Method of forming field effect transistor comprising at least one of a conductive metal or metal compound in electrical connection with transistor gate semiconductor material

• US 6,830,975 B2
• Filed: 01/31/2002
• Issued: 12/14/2004
• Est. Priority Date: 01/31/2002
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Sandhu, Sukesh, Bicksler, Andrew R.
• Primary Examiner(s): Pham, Long
• Assistant Examiner(s): Pizarro-Crespo, Marcos D.
• Application Number:
  US10/061,739
• Publication Number:
  US 20030143814A1
• Time in Patent Office: 1,048 Days
• Field of Search: 438/257-267, 438/584-596
• US Class Current: 438/265
• CPC Class Codes: H01L 21/28247 passivation or protection of the electrode, e.g. using re-oxidation
• CPC Class Codes: H01L 29/40114 the electrodes comprising a conductor-insulator-conductor-insulator-semiconductor structure
• CPC Class Codes: H01L 29/66825 with a floating gate H01L29/6684 takes precedence
• CPC Class Codes: H01L 29/7881 Programmable transistors with only two possible levels of programmation H01L29/7888 takes precedence

Abstract

The invention includes methods of forming field effect transistors. In one implementation, a method of forming a field effect transistor having a gate comprising a conductive metal or metal compound received over conductively doped semiconductive material includes forming transistor gate semiconductive material into a gate line over a semiconductive material channel region. The gate line includes semiconductive material sidewalls. The semiconductive material sidewalls of the gate line are oxidized. After the oxidizing, at least one of a conductive metal or metal compound is formed in electrical connection with the transistor gate semiconductive material to comprise a substantially coextensive elongated portion of a final construction of the gate line of the field effect transistor being formed.

Claims

1. A method of forming a line of field effect transistors respectively having a gate comprising a conductive metal or metal compound received over conductively doped semiconductive material, the method comprising:

forming transistor gate semiconductive material into an elongated continuous gate line over a semiconductive material channel region, the gate line comprising elongated continuous semiconductive material sidewalls of the line of field effect transistors being formed;

oxidizing the elongated continuous semiconductive material sidewalls of the gate line; and

after the oxidizing, forming at least one of a conductive metal or metal compound in electrical connection with the transistor gate semiconductive material to comprise a substantially coextensive elongated portion of a final construction of the elongated continuous gate line of the field effect transistors being formed, the coextensive elongated portion comprising both the transistor gate semiconductive material and the at least one of the conductive metal or metal compound.

2. The method of claim 1 wherein the forming of the transistor gate semiconductive material into a gate line comprises deposition of the transistor gate semiconductive material followed by patterning and subtractive etching of it.

3. The method of claim 1 wherein the semiconductive material channel region comprises bulk semiconductive material.

4. The method of claim 1 wherein the oxidizing is effective to grow oxide on the elongated continuous semiconductive material sidewalls to have a maximum thickness of at least 30 Angstroms.

5. The method of claim 1 wherein the forming of the at least one of a conductive metal or metal compound comprises forming a conductive metal.

6. The method of claim 1 wherein the forming of the at least one of a conductive metal or metal compound comprises forming a conductive metal compound.

7. The method of claim 1 wherein the forming of the at least one of a conductive metal or metal compound comprises deposition of the at least one of a conductive metal or metal compound followed by patterning and subtractive etching of it.

8. The method of claim 1 wherein the forming of the at least one of a conductive metal or metal compound comprises selective formation of it on the transistor gate semiconductive material.

9. The method of claim 1 wherein the field effect transistor gates respectively comprise a floating gate field effect transistor gate, the method further comprising forming the gate line to comprise a plurality of floating gates underlying a continuous elongated control gate line, the oxidizing also oxidizing sidewalls of the floating gates.

10. The method of claim 1 wherein the field effect transistor gate does not comprise a floating gate.

11. The method of claim 1 further comprising conducting a highest dose source/drain implant for the transistors prior to the oxidizing.

12. The method of claim 1 wherein the forming of the at least one of a conductive metal or metal compound comprises deposition of the at least one of a conductive metal or metal compound followed by polishing of it without photolithographic patterning of it.

13. A method of forming a line of floating gate field effect transistors comprising:

forming floating gate semiconductive material over a semiconductive material channel region;

forming dielectric material over the floating gate semiconductive material;

forming control gate semiconductive material over the dielectric material;

in a common masking step, patterning the floating gate semiconductive material and the control gate semiconductive material into a desired elongated final gate line shape comprising floating gate semiconductive material sidewalls and elongated continuous control gate line semiconductive material sidewalls of the line of floating gate field effect transistors being formed;

after the patterning, oxidizing the floating gate semiconductive material sidewalls and the elongated continuous control gate line semiconductive material sidewalls in a common oxidizing step; and

after the oxidizing, forming at least one of a conductive metal or metal compound in electrical connection with the patterned elongated continuous gate line shape of the control gate semiconductive material to comprise a substantially coextensive elongated portion of a final construction of a control gate line of the line of floating gate field effect transistors being formed, the coextensive elongated portion comprising both the control gate semiconductive material and the at least one of the conductive metal or metal compound.

14. The method of claim 13 wherein the masking and patterning comprise photolithography and subtractive etch.

15. The method of claim 13 wherein the oxidizing is effective to grow oxide on the floating gate semiconductive material sidewalls and on the elongated continuous control gate line semiconductive sidewalls to have a maximum thickness of at least 30 Angstroms.

16. The method of claim 13 wherein the forming of the at least one of a conductive metal or metal compound comprises forming a conductive metal.

17. The method of claim 13 wherein the forming of the at least one of a conductive metal or metal compound comprises forming a conductive metal compound.

18. The method of claim 13 wherein the forming of the at least one of a conductive metal or metal compound comprises deposition of the at least one of a conductive metal or metal compound followed by patterning and subtractive etching of it.

19. The method of claim 13 further comprising conducting a highest dose source/drain implant for the floating gate field effect transistors prior to the oxidizing.

20. The method of claim 13 wherein the forming of the at least one of a conductive metal or metal compound comprises deposition of the at least one of a conductive metal or metal compound followed by polishing of it without photolithographic patterning of it.

21. A method of forming a line of field effect transistors respectively having a gate comprising a conductive metal or metal compound received over conductively doped semiconductive material, the method comprising:

forming transistor gate semiconductive material over a semiconductive material channel region;

forming masking material over the transistor gate semiconductive material;

patterning the transistor gate semiconductive material and the masking material into an elongated continuous gate line comprising elongated continuous semiconductive material sidewalls of the line of field effect transistors being formed;

after the patterning, oxidizing the elongated continuous semiconductive material sidewalls of the gate line;

after the oxidizing, depositing insulative material over the gate line including the patterned masking material;

after the depositing, exposing the masking material of the gate line through the insulative material;

after the exposing, removing the masking material effective to form a trough line within the insulative material that is substantially coextensive with and over the transistor gate semiconductive material of the line of field effect transistors being formed; and

after the removing, forming at least one of a conductive metal or metal compound in electrical connection with the transistor gate semiconductive material within the trough line to comprise a substantially coextensive elongated portion of a final construction of the gate line of the field effect transistors being formed.

22. The method of claim 21 wherein the masking material is insulative.

23. The method of claim 21 wherein the masking material is conductive.

24. The method of claim 21 wherein the removing removes all of the masking material remaining overlying the transistor gate semiconductive material.

25. The method of claim 21 wherein the removing does not remove all of the masking material remaining overlying the transistor gate semiconductive material.

26. The method of claim 21 wherein the exposing comprises polishing.

27. The method of claim 21 wherein the removing comprises chemical etching.

28. The method of claim 21 wherein the removing exposes the transistor gate semiconductive material.

29. The method of claim 21 wherein the forming of the at least one of a conductive metal or metal compound comprises deposition of the at least one of a conductive metal or metal compound followed by photolithographic patterning and subtractive etching of it.

30. The method of claim 21 wherein the forming of the at least one of a conductive metal or metal compound comprises deposition of the at least one of a conductive metal or metal compound followed by polishing of it without photolithographic patterning of it.

31. The method of claim 21 wherein the field effect transistor gates respectively comprise a floating gate field effect transistor gate, the method further comprising forming the gate line to comprise a plurality of floating gates underlying a continuous elongated control gate line, the oxidizing also oxidizing sidewalls of the floating gates.

32. The method of claim 21 wherein the field effect transistor gate does not comprise a floating gate.