Polishing with pre deposition spectrum

Patent metadata

Field	Value
Publication number	US-9811077-B2
Application number	US-201414333395-A
Country	US
Kind code	B2
Filing date	Jul 16, 2014
Priority date	Jul 16, 2014
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

A method of controlling polishing includes storing a base spectrum, the base spectrum being a spectrum of light reflected from a substrate after deposition of a deposited dielectric layers overlying a metallic layer or semiconductor wafer and before deposition of a non-metallic layer over the plurality of deposited dielectric layer. After deposition of the non-metallic layer and during polishing of the non-metallic layer on the substrate, measurements of a sequence of raw spectra of light reflected the substrate during polishing are received from an in-situ optical monitoring system. Each raw spectrum is normalized to generate a sequence of normalized spectra using the raw spectrum and the base spectrum. At least one of a polishing endpoint or an adjustment for a polishing rate is determined based on at least one normalized predetermined spectrum from the sequence of normalized spectra.

First claim

What is claimed is:

1. A computer program product, encoded on one or more non-transitory computer storage media, comprising instructions that when executed by one or more computers cause the one or more computers to perform operations comprising:
storing a base spectrum, the base spectrum being a spectrum of light reflected from a substrate after deposition of a plurality of deposited dielectric layers overlying a metallic layer or semiconductor wafer and before deposition of a non-metallic layer over the plurality of deposited dielectric layers;
after deposition of the non-metallic layer over the plurality of deposited dielectric layers and during polishing of the non-metallic layer on the substrate, receiving from an in-situ optical monitoring system measurements of a sequence of raw spectra of light reflected from the substrate during polishing;
normalizing each raw spectrum in the sequence of raw spectra to generate a sequence of normalized spectra using the raw spectrum and the base spectrum; and
determining at least one of a polishing endpoint or an adjustment for a polishing rate based on at least one normalized predetermined spectrum from the sequence of normalized spectra.

2. The computer program product of claim 1 , wherein the base spectrum comprises a spectrum of the substrate measured after deposition of the dielectric layers but before an etching process, after the etching process but before deposition of a nitride layer, or after deposition of the nitride layer but before depositing the non-metallic layer undergoing polishing.

3. The computer program product of claim 1 , wherein normalizing comprises a division operation in which the raw spectrum is in a numerator and the base spectrum is in a denominator.

4. The computer program product of claim 3 , wherein the division operation comprises calculating

R
=

A
-

D
A

B
-

D
B

where R is the normalized spectrum, A is the raw spectrum, B is the base spectrum and D A and D B are dark spectra, the one or more dark spectra being measured by the in-situ optical monitoring system when no substrate is being measured by the in-situ optical monitoring system.

5. The computer program product of claim 1 , wherein the operations further comprise generating a sequence of values from the sequence of normalized spectra, fitting a function to the sequence of values, determining a projected time at which the function reaches a target value, and determining at least one of the polishing endpoint or the adjustment for the polishing rate based on the projected time.

6. The computer program product of claim 5 , wherein the operations further comprise:
for each normalized spectrum from the sequence of normalized spectra, finding a best matching reference spectrum from a library having a plurality of reference spectra, and wherein generating the sequence of values includes determining a value associated with each best matching reference spectrum.

7. The computer program product of claim 6 , wherein the operations further comprise halting the polishing when the function matches or exceeds the target value.

8. The computer program product of claim 1 , wherein polishing the substrate comprises a back-end-of-line portion of an integrated circuit fabrication process.

9. A method of fabricating a substrate comprising:
depositing at least one dielectric layer on a metallic layer or semiconductor wafer of the substrate;
measuring a base spectrum reflected from the substrate, at an optical metrology system, after depositing the at least one dielectric layer but before depositing an outermost layer;
depositing the outermost layer on the at least one dielectric layer;
polishing the outermost layer of the substrate;
during polishing of the outermost layer, measuring a sequence of raw spectra reflected from the substrate, at an in-situ optical monitoring system;
normalizing each raw spectrum in the sequence of raw spectra to generate a sequence of normalized spectra using the raw spectrum and the base spectrum; and
determining at least one of a polishing endpoint or an adjustment for a polishing rate based on at least one normalized predetermined spectrum from the sequence of normalized spectra.

10. The method of claim 9 , comprising
depositing alternating non-metallic layers onto the substrate, the alternating non-metallic layers including the at least one dielectric layer;
etching the substrate to create a staircase structure;
depositing an intermediate layer onto the etched substrate; and
depositing the outermost layer onto the intermediate layer.

11. The method of claim 10 , wherein measuring the base spectrum comprises measuring the base spectrum after depositing the alternating non-metallic layers onto the substrate but before etching the substrate, the alternating non-metallic layers comprising alternating oxide and nitride layers.

12. The method of claim 10 , wherein measuring the base spectrum comprises measuring the base spectrum after etching the substrate but before depositing a nitride layer.

13. The method of claim 10 , wherein measuring the base spectrum comprises measuring the base spectrum after depositing a nitride layer but before depositing the outermost layer.

14. An integrated circuit fabrication system, comprising:
a deposition system configured to receive a substrate, and deposit a stack of layers overlying a metallic layer or semiconductor substrate, the stack of layers including a non-metallic layer to undergo polishing and at least one dielectric layer underlying the non-metallic layer;
a metrology system configured to generate a measurement of a spectrum of light reflected from the substrate after deposition of the at least one dielectric layer and before deposition of the non-metallic layer; and
a polishing system configured to receive the substrate and polish the non-metallic layer on the substrate, wherein the polishing system includes a controller configured to
receive the measurement of the spectrum of light from the metrology system and store the measurement as a base spectrum,
receive measurements of a sequence of raw spectra of light reflected from the substrate during polishing with an in-situ optical monitoring system,
normalize each raw spectrum in the sequence of raw spectra to generate a sequence of normalized spectra using the raw spectrum and the base spectrum, and
determine at least one of a polishing endpoint or an adjustment for a polishing rate based on at least one normalized predetermined spectrum from the sequence of normalized spectra.

15. The system of claim 14 , wherein the base spectrum comprises a spectrum of the substrate measured after deposition of the at least one dielectric layer but before an etching process, after the etching process but before deposition of a nitride layer, or after deposition of the nitride layer but before depositing the non-metallic layer undergoing polishing.

16. The system of claim 14 , wherein the metrology system is an in-line metrology station in the deposition system.

17. The system of claim 14 , wherein the metrology system is a stand-alone metrology system.

Assignees

• Applied Materials Inc

Inventors

• Kitajima Tomohiko
• David Jeffrey Drue
• Qian Jun
• Sekine Taketo
• Leung Garlen C
• Huey Sidney P

Classifications

• H10P95/062

  involving a dielectric removal step · CPC title

• H10P74/238

  comprising acting in response to an ongoing measurement without interruption of processing, e.g. endpoint detection or in-situ thickness measurement · CPC title

• H10P74/203

  Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects · CPC title

• B24B37/013 Primary

  Devices or means for detecting lapping completion · CPC title

• G05B19/418 Primary

  Total factory control, i.e. centrally controlling a plurality of machines, e.g. direct or distributed numerical control [DNC], flexible manufacturing systems [FMS], integrated manufacturing systems [IMS] or computer integrated manufacturing [CIM] · CPC title