Peak-based endpointing for chemical mechanical polishing

• US 8,591,698 B2
• Filed: 08/04/2011
• Issued: 11/26/2013
• Est. Priority Date: 10/31/2006
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Benvegnu, Dominic J., Swedek, Boguslaw A., Lischka, David J.
• Primary Examiner(s): MACARTHUR, SYLVIA
• Application Number:
  US13/198,602
• Publication Number:
  US 20110287694A1
• Time in Patent Office: 845 Days
• Field of Search: 156/345.13, 156/345.25, 156/345.16
• US Class Current: 156/345.25
• CPC Class Codes: B24B 37/013 Devices or means for detecting lapping completion
• CPC Class Codes: B24B 49/12 involving optical means
• CPC Class Codes: B24D 7/12 with apertures for inspecting the surface to be abraded
• CPC Class Codes: H01L 21/31053 involving a dielectric removal step
• CPC Class Codes: H01L 21/3212 by chemical mechanical polishing [CMP]
• CPC Class Codes: H01L 22/26 Acting in response to an ongoing measurement without interruption of processing, e.g. endpoint detection, in-situ thickness measurement endpoint detection arrangements in CMP apparatus B24B37/013, in discharge apparatus H01J37/32

Abstract

A polishing system receives one or more target parameters for a selected peak in a spectrum of light, polishes a substrate, measures a current spectrum of light reflected from the substrate while the substrate is being polished, identifies the selected peak in the current spectrum, measures one or more current parameters of the selected peak in the current spectrum, compares the current parameters of the selected peak to the target parameters, and ceases to polish the substrate when the current parameters and the target parameters have a pre defined relationship.

Claims

1. A polishing endpoint detection system, comprising:

a light source to direct a light to a substrate while the substrate is being polished;

a spectrometer to measure a sequence of current spectra of light reflected from the substrate while the substrate is being polished; and

a controller configured to

store a predetermined criterion for detecting an endpoint using a selected peak or valley in a spectrum of light,

receive the sequence of current spectra from the spectrometer,

identify the selected peak or valley in each current spectrum in the sequence of current spectra, wherein the selected peak or valley persists with at least an evolving location or width through the sequence of current spectra,

measure one or more of a current location or a current width of the selected peak or valley in the current spectrum, and

generate a signal to halt polishing of the substrate when the current location or the current width, respectively, of the selected peak or valley satisfies the predetermined criterion.

2. The system of claim 1, wherein the controller is configured such that for each current spectrum in the sequence of current spectra, the current width of the selected peak or valley in the current spectrum is measured.

3. The system of claim 1, wherein the controller is configured such that for each current spectrum in the sequence of current spectra, the current location of the selected peak in the current spectrum is measured.

4. The system of claim 3, wherein the current location comprises a wavelength of the selected peak or valley.

5. The system of claim 1, wherein the predetermined criterion specifies a target location or target width for the selected peak or valley.

6. The system of claim 1, wherein the predetermined criterion specifies a target amount of change in the current location or the current width, respectively, of the selected peak or valley.

7. The system of claim 6, wherein the target amount of change is measured relative to a predetermined initial location or a predetermined initial width, respectively, for the selected peak.

8. The system of claim 1, wherein the controller is configured to, for each current spectrum in the sequence of current spectra, measure additional spectra of light reflected from the substrate during polishing and combine at least one of the additional spectra with the current spectrum.

9. The system of claim 1, wherein the selected peak or valley comprises a peak.

10. The system of claim 1, wherein the selected peak or valley comprises a valley.

11. The system of claim 1, wherein the light source is a white light source.

12. A polishing system, comprising:

a support to hold a polishing pad;

a carrier head to hold the substrate;

a motor to generate relative motion between the substrate and the polishing pad; and

the polishing endpoint detection system of claim 1.

13. The polishing system of claim 12, wherein:

the light source and the spectrometer are located on a side of the substrate opposite the carrier head.