METHOD OF SELECTIVELY ETCHING FIRST REGION MADE OF SILICON NITRIDE AGAINST SECOND REGION MADE OF SILICON OXIDE

• US 20180166303A1
• Filed: 12/11/2017
• Published: 06/14/2018
• Est. Priority Date: 12/13/2016
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Tabata, Masahiro, Kumakura, Sho
• Granted Patent: US 10,319,613 B2
• Time in Patent Office: Days
• CPC Class Codes: H01J 2237/334 Etching
• CPC Class Codes: H01J 37/00 Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof H01J33/00, H01J40/00, H01J41/00, H01J47/00, H01J49/00 take precedence
• CPC Class Codes: H01J 37/32137 controlling of the discharge by modulation of energy
• CPC Class Codes: H01J 37/32174 Circuits specially adapted for controlling the RF discharge
• CPC Class Codes: H01J 37/32449 Gas control, e.g. control of the gas flow
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/67 Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere processes per se H01L21/30, H01L21/46, H01L23/00; simple temporary support means, e.g. using adhesives, electric or magnetic means H01L21/68, H01L21/302; apparatus for manufacturing arrangements for connecting or disconnecting semiconductor or solid-state bodies and for methods related thereto H01L24/74;
• CPC Class Codes: H01L 21/67069 for drying etching

Abstract

Generation of a deposit can be suppressed and high selectivity can be acquired when etching a first region made of silicon nitride selectively against a second region made of silicon oxide. A method includes preparing a processing target object having the first region and the second region within a chamber provided in a chamber main body of a plasma processing apparatus; generating plasma of a first gas including a gas containing hydrogen within the chamber to form a modified region by modifying a part of the first region with active species of the hydrogen; and generating plasma of a second gas including a gas containing fluorine within the chamber to remove the modified region with active species of the fluorine.

Claims

1. A method of etching a first region made of silicon nitride selectively against a second region made of silicon oxide, comprising:

preparing a processing target object having the first region and the second region within a chamber provided in a chamber main body of a plasma processing apparatus;

generating plasma of a first gas including a gas containing hydrogen within the chamber to form a modified region by modifying a part of the first region with active species of the hydrogen; and

generating plasma of a second gas including a gas containing fluorine within the chamber to remove the modified region with active species of the fluorine.

2. The method of claim 1,

wherein the processing target object is placed, within the chamber, on a stage including therein an electrode to which a high frequency power for attracting ions onto the processing target object is allowed to be supplied, and

the high frequency power is supplied to the electrode in the generating of the plasma of the first gas.

3. The method of claim 1,

wherein the processing target object is placed, within the chamber, on a stage including therein an electrode to which a high frequency power for attracting ions onto the processing target object is allowed to be supplied, and

the high frequency power is not supplied to the electrode in the generating of the plasma of the second gas.

4. The method of claim 1,

wherein the second gas includes a NF₃ gas as the gas containing fluorine.

5. The method of claim 1,

wherein the second gas further includes hydrogen, and

a ratio of a number of atoms of the hydrogen in the second gas to a number of atoms of the fluorine in the second gas is equal to or higher than 8/9.

6. The method of claim 4,

wherein the second gas further includes a H₂ gas.

7. The method of claim 6,

wherein a flow rate ratio of the H₂ gas in the second gas to the NF₃ gas in the second gas is equal to or higher than 3/4.

8. The method of claim 1,

wherein the first gas includes a H₂ gas as the gas containing hydrogen.

9. The method of claim 1,

wherein a plurality of sequences each of which includes the generating of the plasma of the first gas and the generating of the plasma of the second gas are performed in sequence.

10. The method of claim 1,

wherein the processing target object further has a third region made of silicon, and

the first gas further includes a gas containing oxygen.

11. The method of claim 10,

wherein the first region is provided to cover the second region and the third region.

12. The method of claim 1,

wherein a plurality of sequences each of which includes the generating of the plasma of the first gas and the generating of the plasma of the second gas are performed in sequence,

the processing target object further has a third region made of silicon,

the first region is provided to cover the second region and the third region before the plurality of sequences are performed,

the plurality of sequences include one or more first sequences performed until a time immediately before the third region is exposed or until the third region is exposed;

and one or more second sequences performed to oxidize a surface of the third region after the one or more first sequences, and

the first gas further includes a gas containing oxygen in at least one second sequence.

13. The method of claim 12,

wherein the first gas does not contain the gas containing oxygen in the one or more first sequences.

14. The method of claim 12,

wherein the plurality of sequences further include one or more third sequences performed after the one or more second sequences, and

the first gas does not include the gas containing oxygen in the one or more third sequences.

15. The method of claim 10,

wherein a flow rate ratio of the gas containing oxygen in the first gas to the gas containing hydrogen in the first gas is set to be in a range from 3/100 to 9/100.

16. The method of claim 10,

wherein the gas containing oxygen is an O₂ gas.