Adjusting eddy current measurements

Patent metadata

Field	Value
Publication number	US-9636797-B2
Application number	US-201414179297-A
Country	US
Kind code	B2
Filing date	Feb 12, 2014
Priority date	Feb 12, 2014
Publication date	May 2, 2017
Grant date	May 2, 2017

Abstract

Among other things, a method of controlling polishing during a polishing process is described. The method includes receiving a measurement of a thickness, thick(t), of a conductive layer of a substrate undergoing polishing from an in-situ monitoring system at a time t; receiving a measured temperature, T(t), associated with the conductive layer at the time t; calculating resistivity ρ T of the conductive layer at the measured temperature T(t); adjusting the measurement of the thickness using the calculated resistivity ρ T to generate an adjusted measured thickness; and detecting a polishing endpoint or an adjustment for a polishing parameter based on the adjusted measured thickness.

First claim

What is claimed is:

1. A method of controlling polishing during a polishing process, the method comprising:
receiving a measurement of a thickness, thick(t), at a time t of a conductive layer of a substrate undergoing a polishing process from an in-situ monitoring system;
receiving a measured temperature, T(t), associated with the conductive layer at the time t from a sensor configured to monitor a temperature of the polishing process, wherein the measured temperature T(t) is measured while the conductive layer of the substrate is undergoing polishing;
calculating a resistivity ρ T of the conductive layer at the measured temperature T(t);
adjusting the measurement of the thickness using the calculated resistivity ρ T to generate an adjusted measured thickness; and
detecting a polishing endpoint or an adjustment for a polishing parameter based on the adjusted measured thickness.

2. The method of claim 1 , wherein detecting the polishing endpoint comprises comparing the adjusted measured thickness with a predetermined measurement of thickness for determining whether the polishing process has reached the polishing endpoint.

3. The method of claim 1 , wherein the monitoring system comprises an eddy current monitoring system and the measurement of the thickness comprises an eddy current signal A(t).

4. The method of claim 3 , comprising converting the eddy current signal A(t) into a measured thickness thick(t) using a signal to thickness correlation equation.

5. The method of claim 1 , wherein calculating the resistivity ρ T of the conductive layer comprises calculating the resistivity ρ T based on:
ρ T =ρ 0 [1+α( T ( t )− T ini )],

where T ini is an initial temperature of the conductive layer when the polishing process starts, ρ 0 is the resistivity of the conductive layer at T ini , and α is a resistivity temperature coefficient of the conductive layer.

6. The method of claim 5 , comprising determining the measured thickness, thick(t), at the temperature T(t) based on the measurement of the thickness and adjusting the measured thickness to an adjusted thickness thick 0 (t) at T ini using the calculated ρ T .

7. The method of claim 6 , wherein T ini is room temperature.

8. The method of claim 6 , wherein adjusting the measurement of the thickness comprises converting the adjusted thickness thick 0 (t) to a corresponding adjusted eddy current signal.

9. The method of claim 8 , wherein detecting the polishing endpoint comprises comparing the adjusted eddy current signal with a predetermined eddy current signal to determine whether the polishing process has reached the polishing endpoint.

10. The method of claim 1 , wherein the measured temperature, T(t), is the temperature of the conductive layer at time t.

11. The method of claim 1 , wherein the measured temperature, T(t), is the temperature of a polishing pad that polishes the conductive layer at time t.

12. A computer program product, tangibly encoded on a non-transitory computer readable media, operable to cause a data processing apparatus to perform operations comprising:
receiving a measurement of a thickness, thick(t), at a time t of a conductive layer of a substrate undergoing a polishing process from an in-situ monitoring system;
receiving a measured temperature, T(t), associated with the conductive layer at the time t from a sensor configured to monitor a temperature of the polishing process, wherein the measured temperature T(t) is measured while the conductive layer of the substrate is undergoing polishing;
calculating a resistivity ρ T of the conductive layer at the measured temperature T(t);
adjusting the measurement of the thickness using the calculated resistivity ρ T to generate an adjusted measured thickness; and
detecting a polishing endpoint or an adjustment for a polishing parameter based on the adjusted measured thickness.

13. The computer program product of claim 12 , wherein detecting the polishing endpoint comprises comparing the adjusted measurement of the thickness with a predetermined measurement of thickness for determining whether the polishing process has reached the polishing endpoint.

14. The computer program product of claim 12 , wherein calculating the resistivity ρ T of the conductive layer comprises calculating the resistivity ρ T based on:
ρ T =ρ 0 [1+α( T ( t )− T ini )],

where T ini is an initial temperature of the conductive layer when the polishing process starts, ρ 0 is the resistivity of the conductive layer at T ini , and α is a resistivity temperature coefficient of the conductive layer.

15. A polishing system, comprising:
a rotatable platen to support a polishing pad;
a carrier head to hold a substrate against the polishing pad;
a temperature sensor configured to monitor a temperature associated with the conductive layer while the conductive layer of the substrate is undergoing polishing;
an in-situ eddy current monitoring system to generate a eddy current signal depending on a thickness of a conductive layer on the substrate undergoing polishing; and
a controller configured to perform operations comprising
receiving a measurement of a thickness, thick(t), at a time t of the conductive layer of the substrate undergoing polishing from the in-situ eddy current monitoring system,
receiving a measured temperature, T(t), associated with the conductive layer at the time t from the temperature sensor,
calculating a resistivity ρ T of the conductive layer at the measured temperature T(t),
adjusting the measurement of the thickness using the calculated resistivity ρ T to generate an adjusted measured thickness, and
detecting a polishing endpoint or an adjustment for a polishing parameter based on the adjusted measured thickness.

16. The system of claim 15 , wherein detecting the polishing endpoint comprises comparing the adjusted measurement of the thickness with a predetermined measurement of thickness for determining whether the polishing process has reached the polishing endpoint.

17. The system of claim 15 , wherein calculating the resistivity ρ T of the conductive layer comprises calculating the resistivity ρ T based on:
ρ T =ρ 0 [1+α( T ( t )− T ini )],

where T ini is an initial temperature of the conductive layer when the polishing process starts, ρ 0 is the resistivity of the conductive layer at T ini , and α is a resistivity temperature coefficient of the conductive layer.

18. The system of claim 15 , wherein the sensor is configured to measure a temperature of the conductive layer.

19. The system of claim 15 , wherein the sensor is configured to measure a temperature of the polishing pad.

Assignees

• Applied Materials Inc

Inventors

• Xu Kun
• Carlsson Ingemar
• Swedek Boguslaw A
• Bennett Doyle E
• Shen Shih-Haur
• Iravani Hassan G
• Tu Wen-Chiang
• Liu Tzu-Yu

Classifications

• B24B49/14

  taking regard of the temperature during grinding · CPC title

• B24B37/013 Primary

  Devices or means for detecting lapping completion · CPC title

• B24B49/02

  according to the instantaneous size and required size of the workpiece acted upon, the measuring or gauging being continuous or intermittent (B24B49/12 takes precedence) · CPC title

• B24B49/105 Primary

  using eddy currents · CPC title

• B24B49/04

  involving measurement of the workpiece at the place of grinding during grinding operation · CPC title