JPH0688295A - Plating device and method for controlling plating film thickness - Google Patents

Abstract

PURPOSE:To make the plating film thickness uniform and to shorten the plating time. CONSTITUTION:This device is provided with ultrasonic vibrators 31 to 3N for transmitting and receiving an ultrasonic wave to measure the thickness of a plating film formed on a substrate 2, a vibrator control part 4 for supplying vibrator driving currents 41 to 4N and signal currents 41 to 4N received from the vibrator, a part 5 for receiving the signal 51 from the control part and calculating the plating film thickness, a part 6 for receiving plating film thickness information 52 from the part 5, calculating the mean value of the film thicknesses and determining a plating current from the difference between the mean value and the thickness information, a plating current control part 7 for receiving a current value instructing signal 53 from the part 6 and outputting the plating currents 21 to 2N and anodes 11 to 1N connected to the control part 7 and supplied with a plating current.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plating apparatus and a plating film thickness control method, and more particularly to a plating apparatus and a plating film thickness control method for forming a metal thin film on an electric circuit board or the like.

[0002]

2. Description of the Related Art A conventional plating apparatus and plating film thickness control method will be described in detail with reference to the drawings.

FIG. 9 is a block diagram showing a conventional example. The plating apparatus and the plating film thickness control method shown in FIG. 9 include a plating current control unit 7 that controls the plating currents 21 to 2N, and anodes 11 to 1N that receive the plating currents 21 to 2N from the plating current control unit 7. It has a plating solution tank 1 for holding an electrolytic solution for plating.

Here, in order to perform metal plating on the substrate 2 with a uniform thickness, the worker 10 determines the values of the plating currents 21 to 2N to be supplied to the anodes 11 to 1N and determines the current control unit 7.
Adjust with the volume etc. The current controller 7 is the anode 1
The plating is applied to the substrate 2 by supplying the plating currents 21 to 2N to the electrodes 1 to 1N.

FIG. 10 is a flow chart of work until the plating current value for obtaining a uniform film thickness is determined. The operator first sets the initial value 301 of the plating current and then executes the plating (302). After the plating is completed, a plating film thickness measurement 303 is performed to check whether the film thickness is uniform over the entire substrate (304). When the film thickness is uniformly stable, the plating current value at that time is set as a definite value (306), and when the film thickness varies, the next plating current is determined according to the degree of distribution of the film thickness (305). ). When determining the plating current for the next time, along with the variation in the film thickness distribution of the actually plated substrate, the expertise of the plating operator such as "the plating tends to be thicker around the substrate" is reflected.

[0006]

In the conventional plating apparatus and plating film thickness control method described above, since the plating conditions cannot be changed during the execution of the plating, it is necessary to experimentally test several substrates until the optimum plating conditions are obtained. Since it is up to the plating operator to decide the plating current and the plating current is left to the plating operator, it takes a long time to obtain the current value with which the film thickness of the plating becomes uniform. Has a problem that it greatly depends on the skill of the worker.

[0007]

A plating apparatus according to a first aspect of the present invention includes an ultrasonic vibrator for transmitting and receiving ultrasonic waves for measuring a plating film thickness formed on a target substrate, and the ultrasonic vibration. A vibrator control unit that supplies a vibrator drive current to a child and receives a received signal current from the vibrator, and a plating thickness calculation unit that receives a received signal supplied from the vibrator control unit and calculates a plating film thickness A plating current determining unit that receives plating film thickness information from the plating thickness calculating unit, calculates an average value of the film thickness, and determines a plating current from the difference between the average value and the plating film thickness information; And a plating current control unit for receiving a current value instruction signal from the unit and outputting a plating current, and an anode connected to the plating current control unit and supplied with the plating current.

In the plating film thickness control method of the second invention, an initial current setting process for setting the initial current value of plating, a plating starting process for instructing the start of plating, and a plating film thickness distribution during plating are monitored. A film thickness distribution monitoring procedure, a plating condition changing procedure that corrects the bias in the film thickness distribution when there is a deviation, and a plating end determination procedure that determines whether the plating film thickness has reached a target value. .

A plating apparatus according to a third aspect of the present invention is an ultrasonic vibrator for transmitting and receiving ultrasonic waves for measuring a plating film thickness formed on a target substrate, and a vibrator driving current for the ultrasonic vibrator. And a plating thickness calculator that receives the received signal current from the vibrator, calculates the plating film thickness, and receives the received signal current from the vibrator. Plating current determining unit configured by an expert system that receives plating film thickness information from the plating unit and determines plating conditions according to the expertise of the plating operator, and plating that receives a current value instruction signal from the plating current determining unit and outputs the plating current. It is configured to include a current control unit and an anode connected to the plating current control unit and supplied with a plating current.

A plating film thickness control method according to a fourth aspect of the present invention is a knowledge base construction procedure for constructing a knowledge base of an expert system for determining plating conditions, a plating start procedure for instructing the start of plating, and a plating film during plating formation. Includes a film thickness distribution monitoring procedure to monitor the thickness distribution, a plating condition changing procedure to correct the bias in the film thickness distribution if there is a deviation, and a plating end determination procedure to determine whether the plating film thickness has reached the target value. Composed of.

According to a fifth aspect of the present invention, in a plating apparatus, an ultrasonic vibrator for transmitting and receiving ultrasonic waves for measuring a plating film thickness formed on a target substrate, and a vibrator driving current for the ultrasonic vibrator. And a plating thickness calculator that receives the received signal current from the vibrator, calculates the plating film thickness, and receives the received signal current from the vibrator. To the plating current control section, which receives the plating film thickness information from the plating section and which is configured by a fuzzy inference system, the plating current control section which receives the current value instruction signal from the plating current decision section and outputs the plating current. And an anode which is connected and receives a plating current.

According to a sixth aspect of the present invention, there is provided a plating film thickness control method, wherein a fuzzy rule construction procedure for constructing a fuzzy rule of a fuzzy inference system for determining plating conditions, a plating start procedure for instructing the start of plating, and a plating during plating formation. A film thickness distribution monitoring procedure for monitoring the film thickness distribution, a plating condition changing procedure for correcting the film thickness distribution if there is a deviation, and a plating completion judging procedure for judging whether or not the plating film thickness has reached the target value. It is configured to include.

[0013]

The present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. The plating apparatus shown in FIG. 1 includes ultrasonic transducers 31 to 3N for transmitting and receiving ultrasonic waves for measuring the plating film thickness formed on the target substrate 2, and a transducer driving current 41 for the ultrasonic transducers. A vibrator control unit 4 that supplies the received signal currents 41 to 4N from the vibrator,
The plating thickness calculation unit 5 that receives the reception signal 51 supplied from the vibrator control unit 4 and calculates the plating film thickness, and the plating film thickness information 52 from the plating thickness calculation unit 5 to calculate the average value of the film thickness, The plating current determining unit 6 for determining the plating current from the difference between the average value and the plating film thickness information, and the current value instruction signal 53 from the plating current determining unit 6 are received.
To 2N, and the anodes 11 to 1N connected to the plating current controller 7 and supplied with the plating current.

FIG. 2 is a block diagram showing a first example of the plating current determining unit 6 shown in FIG. A reference value holding unit 63 that holds a reference value of the plating current; an average value calculation unit 61 that calculates an average value of the plating film thickness from the plating film thickness information 52;
The difference calculation unit 62 that calculates the difference between the calculated film thickness average value 80 and the film thickness information 71 to 7N included in the plating film thickness information 52, and the reference information 10 output from the reference value holding unit 63.
1 to 10 N and addition / subtraction of difference information, and an addition / subtraction unit that outputs a current value instruction signal 53 is configured.

FIG. 3 is a flow chart showing the plating film thickness control method of the second invention. An initial current setting procedure 201 for setting the initial current value of plating, a plating start procedure 203 for instructing the start of plating, a film thickness distribution monitoring procedure 204 for monitoring the plating film thickness distribution during plating formation, and a film thickness distribution It includes a plating condition changing procedure 206 for correcting the bias when there is a bias and a plating end determining procedure 205 for determining whether the plating film thickness has reached a target value.

Next, the operation of the plating apparatus and the plating film thickness control method will be described. First, in the initial current setting procedure 201, initial values of the plating currents 21 to 2N supplied to the plurality of anodes 11 to 1N for uniformly plating the substrate 2 are set. This initial value of the plating current may be the current value used for the first plating in the plating process described in the conventional example. The initial current value set here is stored in the reference value holding unit 63 of the plating current determination unit 6. next,
When the plating apparatus is instructed to start plating in the plating start procedure 203, the initial current value stored in the reference value holding unit 63 is output as the first reference information 101 to 10N, and the current value instruction signal is passed through the addition / subtraction unit 64. It is supplied to the plating current controller 7 as 53. Based on the current value instruction signal input by the plating current control unit 7, the anodes 11 to 1
The substrate 2 is plated by supplying the plating currents 21 to 2N to N. During the formation of the plated film, the vibrator control unit 4 supplies the vibrator currents 41 to 4N for ultrasonic wave transmission to the ultrasonic vibrators 31 to 3N and reflects the ultrasonic waves received by the ultrasonic vibrators 31 to 3N. Received current 4 caused by waves
1 to 4N are received and supplied to the plating thickness calculation unit 5 as the received wave signal 51. The plating thickness calculation unit 5 calculates the film thickness distribution of the plating film formed on the substrate 2 based on the received signal 51 and supplies it as the plating film thickness information 52 to the plating current determination unit 6.

FIGS. 4A and 4B are schematic diagrams showing the principle of plating film thickness calculation. The ultrasonic waves transmitted from the ultrasonic vibrator 31 pass through the water tank 3 and the plating solution tank wall 9, which is the wall surface of the plating solution tank 1, the substrate 2, and the plating layer 8. In this process all ultrasonic energy does not pass,
The propagation medium boundary surface, that is, the outer wall, the inner wall of the plating solution tank, the lower surface of the substrate, the upper surface of the substrate, and the upper surface of the plating layer are partly reflected and returned to the ultrasonic transducer 31. FIG. 4B shows a state of a reflected wave that is reflected from each boundary surface and returns to the ultrasonic transducer 31 when an impulse sound wave is emitted from the ultrasonic transducer 31. Since the propagation time of ultrasonic waves is proportional to the propagation distance, the film thickness of the plating layer 8 can be calculated by obtaining the difference between the arrival times ta and tb of the reflected waves from the lower surface and the upper surface of the plating layer 8.

Plating film thickness information 5 calculated in this way
The respective pieces of film thickness information 71 to 7N constituting No. 2 are supplied to the average value calculation unit 61 and the difference calculation unit 62 of the plating current determination unit 6. The average value calculation unit 61 calculates the average value of the film thickness information 71 to 7N of each part, that is, the average value 8 of the plating film thickness formed on the substrate 2.
0 is obtained and supplied to the difference calculation unit 62. Difference calculator 62
Calculates the difference between the film thickness information 71 to 7N of each part and the film thickness average value 80 and supplies it to the addition / subtraction unit 64 as difference information 81 to 8N. The addition / subtraction unit 64 uses the reference information 101 to 10N which is the current plating current value supplied from the reference value holding unit 63.
The difference value 81 to 8N is added to or subtracted from the difference information to increase the plating current of the anode corresponding to the portion where the plating film thickness is thin, and conversely, the current value is instructed to reduce the plating current of the anode corresponding to the portion where the plating film thickness is thick. By supplying the signal 53 to the plating current control unit 7 and the reference value holding unit 63 at the same time, the newly set plating current set value 91 is obtained.
9N is the next plating current reference value. The plating current control unit 7 supplies the newly set plating currents 21 to 2N to the respective anodes 11 to 1N based on the current value instruction signal 53 composed of the plating current set values 91 to 9N, so that the plating film thickness More plating current is supplied to the thin portion, and the plating current in the thick portion is suppressed. The above operation is repeated to continue plating until the plating film thickness reaches the target value.

The plating film thickness control method here is to correct the plating film thickness distribution monitoring procedure 204 for monitoring the plating film thickness distribution during the formation of the plating in FIG. Plating condition change procedure 206 and plating termination determination procedure 2 for determining whether the plating film thickness has reached the target value
It is equivalent to 05.

FIG. 5 is a block diagram showing a second example of the plating current determining section 6 shown in FIG. A knowledge base 564 that stores the expertise of the plating operator, and a knowledge base 564.
A knowledge base editor 563 for inputting / correcting the knowledge of
A working memory 562 which receives plating film thickness information and holds an intermediate state of inference, and an inference engine which infers based on the states of the knowledge base 564 and the working memory 562 to determine a plating condition and outputs a current value instruction signal 553. And 565.

FIG. 6 is a flow chart showing a plating film thickness control method of the fourth invention. A knowledge base construction procedure 601 for constructing a knowledge base of an expert system for determining plating conditions, a plating start procedure 203 for instructing the start of plating, and a film thickness distribution monitoring procedure 204 for monitoring the plating film thickness distribution during plating formation, It includes a plating condition changing procedure 206 for correcting the unevenness in the film thickness distribution and a plating end judging procedure 205 for judging whether the plating film thickness reaches a target value.

In the knowledge base construction procedure 601, the expertise of the plating operator regarding plating is input to the knowledge base 564 by the knowledge base editor 563. Here, the knowledge base 564 mainly determines the plating current based on the initial current value setting knowledge for setting the initial values of the plating currents 21 to 2N supplied to the anodes 11 to 1N and the plating film thickness information during the execution of plating. It is roughly divided into plating current control knowledge for controlling and maintaining a uniform plating film thickness. The initial current setting knowledge is, for example, "the initial plating current is proportional to the pattern density of the substrate", "the plating current is smaller in the periphery of the substrate than in the center", and "when the required accuracy of the plating film thickness is 20 μm or less. It is the constraint knowledge for determining the initial plating current such as "the maximum plating current is I1", and the plating current control knowledge is, for example, "corresponding to that portion when the measured plating film thickness is smaller than the expected expected value". It is the knowledge for adjusting the plating current during the execution of plating such as "increasing the plating current of the anode.", "When increasing or decreasing the plating current value, the rate of increase or decrease is proportional to the pattern density." When the plating apparatus is instructed to start plating in the plating start procedure 203, the inference engine 565 makes an inference based on the knowledge of the initial current setting of the knowledge base 564, determines the initial current value, and sets the current value instruction signal 53 as the plating current control unit 53. 7 is supplied.

FIG. 7 is a block diagram showing a third example of the plating current determining unit 6 shown in FIG. A fuzzy rule holding unit 764 that stores a fuzzy rule based on the expertise of a plating operator, and a fuzzy rule editor 763 that inputs and corrects the rules of the fuzzy rule holding unit 764.
An input unit 762 that receives the plating film thickness information, a fuzzy inference based on the rule of the fuzzy rule holding unit 764 and the plating film thickness information 52 input to the input unit 762 is used to determine the plating condition, and the current value instruction signal 53 is set. And a fuzzy operation unit 765 for outputting.

FIG. 8 is a flow chart showing a plating film thickness control method of the sixth invention. A fuzzy rule construction procedure 801 for constructing a fuzzy rule of a fuzzy inference system for determining plating conditions, a plating start procedure 203 for instructing the start of plating, and a film thickness distribution monitoring procedure 204 for monitoring the plating film thickness distribution during plating formation. If the film thickness distribution is uneven, the plating condition changing procedure 20 for correcting the unevenness is corrected.
6 and a plating end determination procedure 205 for determining whether the plating film thickness has reached the target value.

In the fuzzy rule construction procedure 801,
The fuzzy rule editor 763 applies the plating operator's expertise regarding plating to the fuzzy rule holding unit 76.
Enter in 4. Here, the fuzzy rule mainly controls an initial current value setting rule for setting initial values of the plating currents 21 to 2N supplied to the anodes 11 to 1N, and controls the plating current based on the plating film thickness information during the execution of plating. It is roughly divided into plating current control rules for keeping the plating film thickness uniform, and the condition part of the rules is expressed by a fuzzy membership function. The initial current setting rule is, for example, a constraint rule for determining the initial plating current such as "the initial plating current is proportional to the pattern density of the substrate", "the plating current is smaller in the periphery of the substrate than in the center", and The plating current control rule is, for example, “when the measured plating film thickness is smaller than the expected expected value, increase the plating current of the anode corresponding to that portion.”, “When increasing or decreasing the plating current value, the increase / decrease rate is It is a rule for adjusting the plating current during plating, such as "Proportional to pattern density." When the plating apparatus is instructed to start plating in the plating start procedure 203, the fuzzy operation unit 76
A fuzzy rule holding unit 764 performs a fuzzy calculation based on the initial current setting rule (Mamdani method or the like is used as a widely used calculation method) to determine an initial current value and control a plating current as a current value instruction signal 53. It is supplied to the part 7. The plating current controller 7 supplies the plating currents 21 to 2N to the anodes 11 to 1N based on the input current value instruction signal, so that the substrate 2 is plated.

The calculated plating film thickness information 52 is supplied to the plating current determining unit 6 and stored in the input unit 762.
Here, the fuzzy operation unit 765 is the fuzzy rule holding unit 7.
Fuzzy calculation is performed based on the plating current control rule 64 and the plating film thickness information 52 so that the plating film thickness on the entire surface of the substrate becomes uniform, that is, the plating current of the anode corresponding to the thin plating film portion is set. On the contrary, the plating current is adjusted so as to reduce the plating current of the anode corresponding to the thicker portion of the plating film thickness, and the newly set current value instruction signal 53 is supplied to the plating current control unit 7. Based on the current value instruction signal 53, the plating current controller 7 newly sets the plating currents 21 to 2N for the respective anodes 11 to 1N.
Is supplied, a larger amount of plating current is supplied to the portion having a thin plating film thickness, and the plating current to the portion having a large plating film thickness is suppressed. The above operation is repeated to continue plating until the plating film thickness reaches the target value. The plating film thickness control method here is as shown in FIG.
A film thickness distribution monitoring procedure 204 for monitoring the plating film thickness distribution during plating formation, a plating condition changing procedure 206 for correcting the unevenness in the film thickness distribution, and a judgment as to whether the plating film thickness has reached the target value are performed. This is equivalent to the plating end determination procedure 205 to be performed.

[0028]

According to the plating apparatus and the plating film thickness control method of the present invention, it is not necessary to perform experimental plating in order to obtain the optimum plating current value, and the determination of the plating current depends on the skill of the operator. There is an effect that a uniform plating film thickness can be obtained in a short time without depending on it.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing a first example of a plating current determination unit 6 shown in FIG.

FIG. 3 is a flowchart showing a plating film thickness control method of the second invention.

4A and 4B are schematic diagrams showing the principle of calculating the plating film thickness.

5 is a block diagram showing a second example of the plating current determination unit 6 shown in FIG.

FIG. 6 is a flowchart showing a plating film thickness control method of a fourth invention.

FIG. 7 is a block diagram showing a third example of the plating current determination unit 6 shown in FIG.

FIG. 8 is a flow chart showing a plating film thickness control method of a sixth invention.

FIG. 9 is a block diagram showing a conventional example.

FIG. 10 is a flowchart showing a conventional example.

[Explanation of symbols]

 1 Plating Liquid Tank 2 Substrate 3 Water Tank 4 Transducer Control Section 5 Plating Thickness Calculation Section 6 Plating Current Determining Section 7 Plating Current Control Section 8 Plating Layer 9 Plating Solution Bath Wall 10 Worker 11-1N Anode 21-2N Plating Current 31- 3N ultrasonic transducer 41 to 4N transducer current 51 received signal, 52 plating film thickness information 53 current value instruction signal 61 average value calculation unit 62 difference calculation unit 63 reference value holding unit 64 addition / subtraction unit 71 to 7N film thickness information 80 Average plating film thickness 81 to 8N Difference information 91 to 9N Plating current setting value 101 to 10N Reference information 201 Initial current

Claims (6)

[Claims] 1. An ultrasonic oscillator for transmitting and receiving ultrasonic waves for measuring a plating film thickness formed on a target substrate; and an oscillator driving current supplied to the ultrasonic oscillator from the oscillator. Of the received wave signal current, a plating thickness calculation section that receives the received wave signal supplied from the vibrator control section and calculates the plating film thickness, and plating thickness information from the plating thickness calculation section. A plating current determining unit that calculates an average value of the received film thickness and determines a plating current from the difference between the average value and the plating film thickness information, and a plating that receives a current value instruction signal from the plating current determining unit and outputs the plating current. A plating apparatus comprising a current controller and an anode connected to the plating current controller and supplied with a plating current. 2. An initial current setting procedure for setting an initial current value of plating, a plating start procedure for instructing the start of plating, a film thickness distribution monitoring procedure for monitoring a plating film thickness distribution during plating formation, and a film thickness. A plating film thickness control method comprising: a plating condition changing procedure for correcting the distribution unevenness and a plating termination judging procedure for judging whether the plating film thickness reaches a target value. 3. An ultrasonic vibrator for transmitting and receiving ultrasonic waves for measuring a plating film thickness formed on a target substrate, and a vibrator driving current is supplied to the ultrasonic vibrator from the vibrator. Of the received wave signal current, a plating thickness calculation section that receives the received wave signal supplied from the vibrator control section and calculates the plating film thickness, and plating thickness information from the plating thickness calculation section. Receiving a plating current determining unit configured by an expert system that determines plating conditions according to the expertise of a plating operator, a plating current controlling unit receiving a current value instruction signal from the plating current determining unit and outputting a plating current, and the plating A plating apparatus comprising: an anode connected to a current control unit and supplied with a plating current. 4. A knowledge base construction procedure for constructing a knowledge base of an expert system for determining plating conditions, a plating start procedure for instructing the start of plating, and a film thickness distribution monitoring procedure for monitoring a plating film thickness distribution during plating formation. And a plating film thickness control method that includes a plating condition changing procedure that corrects the unevenness in the film thickness distribution and a plating completion determining procedure that determines whether the plating film thickness reaches a target value. . 5. An ultrasonic transducer for transmitting and receiving ultrasonic waves for measuring a plating film thickness formed on a target substrate; and a transducer driving current supplied to the ultrasonic transducer from the transducer. Of the received wave signal current, a plating thickness calculation section that receives the received wave signal supplied from the vibrator control section and calculates the plating film thickness, and plating thickness information from the plating thickness calculation section. A plating current determination unit configured by a reception fuzzy inference system, a plating current control unit that receives a current value instruction signal from the plating current determination unit and outputs a plating current, and a plating current supply unit that is connected to the plating current control unit. A plating apparatus including a receiving anode. 6. A fuzzy rule construction procedure for constructing a fuzzy rule of a fuzzy inference system for determining plating conditions, a plating start procedure for instructing the start of plating, and a film thickness distribution monitoring for monitoring the plating film thickness distribution during plating formation. Plating film thickness control including a procedure, a plating condition changing procedure for correcting the unevenness of the film thickness distribution if there is a deviation, and a plating completion judging procedure for judging whether the plating film thickness reaches a target value. Method.