System and method for forming a gate dielectric

• US 6,858,547 B2
• Filed: 09/27/2002
• Issued: 02/22/2005
• Est. Priority Date: 06/14/2002
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Kher, Shreyas S., Han, Shixue, Metzner, Craig R.
• Primary Examiner(s): Kebede, Brook
• Application Number:
  US10/256,563
• Publication Number:
  US 20030232506A1
• Time in Patent Office: 879 Days
• Field of Search: 438/197, 438/216, 438/287, 438/591, 438/773, 438/785, 438/786, 438/788, 438/798, 427/126.1, 427/126.3
• US Class Current: 438/785
• CPC Class Codes: C23C 14/083 of refractory metals or yttrium
• CPC Class Codes: C23C 14/10 Glass or silica
• CPC Class Codes: C23C 14/5806 Thermal treatment
• CPC Class Codes: C23C 14/5826 Treatment with charged particles C23C14/582 takes precedence
• CPC Class Codes: C23C 14/5853 Oxidation
• CPC Class Codes: C23C 14/586 Nitriding
• CPC Class Codes: C23C 16/0218 in a reactive atmosphere C23C16/0227 takes precedence
• CPC Class Codes: C23C 16/0227 by cleaning or etching
• CPC Class Codes: C23C 16/405 of refractory metals or yttrium
• CPC Class Codes: C23C 16/56 After-treatment
• CPC Class Codes: H01L 21/02148 the material containing hafnium, e.g. HfSiOx or HfSiON
• CPC Class Codes: H01L 21/02181 the material containing hafnium, e.g. HfO2
• CPC Class Codes: H01L 21/022 the layer being a laminate, i.e. composed of sublayers, e.g. stacks of alternating high-k metal oxides adhesion layers or buffer layers H01L21/02304, H01L21/02362
• CPC Class Codes: H01L 21/02205 the layer being characterised by the precursor material for deposition
• CPC Class Codes: H01L 21/02271 deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition H01L21/02266 takes precedence
• CPC Class Codes: H01L 21/02307 treatment by exposure to a liquid
• CPC Class Codes: H01L 21/02337 treatment by exposure to a gas or vapour
• CPC Class Codes: H01L 21/28194 by deposition, e.g. evaporation, ALD, CVD, sputtering, laser deposition H01L21/28202 takes precedence
• CPC Class Codes: H01L 21/3141 Deposition using atomic layer deposition techniques [ALD]
• CPC Class Codes: H01L 21/3143 composed of alternated layers or of mixtures of nitrides and oxides or of oxinitrides, e.g. formation of oxinitride by oxidation of nitride layers
• CPC Class Codes: H01L 21/31604 : Deposition from a gas or vapour H01L21/31691, H01L21/31695 take precedence
• CPC Class Codes: H01L 21/31612 : on a silicon body
• CPC Class Codes: H01L 21/3162 : on a silicon body
• CPC Class Codes: H01L 21/31645 : Deposition of Hafnium oxides, e.g. HfO2
• CPC Class Codes: H01L 21/31683 : of metallic layers, e.g. Al deposited on the body, e.g. formation of multi-layer insulating structures
• 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 29/78 : with field effect produced by an insulated gate H01L29/7725, H01L29/775, H01L29/778 take precedence

Abstract

A method of forming a dielectric stack on a pre-treated surface. The method comprises pre-cleaning a semiconductor wafer to remove native oxide, such as by applying hydroflouric acid to form an HF-last surface, pre-treating the HF-last surface with ozonated deionized water, forming a dielectric stack on the pre-treated surface and providing a flow of NH₃ in a process zone surrounding the wafer. Alternately, the method includes pre-treating the HF-last surface with NH₃, forming the stack after the pre-treating, and providing a flow of N₂ in a process zone surrounding the wafer after the forming. The method also includes pre-treating the HF-last surface using an in-situ steam generation process, forming the stack on the pre-treated surface, and annealing the wafer after the forming. The pre-treating includes providing an inert gas flow in a process zone surrounding the HF-last surface, reacting hydrogen with an oxidizer in the process zone for a very short duration, and providing an inert gas flew in the process zone after the reacting.

Claims

1. A method of forming a dielectric stack on a wafer comprising:

treating the wafer with hydrofluoric acid to form an HF-last surface;

pre-treating the HF-last surface with ozonated deionized water for a specified time period to form a pre-treated surface;

forming the dielectric stack on the pre-treated surface, wherein the dielectric stack comprises a hafnium oxide layer or a hafnium silicate layer; and

providing a flow of NH₃ in a process zone surrounding the wafer after forming the dielectric stack.

16. The method of claim 1 further comprising:

removing the wafer from a first chamber to a second chamber after forming the hafnium oxide layer;

adjusting a temperature and a pressure of the first chamber; and

returning the wafer to the first chamber after adjusting the temperature and the pressure of the first chamber.

20. The method of claim 16 wherein the temperature is in a range from about 400°

C. to about 1100°

C.

21. The method of claim 20 wherein forming the dielectric stack comprises:

forming a first layer of hafnium oxide or hafnium silicate on the pre-treated surface; and

forming a second layer of hafnium oxide or hafnium silicate on the first layer.

22. The method of claim 21 wherein forming the dielectric stack further comprises an annealing step between the forming steps.

23. The method of claim 21, wherein the second layer comprises hafnium silicate.

24. The method of claim 21 wherein the first and second layers are formed using LPCVD, PECVD, VPE, ALD or PVD.

25. The method of claim 21 wherein the first and second layers are formed using pulsed CVD.

26. The method of claim 21, wherein the first layer comprises hafnium oxide and the second layer comprises hafnium silicate.

27. The method of claim 26 wherein

the hafnium oxide layer is formed using TetrakisDiethylamidoHafnium (TDEAH) precursor;

and

the hafnium silicate layer is formed using TetrakisDiethylamidoHafnium (TDEAH) and TetrakisDimthylamidoSilicon (TDMAS) precursors.

28. The method of claim 27 wherein

a specified duration for providing a flow of NH₃ is in the range of about 5 seconds to about 60 seconds;

a specified temperature for providing a flow of NH₃ is in the range of about 400°

C. to about 1100°

C.;

the hafnium oxide layer is formed at a pressure in the range of about 2 torr to about 8 torr and at a temperature in the range of 225°

C.-700°

C.;

the hafnium silicate layer is formed at a temperature in the range of 225°

C.-700°

C. and at a pressure in the range of about 3 torr to about 8 torr; and

a the flow of N₂ is provided for about 5 seconds to about 60 seconds and at a temperature in the range of about 400°

C. to about 1100°

C.

29. The method of claim 28 wherein

the specified duration for providing a flow at NH₃ is about 60 seconds;

the specified temperature for providing a flow of NH₃ is about 700°

C.;

the hafnium oxide layer is formed at a pressure of about 4 torr and at a temperature of about 485°

C.;

the hafnium silicate layer is formed at a temperature of about 600°

C. and at a pressure of about 4 torr; and

the flow of N₂, is provided for about 60 seconds and at a temperature of about 800°

C.

30. The method of claim 26 where the hafnium oxide layer is annealed before the hafnium silicate layer is formed.

31. The method of claim 26 wherein the hafnium oxide layer is about 3 nanometers thick, the hafnium silicate layer is about 1.0 nanometer thick and the hafnium silicate layer comprises about 50% SiO₂.

2. A method of forming a dielectric stack on a wafer comprising:

treating the wafer with hydrofluoric acid to form an HF-last surface;

pre-treating the HF-last surface with ozonated deionized water for a specified time period to form a pre-treated surface;

forming the dielectric stack on the pre-treated surface; and

providing a flow of NH₃ in a process zone surrounding the wafer after forming the dielectric stack, wherein forming the dielectric stack comprises;

forming a first layer of hafnium oxide or hafnium silicate on the pre-treated surface, and

forming a second layer of hafnium oxide or hafnium silicate on the first layer.

3. The method of claim 2 wherein forming the dielectric stack further comprises an annealing step between the forming steps.

4. The method of claim 2, wherein the first layer is hafnium oxide and the second layer is hafnium silicate.

5. The method of claim 2 wherein the first and second layers are formed using metal-organic chemical vapor deposition (MOCVD) process.

6. The method of claim 4 wherein

the hafnium oxide layer is formed using TetrakisDiethylamidoHafnium (TDEAH) precursor;

and

the hafnium silicate layer is formed using TetrakisDiethylamidoHafnium (TDEAH) and TetrakisDimethylamidoSilicon (TDMAS) precursors.

7. The method of claim 6 wherein:

the ozonated deionized water has an O₃ concentration that is in the range of about 10 ppm to about 30 ppm;

the specified time period for pre-treating is in the range of about 5 minutes to about 15 minutes;

the hafnium oxide layer is formed at a pressure in the range of about 2 torr to about 8 torr and at a temperature in the range of 225°

C.-700°

C.;

the hafnium silicate layer is formed at a temperature in the range of 225°

C.-700°

C. and at a pressure in the range of about 3 torr to about 8 torr; and

the flow of NH₃ is provided at a temperature in the range of about 400°

C. to about 1100°

C. for about 5 seconds to about 60 seconds.

8. The method of claim 7 wherein the dielectric stack has an effective oxide thickness (EOT) of less than about 1.7 nanometers.

9. The method of claim 7 wherein the dielectric stack has an effective oxide thickness (EOT) of less than about 1.25 nanometers.

10. The method of claim 6 wherein:

the ozonated deionized water has an O₃ concentration that is about 20 ppm;

the specified time period for pre-treating is about 10 minutes;

the hafnium oxide layer is formed at a temperature of about 485°

C. and at a pressure of about 4 torr;

the hafnium silicate layer is formed at a temperature of about 600°

C. and at a pressure of about 4 torr; and

the flow of NH₃ is provided for about 60 seconds at a temperature of about 700°

C.

11. The method of claim 6 wherein the hafnium oxide layer is about 4 nanometers thick, the hafnium silicate layer is about 1.5 nanometers thick.

12. The method of claim 6 wherein the hafnium silicate layer comprises about 50% SiO₂.

13. The method of claim 2 wherein the first and second layers are formed using alkylamido or alkylamino ligand precursors.

14. The method of claim 2 wherein the hafnium oxide precursors are selected from a group consisting of amino or amido precursors of the form, Hf(NRR′

)₄, wherein R is alkyl and R′

is alkyl and the hafnium silicate precursors are selected from a group consisting of amino or amido precursors of the form SiR₁R₂R₃R₄ where

R₁═

H, NH₂, N(CH₃)₂, NCO, alkoxy, amino, alkyl, or aryl;

R₂═

H, NH₂, N(CH₃)₂, NCO, alkoxy, amino, alkyl, or aryl;

R₃═

H, NH₂, N(CH₃)₂, NCO, alkoxy, amino, alkyl, or aryl; and

R₄═

H, NH₂, N(CH₃)₂, NCO, alkoxy, amino, alkyl, or aryl.

15. The method of claim 2 wherein the hafnium oxide and the hafnium silicate layers are formed using MOCVD, LPCVD, PECVD, VPE, ALD or PVD.

17. A method of forming a dielectric stack on a wafer comprising:

treating the wafer with hydrofluoric acid to form an HF-last surface;

pre-treating the HF-last surface with ozonated deionized water for a specified time period to form a pre-treated surface;

forming the dielectric stack on the pre-treated surface wherein the dielectric stack comprises a hafnium oxide layer or a hafnium silicate layer;

providing a flow of NH₃ in a process zone surrounding the wafer after forming the dielectric stack;

transporting the wafer to a LPCVD chamber after providing the flow of NH₃; and

forming a polycrystalline-Si layer or an amorphous-Si layer over the dielectric stack.

18. The method of claim 17 wherein the polycrystalline-Si layer or the amorphous-Si layer is formed by introducing silane or disilane in a process zone surrounding the wafer at a specified temperature.

19. The method of claim 18 wherein the specified temperature is less than about 600°

C.