Methods for etch of SiN films

• US 9,842,744 B2
• Filed: 05/16/2016
• Issued: 12/12/2017
• Est. Priority Date: 03/14/2011
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Zhang, Jingchun, Wang, Anchuan, Ingle, Nitin
• Primary Examiner(s): Lu, Jiong-Ping
• Application Number:
  US15/155,596
• Publication Number:
  US 20160260619A1
• Time in Patent Office: 575 Days
• Field of Search: None
• CPC Class Codes: C09K 13/00 Etching, surface-brightening or pickling compositions for glass C03C15/00, C03C25/66; for mortars, concrete, artificial or natural stone or ceramics C04B41/5338 ; for metallic material C23F, C23G1/00, C25F1/00; for semi-conductors H01L
• CPC Class Codes: H01J 37/32357 Generation remote from the workpiece, e.g. down-stream
• CPC Class Codes: H01J 37/32422 Arrangement for selecting ions or species in the plasma
• CPC Class Codes: H01L 21/02164 the material being a silicon oxide, e.g. SiO2
• CPC Class Codes: H01L 21/0217 the material being a silicon nitride not containing oxygen, e.g. SixNy or SixByNz H01L21/02126 and H01L21/0214 take precedence
• CPC Class Codes: H01L 21/3065 Plasma etching; Reactive-ion etching
• CPC Class Codes: H01L 21/311 Etching the insulating layers by chemical or physical means H01L21/31058 takes precedence
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/32135 by vapour etching only
• CPC Class Codes: H01L 21/32136 using plasmas
• CPC Class Codes: H01L 21/32137 of silicon-containing layers
• CPC Class Codes: H01L 21/67069 for drying etching

Abstract

A method of selectively etching silicon nitride from a substrate comprising a silicon nitride layer and a silicon oxide layer includes flowing a fluorine-containing gas into a plasma generation region of a substrate processing chamber and applying energy to the fluorine-containing gas to generate a plasma in the plasma generation region. The plasma comprises fluorine radicals and fluorine ions. The method also includes filtering the plasma to provide a reactive gas having a higher concentration of fluorine radicals than fluorine ions and flowing the reactive gas into a gas reaction region of the substrate processing chamber. The method also includes exposing the substrate to the reactive gas in the gas reaction region of the substrate processing chamber. The reactive gas etches the silicon nitride layer at a higher etch rate than the reactive gas etches the silicon oxide layer.

Claims

1. A method of etching a patterned substrate, the method comprising:

transferring the patterned substrate into a substrate processing region of a substrate processing chamber, wherein the patterned substrate has exposed silicon nitride and exposed silicon;

flowing a fluorine-containing precursor into a remote plasma region fluidly coupled to the substrate processing region while forming a remote plasma in the remote plasma region to produce plasma effluents;

flowing water vapor into the substrate processing region without first passing the water vapor through any remote plasma; and

etching the exposed silicon nitride.

2. The method of claim 1 wherein a selectivity of the operation (exposed silicon nitride:

exposed silicon) is greater than or about 50;

1.

3. The method of claim 1 wherein the operation of forming the remote plasma comprises a remote plasma power between 25 W and 500 W.

4. The method of claim 1 wherein a pressure in the substrate processing region is between about 0.1 Torr and about 15 Torr during the operation of etching the exposed silicon nitride.

5. The method of claim 1 wherein an electron temperature in the substrate processing region is less than 0.5 eV during the operation of etching the exposed silicon nitride.

6. The method of claim 1 wherein plasma effluents pass through an ion suppressor disposed between the remote plasma region and the substrate processing region.

7. The method of claim 1 wherein the fluorine-containing precursor comprises NF₃.

8. The method of claim 1 wherein the fluorine-containing precursor comprises a precursor selected from the group consisting of hydrogen fluoride, atomic fluorine, diatomic fluorine, and carbon tetrafluoride.

9. The method of claim 1 wherein a temperature of the patterned substrate is between about 25°

C. and about 90°

C. during the operation of etching the exposed silicon nitride.

10. A method of etching a patterned substrate, the method comprising:

transferring the patterned substrate into a substrate processing region of a substrate processing chamber, wherein the patterned substrate has exposed silicon nitride and exposed silicon;

flowing nitrogen trifluoride into a remote plasma region fluidly coupled to the substrate processing region while forming a remote plasma in the remote plasma region to produce plasma effluents;

flowing water vapor into the substrate processing region without first passing the water vapor through the remote plasma region;

etching the exposed silicon nitride, wherein a temperature of the patterned substrate is between about 40°

C. and about 80°

C. during the operation of etching the exposed silicon nitride; and

removing the patterned substrate from the substrate processing region.