Method of selectively etching silicon oxide film on substrate

Patent metadata

Field	Value
Publication number	US-11205577-B2
Application number	US-201815905213-A
Country	US
Kind code	B2
Filing date	Feb 26, 2018
Priority date	Feb 24, 2015
Publication date	Dec 21, 2021
Grant date	Dec 21, 2021

Abstract

An etching method including: (a) providing a workpiece including a first region made of a first material and a second region made of a second material defining a recess, the first region filling the recess of the second region while covering the second region; (b) generating plasma of a first fluorocarbon gas to etch the first region until before exposing the second region; (c) generating plasma of a second fluorocarbon gas to form fluorocarbon deposits on the first region; (d) generating plasma of an inert gas to etch the first region by fluorocarbon radicals contained in the fluorocarbon deposits; and (e) repeating step (c) and step (d) one or more times until after exposing the second region. An etching rate of the first material of the first region is higher than that of the second material of the second region with respect to the second fluorocarbon gas.

First claim

What is claimed is:

1. An etching method comprising:
(a) providing a workpiece including a first region made of a first material and a second region made of a second material defining a recess, the first region filling the recess of the second region while covering the second region;
(b) generating plasma of a first fluorocarbon gas to etch the first region until before exposing the second region;
(c) generating plasma of a second fluorocarbon gas to form fluorocarbon deposits on the first region;
(d) generating plasma of a processing gas containing only an inert gas to etch the first region by fluorocarbon radicals contained in the fluorocarbon deposits; and
(e) repeating step (c) and step (d) one or more times until after exposing the second region,
wherein during a sequence of steps (c) through (e), the first region is selectively etched with respect to the second region,
wherein a material of the fluorocarbon deposits is different from a material of the first region.

2. The etching method according to claim 1 , wherein the first material includes SiO 2 , and the second material includes SiN.

3. The etching method according to claim 1 , further comprising:
(f) generating plasma of a third fluorocarbon gas to etch the first region after step (e).

4. The etching method according to claim 3 , wherein an etching rate of the etching the first region by the plasma of the third fluorocarbon gas in step (f) is higher than an etching rate of the etching the first region during the sequence of steps (c) through (e).

5. The etching method according to claim 3 , wherein the generating plasma of the third fluorocarbon gas of step (f) continuously etches the first region in the recess to a bottom of the recess.

6. The etching method according to claim 3 , wherein, in the generating plasma of the third fluorocarbon gas of step (f), a negative voltage is applied to an upper electrode which faces the workpiece.

7. The etching method according to claim 3 , wherein a high frequency bias power in the generating plasma of the third fluorocarbon gas is higher than a high frequency bias power in the generating the plasma of the second fluorocarbon gas of step (c).

8. The etching method according to claim 1 , wherein the first fluorocarbon gas is different from the second fluorocarbon gas in a ratio of a number of fluorine atoms to a number of carbon atoms.

9. The etching method according to claim 8 , wherein the ratio of the number of fluorine atoms to the number of carbon atoms is higher in the first fluorocarbon gas than in the second fluorocarbon gas.

10. The etching method according to claim 1 , wherein the workpiece includes a mask formed on the first region providing an opening having a width wider than a width of the recess formed in the second region.

11. The etching method according to claim 1 , wherein the first fluorocarbon gas includes at least one of a CF 4 gas, and a C 4 F 8 gas, and
wherein the second fluorocarbon gas includes a C 4 F 6 gas.

12. The etching method according to claim 1 , wherein, in the generating plasma of the processing gas containing only the inert gas of step (d), a high frequency power for generating plasma and a high frequency bias power are applied to a lower electrode that supports the workpiece.

13. The etching method according to claim 12 , wherein the high frequency power ranges from 100 W to 500 W.

14. The etching method according to claim 12 , wherein the high frequency bias power ranges from 20 W to 300 W.

15. The etching method according to claim 1 , wherein, in the generating plasma of the processing gas containing only the inert gas of step (d), a flow rate of the inert gas ranges from 500 sccm to 1500 sccm.

16. The etching method according to claim 1 , further comprising:
(h) generating plasma of an oxygen-containing gas between the generating plasma of the first fluorocarbon gas of step (b) and the generating plasma of the second fluorocarbon gas of step (c).

17. The etching method according to claim 1 , wherein the material of the first region is silicon oxide.

18. An etching method comprising:
(a) providing a workpiece including a first region made of a first material and a second region made of a second material defining a recess, the first region filling the recess of the second region while covering the second region;
(b) generating plasma of a first fluorocarbon gas to etch the first region until before exposing the second region;
(c) generating plasma of a second fluorocarbon gas to form fluorocarbon deposits on the first region;
(d) generating plasma of a processing gas containing only an inert gas to etch the first region by fluorocarbon radicals contained in the fluorocarbon deposits; and
(e) repeating step (c) and step (d) one or more times until after exposing the second region,
wherein during a sequence of steps (c) through (e), the first region is selectively etched with respect to the second region;
the method further comprising:
(f) generating plasma of an oxygen-containing gas, that does not contain a fluorocarbon gas, and an inert gas either in between the generating plasma of the second fluorocarbon gas of step (c) and the generating plasma of the processing gas containing only the inert gas of step (d), or after the generating plasma of the processing gas containing only the inert gas of step (d),
wherein a material of the fluorocarbon deposits is different from a material of the first region.

19. The etching method according to claim 18 , wherein the generating plasma of the oxygen-containing gas and the inert gas of step (f) is performed for at least 2 seconds between the generating plasma of the second fluorocarbon gas of step (c) and the generating plasma of the processing gas containing only the inert gas of step (d).

20. An etching method comprising:
(a) providing a workpiece including a first region and a second region defining a recess therein, the first region filling the recess of the second region while covering the second region;
(b) generating plasma of a first fluorocarbon gas to etch the first region until before exposing the second region;
(c) generating plasma of a second fluorocarbon gas to form fluorocarbon deposits on the first region;
(d) generating plasma of a processing gas containing only an inert gas to etch the first region by fluorocarbon radicals contained in the fluorocarbon deposits; and
(e) repeating step (c) and step (d) one or more times until after exposing the second region,
wherein the first fluorocarbon gas is different from the second fluorocarbon gas, and
the first region is made of a first material that is etched by the fluorocarbon deposits and the second region is made of a second material different from the first material, and the second region is protected by the fluorocarbon deposits,
wherein a material of the fluorocarbon deposits is different from a material of the first region.

21. The etching method according to claim 20 , wherein the material of the first region is silicon oxide.

Assignees

• Tokyo Electron Ltd

Inventors

• Watanabe Hikaru
• Tsuji Akihiro

Classifications

• H10P50/73

  using masks for insulating materials · CPC title

• H10W20/088

  involving partial etching of via holes · CPC title

• H10W20/085

  involving intermediate temporary filling with material · CPC title

• H10W20/084

  for dual-damascene structures · CPC title

• H10W20/069

  by forming self-aligned vias or self-aligned contact plugs · CPC title