JP2002296231A - Concentration measuring method and measuring device for additive for plating liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To resolve a problem that there is a measurement method capable of rapidly and simply measuring the concentration of an additive for a plating liquid and using cyclic voltammography, but this conventional method causes large dispersion of its measurement results which may affect plating quality of a product, and the dispersion of the measurement results is caused by dispersion of a plating condition of a basic liquid and variation of liquid temperature. SOLUTION: By adjusting the plating condition of the basic liquid to a certain value when measurement is required, measurement accuracy is improved. Regarding influence by the liquid temperature, a measured value is corrected according to the liquid temperature for every plating condition measurement depending on the liquid temperature and plating condition basic data and thus the measurement accuracy is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for measuring the concentration of an additive in a plating solution using cyclic voltammography.

The present invention relates to an apparatus for measuring the concentration of an additive in a plating solution using cyclic voltammography.

[0003]

2. Description of the Related Art First, measurement of a plating state by cyclic voltammography will be described with reference to FIG. Working electrode (711), reference electrode (712) in basic liquid (702),
It has a mechanism (714) for immersing the counter electrode (713) and measuring the current between the working electrode and the counter electrode and the voltage between the working electrode and the reference electrode, and a mechanism (715) for scanning the potential between the working electrode and the counter electrode. When the potential between the working electrode and the counter electrode is repeatedly scanned in a certain range, plating (deposition) and peeling (dissolution) of the plated metal are repeated in the working electrode in accordance with the scanned potential. This relationship is shown in FIG. Part A in FIG. 7B shows the amount of plating on the working electrode, and part B shows the amount of plating peeled off on the working electrode. The area of the part A and the part B are equal. An increase in the area of the portions A and B indicates an increase in the plating amount, and a decrease indicates a decrease in the plating amount.

The measurement of the concentration of an additive in a plating solution using a conventional cyclic voltammography has been performed according to the following procedure (a).

In this example, an additive of an arbitrary plating solution will be described as a plating inhibitor (inhibitor), and a plating state will be described as a plating amount of cyclic voltammography. The relationship between the amount of the inhibitor dripped and the amount of plating will be described with reference to FIG.

(A) The plating amount of the basic solution is measured. The result is defined as A0 (801). (B) A solution having a known inhibitor concentration is dropped dropwise to the basic solution, and the inhibitor mixture is sufficiently stirred.
(C) The plating amount of the inhibitor mixture is measured. (D)
The above (b) and (c) are repeated a plurality of times, and the relationship between the inhibitor dropping amount and the change in the plating amount of the basic solution and the mixed solution is determined as a calibration curve. FIG. 8 shows the relationship, and the curve (802) is used as a calibration curve.

FIG. 8 shows that the amount of plating decreases with the addition of the inhibitor, that is, the amount of plating is suppressed by the inhibitor. (E) Measure the plating amount of the same amount of new basic solution as in (a). The result is defined as A1 (803).
(F) An arbitrary amount of the inhibitor concentration unknown solution is dropped into the basic solution of (e) above, and after sufficient stirring, the plating amount is measured. (80
4) (g) From the calibration curve obtained in (d), (f)
Of inhibitor added based on the plating amount measured in (805)
Is required. Thus, the inhibitor concentration is calculated.

[0008]

Since the additive of the plating solution affects the plating quality, it is very important to control the concentration of the additive. For example, copper wiring of a super LSI is manufactured by an electrolytic plating method. Additives of the plating solution for the copper wiring include a plating accelerator, a plating inhibitor, and a plating flattening agent.
If these additive concentrations are not controlled to the appropriate values,
This causes defects such as voids inside the vias and overplates in which the plating surface is abnormally raised in a convex shape. These defects lower the manufacturing yield of the VLSI and also increase the manufacturing cost. In addition, voids generated in vias may be put on the market without being discovered during the manufacturing process. In such a case, not only the failure of the VLSI alone but also the failure of the entire system using the VLSI may occur.

When the concentration of an additive in a plating solution is measured by a conventional method, the dispersion of the obtained additive concentration may vary as much as ± 20% even when the same sample is measured. Conventional plating solution additive concentration measurement cannot be used depending on the product to be plated.

The reason why the measured value of the additive concentration of the plating solution varies in the conventional method will be described with reference to the example of the preceding section.

A0 and A1 of the basic solution measured in the preceding paragraph (a) and the preceding paragraph (e) should be originally the same value. However, A0 and A1 actually have a certain difference due to the influence of the characteristics of the measuring device and the measuring environment. A1 at the time of measuring the unknown liquid of the inhibitor is A0
Deviates from the previously obtained calibration curve. As the difference between A0 and A1 increases, the measurement result of the liquid with unknown inhibitor concentration deviates from the true value.

Also, the temperature of the basic solution or the mixture of the additive and the basic solution constantly changes depending on the measurement environment, which also causes the measured value of the additive concentration to fluctuate.

The ratio between A0 and A1 is plotted on the abscissa and the variation in the inhibitor concentration is plotted on the ordinate, as shown in the graph (410) of FIG.

In FIG. 4 and the result of the graph (410), A0 and A
It shows that the larger the difference of 1 (away from 1 on the horizontal axis), the greater the variation in the inhibitor concentration.

If the temperature of the basic solution or the mixture of the additive and the basic solution changes by 1 ° C., the plating amount of cyclic voltammography may change by about 1 mC.

[0016]

Means for Solving the Problems According to claim 1,
In the method of measuring the concentration of the additive in the plating solution, the plating state of the basic solution is measured. A known additive concentration solution is dropped into the basic solution,
The plating state of the mixed solution having a known concentration is measured. The relationship between the additive concentration and the change in plating state is grasped by a calibration curve. The plating state of the new basic solution is measured, and the plating state is adjusted according to the plating state. An unknown additive concentration solution is dropped into the basic solution, and the plating state of the unknown concentration mixed solution is measured. Based on the above calibration curve, the additive concentration of the concentration unknown liquid dropped from the plating state is calculated.
The plating state from the above is measured by a plating amount or a plating peeling amount of cyclic voltammography,
In the method for measuring the concentration of an additive in a plating solution, the method for measuring the concentration of an additive in a plating solution is characterized by adjusting the amount of plating or the amount of plating peeling according to the amount of plating or the amount of plating peeling. According to the agent concentration measuring method, the additive concentration can be measured with high accuracy,
Plating defects are reduced. Also, products with excellent plating quality can be supplied.

According to a second aspect of the present invention, there is provided a method for measuring the concentration of an additive in a plating solution, wherein the measured plating conditions of the basic solution and the mixed solution are corrected by the solution temperature. Measurement Method According to the method for measuring the concentration of an additive in a plating solution, the concentration of the additive can be measured with high accuracy, and plating defects are reduced. Also, products with excellent plating quality can be supplied.

According to a third aspect of the present invention, there is provided a method for measuring the concentration of an additive in a plating solution according to the first or second aspect, wherein the plating state is determined during cyclic voltammography plating or peeling. The method for measuring the concentration of an additive in a plating solution according to the method for measuring the concentration of an additive in a plating solution is characterized in that the concentration of the additive is measured by the peak value of the current (charge amount) of the plating solution. Plating defects are reduced. Also, products with excellent plating quality can be supplied.

According to a fourth aspect of the present invention, there is provided an apparatus for measuring the concentration of an additive in a plating solution, the apparatus having the characteristics of the first aspect. According to the apparatus, the additive concentration can be measured with high accuracy, and plating defects are reduced. Also, products with excellent plating quality can be supplied.

According to a fifth aspect of the present invention, there is provided an apparatus for measuring the concentration of an additive in a plating solution, the apparatus comprising: According to the apparatus, the additive concentration can be measured with high accuracy, and plating defects are reduced. Also, products with excellent plating quality can be supplied.

According to a sixth aspect of the present invention, there is provided an apparatus for measuring the concentration of an additive in a plating solution, wherein the apparatus has the characteristics of the third aspect. According to the apparatus, the additive concentration can be measured with high accuracy, and plating defects are reduced. Also, products with excellent plating quality can be supplied.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) This embodiment will be described with reference to FIGS. FIGS. 1, 2, and 3 are a process flow, a configuration diagram, and a graph, respectively, showing a method for measuring the concentration of an additive in a plating solution according to the first embodiment. In this example, the additive of the plating solution to be measured is described as a plating inhibitor (suppressor), and the plating state is described as a plating amount (unit: mC) of voltammography. First, the device configuration will be described with reference to FIG. The dedicated beaker (201) has a basic solution (201) for measuring the plating amount,
Three electrodes of the electrode unit (205) are immersed in the basic liquid. Potential scanning unit when measuring plating amount
From (206), potential scanning is performed via the electrode control unit (204). The current value (charge) that changes as a result of the potential scanning is measured by the current measurement unit (207) and transmitted to the control device (203). In the control section, the potential scanning and the current value are processed in the calculation section, and the plating amount, peeling amount, each peak value and the like by voltammography are calculated. Further, a calibration curve, a drop amount calculation from the plating amount, and the like are performed based on the drop amount and the plating amount of the drop unit (208). The dropping unit (208) drops the known concentration liquid and the unknown concentration liquid according to a command from the control unit.

Next, a description will be given with reference to FIG. In FIGS. 1 (a) to 1 (e), the measurement of "understand the dripping amount of the inhibitor and the change in the plating amount" is performed using the "solution with known inhibitor concentration". (a) The amount of plating of 100 milliliters (hereinafter, ml) of the basic solution (202) prepared in the dedicated beaker (201) is measured and stored in the storage unit of the control unit (203). In this embodiment, the measured plating amount is A0. (b) A solution having a known inhibitor concentration is dropped into 0.05 ml (a) of the basic solution and stirred for 10 seconds. (c) The plating amount of the mixed solution of known concentration in (b) is measured. (d) Return to (b) above and measure the amount of the inhibitor and the amount of plating until the amount of the inhibitor dropped reaches the prescribed number of times. When the drop amount reaches the specified value,
Proceed to (e). (e) The change of the inhibitor dropping amount and the plating amount is grasped by the control unit as a calibration curve. The results are shown in the graph of FIG.
0). The vertical axis of the graph (310) is the plating amount (mC), and the horizontal axis is the drop amount (ml) of known concentration. The plating amount A0 (311) comes to the position where the inhibitor addition amount is 0 ml. This indicates that the plating amount decreases as the dropping amount increases, that is, the plating amount is suppressed by the inhibitor. Dispose of the mixture of base solution and inhibitor used so far.

Next, in (f) to (j), the "solution of unknown inhibitor concentration"
Is measured. (f) The plating amount A1 of 100 ml of the new basic solution is measured. (g) The plating amount A1 (FIG. 3, 322)
Is adjusted to A0 (FIG. 3, 321) by adjusting the electrode unit (204) (FIG. 3, 324). (h) Measure the volume of the inhibitor concentration unknown solution, drop it into the basic solution of (f), and stir for 10 seconds. In this example, 0.5 ml of the unknown concentration liquid was dropped. (i) The plating amount of the mixed solution of unknown concentration in (h) is measured. This value is represented by B1 (323 in FIG. 3).
And (j) Make B1 correspond to the calibration curve obtained in (e),
The amount of the inhibitor added is determined and the concentration is calculated.

After adjusting the plating amount A1 in this example to match A0, the results of measurement of the inhibitor are shown in the graph (320) of FIG. In the graph (320), B1 is 12.5 mC,
The amount of the inhibitor dropped from the calibration curve was 0.5 ml. Subsequent concentration calculations are obtained from the inhibitor concentration, the basic solution amount, the amount of the unknown inhibitor solution dropped, and the inhibitor dropping amount (0.5 ml) obtained from B1.

For the basic liquid volume (100 ml), the liquid droplet volume with a known concentration (0.05 ml), the liquid droplet volume with an unknown concentration (0.5 ml), etc. shown in the present embodiment, preliminary measurements are performed a plurality of times in order to obtain the optimum values. Was. It is considered that the optimum value differs depending on the type of additive and the concentration of the known liquid.

Further, in this embodiment, the dripping of the inhibitor unknown liquid is performed.
Although the method is performed only once, there is also a method in which a small amount is dropped a plurality of times as in the case of dropping a droplet having a known concentration.

As a plating solution additive, a plating accelerator and a plating flattening agent other than the inhibitor described in this embodiment can be measured by the same measuring method.

For the measurement of the plating accelerator, a liquid in which an inhibitor is mixed in a basic solution is used, and for the measurement of the flattening agent, a liquid in which an inhibitor and an accelerator are mixed in the basic solution is used.

(Embodiment 2) This embodiment will be described with reference to FIGS. FIGS. 5 and 6 are a process flow and a configuration diagram showing a method for measuring the concentration of an additive in a plating solution according to the second aspect of the present invention. In this example, the additive of the plating solution to be measured is described as a plating inhibitor (suppressor), and the plating state is described as a plating amount (unit: mC) of voltammography. FIG.
The difference is that the liquid temperature compensating unit is added to the control unit (603) of the first aspect. The recording unit of the control unit stores data for correcting the plating amount based on the solution temperature of the basic solution, and the current data measured by the current measuring unit (607), that is, the plating amount is corrected based on the solution temperature. . In this embodiment, changes in the temperature of the basic solution and the plating amount are measured in advance.

Next, a description will be given with reference to FIG. An input / storage step of (a0) basic solution temperature and plating amount correction data is added to the head of the process flow of claim 1.

In all the processes for measuring the plating amount, a thermometer is used.
The liquid temperature is measured by (609), and the liquid temperature information is transmitted to the control device (603) via the electrode unit (605). In addition, (a) temperature compensation is performed in all steps of measuring the plating amount except for measuring the plating amount of the basic solution. The process flow and the concentration calculation method other than the temperature compensation are the same as those in the first aspect.

In this embodiment, there is also a method in which a small amount of the inhibitor unknown liquid is dropped a plurality of times in small amounts.

As a plating solution additive, a plating accelerating agent and a plating flattening agent other than the inhibitor described in this embodiment can be measured by the same measuring method.

For the measurement of the plating accelerator, a liquid obtained by mixing an inhibitor with a basic liquid is used, and for the measurement of the flattening agent, a liquid obtained by mixing an inhibitor and an accelerator with the basic liquid is used.

[0036]

According to the present invention, the concentration of an additive in a plating solution can be measured with high accuracy, and plating defects are reduced. Also, products with excellent plating quality can be supplied.

For reference, data obtained by measuring the concentration of the additive according to claim 1 of the present invention with high accuracy are shown in FIG. 4 (420). The data of the graph (420) in FIG. 4 are plotted together with the result (421) of the solution with a known inhibitor concentration measured by the measuring method of the present invention and the result (422) measured by the conventional method.

The vertical axis of the graph (420) represents the difference between the measured value and the true value.
(%) = {100 × (measured value−true value) / true value}, the horizontal axis is A1 and A0
Is the ratio of The more the plotted data spreads in the vertical direction, the more the measured value varies, and the more the data spreads in the horizontal direction, the more A1 varies with respect to A0. In the result of the graph (420), the measurement result (421) of the present invention shows that the measurement value variation is -10 to +1 of the conventional method by adjusting A1 to A0.
It shows improvement from 25% width of 5% to 8% width of -8 to 0%.

[Brief description of the drawings]

FIG. 1 is a process flow showing a method for measuring the concentration of an additive in a plating solution according to the invention of claim 1;

FIG. 2 is a configuration diagram showing a method for measuring the concentration of an additive in a plating solution according to the first embodiment of the present invention.

FIG. 3 is a graph showing a method for measuring the concentration of an additive in a plating solution according to the first embodiment.

FIG. 4 is a graph showing the results of measuring the additive concentration of a plating solution according to the prior art and the present invention.

FIG. 5 is a process flow showing a method for measuring the concentration of an additive in a plating solution according to the invention of claim 2;

FIG. 6 is a block diagram showing a method for measuring the concentration of an additive in a plating solution according to the second embodiment.

FIG. 7 is a configuration diagram and a voltammogram for explaining cyclic voltammography.

FIG. 8 is a graph showing the amount of a suppressor dropped and the amount of plating according to a conventional technique.

[Explanation of symbols]

201 Dedicated Beaker 202 Basic Solution 203 Controller 204 Electrode Control Unit 205 Electrode Unit 206 Potential Scanning Unit 207 Current Measurement Unit 208 Dropping Unit 310 Suppressor Concentration Known Drop Volume and Change in Plating Amount 311 Plating A0 320 Inhibitor Concentration Unknown Graph showing solution concentration measurement procedure 321 Plating amount A0 322 Plating amount A1 323 Plating amount of unknown concentration mixed solution B1 324 Plating amount adjustment direction 410 Result of additive concentration measurement by prior art 420 Result of additive concentration measurement by present invention and conventional technology 421 Result of additive concentration measurement according to the present invention 422 Result of additive concentration measurement according to the prior art 601 Dedicated beaker 602 Basic solution 603 Controller 604 Electrode control unit 605 Electrode unit 606 Potential scanning unit 607 Current measurement unit G 608 Dropping unit 609 Thermometer 702 Basic solution 711 Working electrode 712 Reference electrode 713 Counter electrode 714 Current and voltage measurement mechanism 715 Potential scanning mechanism 801 Plating amount A0 802 Calibration curve 803 Plating amount A1 804 Plating amount of unknown concentration liquid mixture 805 Suppression Agent dripping amount

Claims (6)

[Claims] In a method for measuring the concentration of an additive in a plating solution, a plating state of a plating solution containing no additive (hereinafter referred to as a basic solution) is measured. A solution having a known concentration of an additive to be measured is dropped onto the basic solution, and the plating state of a mixture of the solutions having a known concentration (hereinafter, a mixed solution having a known concentration) is measured. Grasp the relationship between the amount of the additive concentration known solution and the plating amount. Then, the plating state of a new basic solution is measured and adjusted as a measurement of an unknown solution of the additive concentration to be measured. A solution of unknown additive concentration to be measured is dropped onto the basic solution, and a plating state of a mixed solution of the unknown concentration solution (hereinafter, a mixed solution of unknown concentration) is measured. Based on the above calibration curve, the amount of the additive of the unknown concentration liquid dropped from the plating state is calculated to calculate the concentration. The plating state from the above is measured by the amount of plating or the amount of plating peeling of cyclic voltammography. Adjusting, method for measuring additive concentration of plating solution 2. The apparatus for measuring the concentration of an additive in a plating solution according to claim 1, wherein the relationship between the temperature of the basic solution and the plating state is grasped in advance and stored in a storage unit.
If there is a difference between the temperature of the base solution and the temperature of the mixed solution, from the relationship between the temperature of the base solution and the plating state of the storage unit,
A method for measuring the concentration of an additive in a plating solution, wherein the plating state measured in (1) is corrected. 3. The method for measuring the concentration of an additive in a plating solution according to claim 1, wherein the plating state is measured by a peak value of a current (charge amount) at the time of plating or peeling of the cyclic voltammography. Method for measuring the concentration of an additive in a plating solution. 4. An apparatus for measuring the concentration of an additive in a plating solution, comprising a mechanism for performing the method for measuring the concentration of an additive in a plating solution according to claim 1. 5. An apparatus for measuring the concentration of an additive in a plating solution, comprising a mechanism for performing the method for measuring the concentration of an additive in a plating solution according to claim 2. 6. An apparatus for measuring the concentration of an additive in a plating solution, comprising a mechanism for performing the method for measuring the concentration of an additive in a plating solution according to claim 3.