JP2720130B2 - Power supply for electroplating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for electroplating for setting and outputting an electrolytic condition value for forming a metal film on a substrate of a product, and more particularly, to a fuzzy variable representing a state of a plating solution. The present invention relates to a power supply device for electroplating in which fuzzy inference is performed on a fuzzy control program by using the state value as an input value on a fuzzy control program, and the inference value controls the output of a plating power supply.

[0002]

2. Description of the Related Art In electroplating, a metal substrate to be plated is inserted as a cathode (cathode) into an aqueous solution containing salts of a metal to be plated, and an appropriate anode (anode) is placed between the metal substrate and the anode. Electrolysis conditions (current value, pulse ON time, pulse O
By passing a direct current or a pulse current output from a power supply controlled by FF time and temperature, metal ions in an aqueous solution are reduced and precipitated as metal on a cathode surface to form a required crystal on a substrate. A metal plating film is formed. Recently, the power supply device used for electroplating controlled by the electrolysis conditions, the demand for streamlining of production, uniform stability of quality and work efficiency, the waveform provided by the power supply device,
In addition to the original functions such as power efficiency and voltage regulation,
There is a tendency to strongly demand a power supply device having various conditions such as a stepless current adjustment function, a remote control function, and automation of the device. Further, in the field of semiconductor devices, there is an increasing demand for forming a coating layer on a metal surface of a lead frame or the like to improve functions such as corrosion resistance, bonding properties and electrical conductivity. With the progress of high integration, there is a demand for high reliability and improved film characteristics of the metal film layer, such as uniform thickness of the metal film layer formation, adhesion and multi-layer film.

[0003]

SUMMARY OF THE INVENTION In order to solve the above-mentioned demands, the present applicant has previously disclosed in Japanese Patent Application No. 3-228253 a setting means for displaying and writing data of electrolysis conditions.
A display setting unit having an arithmetic processing means for calculating an output value based thereon; an output control unit for controlling the output unit with the condition value subjected to the arithmetic processing; and a set value of current or voltage such as DC or pulse. An output unit and a memory unit for registering, storing, and reading the electrolytic condition data set by the display setting unit for each product, and a metal coating having functions such as rust prevention, electrical conductivity, and heat resistance on a substrate of the product. We have proposed a power supply device for electroplating that sets and controls current and voltage such as DC or pulse of electrolysis conditions required for generation. However, the power supply device for electroplating stores and retains plating condition setting data performed in the past, and only allows the stored data to be easily selected to set plating conditions. There is a disadvantage that the range of conditions is limited and the range of plating conditions is not sufficient. Of course, it is theoretically possible to manually set each condition and select the best plating conditions, but the plating conditions are complicated depending on, for example, the plating solution temperature, the plating solution concentration, the current value, and the current passage ratio. On the contrary, it was extremely difficult to set all these conditions. The present invention provides a power supply device for electroplating that improves remote control, automation and workability of output control of state values such as concentration, temperature, pulse-on time and pulse-off time, and current value of electrolysis conditions. It is an object of the present invention to make the thickness of a metal coating layer formed uniform and to improve the reliability and coating properties of the metal coating layer.

[0004]

According to the present invention, there is provided a semiconductor device comprising:
The power supply device for electroplating described is a setting means for displaying and writing data of electrolysis conditions, a display setting unit including an arithmetic processing means for calculating an output value based thereon, and the condition values subjected to the arithmetic processing, An output control unit that controls an output unit that outputs a set value of a current or a voltage such as a direct current or a pulse; and a communication that performs calling, transfer, and output control of data from an external device is provided in the display setting unit. Means for forming a metal film having functions such as rust prevention, conductivity, heat resistance, etc. on a substrate of a product, the fuzzy inference using a state value of a plating solution as an input value. And an operation unit for calculating and outputting an inference value of the fuzzy variable, and comparing the inference value output by the operation unit with a setting value calculated based on plating conditions, wherein the setting value and the inference value are Match That until comprising a fuzzy control program for fuzzy inference for inferring the optimum control value by repeating the fuzzy feedback for adjusting the correction value to the inference value, calculation of the fuzzy control CPU of the display setting unit
, And the output of the plating condition is controlled by inputting the optimum control value to the output control unit.

According to a second aspect of the present invention, in the power supply device for electroplating according to the first aspect, an output value of the fuzzy control unit is input to the display setting unit via communication means. . The power supply device for electroplating according to claim 3, wherein the fuzzy variables of the state value of the plating solution are concentration C, temperature T, current I, pulse period τ, and pulse on time τ. It is configured to be _ON . According to a fourth aspect of the present invention, in the power supply apparatus for electroplating, the state value C of the concentration is such that the initial concentration of the plating solution is C ₀ , the plating weight deposited by the pulse-on time is W _ON , Assuming that the volume of the tank is Ca, the tank is configured to be expressed as C = C ₀ −W _ON / Ca. The power supply device for electroplating according to claim 5, wherein in the apparatus according to any one of claims 1 to 4, the expression of the consequent part is such that concentration is C, temperature is T, pulse on time is τ _ON , and pulse period τ is K ₁ ,
Assuming that K ₂ and K ₃ are constants, I ₀ = K ₁ · C + K ₂ · T + K ₃ · 1 / (τ _ON / τ) +
K ₄ is configured as an approximation formula of the current value represented by. The power supply apparatus for electroplating according to claim 6 is the apparatus according to claim 1, wherein the set values are a pulse period (τ) manually input by an operator, a plating time (t ₀ ), a plating area ( S) and the current value (I) corresponding to the deposition amount per pulse calculated from the information of the plating thickness (d). The power supply device for electroplating according to claim 7 is the device according to claim 1, wherein the plating solution state value input to the fuzzy inference rule includes a plating solution state detection value and an operator's condition value. It is configured to include information on manually input values. The power supply device for electroplating according to claim 8 is the device according to claim 1, wherein the plating tank includes a plating solution injection valve, and operates when the concentration of the plating solution decreases. It is configured such that the concentration of the plating solution is kept within a predetermined range. The power supply device for electroplating according to claim 9 is the device according to claim 8, wherein the operation of the plating solution injection valve is such that the pulse-on time τ _ON corrected by the fuzzy control program is larger than the maximum value τ _ON ^H thereof. It is configured in such a way as to be the case.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will now be described with reference to the accompanying drawings to provide an understanding of the present invention. Here, FIG. 1 is a flowchart showing an operation state of a power supply device for electroplating according to an embodiment of the present invention, FIG. 2 is a schematic block diagram of the power supply device for electroplating, and FIG. It is a graph shown.

As shown in FIG. 2, a power supply device 10 for electroplating according to an embodiment of the present invention includes an output unit 11 that receives an AC power and outputs a DC, and an output connected to the output unit 11. It comprises a control unit 12 and a display setting unit 13 for performing data setting, calculation and communication. Hereinafter, these will be described in detail. The output unit 11 includes a transformer for stepping down an AC voltage, a rectifier for converting the stepped-down AC into DC, a capacitor for smoothing the rectified pulsating current, and a power connected in parallel to control the smoothed DC. A MOS-FET, and the power MOS-FET
To control the output to DC or pulse, and further to control the voltage or current.

The output section 11 has a current detection section and a voltage detection section. The output section 11 can perform digital conversion by the AD converter 14 and send detection data to the CPU 16 of the output control section 12 via the interface circuit 15. It has become. The CPU 16 is connected to a ROM 17 in which an execution program of the CPU 16 is recorded, a RAM 18 for storing data as necessary, and a dual port RAM 19. The dual port RAM 19 is readable and writable from the CPU 16 and the CPU 20 of the display setting unit 13.
It has a structure that can read and write data from. The D / A converter 21 and the amplifier 22 are connected to the CPU 16 via the interface circuit 15 so that the output unit 11 can be driven by current or voltage conditions calculated by the CPU 16.

On the other hand, the CPU 20 includes the CPU 20
And a RAM 24 for temporarily storing data. And
In the ROM 23 connected to the CPU 20, the writing setting of the plating condition data can be independently performed based on a signal manually input from an input key provided on the operation panel 25, and an operation for calculating an output value based on the setting can be performed. A program with processing means and a fuzzy control program are described. The CPU 20 is connected to another external control device (for example, a personal computer) via the interface circuit 26 and the RS422A terminal 27.
The fuzzy control program stored in the ROM 23 constitutes a fuzzy control unit 28 described below.

As described in detail in Japanese Patent Application No. 3-228253 filed earlier, the plating conditions performed through the output section 11 are, for example, the current set value and the constant voltage when performing the constant current control. In the case of performing the control, a voltage setting value, a pulse on time, a pulse off time, a slow-up, a slow-down, and the like can be set in advance, and a memory unit capable of registering 250 or more types in which these are combined is provided. This memory unit may use any of the above-mentioned RAMs 18, 19 and 24 or may be provided separately. Therefore, by combining the above conditions, the DC output can be slowed up and slowed down, and the pulse output can be slowed up and slowed down.

Further, in order to monitor the abnormality of the power supply, an alarm is generated by comparing the output of the current detecting section and the voltage detecting section with the set current and voltage, and an alarm is generated. Are classified into short circuit, open circuit, abnormal voltage, and abnormal current according to the conditions described above, and these are displayed on the panel display section of the operation panel 25 in Japanese. Further, a temperature controller 30 having a heater, a temperature sensor, and a control unit for these components is provided in the plating tank 29,
A predetermined temperature can be controlled by a signal from the output control unit 12. The plating tank 29 is provided with a concentration sensor 31 for detecting an initial concentration of the plating solution.
The output is a digital signal via an AD converter 32, which is a CP.
It has been input to U16.

Next, the entire process of the programs stored in the ROMs 17 and 23 will be described with reference to FIG. First, the operator operates the operation panel 2
From 5, the plating thickness d, plating area S, plating time t ₀ ,
A plating condition such as a rectangular wave period τ when pulse plating is performed is input. The plating conditions may be set in advance and input by a signal from a line or another control device. In this embodiment, a plating process is performed by the pulse plating. By inputting the plating conditions, the plating weight W is calculated (step 10).
0), the number of pulses n is calculated (step 101), and the plating weight W 'per pulse is calculated (step 102). Then, the required current value I to be the set value is calculated by the following equation derived from the Faraday's law from the previously input pulse-on time initial value τ _ON and the plating weight W ′ (step 103). I = W ′ · F / (τ _ON · eq) Here, F represents the Faraday coefficient, and eq represents the gram equivalent of the metal to be plated.

Next, the concentration sensor 31 detects the initial concentration of the plating solution previously charged in the plating tank 29.
Then, the temperature T of the plating solution, which is considered to be the optimum temperature determined by past experiments (for example, 60 ° C.), is input from the operation panel 25 and set in advance by the temperature controller 30. Then, a fuzzy calculation (step 104), which will be described later, is performed on the basis of the data experimentally performed based on the concentration C of the plating solution, the temperature T of the plating solution, the pulse period τ, and the pulse on time τ _ON to obtain a fuzzy inference value. Inferred current value I ₀
Is calculated.

Next, the inferred current value I ₀ becomes the maximum current value I
It is determined whether or not the _maximum is exceeded (step 10
5), if they exceed the maximum current value I _max is an alarm and stops the plating process (step 106). The inference current value I ₀ is a condition that does not exceed the maximum current value, the inference current value I ₀ is the required plating current value I greater, it is determined whether more or less (step 107, 108), if the amount is large, the preset short time Δτ is subtracted in step 109, and if the amount is small, the Δτ is added to step 110, and the corrected pulse-on time τ _ON is determined by plating in advance by experiment. Is confirmed to be between the set minimum pulse on time τ _ON ^L and the maximum pulse on time τ _ON ^H (step 111), and the pulse on time τ _ON is stored (step 112). ).

Then, the stored pulse on time τ _ON is subjected to fuzzy inference in the fuzzy control unit 28 to calculate an inference current value I ₀ again, and further inputted to step 103 to calculate a required current value I. . The above result is compared again in steps 105, 107 and 108 again, and the inferred current value I ₀ calculated by the fuzzy controller is calculated.
If the required current value I does not match
In steps 9 and 110, necessary corrections are made. Even after the above process, the inferred current value I ₀ and the required current value I do not match, and as a result of gradually correcting the pulse on time τ _ON ,
_{If ON} is smaller than the minimum value, a command to lower the temperature T of the plating tank 29 by 1 ° C. is issued (step 11).
3) Operate the temperature controller 30 to set the temperature of the plating tank to 1
C lower. This result is again calculated by the fuzzy control unit 28, and the process of calculating the inferred current value I ₀ is repeated.

If the corrected pulse-on time τ _ON exceeds the maximum value, the plating tank 2
When the required current value I matches the result calculated by the fuzzy control unit 28 by repeatedly performing the calculation process of raising the temperature of 1 by 1 ° C. (step 114), the output control unit 12 is controlled by the value. Control the predetermined current I
_{At O} (substantially equal to the required current value I), plating is performed for a predetermined pulse on time τ _ON . Here, since it takes time to control the temperature controller 30 and adjust the temperature of the plating tank, the temperature of the plating tank 29 is measured by measuring the actual temperature T _t and controlling the temperature T _t by fuzzy control. The input temperature of the unit 28 may be used.

As a result of performing the above operations, the plating current I
When (= I _O) flows, the metal amount corresponding to the plating current is removed from the plating solution, subjected to computation by the value calculated (step 115) every moment fuzzy control unit 28 the condition, plating The temperature T of the plating bath and the pulse _ON time τ _ON are controlled so that the current is an optimum value. Thereby, stable plating can be always performed. When plating is performed by repeating the above steps, the concentration of the plating solution becomes low, and even if the temperature of the plating solution is increased, appropriate plating cannot be performed. In this case, the work is interrupted and the plating solution is replaced. This interruption may be performed by the fuzzy control unit 28 or may be performed by judging the plating current from the integrated value. Further, in some cases, the concentration may be detected by the concentration sensor 31 of the plating tank 29, and when the concentration C becomes equal to or less than a predetermined value, an alarm may be issued and the operation may be interrupted.

Next, an example of fuzzy control performed by the fuzzy control unit 28 will be described. The non-defective area is measured in advance by experiments under the conditions of actually using the plating, and the temperature T of the plating solution, the concentration C of the plating solution,
A linear function is created by the pulse-on time τ _ON , for example, four points between the upper limit and the lower limit of the non-defective area are obtained, the simultaneous equations are solved to obtain the coefficients, and the approximate experimental equation is obtained. Based on the empirical formula, the temperature T, the concentration C, and the pulse-on time τ _ON are used as fuzzy variables, and these are represented by fuzzy labels. Next, eight approximate expressions to be rules are created.

[0019]

[Table 1]

If this formula does not apply to the actual measurement, a new formula is created by appropriately weighting the formula. At the time of input, the minimum value of the weight of the antecedent part of each rule is taken, and the value of each expression of the consequent part is multiplied. Then, the sum of the values of the consequent parts of the eight rules is divided by the sum of the weights of the antecedent parts to obtain an inference value. For example, temperature T = 55 ° C., concentration C = 65 g / l, τ
Assuming that _ON = 4 ms is input, the membership functions of temperature, concentration, and pulse-on time at this time are as shown in FIG. 3, and from FIG. 3 and Table 1, an equation as shown in Table 2 is obtained. From this equation, the current density is as shown in Equation 1.

[0021]

[Table 2]

[0022]

(Equation 1)

In this manner, the inferred current value I ₀ is calculated by the fuzzy control unit 28, and the inferred current value I ₀ and the required current value I are compared and determined in steps 105, 107, and 108, and First, the pulse on time τ _ON is changed, and if the inferred current value I ₀ still does not fall within a predetermined range near I, the temperature is changed to automatically calculate the plating condition.

In the above embodiment, the fuzzy control unit is built in the power supply unit. However, the fuzzy control unit is externally connected, and the output value of the calculation is input to the display setting unit using a communication line. Is also possible.

[0025]

As is apparent from the above description, the power supply apparatus for electroplating according to the first to ninth aspects has a fuzzy know-how for determining plating conditions by utilizing empirical knowledge possessed by an operator. Since it has knowledge of the inference rules, it is possible to obtain the optimal plating conditions by taking into account various multi-dimensional information and elements in the same way as the operator does.
Fine output control of plating current can be realized. And, by using multiple detection sensors and multiple information by manual input, it is possible to determine the optimum condition in consideration of various information, and therefore, the empirical knowledge of the operator is utilized and the design range of the real-time plating control system can be determined. Expands.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an operation state of a main part of a power supply device for electroplating according to an embodiment of the present invention.

FIG. 2 is a schematic block diagram of the power supply device for electroplating.

FIG. 3 is a graph of a membership function.

[Explanation of symbols]

 Reference Signs List 10 Power supply device for electroplating 11 Output unit 12 Output control unit 13 Display setting unit 14 AD converter 15 Interface circuit 16 CPU 17 ROM 18 RAM 19 Dual port RAM 20 CPU 21 DA converter 22 Amplifier 23 ROM 24 RAM 25 Operation panel 26 Interface circuit 27 RS422A terminal 28 Fuzzy control unit 29 Plating tank 30 Temperature controller 31 Concentration sensor 32 AD converter

Claims (9)

(57) [Claims] 1. A setting unit for displaying and writing electrolysis condition data, a display setting unit having an arithmetic processing unit for calculating an output value based on the electrolysis condition data, An output control unit that controls an output unit that outputs set values of current and voltage; and the display setting unit includes a communication unit that performs calling, transfer, and output control of data from an external device. A power supply device for electroplating, which forms a metal film having functions such as rust prevention, conductivity, heat resistance, etc. on the substrate of a product, and performs fuzzy inference using the state value of the plating solution as an input value.
An arithmetic unit for calculating and outputting an inference value of the fuzzy variable; comparing the inference value output by the arithmetic unit with a set value calculated based on a plating condition; and until the set value matches the inference value. A fuzzy control program for performing fuzzy inference for inferring an optimal control value by repeating fuzzy feedback for adding and subtracting a correction value to and from an inferred value, wherein the calculation of the fuzzy control is performed by the CPU of the display setting unit, and the optimal control value is calculated. A power supply device for electroplating, wherein the power supply device controls the output of a plating condition by inputting to the output control unit. 2. The power supply device for electroplating according to claim 1, wherein an output value of said fuzzy control unit is input to said display setting unit via a communication unit. 3. The electroplating method according to claim 1, wherein the fuzzy variables of the state value of the plating solution are a concentration C, a temperature T, a current I, a pulse period τ, and a pulse on time τ _ON . Power supply. 4. The condition value C of the concentration is as follows: C = C ₀ −W _ON , where C _{0 is} the initial concentration of the plating solution, W _{ON is} the weight of plating deposited by the pulse-on time, and Ca is the volume of the plating tank. The power supply device for electroplating according to claim 3, wherein the power supply device is expressed by / Ca. 5. The equation of the consequent part is as follows: concentration is C, temperature is T, pulse on time is τ _ON , and pulse period τ
Assuming that K ₁ , K ₂ , and K ₃ are constants, I ₀ = K ₁ · C + K ₂ · T + K ₃ · 1 / (τ _ON / τ) +
Power device for electroplating of the preceding claims, wherein the at K ₄ is an approximate expression of the current value represented. 6. The deposition value per pulse calculated from information of a pulse period (τ), a plating time (t ₀ ), a plating area (S) and a plating thickness (d) manually input by an operator. 5. The power supply device for electroplating according to claim 1, wherein the current value is a current value (I) corresponding to the amount. 7. The plating solution state value inputted to the fuzzy inference rule includes information on an operator's manual input value in addition to the plating solution state detection value.
A power supply for electroplating according to the above. 8. The plating tank is provided with a plating solution injection valve, and when the concentration of the plating solution becomes low, the plating solution injection valve is operated to keep the concentration of the plating solution within a predetermined range. 7. The power supply device for electroplating according to 7. 9. The operation of the plating solution injection valve is performed when the pulse-on time τ _ON corrected by the fuzzy control program becomes longer than its maximum value τ _ON ^H.
A power supply for electroplating according to the above.