Method for fault detection in a plasma process

• US 20040055868A1
• Filed: 11/15/2002
• Published: 03/25/2004
• Est. Priority Date: 09/24/2002
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Scientific Systems Research Limited
• Inventors: OʼMorain, Ciaran, OʼLeary, Kevin, Scanlan, John
• Granted Patent: US 6,781,383 B2
• Time in Patent Office: Days
• US Class Current: 204/157.15
• CPC Class Codes: H01J 37/32082 Radio frequency generated discharge H01J37/32357, H01J37/32366, H01J37/32394 and H01J37/32403 take precedence
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge

Abstract

A method of fault detection is described for use in a plasma process chamber powered by an RF source and subject to periodic standard preventive maintenance. Prior to a production run, the changes in magnitude of a plurality of Fourier components of the RF source resulting from known changes in a plurality of process conditions are determined and a single parameter which is a linear combination of a selected subset of said components is constructed. The construction is such that the combination is relatively sensitive to pre-selected process changes and relatively insensitive to said standard preventive maintenance. Then, during the production run, the single parameter is monitored to determine if there is a fault in the plasma process.

Claims

1. A method of fault detection in a plasma process chamber powered by an RF source and subject to periodic standard preventive maintenance events, comprising the steps of:

prior to a production run using a predetermined plasma process, determining the changes in magnitude of a plurality of Fourier components of the RF source resulting from known changes in a plurality of process conditions and constructing a single parameter which is a linear combination of a selected subset of said components, said combination being relatively sensitive to pre-selected process changes and relatively insensitive to said standard preventive maintenance events,

running the plasma process during a subsequent production run, and

during said production run, monitoring said single parameter to determine if there is a fault in the plasma process.

2. A method as claimed in claim 1, wherein the changes in process conditions include variations in the process input parameters.

3. A method as claimed in claim 1, wherein the changes in process conditions include induced faults in the process.

4. A method as claimed in claim 3, wherein the induced faults include hardware faults.

5. A method as claimed in claim 1, wherein the pre-selected process changes are those which especially affect the yield of the process.

6. A method as claimed in claim 1, wherein the Fourier components are those of the voltage, current and phase of the RF power signal.