Continuous and pulsed rf plasma for etching metals

Patent metadata

Field	Value
Publication number	US-2018061663-A1
Application number	US-201715687775-A
Country	US
Kind code	A1
Filing date	Aug 28, 2017
Priority date	Aug 30, 2016
Publication date	Mar 1, 2018
Grant date	—

Abstract

Methods for etching tungsten and other metal or metal-containing films using a nitrogen-containing etchant gas are provided. The methods involve exposing the film to a continuous wave (CW) plasma and switching to a pulsed plasma toward the end of the etching operation. The pulsed plasma has a lower concentration of nitrogen radicals and can mitigate the effects of nitridation on the tungsten surface. In some embodiments, subsequent deposition on etched surfaces is performed with no nucleation delay. Apparatuses for performing the methods are also provided.

First claim

What is claimed is:

1 . A method comprising:
providing a substrate having a feature partially filled with tungsten; exposing the substrate to a continuous wave (CW) plasma generated from a nitrogen-containing and fluorine-containing gas; and exposing the substrate to a pulsed plasma generated from the nitrogen-containing and fluorine-containing gas, wherein the tungsten is preferentially etched from the top of the feature by exposure to the CW plasma and the pulsed plasma.

2 . The method of claim 1 , wherein exposing the substrate to a CW plasma generated from a nitrogen-containing and fluorine-containing gas and exposing the substrate to a pulsed plasma generated from the nitrogen-containing and fluorine-containing gas comprises: igniting a plasma in a plasma processing chamber using a power supply operating in a CW mode and transitioning from the CW mode to a pulsed mode while maintaining the plasma in the plasma processing chamber.

3 . The method of claim 1 , wherein the substrate is exposed to the CW plasma for a first duration and exposed to the pulsed plasma for a second duration, wherein the first duration is longer than the second duration.

4 . The method of claim 3 , wherein the first duration is at least twice as long as the second duration.

5 . The method of claim 1 , further comprising depositing tungsten in the feature to completely fill the feature with tungsten.

6 . The method of claim 5 , wherein there is no nucleation delay during the deposition of tungsten in the feature to completely fill the feature with tungsten.

7 . The method of claim 1 , further comprising, after exposing the substrate to the pulsed plasma, exposing the substrate to a non-fluorine nitrogen-containing plasma to inhibit tungsten nucleation.

8 . The method of claim 7 , wherein the non-fluorine nitrogen-containing plasma is a remotely generated plasma.

9 . The method of claim 1 , wherein the CW plasma and the pulsed plasma are capacitively-coupled.

10 . The method of claim 1 , wherein the CW plasma and the pulsed plasma are inductively-coupled.

11 . The method of claim 1 , wherein the CW plasma and the pulsed plasma are generated in a remote plasma generator.

12 . The method of claim 1 , wherein the CW plasma and the pulsed plasma are generated in a chamber housing the substrate.

13 . The method of claim 1 , wherein the duty cycle of the pulsed plasma is no more than 50%.

14 . A method comprising:
exposing a first layer of a metal-containing film on a substrate to a continuous wave (CW) plasma generated from a halogen etchant gas that includes one or more of carbon and nitrogen to etch a first portion of the metal-containing film; after etching the first portion, exposing the first layer of the metal-containing film to a pulsed plasma generated from the halogen etchant gas to etch a second portion of the first layer of the metal-containing film; and after etching the second portion, depositing a second layer of the metal-containing film on the substrate.

15 . The method of claim 14 , wherein the first layer is exposed to the CW plasma for a first duration and exposed to the pulsed plasma for a second duration, wherein the first duration is longer than the second duration.

16 . The method of claim 15 , wherein the first duration is at least twice as long as the second duration.

17 . The method of claim 14 , wherein the halogen etchant gas is NF 3 .

18 . The method of claim 14 , wherein the first layer of the metal-containing film partially fills a feature on the substrate.

19 . The method of claim 18 , wherein etching the first and second portions of the first layer comprises preferentially etching the first layer at the top of the feature.

Assignees

• Lam Res Corp

Inventors

• Chandrashekar Anand
• Mutyala Madhu Santosh Kumar

Classifications

• H10P14/432

  using selective deposition · CPC title

• H10P14/43

  Chemical deposition, e.g. chemical vapour deposition [CVD] · CPC title

• H10W20/045

  for deposition from the gaseous phase, e.g. for chemical vapour deposition [CVD] · CPC title

• H10W20/056

  by filling conductive material into holes, grooves or trenches · CPC title

• H10P50/267 Primary

  using plasmas · CPC title