In-situ measurement of deposition on reactor chamber members

• US 6,019,000 A
• Filed: 11/20/1997
• Issued: 02/01/2000
• Est. Priority Date: 11/20/1997
• Status: Expired due to Fees

• Current Assignee: Sensys Instruments Corporation (KLA Corporation)
• Original Assignee: Sensys Instruments Corporation (KLA Corporation), Board of Trustees of the Leland Stanford Junior University (Stanford University)
• Inventors: Degertekin, Fahrettin Levent, Stanke, Fred E, Khuri-Yakub, Butrus T., Pham, Hung
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): TRAN, THUY V
• Application Number:
  US08/975,531
• Time in Patent Office: 803 Days
• Field of Search: 73/597, 73/598, 73/602, 73/620, 73/627, 73/628, 73/643, 73/655, 73/657, 73/571, 73/629, 73/622, 73/624, 73/625, 73/617, 73/644, 376/252, 376/245, 976/DIG. 232
• US Class Current: 73/622
• CPC Class Codes: G01H 5/00 Measuring propagation velocity of ultrasonic, sonic or infrasonic waves , e.g. of pressure waves
• CPC Class Codes: G01N 2291/012 Phase angle
• CPC Class Codes: G01N 2291/0231 Composite or layered materials
• CPC Class Codes: G01N 2291/02854 Length, thickness
• CPC Class Codes: G01N 2291/02881 Temperature
• CPC Class Codes: G01N 2291/0421 Longitudinal waves
• CPC Class Codes: G01N 2291/0422 Shear waves, transverse waves, horizontally polarised waves
• CPC Class Codes: G01N 29/075 by measuring or comparing phase angle measuring frequencies or phase angles per se G01R23/00, G01R25/00
• CPC Class Codes: G01N 29/326 compensating for temperature variations
• CPC Class Codes: G01N 29/348 with frequency characteristics, e.g. single frequency signals, chirp signals measuring frequency of mechanical vibrations or acoustic waves in general G01H1/06, G01H3/04; measuring frequency or analysing frequency spectra G01R23/00

Abstract

A system is disclosed that employs ultrasonic waves to perform in-situ measurements to determine the properties of films deposited on substrates in the course of various semiconductor or processing steps. In one embodiment a single transducer excites incident acoustic waves at multiple frequencies that reflect from the films. The reflected waves are received by the same transducer. An analysis system determines the phase shift of the received reflected waves and, based on the phase shift, determines the film properties. Other embodiments employ distinct source and receiving transducers. Embodiments are also disclosed that compensate the measured phase shift for temperature variations in the substrate. In one such system, temperature compensation is performed based on the processing of phase measurements made at multiple frequencies or incidence angles or with multiple ultrasonic modes. The disclosed techniques are equally applicable to determining the degree of erosion of chamber members.

Claims

1. An apparatus for measuring properties including thickness of one or more films on a chamber member, comprising:

one or more source transducers, each configured to excite acoustic waves at a plurality of frequencies in the substrate at a corresponding excitation location;

one or more receiving transducers, each configured to detect acoustic waves at a probe location in the substrate, wherein the acoustic waves include reflected waves received at the probe location due to a composite reflection of the excited acoustic waves from the one or more films, wherein the one or more source and the one or more receiving transducers are not necessarily different transducers and the probe and excitation locations are not necessarily different locations; and

a processing module coupled to the receiving transducers configured to determine the properties of the one or more films from measurements including a phase measurement at each of a plurality of frequencies on a selected waveform group.

2. The apparatus of claim 1, wherein the chamber member comprises a one of:

a chamber wall;

a shield;

a window;

a shower head;

a collimator; and

a gas distribution plate.

3. The apparatus of claim 1, wherein the plurality of frequencies are between 1 MHz and 120 MHz.

4. The apparatus of claim 1, wherein the one or more source and the one or more receiving transducers comprise a single transducer.

5. The apparatus of claim 1, wherein the processing module and the transducers are used to determine degree of erosion of the chamber member due to over-etching caused by a cleaning process used to clean the chamber member.

6. An apparatus for measuring properties of one or more films on a substrate while compensating for temperature differences in the substrate, comprising:

one or more source transducers, each configured to excite acoustic waves in the substrate at a corresponding excitation location;

one or more receiving transducers, each configured to detect acoustic waves at a probe location in the substrate, wherein the acoustic waves include reflected waves received at the probe location due to reflection of the excited acoustic waves from the one or more films, wherein the one or more source and the one or more receiving transducers are not necessarily different transducers and the probe and excitation locations are not necessarily different locations; and

a processing module coupled to the receiving transducers configured to determine the properties of the one or more films from measurements on a selected waveform group;

wherein at least one of the one or more source transducers, the one or more receiving transducers, and processing module are configured to compensate for the effects of the temperature differences in the substrate when determining the film properties;

wherein the one or more receiving transducers and the one or more source transducers are configured to compensate for the effects of the temperature differences by respectively exciting and receiving waves characterized by a plurality of acoustic modes; and

wherein the processing module is configured to compensate for the effects of the temperature differences by inverting the measurements with the plurality of modes for the film properties and temperature.

7. The apparatus of claim 6, wherein the measurements include a phase measurement.

8. The apparatus of claim 6, wherein the properties include thickness.

9. The apparatus of claim 6, wherein:

the one or more receiving transducers and the one or more source transducers are configured to compensate for the effects of the temperature differences by respectively exciting and receiving the waves at a plurality of incident angles; and

the processing module is configured to compensate for the effects of the temperature differences by inverting the measurements at the plurality of angles for the film properties and temperature.

10. The apparatus of claim 6, wherein the plurality of modes comprise shear and compressional modes.

11. The apparatus of claim 6, wherein:

the one or more receiving transducers, the one or more source transducers and the processing module are configured so that a first phase measurement is made in an area where there is no film buildup and a second phase measurement is made in an area where there is film buildup; and

the processing module is further configured to derive the properties by comparing the first and second phase measurements.

12. The apparatus of claim 6, wherein the processing module and the transducers are used to determine degree of erosion of the substrate due to over-etching caused by a cleaning process used to clean the chamber member.

13. An apparatus for measuring properties of one or more films on a chamber member, comprising:

one or more transducers, each configured to excite acoustic waves in the member and to detect acoustic waves at a probe location in the substrate, wherein the acoustic waves include reflected waves received due to reflection of the excited acoustic waves from the one or more films; and

a processing module coupled to the transducers configured to determine from measurements on a selected waveform group degree of erosion of the chamber member due to over-etching caused by a cleaning process used to clean the chamber member.

14. The apparatus of claim 13, wherein the measurements include a phase measurement.

15. The apparatus of claim 13, wherein the processing module and the transducers are used to determine an endpoint of a chamber cleaning process.

16. The apparatus of claim 13, wherein the processing module and the transducers are used to determine the properties of the one or more films.

17. The apparatus of claim 13, wherein the transducers are bonded to the chamber member.

18. The apparatus of claim 16, wherein the film properties comprise film thickness.

19. The apparatus of claim 16, wherein the processing module and the transducers are configured to provide stable measurements of the film properties over a period of weeks.

20. The apparatus of claim 16, wherein the measurements of the film properties are used to determine when chamber cleaning is required.