Footing removal for nitride spacer

• US 10,629,473 B2
• Filed: 09/09/2016
• Issued: 04/21/2020
• Est. Priority Date: 09/09/2016
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Ko, Jungmin, Choi, Tom
• Primary Examiner(s): Lee, Jae
• Application Number:
  US15/260,705
• Publication Number:
  US 20180076083A1
• Time in Patent Office: 1,320 Days
• CPC Class Codes: H01J 37/32091 the radio frequency energy being capacitively coupled to the plasma
• CPC Class Codes: H01J 37/32357 Generation remote from the workpiece, e.g. down-stream
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/76213 introducing electrical inactive or active impurities in the local oxidation region, e.g. to alter LOCOS oxide growth characteristics or for additional isolation purpose

Abstract

Processing methods may be performed to remove unwanted materials from a substrate, such as an oxide footing. The methods may include forming an inert plasma within a processing region of a processing chamber. Effluents of the inert plasma may be utilized to modify a surface of an exposed material on a semiconductor substrate within the processing region of the semiconductor chamber. A remote plasma may be formed from a fluorine-containing precursor to produce plasma effluents. The methods may include flowing the plasma effluents to the processing region of the semiconductor processing chamber. The methods may also include removing the modified surface of the exposed material from the semiconductor substrate.

Claims

1. An etching method comprising:

forming an inert plasma within a processing region of a semiconductor processing chamber;

modifying a surface of an exposed material on a semiconductor substrate within the processing region of the semiconductor processing chamber with effluents of the inert plasma, wherein the exposed material comprises silicon oxide, wherein modifying the surface of the exposed material comprises damaging the surface of the exposed material with the effluents of the inert plasma, wherein damaging the surface of the exposed material comprises breaking bonds between silicon and oxygen atoms with the effluents of the inert plasma, and wherein the effluents of the inert plasma break the bonds between the silicon and oxygen atoms without chemically bonding to the silicon or oxygen atoms;

forming a remote plasma from a fluorine-containing precursor to produce plasma effluents;

flowing the plasma effluents to the processing region of the semiconductor processing chamber; and

removing the modified surface of the exposed material from the semiconductor substrate, wherein during the etching method essentially no solid byproducts of the exposed material are produced.

2. The etching method of claim 1, wherein the inert plasma comprises a hydrogen plasma.

3. The etching method of claim 1, wherein the inert plasma is formed from a bias power below about 100 W.

4. The etching method of claim 1, wherein the surface of the exposed material on the semiconductor substrate is modified to a depth from the exposed surface within the semiconductor substrate of less than about 4 nm.

5. The etching method of claim 1, wherein a pressure within the semiconductor processing chamber while forming the inert plasma and during the modifying is maintained below about 50 mTorr.

6. The etching method of claim 1, wherein the remote plasma is formed in a remote region of the semiconductor processing chamber fluidly isolated from the processing region of the semiconductor processing chamber or is formed in a remote plasma unit fluidly coupled with the semiconductor processing chamber.

7. The etching method of claim 1, wherein the semiconductor substrate is maintained at a temperature above or about 80°

C. during the removal of the modified surface of the exposed material.

8. The etching method of claim 1, wherein the exposed material on the semiconductor substrate comprises a footing located proximate a nitride spacer positioned along the semiconductor substrate.

9. The etching method of claim 1, wherein the remote plasma is additionally formed from a hydrogen-containing precursor.

10. The etching method of claim 1, wherein each operation of the etching method is repeated in at least one additional cycle, and wherein a total removal after all cycles is less than 10 nm.

17. The etching method of claim 1, wherein the inert plasma is formed exclusively of hydrogen.

18. The etching method of claim 1, wherein breaking the bonds between silicon and oxygen atoms with the effluents of the inert plasma forms oxygen dangling bonds at the surface of the exposed material.

11. An etching method comprising:

forming an inert plasma within a processing region of a semiconductor processing chamber;

modifying a surface of an exposed region of silicon oxide on a semiconductor substrate within the processing region of the semiconductor processing chamber with effluents of the inert plasma, wherein modifying the surface of the exposed region of silicon oxide comprises damaging the surface of the exposed region of silicon oxide, wherein damaging the surface of the exposed region of silicon oxide comprises breaking bonds between silicon and oxygen atoms, and wherein the effluents of the inert plasma break the bonds between the silicon and oxygen atoms while limiting chemical interaction with the silicon or oxygen atoms; and

contacting the modified silicon oxide with plasma effluents of a fluorine-containing precursor, wherein the plasma effluents of the fluorine-containing precursor are formed in a remote region of the semiconductor processing chamber fluidly coupled with, and physically separated from, the processing region of the semiconductor processing chamber.

12. The etching method of claim 11, wherein the etching is performed at a temperature of about 100°

C.

13. The etching method of claim 11, wherein the plasma effluents of the fluorine-containing precursor are produced by a capacitively-coupled plasma at a power level of about 300 W.

19. The etching method of claim 11, wherein the remote region of the semiconductor processing chamber is fluidly coupled with, and physically separated from, the processing region of the semiconductor processing chamber by an electrode, wherein the electrode is configured to energize the fluorine-containing precursor to form the plasma effluents of the fluorine-containing precursor, and wherein the electrode in part defines the remote region of the semiconductor processing chamber.

20. The etching method of claim 11, further comprising:

contacting the modified silicon oxide with a hydrogen-containing precursor, wherein the hydrogen-containing precursor bypasses the remote region of the semiconductor processing chamber, and wherein the hydrogen-containing precursor interacts with the plasma effluents of the fluorine-containing precursor subsequent to the plasma effluents of the fluorine-containing precursor exiting the remote region of the semiconductor processing chamber; and

etching the modified silicon oxide, wherein the modifying, contacting, and etching are all performed in the semiconductor processing chamber, and wherein essentially no solid byproducts of the modified silicon oxide are produced during the etching method.

14. An etching method comprising:

forming an inert plasma within a processing region of a semiconductor processing chamber, wherein the inert plasma comprises a hydrogen plasma formed by a bias power of less than 100 W;

modifying an exposed region of silicon oxide on a semiconductor substrate within the processing region of the semiconductor processing chamber with effluents of the inert plasma, wherein the exposed region of silicon oxide comprises a footing positioned about an intersection of a nitride spacer with a surface of silicon oxide from which the nitride spacer extends, wherein a pressure within the semiconductor processing chamber is maintained below about 100 mTorr during the modifying;

forming a plasma of a fluorine-containing precursor in a remote region of the semiconductor processing chamber that is separated from the processing region of the semiconductor processing chamber by a showerhead;

contacting the modified silicon oxide with plasma effluents of the fluorine-containing precursor; and

etching the modified silicon oxide footing at a temperature of about 100°

C., wherein the modifying, contacting, and etching are all performed in the semiconductor processing chamber, and wherein no solid byproducts are produced during the etching.

15. The etching method of claim 14, wherein the remote region of the semiconductor processing chamber is a region defined within the semiconductor processing chamber.

16. The etching method of claim 14, wherein the remote region of the semiconductor processing chamber is a region external to the semiconductor processing chamber, but fluidly coupled with an inlet to the semiconductor processing chamber.