Methods for anisotropic control of selective silicon removal

• US 10,170,336 B1
• Filed: 08/04/2017
• Issued: 01/01/2019
• Est. Priority Date: 08/04/2017
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Li, Zihui, Kao, Chia-Ling, Wang, Anchuan, Ingle, Nitin K.
• Primary Examiner(s): Vinh, Lan
• Application Number:
  US15/669,326
• Time in Patent Office: 515 Days
• Field of Search: 438706, 438710, 438712, 438714, 438719, 438923, 438736, 438778, 438700
• CPC Class Codes: H01J 37/32357 Generation remote from the workpiece, e.g. down-stream
• CPC Class Codes: H01J 37/32422 Arrangement for selecting ions or species in the plasma
• CPC Class Codes: H01J 37/3244 Gas supply means
• CPC Class Codes: H01L 21/02123 the material containing silicon
• CPC Class Codes: H01L 21/02252 formation by plasma treatment, e.g. plasma oxidation of the substrate after treatment of an insulating film by plasma H01L21/3105 and subgroups
• CPC Class Codes: H01L 21/3065 Plasma etching; Reactive-ion etching
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/31138 by dry-etching
• CPC Class Codes: H01L 21/32137 of silicon-containing layers
• CPC Class Codes: H01L 21/67069 for drying etching
• CPC Class Codes: H01L 29/401 Multistep manufacturing processes
• CPC Class Codes: H01L 29/66545 using a dummy, i.e. replacement gate in a process wherein at least a part of the final gate is self aligned to the dummy gate

Abstract

Embodiments of the present technology may include a method of etching. The method may include flowing a gas through a plasma to form plasma effluents. The method may also include reacting plasma effluents with a first layer defining a first feature. The first feature may include a first sidewall, a second sidewall, and a bottom. The first sidewall, the second sidewall, and the bottom may include the first layer. The first layer may be characterized by a first thickness on the sidewall. The method may further include forming a second layer from the reaction of the plasma effluents with the first layer. The first layer may be replaced by the second layer. The second layer may be characterized by a second thickness. The second thickness may be greater than or equal to the first thickness. The method may also include removing the second layer to expose a third layer.

Claims

1. A method of etching, the method comprising:

flowing a gas through a plasma to form plasma effluents;

reacting plasma effluents with a first layer defining a first feature, wherein;

the first feature comprises a first sidewall, a second sidewall, and a first bottom,

the first sidewall, the second sidewall, and the bottom comprise the first layer, and

the first layer is characterized by a first thickness on the first sidewall;

forming a second layer from the reaction of the plasma effluents with the first layer to define a third feature, wherein;

the third feature comprises a third sidewall, a fourth sidewall, and a second bottom,

the first layer is replaced by the second layer,

the third sidewall, the fourth sidewall, and the second bottom comprise the second layer,

the first sidewall is replaced by the third sidewall,

the second layer is characterized by a second thickness on the third sidewall, and

the second thickness is greater than or equal to the first thickness; and

removing the second layer to expose a third layer, the third layer defining a second feature.

2. The method of claim 1, wherein:

the first feature is a trench or via characterized by a height,

the height is a first height before reacting plasma effluents with the first layer, and

forming the second layer comprises reducing the height of the trench or via from the first height to a second height.

3. The method of claim 1, wherein the second feature is a trench or via.

4. The method of claim 1, wherein reacting plasma effluents with the first layer is at a pressure greater than or equal to 1 Torr.

5. The method of claim 1, wherein reacting plasma effluents with the first layer is at a temperature of less than or equal to 70°

C.

6. The method of claim 1, wherein the first layer comprises silicon.

7. The method of claim 1, wherein the second layer comprises (NH₄)₂SiF₆.

8. The method of claim 1, wherein the second layer comprises N—

H and Si—

F bonds.

9. The method of claim 1, wherein the gas comprises:

a fluorine-containing gas, and

a hydrogen-containing gas, wherein;

the fluorine-containing gas comprises NF₃, F₂, or HF, and

the hydrogen-containing gas comprises H₂, NH₃, or an amine.

10. The method of claim 1, wherein the first thickness is in a range from 15 Angstroms to 300 Angstroms.

11. The method of claim 1, wherein the first layer comprises polysilicon.

12. The method of claim 11, wherein the second layer comprises N—

H and Si—

F bonds.

13. The method of claim 11, wherein the second layer comprises (NH₄)₂SiF₆.

14. A method of etching, the method comprising:

flowing a gas through a plasma to form plasma effluents;

reacting plasma effluents with a first layer defining a first trench, wherein;

the first trench comprises a first sidewall, a second sidewall, and a bottom,

the first sidewall, the second sidewall, and the bottom comprise the first layer,

the first layer is characterized by a first thickness at a first position on the first sidewall, and

the first layer is characterized by a second thickness at a second position above the first position on the first sidewall;

forming a second layer from the reaction of the plasma effluents with the first layer, wherein a portion of the first layer is replaced by a second layer; and

removing the second layer to expose a remaining portion of the first layer and to define a second trench, wherein;

the remaining portion of the first layer is characterized by a third thickness at the second position on the first sidewall,

the remaining portion of the first layer is characterized by a fourth thickness at the first position on the first sidewall, and

the fourth thickness is greater than the third thickness.

15. The method of claim 14, wherein the third thickness is the minimum thickness of the remaining portion of the first layer on the first sidewall.

16. The method of claim 14, wherein:

the first position is located at the top of the second trench where the second trench becomes substantially perpendicular to the first sidewall, and

the second position is located at a location where immediately below the second position, the first layer does not contact a void defined by the second trench in a direction perpendicular to the first sidewall.

17. The method of claim 14, wherein the first layer comprises polysilicon.

18. The method of claim 17, wherein the second layer comprises N—

H and Si—

F bonds.

19. The method of claim 18, wherein the second layer comprises (NH₄)₂SiF₆.

20. A method of etching, the method comprising:

flowing a gas through a plasma to form plasma effluents;

reacting plasma effluents with a polysilicon layer defining a first trench, wherein;

the first trench comprises a first sidewall, a second sidewall, and a bottom,

the first sidewall, the second sidewall, and the bottom comprise the polysilicon layer, and

the polysilicon layer is characterized by a first thickness on the first sidewall;

forming a first solid layer from the reaction of the plasma effluents with the polysilicon layer, wherein;

the polysilicon layer is replaced by the first solid layer,

the first solid layer comprises (NH₄)₂SiF₆,

the first solid layer is characterized by a second thickness, and

the second thickness is greater than or equal to the first thickness; and

removing the first solid layer to expose a second solid layer, the second solid layer defining a portion of a second trench.