Method of Analyzing at Least Two Inhibitors Simultaneously in a Plating Bath

Patent metadata

Field	Value
Publication number	US-2016041125-A1
Application number	US-201414453636-A
Country	US
Kind code	A1
Filing date	Aug 7, 2014
Priority date	Aug 7, 2014
Publication date	Feb 11, 2016
Grant date	—

Abstract

The presently claimed invention provides an accurate, fast, and cost effective method for determining the additive concentrations of at least two inhibitors simultaneously in an electroplating bath by using different electrical load conditions. The method of the present invention is able to determine additive concentrations of different inhibitors effectively during on-line feedback control for adjusting the amount of additives in the electroplating bath to maintain the additive concentrations within pre-defined limits during device production.

First claim

What is claimed is:

1 . A method for determining additive concentrations of a first and a second inhibitors in a plating bath, comprising:
determining a first and a second inhibition factors of the first and the second inhibitors by applying a first and a second electrical load conditions respectively on a first and a second supporting solutions; determining equivalent suppressor concentrations of a testing solution under the first and the second electrical load conditions respectively, wherein the testing solution comprises a virgin make-up solution and a portion of the plating bath, and the virgin make-up solution is an electrolyte solution comprising substances of the plating path except the first and the second inhibitors; and determining the additive concentrations of the first and the second inhibitors in the plating bath based on the first and the second inhibition factors and the equivalent suppressor concentrations of the testing solution under the first and the second electrical load conditions.

2 . The method of claim 1 , wherein the step of determining the first and the second inhibition factors further comprises steps of:
(a) providing a standard solution of the first inhibitor, having a known amount of the first inhibitor; (b) providing the virgin make-up solution; (c) measuring an original deposition rate (R 0 ) of the virgin make-up solution under the first electrical load condition; (d) adding a first volume of the standard solution of the first inhibitor into the virgin make-up solution to form the first supporting solution comprising the first volume of the standard solution of the first inhibitor; (e) measuring a first deposition rate (R 1 ) of the first supporting solution comprising the first volume of the standard solution of the first inhibitor under the first electrical load condition to determine a first deposition rate ratio calculated by R 1 /R 0 ; (f) repeating the steps (d)-(e) by adding another volume of the standard solution of the first inhibitor to the virgin make-up solution to determine another deposition rate ratio till obtaining a calibration curve of the first inhibitor; (g) repeating the steps (a)-(f) by using a standard solution of the second inhibitor to obtain a calibration curve of the second inhibitor; (h) determining a calibrated concentration of the first inhibitor (C 1,cali,p1 ) and a calibrated concentration of the second inhibitor (C 2,cali,p1 ) for the first electrical load condition at a predetermined value of the deposition rate ratio based on the calibration curves of the first inhibitor and the second inhibitor; (i) repeating the steps (a)-(g) under the second electrical load condition, and determining a calibrated concentration of the first inhibitor (C 1,cali,p2 ) and a calibrated concentration of the second inhibitor (C 2,cali,p2 ) for the second electrical load condition at the predetermined value of the deposition rate ratio; and (j) determining the first inhibition factor (f 1 ) for the first electrical load condition by C 1,cali,p1 /C 2,cali,p1 , and the second inhibition factor (f 2 ) for the second electrical load condition by C 1,cali,p2 /C 2,cali,p2 .

3 . The method of claim 2 , wherein the step of determining the equivalent suppressor concentrations of the testing solution further comprises steps of:
(a) providing a volume of the virgin mark-up solution (V 0 ); (b) measuring an original deposition rate of the volume of the virgin make-up solution (R 0 ′) under the first electrical load condition; (c) adding a first volume of the plating bath into the virgin make-up solution to form the testing solution comprising the first volume of the plating bath; (d) measuring a first deposition rate (R 1 ′) of the testing solution comprising the first volume of the plating bath under the first electrical load condition to determine a first deposition rate ratio calculated by R 1 ′/R 0 ′; (e) repeating the steps (c)-(d) by adding another volume of the plating bath to determine another deposition rate ratio till obtaining an analysis curve of the plating bath solution; (f) determining a volume of plating bath sample addition for the first electrical load condition at the predetermined value of the deposition rate ratio (V samp,p1 ); (g) repeating steps (a)-(e) under the second electrical load condition and determining a volume of plating bath sample addition for the second electrical load condition at the predetermined value of the deposition rate ratio (V samp,p2 ); and (h) determining the equivalent suppressor concentrations of the plating bath solution for the first electrical load condition (e 1 ) with C 1,cali,p1 *(V 0 +V samp,p1 )/V samp,p1 , and for the second electrical load condition (e 2 ) with C 1,cali,p2 *(V 0+ V samp,p2 )/V samp,p2 .

4 . The method of claim 3 , wherein the additive concentration of the first inhibitor (C 1 ) and the additive concentration of the second inhibitor (C 2 ) in the plating bath are determined as follows:
C 1 =( f 1 e 2 −f 2 e 1 )/( f 1 −f 2 ) C 2 =( e 1 −e 2 )/( f 1 −f 2 )

5 . The method of claim 1 , wherein the first and the second electrical load conditions are applied by cyclic voltammetric stripping, cyclic pulse voltammetric stripping, chronoamperometry, or chronopotentiometry.

6 . The method of claim 5 , wherein the cyclic voltammetric stripping provides plating potential for the electrical load conditions, and the chronoamperometry provides plating current for the electrical load conditions.

7 . The method of claim 1 , wherein the first inhibitor is a leveler, and the second inhibitor is a suppressor.

8 . A method for determining additive concentrations of at least two inhibitors in a plating bath, comprising:
determining at least two inhibition factors of the at least two inhibitors by applying at least two electrical load conditions on at least two supporting solutions respectively; determining equivalent suppressor concentrations of a testing solution under the at least two electrical load conditions respectively, wherein the testing solution comprises a virgin make-up solution and a portion of the plating bath, and the virgin make-up solution is an electrolyte solution comprising substances of the plating bath except the at least two inhibitors; and determining the additive concentrations of the at least two inhibitors based on the at least two inhibition factors and the equivalent suppressor concentrations of the testing solution under the at least two electrical load conditions.

9 . The method of claim 8 , wherein the step of determining the at least two inhibition factors further comprises steps of:
(a) providing a first standard solution of a first inhibitor from the at least two inhibitors, having a known amount of the first inhibitor; (b) providing the virgin make-up solution; (c) measuring an original deposition rate (R 0 ) of the virgin make-up solution under a first electrical load condition from one of the at least two electrical load conditions; (d) adding a first volume of the first standard solution of the first inhibitor into the virgin make-up solution to form the supporting solution comprising the first volume of the first standard solution of the first inhibitor; (e) measuring a first deposition rate (R 1 ) of the supporting solution comprising the first volume of the first standard solution of the first inhibitor under the first electrical load condition to determine a first deposition rate ratio calculated by R 1 /R 0 ; (f) repeating the steps (d)-(e) by adding another volume of the first standard solution of the first inhibitor to determine another deposition rate ratio till obtaining a calibration curve of the first inh

Assignees

• Hk Applied Science & Tech Res

Inventors

• Sun Yaofeng
• Gao Minghui
• Xia Hai

Classifications

• C25D21/18

  of electrolytes (C25D21/22 takes precedence) · CPC title

• C25D21/12

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

• G01N27/26

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

• C25D21/14

  Controlled addition of electrolyte components · CPC title

• G01N27/48 Primary

  using polarography, i.e. measuring changes in current under a slowly-varying voltage · CPC title