Dry-etch for selective tungsten removal

Patent metadata

Field	Value
Publication number	US-9412608-B2
Application number	US-201514617779-A
Country	US
Kind code	B2
Filing date	Feb 9, 2015
Priority date	Nov 30, 2012
Publication date	Aug 9, 2016
Grant date	Aug 9, 2016

Abstract

Methods of selectively etching tungsten relative to silicon-containing films (e.g. silicon oxide, silicon carbon nitride and (poly)silicon) as well as tungsten oxide are described. The methods include a remote plasma etch formed from a fluorine-containing precursor and/or hydrogen (H 2 ). Plasma effluents from the remote plasma are flowed into a substrate processing region where the plasma effluents react with the tungsten. The plasma effluents react with exposed surfaces and selectively remove tungsten while very slowly removing other exposed materials. Sequential and simultaneous methods are included to remove thin tungsten oxide which may, for example, result from exposure to the atmosphere.

First claim

What is claimed is:

1. A method of etching a patterned substrate in a substrate processing region of a substrate processing chamber, wherein the patterned substrate has a exposed tungsten region and an exposed second material region, the method comprising:
flowing a fluorine-containing precursor into a remote plasma region fluidly coupled to the substrate processing region while forming a plasma in the plasma region to produce plasma effluents, wherein the fluorine-containing precursor comprises a combination of nitrogen trifluoride (NF 3 ) and methyl fluoride (CH 3 F);
flowing the plasma effluents through a showerhead disposed between the remote plasma region and the substrate processing region; and
etching the exposed tungsten from the substrate.

2. The method of claim 1 wherein the exposed tungsten region has a thickness of at least 5 nm.

3. The method of claim 1 wherein the exposed tungsten region consists of tungsten.

4. The method of claim 1 wherein etching the exposed tungsten region comprises etching the exposed tungsten region comprises etching tungsten with a tungsten etch rate greater than ten times the etch rate of the exposed second material region.

5. The method of claim 1 wherein the operation of etching the tungsten comprises etching tungsten faster than an exposed second material region of silicon by a ratio of about 100:1 or more, faster than an exposed second material region of silicon oxide by a ratio of about 15:1 or more, faster than an exposed second material region of silicon carbon nitride by a ratio of about 3:1 or more or faster than an exposed second material region of tungsten oxide by a ratio of about 10:1 or more.

6. The method of claim 1 wherein the fluorine-containing precursor comprises a partially fluorinated hydrocarbon.

7. The method of claim 1 further comprising a pretreatment step which occurs prior to etching the exposed tungsten region, wherein the pretreatment step comprises flowing hydrogen (H 2 ) into the remote plasma region and flowing the produced plasma effluents into the substrate processing region to remove a thin tungsten oxide layer overlying a near-surface tungsten region to create the exposed tungsten region.

8. The method of claim 1 wherein the fluorine-containing precursor comprises carbon tetrafluoride.

9. The method of claim 1 wherein flowing a fluorine-containing precursor and hydrogen (H 2 ) results in an atomic flow ratio (H:F) of greater than 1:1 entering the substrate processing region.

10. The method of claim 1 wherein flowing a fluorine-containing precursor and hydrogen (H 2 ) results in an atomic flow ratio (H:F) of less than 15:1 entering the substrate processing region.

11. The method of claim 1 wherein a pressure within the substrate processing region is between about 0.01 Torr and about 50 Torr during the etching operation.

12. The method of claim 1 wherein forming a plasma in the plasma region to produce plasma effluents comprises applying RF power between about 10 watts and about 400 watts to the plasma region.

13. The method of claim 1 wherein a temperature of the substrate is greater than or about −30° C. and less than or about 400° C. during the etching operation.

14. A method of etching a patterned substrate in a substrate processing region of a substrate processing chamber, the method comprising:
exposing a tungsten region on the patterned substrate, wherein the exposure comprises flowing plasma effluents of a hydrogen-containing precursor into the substrate processing region;
subsequently flowing a fluorine-containing precursor into a remote plasma region fluidly coupled with a substrate processing region of a processing chamber while forming a plasma in the plasma region to produce plasma effluents, wherein the fluorine-containing precursor comprises a combination of nitrogen trifluoride (NF 3 ) and methl fluoride (CH 3 F);
flowing the plasma effluents through a showerhead disposed between the remote plasma region and the substrate processing region; and
etching the exposed tungsten from the substrate.

15. The method of claim 14 , wherein the exposure comprises removing tungsten oxide from the tungsten region.

16. A method of etching a patterned substrate in a substrate processing region of a substrate processing chamber, the method comprising:
flowing a hydrogen-containing precursor into a remote region fluidly coupled with a substrate processing region of a processing chamber while forming a plasma in the plasma region to produce hydrogen-containing plasma effluents;
subjecting tungsten oxide on the patterned substrate to the hydrogen-containing plasma effluents to expose tungsten;
flowing a fluorine-containing precursor into the remote plasma region while forming a plasma to produce fluorine-containing plasma effluents, wherein the fluorine-containing precursor comprises a combination of nitrogen trifluoride (NF 3 ) and methyl fluoride (CH 3 F); and
etching the exposed tungsten from the substrate with the fluorine-containing plasma effluents.

17. The method of claim 16 , wherein the hydrogen-containing precursor is molecular hydrogen (H 2 ).

Assignees

• Applied Materials Inc

Inventors

• Wang Xikun
• Hsu Ching-Mei
• Ingle Nitin K
• Li Zihui
• Wang Anchuan

Classifications

• H10P70/125

  with gaseous HF · CPC title

• H10P50/267 Primary

  using plasmas · CPC title

• H10P50/242 Primary

  of Group IV materials · CPC title

• H01J37/32357

  Generation remote from the workpiece, e.g. down-stream · CPC title

• H01L21/3065 Primary

  Electricity · mapped topic