Methods of forming field effect transistors on substrates

• US 20070048942A1
• Filed: 08/30/2005
• Published: 03/01/2007
• Est. Priority Date: 08/30/2005
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Tang, Sanh, Hanson, Robert
• Granted Patent: US 7,867,851 B2
• Time in Patent Office: Days
• US Class Current: 438/268
• CPC Class Codes: H01L 21/26513 of electrically active species
• CPC Class Codes: H01L 21/823418 with a particular manufacturing method of the source or drain structures, e.g. specific source or drain implants or silicided source or drain structures or raised source or drain structures
• CPC Class Codes: H01L 21/823437 with a particular manufacturing method of the gate conductors, e.g. particular materials, shapes
• CPC Class Codes: H01L 21/823487 with a particular manufacturing method of vertical transistor structures, i.e. with channel vertical to the substrate surface with a current flow parallel to the substrate surface H01L21/823431
• 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 29/66621 using etching to form a recess at the gate location etching of semiconductor bodies H01L21/302
• CPC Class Codes: H01L 29/66666 Vertical transistors H01L29/66712, H01L29/66742 take precedence
• CPC Class Codes: H01L 29/7834 with a non-planar structure, e.g. the gate or the source or the drain being non-planar

Abstract

The invention includes methods of forming field effect transistors. In one implementation, the invention encompasses a method of forming a field effect transistor on a substrate, where the field effect transistor comprises a pair of conductively doped source/drain regions, a channel region received intermediate the pair of source/drain regions, and a transistor gate received operably proximate the channel region. Such implementation includes conducting a dopant activation anneal of the pair of source/drain regions prior to depositing material from which a conductive portion of the transistor gate is made. Other aspects and implementations are contemplated.

Claims

1. A method of forming a field effect transistor on a substrate, the field effect transistor comprising a pair of conductively doped source/drain regions, a channel region received intermediate the pair of source/drain regions, and a transistor gate received operably proximate the channel region, the method comprising conducting a dopant activation anneal of the pair of source/drain regions prior to depositing material from which a conductive portion of the transistor gate is made.

2. The method of claim 1 wherein the dopant activation anneal is at least of highest dopant concentration portions of the pair of source/drain regions.

3. The method of claim 1 wherein each of the pair of conductively doped source/drain regions comprises a highest dopant concentration portion and at least one lower dopant concentration portion, the dopant activation anneal being at least of each of said highest and lower dopant concentration portions.

4. The method of claim 3 wherein the dopant in the highest dopant concentration portions is of the same conductivity type as the dopant in said lower dopant concentration portions.

5. The method of claim 3 wherein the dopant in the highest dopant concentration portions and the dopant in said lower dopant concentration portions are of different conductivity types.

6. The method of claim 1 wherein the field effect transistor is p-channel.

7. The method of claim 1 wherein the field effect transistor is n-channel.

8. The method of claim 1 wherein the dopant activated by the dopant activation anneal was provided to the substrate by ion implantation.

9. The method of claim 1 wherein the pair of source/drain regions is formed within bulk monocrystalline semiconductive material of the substrate.

10. The method of claim 9 wherein the field effect transistor gate is formed outwardly of the bulk monocrystalline semiconductive material.

11. The method of claim 9 wherein the field effect transistor gate is formed within an opening formed within the bulk monocrystalline semiconductive material.

12. The method of claim 1 wherein the pair of source/drain regions comprises elevated source/drain regions of a horizontally oriented field effect transistor.

13. The method of claim 12 wherein the substrate comprises bulk monocrystalline semiconductive material, the elevated source/drain regions being formed on the bulk monocrystalline semiconductive material.

14. A method of forming a field effect transistor on a substrate, the field effect transistor comprising a pair of conductively doped source/drain regions, a channel region received intermediate the pair of source/drain regions, and a transistor gate received operably proximate the channel region, the method comprising:

ion implanting conductivity enhancing impurity dopant into semiconductive material of the substrate to form highest dopant concentration portions of the pair of source/drain regions;

conducting a dopant activation anneal of the highest dopant concentration portions of the pair of source/drain regions; and

after the dopant activation anneal, depositing material from which a conductive portion of the transistor gate is made.

15. The method of claim 14 wherein the deposited material from which a conductive portion of the transistor gate is made comprises elemental-form metal.

16. The method of claim 14 wherein the deposited material from which a conductive portion of the transistor gate is made comprises a conductive metal compound.

17. The method of claim 14 wherein the deposited material from which a conductive portion of the transistor gate is made comprises conductively doped semiconductive material.

18. The method of claim 14 further comprising prior to conducting the dopant activation anneal, ion implanting conductivity modifying impurity dopant into semiconductive material of the substrate to form at least one lower dopant concentration portion proximate each highest dopant concentration portion.

23. The method of claim 14 wherein the pair of source/drain regions is formed within bulk monocrystalline semiconductive material of the substrate.

24. The method of claim 23 wherein the field effect transistor gate is formed outwardly of the bulk monocrystalline semiconductive material.

25. The method of claim 23 wherein the field effect transistor gate is formed within an opening formed within the bulk monocrystalline semiconductive material.

26. The method of claim 14 wherein the pair of source/drain regions comprises elevated source/drain regions of a horizontally oriented field effect transistor.

27. The method of claim 26 wherein the substrate comprises bulk monocrystalline semiconductive material, the elevated source/drain regions being formed on the bulk monocrystalline semiconductive material.

19-22. -22. (canceled)

28. A method of forming a field effect transistor on a substrate, the field effect transistor comprising a pair of conductively doped source/drain regions, a channel region received intermediate the pair of source/drain regions, and a transistor gate received operably proximate the channel region, the method comprising:

ion implanting conductivity enhancing impurity dopant into an implant region of semiconductive material of the substrate to a highest dopant concentration for the pair of source/drain regions;

after the ion implanting, conducting a dopant activation anneal of the implant region;

after the dopant activation anneal, etching an opening through the implant region into semiconductive material of the substrate; and

forming gate dielectric and conductive material of the transistor gate within the opening.

29. The method of claim 28 wherein the opening is laterally centered relative to the implant region in at least one straight line cross section of the substrate.

30. The method of claim 28 further comprising prior to conducting the dopant activation anneal, ion implanting conductivity modifying impurity dopant into semiconductive material of the substrate to form at least one lower dopant concentration portion below the implant region, the opening being etched through the portion.

31-39. -39. (canceled)

40. A method of forming an n-channel field effect transistor and a p-channel field effect transistor on a substrate, said transistors respectively comprising a pair of conductively doped source/drain regions, a channel region received intermediate the pair of source/drain regions, and a transistor gate received operably proximate the channel region, the method comprising:

ion implanting p-type conductivity enhancing impurity dopant into semiconductive material of the substrate to form highest dopant concentration portions of the pair of source/drain regions of the p-channel field effect transistor;

ion implanting n-type conductivity enhancing impurity dopant into semiconductive material of the substrate to form highest dopant concentration portions of the pair of source/drain regions of the n-channel field effect transistor;

simultaneously conducting a dopant activation anneal of the highest dopant concentration portions of the pair of source/drain regions of each of the n-channel field effect transistor and of the p-channel field effect transistor; and

after the dopant activation anneal, depositing material from which conductive portions of the transistor gates are made.

41. The method of claim 40 comprising depositing different conductive gate materials for the respective p-channel and n-channel field effect transistors.

42. The method of claim 40 comprising depositing the same conductive gate material for the respective p-channel and n-channel field effect transistors.

43-48. -48. (canceled)

49. A method of forming an n-channel field effect transistor and a p-channel field effect transistor on a substrate, said transistors respectively comprising a pair of conductively doped source/drain regions, a channel region received intermediate the pair of source/drain regions, and a transistor gate received operably proximate the channel region, the method comprising:

ion implanting p-type conductivity enhancing impurity dopant into a first region of semiconductive material of the substrate to a highest dopant concentration for the pair of source/drain regions of the p-channel field effect transistor;

ion implanting n-type conductivity enhancing impurity dopant into a second region of semiconductive material of the substrate to a highest dopant concentration for the pair of source/drain regions of the n-channel field effect transistor;

simultaneously conducting a dopant activation anneal of the first and second regions;

after the dopant activation anneal, etching a first opening through the first region into semiconductive material of the substrate and etching a second opening through the second region into semiconductive material of the substrate;

forming gate dielectric within the first and second openings; and

forming conductive material of the transistor gate of the p-channel field effect transistor over the gate dielectric within the first opening and conductive material of the transistor gate of the n-channel field effect transistor over the gate dielectric within the second opening.

50-54. -54. (canceled)