JP2001073183A - Method for measuring leveler concentration in copper sulfate plating liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for measuring the leveler concentration in a copper sulfate electroplating liquid which is capable of measuring the concentration of the leveler which is an additive in the copper sulfate electroplating liquid considered heretofore infeasible even by the conventional CV method or CVS method. SOLUTION: The method for measuring the leveler concentration in the copper sulfate electroplating liquid, which measures the concentration of the additive containing nitrogen called as the leveler among the organic additives to be included in the copper sulfate electroplating liquid, consists in analyzing the concentrations of a brightening agent (a carrier), moistening agent or polarizing agent (polymer) which is another organic addictive in the plating liquid, then determining the leveler concentration by the peak value area (Ar value) measurement in a peeling region by the CV method or CVS method using a calibration curve of the leveler concentration formed by the carrier and polymer concentrations.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the leveler concentration of a plating solution in a copper sulfate plating apparatus used for filling wiring grooves and holes formed on the surface of a semiconductor substrate or the like with copper plating. .

[0002]

BACKGROUND OF THE INVENTION When performing the filling of the wiring grooves and holes on the surface of a semiconductor substrate (buried) in copper sulfate electroplating, a copper sulfate is a basic composition _{(CuSO 4 · 5H 2 O)} , sulfuric acid (H
₂ SO ₄ ) and chlorine (Cl), to improve the quality of the plating film and to improve the filling (embedding) of grooves and holes.
The following three types of organic additives are often mixed.

[0003] One is a carrier (also referred to as a brightener) that makes the plating film dense and increases the gloss. Generally the sulfur compounds _{(e.g., HS-C n H 2n -SO} 3 Mercap
to alkylsulfonic acid) as an anion, which prevents copper ion precipitation and promotes miniaturization.

[0004] The second is a polymer (also referred to as a suppressor or a carrier) that increases activation polarization by suppressing the deposition of adsorbed copper ions on the cathode surface and increases the throwing power. Surfactants such as PPG.

The third is a leveler made of a nitrogen-containing compound such as polyamine. It exists as a cation in the plating solution.

[0006] The leveler is attracted to places where the current density is high, and where the leveler is attracted, the activation overvoltage is increased and the deposition of copper is suppressed. Conversely, at the bottoms of the fine grooves and holes, the leveler is less adsorbed, and copper deposition is prioritized. The state of bottom-up deposition is said to be excellent in leveling properties.

It is important to control the concentration of the additive in the copper sulfate plating solution in order to control the quality of the plating film and the filling property. However, there is currently no method for measuring the absolute concentration of a trace amount of an organic compound in a strong acid.

[0008] At present, the method of analyzing the concentration of an additive in a plating solution is a CV (Cyclic Voltammetric) method or a CV method.
By measuring the amount of copper deposited on the rotating cathode electrode by a method called S (Cyclic Voltammetric Stripping) method, the concentration is converted into the concentration of an additive called a deposition inhibitor or accelerator.

However, what can be measured by the above method is the concentration of the carrier and the polymer, and the concentration of the leveler cannot be measured. The leveler concentration is the smallest among the above three additives, is similar in properties to the polymer, and has been said to be unmeasurable by the CV method or the CVS method.

[0010]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above points, and has been made in consideration of the concentration of the leveler as an additive in a copper sulfate plating solution, which is said to be impossible with the conventional CV method or CVS method. It is an object of the present invention to provide a method for measuring a leveler concentration in a copper sulfate plating solution, which can measure the concentration of copper.

[0011]

In order to solve the above-mentioned problems, the invention according to claim 1 measures the concentration of a nitrogen-containing additive called a leveler among the organic additives contained in the copper sulfate electrolytic plating solution. In the method for measuring the leveler concentration in a copper sulfate plating solution, the leveler concentration of the plating solution is obtained from a peak value area (Ar value) in a peeling region of the plating solution measured by a CV method or a CVS method. .

Further, according to the present invention, a leveler concentration measurement in a copper sulfate plating solution for measuring the concentration of a nitrogen-containing additive called a leveler among the organic additives contained in the copper sulfate electrolytic plating solution. In the method, after analyzing the concentration of a brightener (carrier), a wetting agent or a polarizer (polymer), which is another organic additive of the plating solution, a leveler is prepared using a reference solution prepared with the carrier concentration and the polymer concentration. A concentration calibration curve is prepared, and a leveler concentration of the plating solution is determined from a peak value area (Ar value) in a peeling region of the plating solution measured by the CV method or the CVS method.

[0013] The invention according to claim 3 is a method for measuring the leveler concentration in a copper sulfate plating solution for measuring the concentration of a nitrogen-containing additive called a leveler among the organic additives contained in the copper sulfate electrolytic plating solution. In the method, a sulfur-containing accelerating additive called a carrier is added in an amount of 2 to 40 to a standard amount.
It is characterized in that a concentration of the leveler is calculated by preparing a measurement solution having twice the concentration and measuring the difference in the amount of copper deposited on the rotating electrode by the CV method or the CVS method.

The effectiveness of the leveler in the copper sulfate plating solution is not determined by the concentration of the leveler alone, but is affected by the concentration of other carriers and polymers. In particular, the carrier concentration affects the leveling property. When a non-dye type nitrogen compound such as polyamine is used for the leveler, the carrier concentration in the plating solution to be analyzed is relatively increased by 2 to 40 times, so that the leveling property becomes remarkable and the calibration curve can be clearly drawn. it can.

[0015] The invention according to claim 4 is a method for measuring the leveler concentration in a copper sulfate plating solution for measuring the concentration of a nitrogen-containing additive called a leveler among the organic additives contained in the copper sulfate electrolytic plating solution. In the method, a sulfur-containing accelerating additive called a carrier is passed through an organic anion-selective adsorption membrane and removed from the plating solution, and then the CV method or C
The leveler concentration is calculated by measuring the difference in the amount of copper deposited on the rotating electrode by the VS method.

When a nitrogen compound such as Janus Green is used for the leveler, the leveling properties become more remarkable when the amount of the carrier is made closer to zero, and the calibration curve can be drawn clearly. Therefore, by passing the plating solution through the organic anion-selective adsorption membrane as described above, the carrier in the plating solution is removed, and a calibration curve can be drawn.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of an apparatus for implementing a method for measuring a leveler concentration in a copper sulfate plating solution according to the present invention. In FIG. 1, the apparatus includes a measuring cell 10 in which a rotating disk electrode 12 held by an electrode holder 11 is arranged, and a stirring blade 13 driven in a non-contact manner by a stirrer 14. Is arranged. The electrode holder 11 is connected to a potentiostat 15 for automatically adjusting the current so that the potential between the electrodes becomes a set value.

Reference numeral 21 denotes a low-concentration basic liquid tank containing the low-concentration basic liquid Q1, 22 a high-concentration basic liquid tank containing the high-concentration basic liquid Q2, 23 a test liquid tank containing the test liquid Q3, 24
Is an additive liquid tank containing an additive A (polymer) liquid Q4,
Reference numeral 25 denotes an additive liquid tank containing an additive B (carrier) liquid Q5, reference numeral 26 denotes an additive liquid tank containing an additive C (leveler) liquid Q6, and reference numeral 27 denotes a standard liquid tank containing a standard liquid Q7.
Here, the basic solution is given a copper sulfate _{(CuSO 4 · 5H 2 SO 4} ) sulfuric acid (H ₂ SO ₄₎ solution was mixed at a predetermined ratio, etc., the standard solution is more additives and hydrochloric acid to the basic solution Is a solution for polymer assay, and a predetermined amount of an additive is mixed in the basic solution.

A burette 29 is connected to the low-concentration basic liquid tank 21 through a three-way valve 28. The buret 29 extracts a predetermined amount of the low-concentration basic liquid Q1 from the low-concentration basic liquid tank 21 and supplies the same to the inside of the measuring cell 10. Can be supplied. In addition, the high concentration basic liquid tank 22, the test liquid tank 23, the additive liquid tank 2
4. Three-way valves 30, 32, 34, 36, 38, 40 are provided in the additive liquid tank 25, the additive liquid tank 26, and the standard liquid tank 27, respectively.
Through the bullets 31, 33, 35, 37, 39, 4
1 are connected, and a predetermined amount of a high concentration basic solution Q2 and a test solution Q
3. Additive A liquid Q4, Additive B liquid Q5, Additive C liquid Q
6. The standard solution Q7 can be extracted and supplied into the measuring cell 10.

Reference numeral 42 denotes a control device having a CPU.
As described later, the three-way valves 28, 30, 32, 34, 36, 38, and 40 are switched according to the polymer concentration measurement mode, the carrier concentration measurement mode, and the leveler concentration measurement mode, and the burettes 29, 31, 33, 35, and 37 are provided. , 39,
The control of the driver 43 and the various units for starting and stopping the 41 is performed.

Reference numeral 44 denotes a sample tank for containing a sample plating solution whose concentration is to be measured. The sample plating solution flows into the sample tank 44 from a sample inlet 45 and overflows from the sample return port 46 to a plating apparatus (not shown). I'm going back. 47 is a sample nozzle,
A burette 48 is connected to the sample nozzle 47 via a three-way valve 49, and the buret 48 extracts a predetermined amount of the sample plating solution through the sample nozzle 47,
The sample nozzle 47 is moved above the measurement cell 10,
The sample plating solution can be supplied into the measurement cell 10.

Reference numeral 51 denotes a pump for sending pure water. The pump 51 sends pure water to the burette 48 and the sample nozzle 47 through the three-way valve 49 so that these can be washed. Further, the inside of the measurement cell 10 is also washed with pure water. Reference numeral 50 denotes a pump for discharging the solution in the measurement cell 10. Hereinafter, in the concentration measurement device having the above configuration, a polymer concentration measurement mode for measuring the polymer concentration,
An example of the carrier concentration measurement mode for measuring the carrier concentration and the leveler concentration measurement mode for measuring the leveler concentration will be described.

[Polymer concentration measurement mode] First, it is confirmed that the electrode is stable. This confirmation was made by extracting 50 ml of the low-concentration basic solution Q1 from the low-concentration basic solution tank 21 and supplying the same to the measurement cell 10 to obtain the Ar value by the CVS method, that is, the peak value area in the separation region (time × current density = electric quantity ) Is determined to determine whether the Ar value is an appropriate value. If the Ar value is not appropriate, the low-concentration basic solution is discharged from the measuring cell 10, washed, and 50 ml of the low-concentration basic solution Q1 is extracted again. , And the above operation is repeated.

When the Ar value is an appropriate value, 1 ml of the test solution Q3 is extracted from the test solution tank 23 and
And the Ar value is measured by the CVS method. The extraction and supply of the test solution Q3 and the measurement of the Ar value by the CVS method are repeated a predetermined number of times (usually 5 times, up to 10 times) to create a calibration curve. After the completion of the preparation of the calibration curve, the liquid in the measuring cell 10 is discharged and the inside is washed.

Subsequently, 50 ml of the low-concentration basic solution Q1 is extracted from the low-concentration basic solution tank 21, supplied to the measuring cell 10, and
It is determined whether or not the r value is an appropriate value (confirmation of stability of the electrode). If the value is appropriate, 1 ml of a sample plating solution (sample) is extracted, added to the measuring cell 10, and CVS
The Ar value is measured by the method. The extraction and addition of the sample solution and the measurement of the Ar value by the CVS method were performed a predetermined number of times (usually 5 times,
Repeat up to 10 times to create a calibration curve. After the completion of the preparation of the calibration curve, the liquid in the measuring cell 10 is discharged and the inside is washed. From the comparison between the above calibration curve and this calibration curve, the polymer concentration of the sample plating solution is determined. That is, the test solution Q
Since the polymer concentration is already known in No. 3, this assay solution Q
By comparing the calibration curve obtained in Step 3 with the calibration curve of the sample plating solution, the polymer concentration of the sample plating solution can be obtained.

[Carrier concentration measurement mode] First, as described above, it is confirmed that the electrode is stable. That is, 50 ml of the low concentration basic solution Q1 is extracted from the low concentration basic solution tank 21,
It is supplied to the measurement cell 10. Ar value is measured by CVS method,
Confirm that the Ar value is an appropriate value.

After confirming that the Ar value is an appropriate value, the liquid in the measuring cell 10 is discharged and washed, and then 48.5 ml of the high-concentration basic liquid Q2 is added from the high-concentration basic liquid tank 22 to the additive liquid tank 24. 1 ml of additive A liquid Q4 from the additive liquid tank 26
, 0.5 ml of each of the additive C liquids Q6 is extracted and supplied to the measurement cell 10, and the Ar value is measured by the CVS method. Subsequently, 0.5 ml of the additive B liquid Q5 is extracted from the additive liquid tank 25, supplied to the measurement cell 10, and the Ar value is measured by the CVS method. An operation of extracting 0.5 ml of the additive B solution Q5 and adding it to the measurement cell 10 and measuring the Ar value by the CVS method a predetermined number of times (usually four times) is repeated to prepare a calibration curve. The measured data is judged, and if the measured data is appropriate, the liquid in the measuring cell 10 is discharged and washed.

Next, it is confirmed again that the electrode is stable. That is, the low-concentration basic solution Q
50 ml is extracted and supplied to the measuring cell 10. CVS
The Ar value is measured by the method, and it is confirmed that the Ar value is an appropriate value.

After confirming that the Ar value is an appropriate value, the solution in the measuring cell 10 is drained and washed, and then 99.6 ml of a sample plating solution is extracted and supplied to the measuring cell 10 and an additive solution tank is provided. 1 ml of the additive A solution Q4 was extracted from 24 and added into the measurement cell 10, the Ar value was measured by the CVS method, and the carrier concentration of the sample plating solution was measured from the calibration curve shown in FIG.

[Leveler Density Measurement Mode] There are three methods for leveler density measurement, that is, the leveler density measurement method according to the first, second, third, and fourth aspects of the present invention. Hereinafter, each leveler measuring method will be described.

In the leveler concentration measuring method according to the first and second aspects of the present invention, first, it is confirmed that the electrode is stable. That is, 100 ml of the low concentration basic solution Q1 is extracted from the low concentration basic solution tank 21 and supplied to the measurement cell 10. The Ar value is measured by the CVS method, and it is confirmed that the Ar value is an appropriate value.

After confirming that the Ar value is an appropriate value, the liquid in the measuring cell 10 is discharged and washed, and then 48 ml of the high-concentration basic liquid Q2 is added from the high-concentration basic liquid tank 22 and added from the additive liquid tank 24. 1 ml of the solution A4 of the solution and 1 ml of the solution Q5 of the additive B were extracted from the additive solution tank 25 and supplied to the measurement cell 10, and the Ar value was measured by the CVS method.

Subsequently, the additive C liquid Q is supplied from the additive liquid tank 26.
6 was extracted in 0.1 ml, supplied into the measuring cell 10, and CV
The Ar value is measured by the S method. Additive Q6 to 0.1
ml, extracted and supplied to the measurement cell 10, and Ar
The operation of measuring the value is repeated a predetermined number of times (usually four times), and FIG.
Create a calibration curve as shown in. Judge the measured data,
If the measurement data is appropriate, the liquid is discharged from the measurement cell 10 and washed.

50 ml of the sample plating solution was extracted and supplied to the measuring cell 10, and the Ar value was measured by the CVS method.
The leveler concentration of the sample plating solution is measured from the calibration curve shown in FIG. In FIG. 2, if the Ar value of the sample plating solution is y, the corresponding leveler concentration is obtained as x.

In the leveler concentration measuring method according to the third aspect of the present invention, when it is confirmed that the electrode is stable, a predetermined amount of the high concentration basic solution Q2 is added from the high concentration basic solution tank 22 to the additive solution tank. 25 to the additive B solution Q5 in a predetermined amount (the high-concentration basic solution Q2 +
(Additive B liquid Q5 = 50 ml) is extracted, supplied to the measurement cell 10, and the Ar value is measured by the CVS method.

Subsequently, the additive C liquid Q is supplied from the additive liquid tank 26.
6 was extracted in 0.1 ml, supplied into the measuring cell 10, and CV
The Ar value is measured by the S method. Additive Q6 to 0.1
ml, extracted and supplied to the measurement cell 10, and Ar
The operation of measuring the value is repeated a predetermined number of times (usually four times) to create a calibration curve (not shown). The measured data is judged, and if the measured data is appropriate, the liquid is discharged from the measuring cell 10 and washed.

A 50 ml sample plating solution was extracted and supplied to the measuring cell 10, and the Ar value was measured by the CVS method.
The leveler concentration of the sample plating solution is measured from the calibration curve with the r value.

In the leveler concentration measuring method according to the fourth aspect of the present invention, when it is confirmed that the electrode is stable, the high-concentration basic solution Q2 is discharged from the high-concentration basic solution tank 22 by 49 m.
1, 1 ml of the additive A liquid Q4 is extracted from the additive liquid tank 24, supplied to the measurement cell 10, and the Ar value is measured by the CVS method.

Subsequently, the additive C liquid Q is supplied from the additive liquid tank 26.
6 was extracted in 0.1 ml, supplied into the measuring cell 10, and CV
The Ar value is measured by the S method. Additive Q6 to 0.1
ml, extracted and supplied to the measurement cell 10, and Ar
The operation of measuring the value is repeated a predetermined number of times (usually four times) to create a calibration curve (not shown). The measured data is judged, and if the measured data is appropriate, the liquid is discharged from the measuring cell 10 and washed.

The sample plating solution was passed through an organic anion-selective adsorption membrane, and 50 ml of the sample plating solution from which the carrier had been removed was extracted and supplied to the measurement cell 10, and the Ar value was measured by the CVS method. The leveler concentration of the sample plating solution is measured from the calibration curve with the Ar value.

In the concentration measuring apparatus having the above configuration, a number of leveler calibration curves in which the concentrations of the carrier and the polymer are changed are stored in advance in the computer of the control unit 42, and the sample analyzing operation is performed more easily and in a shorter time. be able to.

[0042]

As described above, according to the invention described in each claim, it is possible to measure the leveler concentration in the plating solution which cannot be measured by the conventional CV method or CVS method. The effect is obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an apparatus for implementing a method for measuring a leveler concentration in a copper sulfate plating solution according to the present invention.

FIG. 2 is a diagram showing a calibration curve of a leveler concentration and an Ar value.

[Explanation of symbols]

 Reference Signs List 10 measuring cell 11 electrode holder 12 rotating disk electrode 13 stirring blade 14 stirrer 15 potentiostat 21 low-concentration basic liquid tank 22 high-concentration basic liquid tank 23 test liquid tank 24 additive liquid tank 25 additive liquid tank 26 additive liquid tank 27 Standard liquid tank 28 Three-way valve 29 Bullet 30 Three-way valve 31 Bullet 32 Three-way valve 33 Bullet 34 Three-way valve 35 Bullet 36 Three-way valve 37 Bullet 38 Three-way valve 39 Bullet 40 Three-way valve 41 Bullet 42 Controller 43 Driver 44 Sample tank 45 Sample inlet 46 Sample return port 47 Sample nozzle 48 Burette 49 Three-way valve

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroyuki Ueyama 11-1 Haneda Asahimachi, Ota-ku, Tokyo Inside Ebara Corporation (72) Inventor Akihisa Hongo 11-1 Haneda Asahi-cho, Ota-ku, Tokyo Inside the EBARA CORPORATION (72) Ryoichi Kimizuka, 1-1-6 Yoshiyukizaka, Fujisawa-shi, Kanagawa Prefecture Inside Ebara Ujilight Co., Ltd. (72) Emi Maruyama 1-1-6, Yoshiyukizaka, Fujisawa-shi, Kanagawa Ebara Ujilight Inc. F-term (reference) 4K023 AA19 BA06 CB32

Claims (4)

[Claims] A method for measuring the concentration of a nitrogen-containing additive, called a leveler, among organic additives contained in a copper sulfate electrolytic plating solution, the method comprising: a CV (Cyclic Voltammetric) method. Or CVS (Cyclic Vo
A leveler concentration measuring method in a copper sulfate plating solution, wherein a leveler concentration of the plating solution is obtained from a peak value area (Ar value) in a peeling region of the plating solution measured by a ltammetric stripping method. 2. A method for measuring the concentration of a nitrogen-containing additive called a leveler among organic additives contained in a copper sulfate electrolytic plating solution, the method comprising: Brightener (carrier) as an additive,
After analyzing the concentration of the wetting agent or the polarizer (polymer), a calibration curve of the leveler concentration is prepared using the reference solution prepared with the carrier concentration and the polymer concentration, and the CV method or CVS is performed.
A method for measuring a leveler concentration in a copper sulfate plating solution, wherein a leveler concentration of the plating solution is determined from a peak value area (Ar value) in a peeling region of the plating solution measured by a method. 3. A method for measuring the concentration of a nitrogen-containing additive called a leveler among organic additives contained in a copper sulfate electroplating solution, the method comprising the steps of: Calculate the leveler concentration by preparing a measurement solution with the concentration of the accelerating additive containing 2 to 40 times the standard amount and measuring the difference in the amount of copper deposited on the rotating electrode by the CV method or the CVS method. A method for measuring a leveler concentration in a copper sulfate plating solution. 4. A method for measuring the concentration of a nitrogen-containing additive, called a leveler, among organic additives contained in a copper sulfate electroplating solution, the method comprising the steps of: The leveling agent concentration is calculated by measuring the difference in the amount of copper deposited on the rotating electrode by the CV method or the CVS method after removing the accelerating additive containing from the organic anion-selective adsorption membrane and removing it from the plating solution. A method for measuring a leveler concentration in a copper sulfate plating solution.