Detection of arcing events in wafer plasma processing through monitoring of trace gas concentrations

• US 20090280581A1
• Filed: 05/12/2008
• Published: 11/12/2009
• Est. Priority Date: 05/12/2008
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Hudson, Eric
• Granted Patent: US 8,158,017 B2
• Time in Patent Office: Days
• US Class Current: 438/9
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge
• CPC Class Codes: H01J 37/32972 Spectral analysis

Abstract

A method of detecting substrate arcing in a semiconductor plasma processing apparatus is provided. A substrate is placed on a substrate support in a reaction chamber of a plasma processing apparatus. Process gas is introduced into the reaction chamber. A plasma is generated from the process gas and the substrate is processed with the plasma. Intensities of real-time spectrometry signals of selected gas species produced in the reaction chamber during plasma processing are monitored. The selected gas species are generated by a substrate arcing event. The arcing event is detected when the intensities are above a threshold value.

Claims

1. A method of detecting substrate arcing in a semiconductor plasma processing apparatus, comprising:

placing a substrate on a substrate support in a reaction chamber of a plasma processing apparatus;

introducing process gas into the reaction chamber;

generating a plasma from the process gas;

processing the substrate with the plasma;

monitoring intensities of real-time spectrometry signals of selected gas species produced in the reaction chamber during plasma processing, wherein the selected gas species are generated by a substrate arcing event; and

detecting the arcing event when the intensities are above a threshold value.

2. The method of claim 1, wherein the substrate contains aluminum, copper, silicon, organic dielectric or organic photoresist;

and the selected gas species generated by the substrate arcing event include aluminum-, copper- or silicon-bearing species and/or decomposition products of the organic material.

3. The method of claim 1, further comprising identifying selected gas species generated by the substrate arcing event, comprising:

monitoring intensities of real-time spectrometry signals of the process gases in the absence of the substrate arcing event;

monitoring intensities of real-time spectrometry signals during the substrate arcing event; and

comparing the intensities of real-time spectrometry signals of the process gases in the absence of the substrate arcing event to the intensities of real-time spectrometry signals during the substrate arcing event.

4. The method of claim 1, wherein monitoring intensities of real-time spectrometry signals is performed by a residual gas analyzer (RGA) mass spectrometer, an inductively coupled plasma optical emission (ICP-OE) spectrometer, an infrared absorption spectrometer or a Fourier transform infrared (FTIR) spectrometer.

5. The method of claim 3, wherein the selected gas species include decomposition products which produce signals at 12, 15, 25, 26, 85 or 86 atomic mass units (AMU) in a residual gas analyzer (RGA).

6. The method of claim 1, further comprising generating a warning signal when an arcing event is detected to terminate the plasma process.

7. The method of claim 1, wherein introducing process gases into the reaction chamber is performed by injecting processing gases through a showerhead;

and monitoring intensities of real-time spectrometry signals of selected gas species includes collecting gas species from a channel in the showerhead or a sampling tube adjacent to the substrate.

8. The method of claim 1, wherein processing the substrate with the plasma includes:

(a) plasma etching of semiconductors, metals or dielectrics;

or (b) deposition of conductive or dielectric material.

9. The method of claim 8, wherein the process gases for plasma etching include hydrocarbon gases, fluorocarbon gases, hydrofluorocarbon gases, halogen-containing gases, oxygen-containing gases, nitrogen-containing gases and inert gases;

and mixtures thereof.

10. The method of claim 8, wherein process gases for deposition include silicon-containing reactant gas selected from the group consisting of SiH₄, SiF₄, Si₂H₆, tetraethylorthosilicate (TEOS), tetramethylcyclotetrasiloxane (TMCTS), alone or in combination with additional process gases including H₂, O₂, N₂, NH₃, NF₃, N₂O and NO;

and mixtures thereof.

11. A plasma processing apparatus comprising:

a substrate holder for supporting a substrate within an interior of a reaction chamber;

a gas supply supplying process gas to the interior of the reaction chamber using a gas distribution member;

a power source supplying energy into the interior of the reaction chamber and energizing the process gas into a plasma state for processing the substrate;

a gas sensor adapted to monitor gas species in the reaction chamber during plasma processing to identify gas species produced by substrate arcing; and

an alarm to generate a warning signal when gas species produced by substrate arcing are identified.

12. The plasma processing apparatus of claim 11, wherein the gas sensor is a residual gas analyzer (RGA) mass spectrometer, an inductively coupled plasma optical emission (ICP-OE) spectrometer, an infrared absorption spectrometer or a Fourier transform infrared (FTIR) spectrometer.

13. The plasma processing apparatus of claim 11, wherein the gas sensor is a residual gas analyzer (RGA) mass spectrometer adapted to monitor a real-time signal from mass spectrometry of processes gases during plasma processing and the gas species produced by substrate arcing are decomposition products of an organic photoresist.

14. The plasma processing apparatus of claim 11, wherein the plasma processing apparatus is a plasma etcher adapted to semiconductors, metals or dielectrics;

or a deposition chamber adapted to deposit conductive or dielectric material.

15. The plasma processing apparatus of claim 11, wherein the gas distribution member is a showerhead.

16. The plasma processing apparatus of claim 15, further comprising:

a sampling structure adapted to collect gas species from the reaction chamber during plasma processing; and

a gas line adapted to transfer gas species to the gas sensor.

17. The plasma processing apparatus of claim 16, wherein the sampling structure is a channel in the showerhead or a tube adjacent to the substrate holder;

and the gas line is heated.

18. The plasma processing apparatus of claim 11, wherein the gas distribution member is a showerhead electrode;

and the power source is a radio-frequency (RF) power source.

19. The plasma processing apparatus of claim 18, further comprising a plasma confinement ring assembly located outwardly of the showerhead electrode and the substrate holder.