterned gate stack, and a patterned second threshold voltage adjusting layer is located between the patterned gate dielectric and the patterned gate conductor in the second patterned gate stack, said first patterned threshold voltage layer is either a pFET threshold voltage adjusting material or an nFET threshold voltage material, while the second patterned threshold voltage layer is the other of a pFET threshold voltage adjusting material or an nFET threshold voltage material not used as the first patterned threshold voltage layer; and

forming a conformal nitride-containing liner on at least exposed sidewalls of the patterned gate dielectric material in both device regions, wherein said forming the conformal nitride-containing liner is performed at a temperature of less than 500°

C. in a nitrogen-containing ambient.

16. The method of claim 15 wherein said pFET threshold adjusting material includes Al, Al₂O₃, Ge, GeO₂, Ta, Ta₂O₅, Ti, or TiO₂.

17. The method of claim 15 wherein said nFET threshold adjusting material includes a rare earth metal-containing material or an alkaline earth metal-containing material.

18. The method of claim 15 further comprising forming an embedded semiconductor material having a different lattice constant than the semiconductor substrate within the semiconductor substrate at a footprint of one of the patterned gate stacks, wherein said forming the embedded semiconductor material is performed before the forming the conformal nitride-containing liner or after forming the conformal nitride-containing liner.

19. The method of claim 18 wherein said embedded semiconductor material is formed prior to forming the conformal nitride-containing liner, and said conformal nitride-containing liner is present only on exposed sidewalls of the patterned gate dielectric material.