# US 9,437,450 B2 · Plasma etching method

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- Number: US 9,437,450 B2
- Document ID: US9437450B2
- Status: Granted
- Kind: B2
- Application number: 14/427,076
- Filed: 2013-09-24
- Published: 2015-11-26
- Granted: 2016-09-06
- Earliest claimed: 2012-10-12
- Assignees: Tokyo Electron Limited
- Applicants: Tokyo Electron Limited
- Inventors: Tetsuro Kikuchi
- Web page: https://patentgrep.com/patent/US9437450B2

## CPC

- H10P 50/283: {by chemical means}
- H10P 50/73: {using masks for insulating materials}
- H01J 37/32091: {the radio frequency energy being capacitively coupled to the plasma}
- H01J 2237/334: Etching
- H10P 72/0434: {mainly by convection}
- H10P 72/72: using electrostatic chucks
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)

## Abstract

In a plasma etching method, with respect to a substrate to be processed, which has a base layer, a silicon oxide film, and an etching mask formed in this order, the etching mask having an etching pattern formed thereon and being formed of polysilicon, a silicon-containing deposit is deposited on a surface of the etching mask using a plasma generated from a processing gas, while applying a negative direct current voltage to an upper electrode formed of silicon. Furthermore, in the plasma etching method, the silicon oxide film is etched using plasma generated from a first CF-based gas using, as a mask, the etching mask having the silicon-containing deposit deposited thereon.

## Claims

### Claim 1

A plasma etching method comprising:
providing a substrate including a base layer, a silicon oxide film disposed on the base layer, and an etching mask formed of a polysilicon and having an etching pattern;
a deposition step of depositing a silicon-containing deposit on the substrate by a plasma of a processing gas while applying a negative DC voltage to an upper electrode made of silicon, wherein during the deposition step the silicon-containing deposit is deposited on the etching mask; and
an etching step of etching the silicon oxide film by a plasma of a first CF-based gas while using as a mask the etching mask having the silicon-containing deposit deposited thereon,
wherein the silicon-containing deposit includes silicon that originated from the upper electrode.

### Claim 2 (depends on 1)

The plasma etching method of claim 1, wherein the processing gas is selected among H2/Ar gas, CF4/H2/Ar gas and CF4/COS/Ar gas.

### Claim 3 (depends on 1)

The plasma etching method of claim 1, further comprising, after the deposition step and before the etching step, a deposition step of depositing a CF-based deposit by a plasma of a second CF-based gas.

### Claim 4 (depends on 1)

The plasma etching method of claim 1, wherein the first CF-based gas is C4F6/C4F8/Ar/O2 gas.

### Claim 5 (depends on 3)

The plasma etching method of claim 3, wherein the second CF-based gas is C4F6/Ar/O2 gas.