Method for selective etching of a block copolymer

Patent metadata

Field	Value
Publication number	US-10875236-B2
Application number	US-201615759086-A
Country	US
Kind code	B2
Filing date	Sep 9, 2016
Priority date	Sep 11, 2015
Publication date	Dec 29, 2020
Grant date	Dec 29, 2020

Abstract

A method for etching a layer of assembled block copolymer including first and second polymer phases, the etching method including a first step of etching by a first plasma formed from carbon monoxide or a first gas mixture including a fluorocarbon gas and a depolymerising gas, the first etching step being carried out so as to partially etch the first polymer phase and to deposit a carbon layer on the second polymer phase, and a second step of etching by a second plasma formed from a second gas mixture including a depolymerising gas and a gas selected among the carbon oxides and the fluorocarbon gases, the second etching step being carried out so as to etch the first polymer phase and the carbon layer on the second polymer phase.

First claim

The invention claimed is:

1. A method for etching an assembled block copolymer layer comprising first and second polymer phases, the etching method comprising:
a first step of etching by a first plasma formed from carbon monoxide or a first gas mixture comprising a fluorocarbon gas and a depolymerising gas, the first etching step being carried out so as to partially etch the first polymer phase and to deposit a carbon layer on the second polymer phase, and
a second step of etching by a second plasma formed from a second gas mixture comprising a depolymerising gas and a gas selected among the carbon oxides and the fluorocarbon gases, the second etching step being carried out so as to etch the first polymer phase and the carbon layer on the second polymer phase.

2. The method according to claim 1 , comprising a plurality of successive etching cycles, each etching cycle successively comprising the first etching step and the second etching step.

3. The method according to claim 1 , wherein the first plasma and the second plasma are formed using a same gas other than the depolymerising gas.

4. The method according to claim 3 , wherein the second mixture comprises carbon monoxide.

5. The method according to claim 3 , wherein the first etching step has a ratio of the flow rate of fluorocarbon gas over the flow rate of depolymerising gas comprised between 0.8 and 1.2 and wherein the second etching step has a ratio of the flow rate of fluorocarbon gas over the flow rate of depolymerising gas comprised between 0.3 and 0.7.

6. The method according to claim 1 , wherein the second etching step has a ratio of the flow rate of carbon oxide over the flow rate of depolymerising gas comprised between 0.3 and 50.

7. The method according to claim 1 , wherein the first etching step is carried out in conditions such that the carbon layer is only deposited on the second polymer phase.

8. The method according to claim 7 , wherein the first etching step has a duration comprised between 5 s and 30 s.

9. The method according to claim 1 , wherein the first etching step is carried out in conditions such that the carbon layer is further deposited on the first partially etched polymer phase, the carbon layer having a thickness on the first polymer phase lower than on the second polymer phase.

10. The method according to claim 1 , wherein the second etching step has a duration comprised between 5 s and 30 s.

11. The method according to claim 1 , wherein the first polymer phase is PMMA or PLA, and wherein the second polymer phase is PS, PDMS, or PDMSB.

12. The method according to claim 1 , wherein the depolymerising gas of the first mixture and the depolymerising gas of the second mixture are selected from H 2 , N 2 , O 2 , Xe, Ar and He.

Assignees

• Commissariat Energie Atomique

Inventors

• Posseme Nicolas
• Barnola Sébastien
• Pimenta Barros Patricia
• Sarrazin Aurélien

Classifications

• H10P14/3406

  Carbon, e.g. diamond-like carbon · CPC title

• H10W20/048

  by using plasmas or gaseous environments, e.g. by nitriding · CPC title

• G03F7/0002 Primary

  Lithographic processes using patterning methods other than those involving the exposure to radiation, e.g. by stamping · CPC title

• C08F8/50

  Partial depolymerisation · CPC title

• C08F299/024

  the unsaturation being in acrylic or methacrylic groups · CPC title