Plasma etching method for selectively etching silicon oxide with respect to silicon nitride

Patent metadata

Field	Value
Publication number	US-2020161138-A1
Application number	US-202016750530-A
Country	US
Kind code	A1
Filing date	Jan 23, 2020
Priority date	Jan 16, 2015
Publication date	May 21, 2020
Grant date	—

Abstract

An etching method is provided for selectively etching a first region of silicon oxide with respect to a second region of silicon nitride by performing plasma processing on a target object including the first region and the second region. In the etch method, first, a plasma of a processing gas including a fluorocarbon gas is generated in a processing chamber where the target object is accommodated. Next, the plasma of the processing gas including the fluorocarbon gas is further generated in the processing chamber where the target object is accommodated. Next, the first region is etched by radicals of fluorocarbon contained in a deposit which is formed on the target object by the generation and the further generation of the plasma of the processing gas containing the fluorocarbon gas. A high frequency powers used for the plasma generation is smaller than a high frequency power used for plasma further generation.

First claim

What is claimed is:

1 . An apparatus for etching a target object, the target object including a first silicon containing material and a second silicon containing material different from the first silicon containing material, the apparatus comprising:
a chamber having a gas inlet and a gas outlet; a plasma generator; a controller configured to cause:
(a) generating a first plasma from a processing gas with a first radio frequency power, and
exposing the target object to the first plasma to form a first deposit on the target object;
(b) generating a second plasma from the processing gas with a second radio frequency power greater than the first radio frequency power, and exposing the target object to the second plasma to form a second deposit on the target object; and
(c) generating a third plasma from an inert gas, and exposing the first deposit and the second deposit on the target object to the third plasma to etch the first region.

2 . The apparatus of claim 1 , wherein the processing gas includes carbon species and fluorine species.

3 . The apparatus of claim 1 , wherein the first deposit is thinner than the second deposit.

4 . The apparatus of claim 1 , wherein the target object is etched in (a) and (b) and an etching amount of the target object in (a) is smaller than an etching amount of the target object in (b).

5 . The apparatus of claim 1 , wherein a sequence including (a) to (c) is repeatedly performed.

6 . The apparatus of claim 1 , wherein the controller is further configured to cause:
(d) generating a forth plasma from an another processing gas, and exposing the target object to the forth plasma to etch the first region before (a).

7 . The apparatus of claim 6 , wherein each of the processing gas and the another processing gas includes carbon and fluorine, and
wherein a ratio of fluorine atoms to carbon atoms in the another processing gas used in (d) is higher than that in the processing gas used in (a) and (b).

8 . The apparatus of claim 6 , wherein (d) is performed with a bias power for attracting ions to the target object, and
wherein the bias power used in (d) is greater than bias powers used in (a) and (b).

9 . The apparatus of claim 6 , wherein the processing gas used in (a) and (b) includes C 4 F 6 gas, and
wherein a ratio of fluorine atoms to carbon atoms in the another processing gas used in (d) is higher than that in the C 4 F 6 gas.

10 . The apparatus of claim 1 , wherein the controller is further configured to cause:
(e) generating a fifth plasma from an oxygen-containing gas and an inert gas, and exposing the target object.

11 . The apparatus of claim 10 , wherein (e) is performed after (b).

12 . The apparatus of claim 10 , wherein (e) is performed before (c).

13 . The apparatus of claim 1 , wherein (c) is performed with a radio frequency bias power for attracting ions to the target object, and
wherein the radio frequency bias power used in (c) is greater than radio frequency bias powers used in (a) and (b).

14 . The apparatus of claim 1 , wherein the second region is formed to have a recess,
wherein the first region fills the recess and covers the second region, wherein the target object includes a mask that is provided on the first region and has an opening provided over the recess, and wherein the controller is further configured to cause:
(f) generating a sixth plasma from an oxygen-containing gas, and exposing the target object to increase the width of the opening before (a).

15 . The apparatus of claim 1 , wherein the first silicon containing material is silicon oxide and the second silicon containing material is silicon nitride.

16 . The apparatus of claim 1 , wherein the second region is formed to have a recess,
wherein the first region fills the recess and covers the second region,
wherein the target object includes a mask that is provided on the first region and has an opening provided over the recess, and
wherein the controller configured to further cause:
(g) etching the first region until immediately before the second region is exposed before (a).

17 . The apparatus of claim 1 , wherein (a) is executed in a period including a time when the second region is exposed.

18 . An apparatus for etching a first silicon containing material with respect to a second silicon containing material different with the first silicon containing material, the apparatus comprising:
a chamber having a gas inlet and a gas outlet; a plasma generator; a controller configured to cause:
(a) generating a first plasma from a processing gas with a first radio frequency power, and exposing a target object to the first plasma, the target object including the first silicon containing material and the second silicon containing material;
(b) generating a second plasma from the processing gas with a second radio frequency power greater than the first radio frequency power, and exposing the target object to the second plasma; and
(c) generating a third plasma from an inert gas; and exposing the target object to the third plasma.

Assignees

• Tokyo Electron Ltd

Inventors

• Watanabe Hikaru
• Tsuji Akihiro

Classifications

• H01J37/32449

  Gas control, e.g. control of the gas flow · CPC title

• H01J37/32174

  Circuits specially adapted for controlling the RF discharge · CPC title

• H01J37/3244 Primary

  Gas supply means · CPC title

• H01L21/76813

  Electricity · mapped topic

• H01L21/32137

  Electricity · mapped topic