Plasma etching method and plasma etching apparatus

• US 9,330,935 B2
• Filed: 11/07/2013
• Issued: 05/03/2016
• Est. Priority Date: 11/09/2012
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Honda, Masanobu, Kihara, Yoshihide, Hisamatsu, Toru
• Primary Examiner(s): Tran, Binh X
• Assistant Examiner(s): CATHEY JR, DAVID A
• Application Number:
  US14/074,020
• Publication Number:
  US 20140134848A1
• Time in Patent Office: 908 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H01J 2237/334 Etching
• CPC Class Codes: H01L 21/0273 characterised by the treatment of photoresist layers
• CPC Class Codes: H01L 21/31138 by dry-etching
• CPC Class Codes: H01L 21/31144 using masks

Abstract

Disclosed is a plasma etching method which suppresses the narrowing of the line-width of the line formed by etching and maintain the height of a remaining photoresist. The plasma etching method includes a modification process and an etching process. The modification process modifies a photoresist having a predetermined pattern by plasma of HBr/Ar gas while applying a negative DC voltage to an upper electrode containing silicon disposed to face a target object in which an organic film and the photoresist are sequentially laminated. The etching process etches the organic film by plasma of a processing gas which contains a CF-based gas and a CHF-based gas.

Claims

1. A plasma etching method comprising:

providing a target object on a mounting table serving as a lower electrode, the target object being sequentially laminated with an organic film and a photoresist, the photoresist being one of an ArF resist and an Extreme Ultra-Violet (EUV) resist and having a predetermined pattern;

applying plasma of HBr/Ar gas to a surface of the photoresist while introducing the HBr/Ar gas into a processing chamber and applying a first high frequency power and a negative DC voltage a shower head serving as to an upper electrode containing silicon disposed to face the target object without applying a second high frequency power having a frequency lower than that of the first high frequency power to the lower electrode in order to perform at least one of;

(i) smoothing the surface of the photoresist by allowing the surface of the photoresist to absorb both hydrogen radicals and light energy from the plasma of HBr/Ar gas,

(ii) hardening the surface of the photoresist by irradiating electrons from the upper electrode supplied with the negative DC voltage to the surface of the photoresist, and

(iii) depositing SiBr-containing material on the surface of the photoresist from the plasma of HBr/Ar gas and the upper electrode supplied with the negative DC voltage, thereby reinforcing resistance of the photoresist to the plasma and improving a surface roughness of the photoresist; and

using the photoresist where the resistance to the plasma is reinforced and the surface roughness is improved at the applying, etching the organic film by plasma of a processing gas which contains a CF-based gas and a CHF-based gas.

2. The plasma etching method according to claim 1, wherein the ArF resist is formed by using an ArF excimer laser and has a property of absorbing light with a wavelength ranging from 150 nm to 160 nm.

3. The plasma etching method according to claim 1, wherein the Extreme Ultra-Violet (EUV) resist is formed by using EUV light and has a property of absorbing light with a wavelength ranging from 150 nm to 160 nm.

4. The plasma etching method according to claim 1, wherein the CF-based gas is a CF₄ gas and the CHF-based gas is a CHF₃ gas.

5. The plasma etching method according to claim 1, wherein the organic film is a Si-ARC film.

6. The plasma etching method according to claim 1, wherein the negative DC voltage applied to the upper electrode is in an amount of −

900 V.

7. The plasma etching method according to claim 6, wherein the ratio of the HBr gas to the Ar gas is 100 to 800 sccm.