TSV bath evaluation using field versus feature contrast

Patent metadata

Field	Value
Publication number	US-9689083-B2
Application number	US-201414275750-A
Country	US
Kind code	B2
Filing date	May 12, 2014
Priority date	Jun 14, 2013
Publication date	Jun 27, 2017
Grant date	Jun 27, 2017

Abstract

The embodiments herein relate to methods and apparatus for determining whether a particular test bath is able to successfully fill a feature on a substrate. In various cases, the substrate is a semiconductor substrate and the feature is a through-silicon-via. Generally, two experiments are used: a first experiment simulates the conditions present in a field region of the substrate during the fill process, and the second experiment simulates the conditions present in a feature on the substrate during the fill process. The output from these experiments may be used with various techniques to predict whether the particular bath will result in an adequately filled feature.

First claim

What is claimed is:

1. A method of evaluating whether additives in an electroplating bath of interest meet an electroplating specification, the method comprising:
performing a first experiment by:
contacting an electrode with the electroplating bath of interest,
applying a current density waveform to the electrode, wherein the current density waveform applied approximates a current density experienced in a field region of a substrate when electroplated in the electroplating bath of interest, and
recording a first potential trace output during the first experiment;

performing a second experiment by:
contacting a second electrode with an acceleration solution comprising accelerator until the second electrode is substantially fully accelerated,
rinsing the acceleration solution from the second electrode,
contacting the second electrode with the electroplating bath of interest,
applying a second current density waveform or a potential waveform to the second electrode, wherein the second current density waveform or potential waveform approximates the current density or potential experienced within a feature on the substrate when electroplated in the electroplating bath of interest,
where a second current density waveform is applied, recording a second potential trace output during the second experiment, and where a potential waveform is applied to the second electrode, recording a current trace output during the second experiment; and

determining, based on two or more parameters selected from the group consisting of the first potential trace output, the second potential trace output, the current trace output, and calibration data, whether the additives in the electroplating bath of interest meet the electroplating specification.

2. The method of claim 1 , wherein the electroplating specification relates to the capability of the additives in the electroplating bath of interest to fully fill the feature on the substrate through a bottom-up mechanism in an acceptable timeframe.

3. The method of claim 1 , wherein the current density waveform applied during the first experiment corresponds to a current density waveform used for electroplating material on the substrate in a target filling process.

4. The method of claim 3 , wherein the current density waveform applied during the first experiment corresponds to a current density waveform used for electroplating material on the substrate in a target filling process, as modified by a field current density correction factor.

5. The method of claim 3 , wherein a rotation rate of the second electrode during the second experiment is higher than a rotation rate of the substrate during the target filling process.

6. The method of claim 3 , wherein a temperature of the electroplating bath of interest during the second experiment is higher than a temperature of the electroplating bath of interest during the target filling process.

7. The method of claim 1 , wherein the first potential trace output from the first experiment is used to select the potential waveform applied in the second experiment.

8. The method of claim 7 , wherein the potential waveform is selected based on the potential experienced during a final period of electroplating during the first experiment.

9. The method of claim 8 , wherein the potential waveform is selected based on an average potential of the first potential trace output during a final period of electroplating during the first experiment.

10. The method of claim 7 , wherein the first potential trace output from the first experiment is used to calculate a predicted potential, the predicted potential corresponding to a potential that would be experienced if electroplating were to continue after a final electroplating period in the first experiment, and wherein the potential waveform in the second experiment is based on the predicted potential.

11. The method of claim 2 , wherein the second current density waveform is selected based on a current density to fully fill the feature in the acceptable timeframe.

12. The method of claim 1 , wherein the electrode and the second electrode are the same electrode, and further comprising removing material deposited on the electrode during the first experiment before contacting the electrode with the acceleration solution.

13. The method of claim 1 , wherein the determining comprises comparing a current density at a relevant time from the current density trace output from the second experiment to a threshold current density.

14. The method of claim 1 , wherein the determining comprises comparing a time at which the current density trace output from the second experiment reaches a threshold current density to a threshold time.

15. The method of claim 1 , wherein the determining comprises integrating the current density trace output from the second experiment between a first time and a second time to calculate a charge density, and comparing the charge density to a threshold charge density.

16. The method of claim 1 , wherein the determining comprises calculating a ratio between a potential from the first potential trace output at a first time during the first experiment to a potential from the second potential trace output at a second time during the second experiment, and comparing the ratio to a threshold ratio.

17. The method of claim 1 , wherein the calibration data is generated by performing the first and/or second experiment on electrolytes that are known to produce acceptable fill results and electrolytes that are known to produce unacceptable fill results.

18. The method of claim 17 , wherein the calibration data comprises one or more of the parameters selected from the group consisting of: a threshold current density, a threshold charge density, a threshold time, and a threshold ratio of potentials.

19. The method of claim 2 , wherein the acceptable timeframe is about 1 hour or less.

20. The method of claim 1 , further comprising electroplating metal onto the electrode before contacting the electrode with the electroplating bath of interest in the first experiment, and electroplating metal onto the second electrode before contacting the second electrode with the acceleration solution.

21. The method of claim 1 , wherein a concentration of accelerator in the acceleration solution is at least about 10 times a concentration of accelerator in the electroplating bath of interest.

22. A method of monitoring the additives in an electroplating bath of interest, the method comprising:
(a) applying a defined current density to a first electrode while in contact with the electroplating bath of interest,
wherein the defined current density represents a current density experienced in a field region of a substrate when electroplated in the electroplating bath of interest, and
wherein the first electrode's surface is not substantially fully accelerated;

(b) recording a potential trace output of the first electrode when applying the defined current density;
(c) applying a second defined current density or a defined potential to a substantially fully accelerated surface of a second electrode while in contact with the electroplating bath of interest,
wherein the second defined current density or the defined potential represents the current density or potential experienced within a feature on the substrate when electroplated in the electroplating bath of interest;

(d) recording a second potential trace output and/or a current density trace output of the second electrode when applyi

Assignees

• Lam Res Corp

Inventors

• Brogan Lee
• Mayer Steven T
• Thorum Matthew
• Richardson Joseph
• Porter David W
• Fu Haiying

Classifications

• B41C1/18

  Curved printing formes or printing cylinders {(B41C1/10, B41C1/14 take precedence)} · CPC title

• G01N27/416

  Systems (G01N27/27 takes precedence) · CPC title

• G01N27/26

  by investigating electrochemical variables; by using electrolysis or electrophoresis · CPC title

• C25D21/12 Primary

  Process control or regulation (controlling or regulating in general G05) · CPC title

• G01N27/413

  Concentration cells using liquid electrolytes {measuring currents or voltages in voltaic cells} · CPC title