PLASMA ETCHING METHOD, METHOD FOR PRODUCING SEMICONDUCTOR DEVICE, AND PLASMA ETCHING DEVICE

• US 20130029494A1
• Filed: 03/03/2011
• Published: 01/31/2013
• Est. Priority Date: 03/04/2010
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Moyama, Kazuki, Sasaki, Masaru, Inoue, Masaki, Noto, Yoko
• Granted Patent: US 9,324,572 B2
• Time in Patent Office: Days
• US Class Current: 438/724
• CPC Class Codes: H01J 37/32192 Microwave generated discharge H01J37/32357, H01J37/32366, H01J37/32394, H01J37/32403 take precedence
• CPC Class Codes: H01J 37/32238 Windows
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 29/6653 using the removal of at least part of spacer, e.g. disposable spacer
• CPC Class Codes: H01L 29/6659 with both lightly doped source and drain extensions and source and drain self-aligned to the sides of the gate, e.g. lightly doped drain [LDD] MOSFET, double diffused drain [DDD] MOSFET
• CPC Class Codes: H01L 29/66795 with a horizontal current flow in a vertical sidewall of a semiconductor body, e.g. FinFET, MuGFET
• CPC Class Codes: H01L 29/7833 with lightly doped drain or source extension, e.g. LDD MOSFET's; DDD MOSFET's for thin film transistors H01L29/78618

Abstract

Provided is a plasma etching method increasing the selectivity of a silicon nitride film in relation to the silicon oxide film or silicon functioning as a base. In a plasma etching method setting a pressure in a processing container as a predetermined level by exhausting a processing gas while supplying the processing gas into the processing container, generating plasma by supplying external energy to the processing container, and setting a bias applied to a holding stage holding a substrate in the processing container as predetermined value to selectively etch the silicon nitride film with respect to a silicon and/or silicon oxide film, the processing gas includes a plasma excitation gas, a CHxFy gas, and at least one oxidizing gas selected from the group consisting of O₂, CO₂, CO, and a flow rate of the oxidizing gas with respect to the CHxFy gas is set to be 4/9 or greater.

Claims

1. A plasma etching method comprising:

setting a pressure in a processing container as a predetermined value by supplying a processing gas into the processing container while exhausting the processing gas;

generating plasma by supplying external energy to the processing gas; and

setting a bias applied to a holding stage, on which a substrate is placed, in the processing container to be a predetermined value, to selectively etch a silicon nitride film with respect to silicon and/or a silicon oxide film,

wherein the processing gas includes a plasma excitation gas, a CHxFy gas, where x and y are 1 or greater integers, and at least one oxidizing gas selected from the group consisting of O₂, CO₂, and CO,

a flow rate of the oxidizing gas with respect to the CHxFy gas is set to be 4/9 or greater when O₂ or CO₂ is used as the oxidizing gas, 8/9 or greater when CO is used as the oxidizing gas, and 4/9 or greater in a converted flow rate to O₂ when at least two of O₂, CO₂, and CO are mixed to be used as the oxidizing gas.

2. The plasma etching method of claim 1, wherein a microwave is introduced in the processing container via a dielectric window on an upper portion of the processing container as the external energy, and a radio frequency (RF) of 30 W/(15×

15×

π

cm²) or less per 1 cm² of the substrate is applied to a holding stage where the substrate is placed in the processing container.

3. The plasma etching method of claim 1, wherein the pressure in the processing container is set to be 13.3 Pa (100 mTorr) or less.

4. The plasma etching method of claim 1, wherein the plasma etching method is to form spacers formed of a silicon nitride film on side walls of a gate electrode.

5. A method for producing a semiconductor device, the method comprising:

setting a pressure in a processing container as a predetermined value by supplying a processing gas into the processing container while exhausting the processing gas;

generating plasma by supplying external energy to the processing gas; and

setting a bias applied to a holding stage, on which a substrate is placed, in the processing container to be a predetermined value, to selectively etch a silicon nitride film with respect to silicon and/or a silicon oxide film;

wherein the processing gas includes a plasma excitation gas, a CHxFy gas, where x and y are 1 or greater integers, and at least one oxidizing gas selected from the group consisting of O₂, CO₂, and CO,

a flow rate of the oxidizing gas with respect to the CHxFy gas is set to be 4/9 or greater when O₂ or CO₂ is used as the oxidizing gas, 8/9 or greater when CO is used as the oxidizing gas, and 4/9 or greater in a converted flow rate to O₂ when at least two of O₂, CO₂, and CO are mixed to be used as the oxidizing gas.

6. A plasma etching device for selectively etching a silicon nitride film with respect to silicon and/or a silicon oxide film, the plasma etching device comprising:

a processing container, inside of which can be depressurized;

a holding stage which is provided in the processing container;

a processing gas supply unit which supplies a processing gas into the processing container;

a gas exhaust unit which exhausts the processing gas in the processing container;

an energy supply unit which supplies external energy to the processing gas in order to generate plasma;

a bias application unit which applies a radio frequency (RF) to the holding stage; and

a controller which controls a flow of the processing gas, a pressure in the processing container, and a bias applied to the holding stage,

wherein the processing gas includes a plasma excitation gas, a CHxFy gas, where x and y are 1 or greater integers, and at least one oxidizing gas selected from the group consisting of O₂, CO₂, and CO,

a flow rate of the oxidizing gas with respect to the CHxFy gas is set to be 4/9 or greater when O₂ or CO₂ is used as the oxidizing gas, 8/9 or greater when CO is used as the oxidizing gas, and 4/9 or greater in a converted flow rate to O₂ when at least two of O₂, CO₂, and CO are mixed to be used as the oxidizing gas, by using the controller.

7. A plasma etching method for selectively etching a silicon nitride film, the plasma etching method comprising:

setting a pressure in a processing container to be 40.0 Pa (300 mTorr) or greater by supplying the processing gas for performing an etching process in the processing container while exhausting the processing gas;

generating plasma in the processing container by introducing a microwave in the processing container via a dielectric window formed on an upper portion of the processing container; and

selectively etching the silicon nitride film in a non-bias state where a radio frequency (RF) is not applied to a holding stage where a substrate is placed in the processing container.

8. The plasma etching method of claim 7, wherein the processing gas includes a plasma excitation gas, a CHxFy gas, where x and y are 1 or greater integers, and at least one oxidizing gas selected from the group consisting of O₂, CO₂, and CO.

9. The plasma etching method of claim 7, wherein spacers formed of a silicon nitride film on side walls of a gate electrode are etched.

10. A plasma etching device selectively etching a silicon nitride film, wherein the plasma etching device comprising:

a processing container, inside of which can be depressurized;

a holding stage which is provided in the processing container;

a microwave introduction unit which introduces a microwave in the processing container via a dielectric window on an upper portion of the processing container;

a processing gas supply unit which supplies a processing gas into the processing container;

a gas exhaust unit which exhausts the processing gas in the processing container; and

a controller which controls a pressure in the processing container,

wherein the controller controls the pressure in the processing container to be 40.0 Pa (300 mTorr) or greater, and the silicon nitride film is selectively etched in a non-bias state where a radio frequency (RF) is not applied to the holding stage where a substrate is placed in the processing container.