Nitrogen treatment to improve high-k gate dielectrics

• US 20060131672A1
• Filed: 04/27/2005
• Published: 06/22/2006
• Est. Priority Date: 12/20/2004
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: Wang, Ta-Wei, Wang, Chih-Hao, Chen, Shang-Chih, Tsai, Ching-Wei
• Granted Patent: US 7,564,108 B2
• Time in Patent Office: Days
• US Class Current: 257/410
• CPC Class Codes: H01L 21/28202 in a nitrogen-containing ambient, e.g. nitride deposition, growth, oxynitridation, NH3 nitridation, N2O oxidation, thermal nitridation, RTN, plasma nitridation, RPN
• CPC Class Codes: H01L 21/76829 characterised by the formation of thin functional dielectric layers, e.g. dielectric etch-stop, barrier, capping or liner layers
• CPC Class Codes: H01L 21/823462 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 21/823857 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 29/513 the variation being perpendicular to the channel plane
• 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 29/518 the insulating material containing nitrogen, e.g. nitride, oxynitride, nitrogen-doped material
• CPC Class Codes: H01L 29/665 using self aligned silicidation, i.e. salicide formation of conductive layers comprising silicides H01L21/28518
• 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 29/7833 with lightly doped drain or source extension, e.g. LDD MOSFET's; DDD MOSFET's for thin film transistors H01L29/78618
• CPC Class Codes: H01L 29/7843 the means being an applied insulating layer

Abstract

A MOSFET having a nitrided gate dielectric and its manufacture are disclosed. The method comprises providing a substrate and depositing a non-high-k dielectric material on the substrate. The non-high-k dielectric comprises two layers. The first layer adjacent the substrate is essentially nitrogen-free, and the second layer includes between about 10¹⁵ atoms/cm³ to about 10²² atoms/cm³ nitrogen. The MOSFET further includes a high-k dielectric material on the nitrided, non-high-k dielectric. The high-k dielectric preferably includes HfSiON, ZrSiON, or nitrided Al₂O₃. Embodiments further include asymmetric manufacturing techniques wherein core and peripheral integrated circuit areas are separately optimized.

Claims

1. A gate dielectric for use in a transistor comprising:

a nitrogen-containing, high-k dielectric layer; and

an underlying dielectric layer, the underlying dielectric layer having a nitrogen-containing first portion in contact with the high-k dielectric layer, and a substantially nitrogen-free second portion in contact with an underlying substrate.

2. The gate dielectric of claim 1, wherein the high-k dielectric layer has a permittivity of greater than about 8.

3. The gate dielectric of claim 1, wherein the high-k dielectric has a thickness from about 5 to 50 Å

, and wherein the underlying dielectric layer has a thickness from about 15 to 80 Å

.

4. The gate dielectric of claim 1, wherein the underlying dielectric layer has a dielectric constant less than about 8.

5. The gate dielectric of claim 1, wherein the nitrogen-containing first portion of the underlying dielectric layer has a thickness greater than about 1 nm.

6. The gate dielectric of claim 1, wherein the substantially nitrogen-free second portion of the underlying dielectric layer has a thickness greater than about 0.5 nm.

7. The gate dielectric of claim 1, wherein the high-k gate dielectric comprises a material selected from the group consisting essentially of silicon, oxygen, nitrogen, Hf, Ta, Al, La, Ge, Ti, Co, HfSiON, amorphous HfSiON, Ta₂O₅, TiO₂, Al₂O₃, ZrO₂, HfO₂, Y₂O₃, La₂O₃, aluminates, silicates, HfAlOx, TiO₂, PbTiO₃, BaTiO₃, SrTiO₃, and PbZrO₃, and combinations thereof.

8. The gate dielectric of claim 1, wherein the underlying substrate comprises a material selected from the group consisting essentially of Si, strained Si, Ge, SiC, SiGe, SiGeC, strained SiGe, SOI, SiGeOI, GeOI, GaAs, a stacked arrangement of layers, and combinations thereof.

9. A transistor comprising:

a substrate;

a gate structure comprising,

a first dielectric layer on the substrate, the first dielectric layer having a substantially nitrogen-free region adjacent the substrate and a nitrogen-containing region adjacent the nitrogen-free region,

a nitrogen-containing, high-k dielectric layer on the first dielectric layer, and

a gate electrode on a second dielectric layer,

a source region and a drain region adjacent and on opposed sides, respectively, of the gate structure and defining there between a channel region, the channel region having a length of less than about 100 nm.

10. The transistor of claim 9, wherein the first dielectric layer has a dielectric constant less than about 8.

11. The transistor of claim 9, wherein the nitrogen-containing region is greater than about 1 nm thick.

12. The transistor of claim 9, wherein the substantially nitrogen-free region is greater than about 0.5 nm thick.

13. The transistor of claim 9, wherein the high-k dielectric has a dielectric constant greater than about 8.

14. The transistor of claim 9, wherein the high-k dielectric comprises a material selected from the group consisting essentially of silicon, oxygen, nitrogen, Hf, Ta, Al, La, Ge, Ti, Co, HfSiON, amorphous HfSiON, Ta₂O₅, TiO₂, Al₂O₃, ZrO₂, HfO₂, Y₂O₃, La₂O₃, aluminates, silicates, HfAlOx, TiO₂, PbTiO3, BaTiO₃, SrTiO₃, and PbZrO₃, and combinations thereof.

15. A semiconductor device having a core region and an input/output (I/O) region on a substrate, the semiconductor device comprising:

an underlying dielectric layer on the substrate, the underlying dielectric layer having a first thickness over the I/O region and a second thickness over the core region, wherein the first thickness is greater than the second thickness;

a high-k dielectric layer on the underlying dielectric layer over the I/O region and the core region, wherein the underlying dielectric layer over the I/O region is partially nitrided, and the underlying dielectric layer over the core region is fully nitrided.

16. The semiconductor device of claim 15, wherein the underlying dielectric layer has a dielectric constant less than about 8.

17. The semiconductor device of claim 15, wherein the first thickness is at least about 0.1 nm greater than the second thickness.

18. The semiconductor device of claim 15, wherein an upper first portion of the underlying dielectric layer over the I/O region is nitrogen-containing and a bottom second portion of the underlying dielectric layer over the I/O region is substantially nitrogen-free.

19. The semiconductor device of claim 18, wherein the upper first portion of the underlying dielectric layer has a thickness greater than about 1 nm.

20. The semiconductor device of claim 18, wherein the bottom second portion of the underlying dielectric layer has a thickness greater than about 0.5 nm.

21. The semiconductor device of claim 15, wherein the high-k dielectric layer has a dielectric constant greater than about 8.

22. The semiconductor device of claim 15, wherein the underlying dielectric layer over the core region is less than about 1.5 nm thick.

23. The semiconductor device of claim 15, wherein the high-k dielectric layer comprises a material selected from the group consisting essentially of silicon, oxygen, nitrogen, Hf, Ta, Al, La, Ge, Ti, Co, HfSiON, amorphous HfSiON, Ta₂O₅, TiO₂, Al₂O₃, ZrO₂, HfO₂, Y₂O₃, La₂O₃, aluminates, silicates, HfAlOx, TiO₂, PbTiO3, BaTiO₃, SrTiO₃, and PbZrO₃, and combinations thereof.