JPH02298296A - Thin film forming device - Google Patents

Abstract

PURPOSE:To form a plating layer having an accurate thickness by forming a spectrum from the reflected wave of an ultrasonic wave irradiating the plating layer through a plating soln. and calculating the thickness of the plating layer from the spectrum. CONSTITUTION:A voltage is impressed between a material 22 to be worked as the cathode and an anode 16 in the plating soln. 15 in a plating bath 14 to form a plating layer 30 on a base 24 while measuring the thickness by a film thickness measuring device 12. The plating layer 30 is irradiated with an ultrasonic wave at a specified incident angle by the transducers 32 and 34 of the measuring device 12 in the plating device main body 10 of the thin film forming device, and the reflected wave is received. A reflected wave spectrum is formed from the received ultrasonic wave by a spectrum analyzer 50 and subtracted by the reflection spectrum of a reference base 18 to obtain a relative spectrum. Furthermore, the film thickness of the plating layer 30 is calculated from the frequency at the minimum reflection intensity part of the relative spectrum. The plating device main body 10 is operated in accordance with the calculated film thickness through a controller 52 and stopped when a desired film thickness is reached.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a thin film forming apparatus for forming a thin film on a substrate surface of, for example, a plating apparatus.

(Prior Art) In a plating device, for example, an electroplating device, a direct current is generally applied between an anode provided in a plating solution and a workpiece immersed in the plating solution and acting as a cathode. The plating work is done by The thickness of the plating layer is then controlled by the current density and time of the applied current. In addition, when determining the thickness of the plating layer by +1p1 during plating work, this is done by first pulling the workpiece out of the plating solution, breaking a part of the workpiece, and observing its cross section. There is.

(Problem to be Solved by the Invention) As described above, in conventional plating equipment, when measuring the thickness of a plating layer during plating work, the workpiece must be pulled out of the plating solution while the plating work is temporarily stopped. This resulted in laborious work and reduced work efficiency. Therefore, it is substantially difficult to measure the thickness of the plating layer during the plating operation, and the actual situation is that the thickness of the plating layer is controlled only by controlling the applied current. As a result, it has become extremely difficult to form a plating layer with an accurate thickness using conventional plating equipment.

This invention was made in view of the above points, and its purpose is to be able to perform plating work while measuring the thickness of the plating layer, and as a result, to form a plating layer with an accurate thickness. The object of the present invention is to provide a thin film forming apparatus that can perform the following steps.

[Structure of the Invention] (Means and Effects for Solving the Problems) In order to achieve the above object, the thin film forming apparatus of the present invention includes a plating apparatus main body that forms a plating layer on the surface of a workpiece, and a plating apparatus main body that forms a plating layer on the surface of a workpiece, and A film thickness measuring device for measuring the film thickness of a plating layer formed on the surface of an object is provided. The film thickness 7?1 determining device includes an ultrasonic irradiation means for irradiating ultrasonic waves at a predetermined incident angle onto the plating layer through the plating solution, and a receiving means for receiving the ultrasonic waves reflected by the plating layer. a spectrum forming means for forming a reflected wave spectrum of the workpiece from the ultrasonic waves received by the receiving means; and a spectrum forming means for forming a reflected wave spectrum of the workpiece from the ultrasonic waves received by the receiving means; subtraction means for subtracting from the reflected wave spectrum to form a relative spectrum, detection means for detecting the frequency of the minimal reflection intensity portion on the relative spectrum, and calculation for calculating the film thickness of the plating layer from the detected frequency. have the means and. Further, the plating apparatus main body includes a plating apparatus control means, and this control means operates the plating apparatus main body according to the set desired film thickness, and also operates the plating apparatus main body according to the set desired film thickness. When the calculated film thickness reaches the desired film thickness, the operation of the plating apparatus main body is stopped.

According to the 7S film forming apparatus having the above configuration, plating work can be performed while measuring the thickness of the plating layer using the film thickness measuring device. Then, by comparing the measured film thickness with the set desired film thickness and stopping the plating operation when these film thicknesses match, it is possible to form a plating layer with an accurate film thickness. becomes.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, a thin film forming apparatus according to an embodiment of the present invention includes a plating apparatus main body 10 and a film thickness i1? for measuring the film thickness of a plating layer formed by the plating apparatus main body. j
A fixed device 12 is provided.

The plating apparatus main body 10 includes a plating bath 14, and a plating solution 15, such as a copper sulfate aqueous solution, is contained in the plating layer. Inside the plating bath 14, an anode 16 is provided, and a reference substrate 18, for example, a thick copper plate, is provided for obtaining a reference spectrum to be described later.

Further, a workpiece 22 held by a holder 20 is immersed in the plating solution 15 . In an example,
As the workpiece 22, a glass epoxy base 24 for forming a printed circuit board is used. The workpiece 22 then acts as a cathode.

The plating apparatus main body 10 includes a power supply drive circuit 26 that applies a direct current between the workpiece 22 acting as a cathode and the anode 16, and a plating controller 28 that controls the operation of the power supply drive circuit. In other words, the plating controller 28 as a plating device control means is connected to the base plate 24.
The current density and supply time of the current supplied from the power supply drive circuit 26 are controlled so that the plating layer 30 having a desired thickness is formed on the surface of the plating layer 30 . At the same time, the plating controller 28 stops the operation of the power supply driving circuit 26 when the thickness of the plating layer measured by the thickness i1!1 determining device 12 reaches the desired thickness.

Note that a manual stop switch 27 is connected to the power supply drive circuit 26 . In the event of equipment failure, etc., the plating work can be stopped by turning on the stop switch 27.

On the other hand, the film thickness measuring device 12 includes first and second transducers 32 and 34, which are immersed in the plating solution 15 and facing the surface of the substrate 24. Also, the first and second transducers 32.
34 is supported by a posture control device 36 so that the angle with respect to the surface of the base 24 can be adjusted to: J3. The attitude control device 36 is suspended from the ceiling via a lifting mechanism 38 and a transport mechanism 40. Then, the attitude control device 36
It can be immersed into and pulled up from the plating tank 14 by the lifting mechanism 38, and can be transported between the plating tank and a water tank (not shown) by the transport mechanism 40.

The first transducer 32 includes a pulse transmitter 42,
Clock generators 44 are connected in sequence. Then, the pulse transmitter 42 transmits a high frequency pulse according to the clock generated by the clock generator 4j and applies it to the first transducer 32. Thereby, the first transducer 32 emits a plane wave ultrasonic wave, and this plane wave ultrasonic wave passes through the plating liquid 15 to the plated layer 3 of the workpiece 22.
0 at an incident angle θ. In this way, the first transducer 32, the pulse transmitter 42, and the clock generator 44 constitute the ultrasonic irradiation means in this invention.

The second transducer 34 as receiving means includes an amplifier 46, a gate 48, and a spectrum analyzer 50.
, controller 52 are connected in this order. Further, the gate 48 is connected to the clock generator 44 via a delay circuit 54. Then, the second transducer 34 transmits the signal transmitted from the first transducer 32 to the workpiece 2.
The ultrasonic wave reflected by the plating layer 30 of No. 2 is received, and the reflected ultrasonic wave is converted into an electric signal. This electrical signal is then amplified by an amplifier 46.

On the other hand, the delay circuit 54 delays the generation timing of the clock generated by the clock generator 44 by a predetermined time and sends it to the gate 48, and opens the gate for a predetermined time width in accordance with the delayed generation timing. Thereby,
Gate 48 is 1. Only the desired reflected wave waveform is extracted from the electrical signal amplified by the amplifier 46 and sent to the spectrum analyzer 50. Then, the spectrum analyzer 50 forms a spectrum of the input waveform.

Note that, as will be described later, a reference spectrum obtained from the reference base 18 is input to the spectrum analyzer 50 in advance. Then, the controller 52 outputs a command to the spectrum analyzer 50 to subtract the reference spectrum from the reflected wave spectrum of the workpiece 22, and activates the minimum value search function of the spectrum analyzer to generate a new reflected wave obtained by the above subtraction. Detect the frequency of the minimum reflection intensity on the spectrum. The controller 52 calculates the film thickness d of the plating layer 30 from the detected frequency and displays it on the display 56. Also,
The controller 52 manually inputs the calculated film thickness d to the plating controller 28 of the plating apparatus main body 10.

In this way, the spectrum analyzer 50 constitutes a spectrum forming means, a subtracting means, and a detecting means in the present invention. Further, the controller 52 constitutes calculation means in the present invention.

Next, the operation of the thin film forming apparatus configured as above will be explained.

First, prior to the plating process, the base ff12 of the workpiece 22 is
A sample having a substrate and a thin film formed of the same material as those of the plated layer 30 and the plated layer 30 is prepared. Then, by irradiating the thin film of this sample with ultrasonic waves at various incident angles, the incident angle θ at which the minimum reflection intensity portion appears in the reflected wave vector is determined. Next, various reflected wave spectra are formed by varying the thickness of the thin film of the sample, and from these reflected wave spectra, the frequency f at the minimum part of the reflected wave is determined.
Find the function d-C/f of the film thickness d with d as a variable.

Here, C is a constant determined by the elastic constants of the thin film and the substrate, and the sound velocity and density of the plating solution 15 as an ultrasonic transmission medium. The functions of the incident angle θ and the film thickness d are determined in advance by the controller 5 of the film thickness measuring device 12.
2 is stored.

Subsequently, an initialization signal is manually input from the controller 52 to the spectrum analyzer 50, and the spectrum analyzer is initialized.

Next, the first and second transducers 32,34 are plated)! The attitude control device 36 is conveyed by the conveyance mechanism 40 so as to face the reference base 18 in the substrate 14 . In this state, from the first transducer 32 to the reference substrate 1
8. Ultrasonic waves are irradiated onto the surface. Then, the spectrum analyzer 50 determines the reflected wave spectrum of the reference base based on the reflected ultrasound received by the second transducer 34.
In other words, a reference spectrum SR(f) is formed. As shown in FIG. 2, the reference spectrum SR(f) has no reflection intensity minimum. This reference spectrum 5R(f) is stored in channel 2 of the spectrum analyzer 50.

Subsequently, after the posture control device 36 and the first and second transducers 32, 34 are lifted up from the plating bath 14 by the lifting mechanism 38, the substrate 24 as the workpiece is held in the holder 20. It is immersed in the plating solution 15. Thereafter, the first and second transducer 3
The attitude control device 36 is again immersed in the plating solution 15 by the elevating mechanism 38 and the transport mechanism 40 so that 2.34 faces the surface of the substrate 24. In addition, the first transducer 32 is configured such that the incident angle of the ultrasonic wave with respect to the surface of the base 24 is θ, and the second transducer 34 is configured to
Each angle is adjusted by the attitude control device 36 so that the ultrasonic waves reflected from the base surface can be received.

On the other hand, the desired film thickness d of the plating layer to be formed on the surface of the substrate 24 is input to the plating controller 28 of the plating apparatus main body 10, and the plating controller 28 controls the current density and supply time according to this film thickness dL. Set.

In this state, plating work by the plating apparatus main body 10 and measurement of the thickness of the plating layer by the film thickness measuring device 12 are simultaneously started.

First, the power supply drive circuit 26 is driven according to the current density and supply time set by the plating controller 28, so that a DC current with the above current density is applied between the anode 16 and the substrate 24 for the above supply time. Ru. As a result, copper ions contained in the plating solution 15 are electrolytically deposited, and a copper plating layer 30 is sequentially formed on the surface of the substrate 24.

During the above plating process, film thickness? #1 constant device 12 is the base gi
The thickness of the plating layer 30 formed on the surface of the i24 is continuously measured, and the measurement results are displayed on the display 56 and manually inputted to the plating controller 28 of the plating apparatus main body 10. FIG. 3 is a flow chart showing the operation of the film thickness measuring device 12, and the measuring operation will be explained with reference to this figure.

First, the first transducer 32 irradiates the plating layer 30 that is being formed with ultrasonic waves, and from the reflected ultrasonic waves, the spectrum analyzer 50 determines the reflected wave spectrum of the workpiece 22 as shown in FIG. Form ST (f). The obtained reflected wave spectrum ST (f) is stored in channel 1 of the spectrum analyzer 50.

The spectrum analyzer 50 responds to a subtraction command from the controller 52 to calculate a reflected wave spectrum ST (f
) by subtracting the reference spectrum SR(f), a new spectrum as shown in FIG. 5, that is, the relative spectrum S
form N (f). Obtained relative spectrum sN
(f) is stored in channel 1 of the spectrum analyzer 50.

As can be seen from FIG. 5, the relative spectrum 5N(f) can be shown with the minimum reflection intensity emphasized as compared to the reflected wave spectrum ST(f).

Next, in response to a command from the controller 52, the spectrum analyzer 50 uses a minimum value search function to determine the frequency f of the minimum reflection intensity portion on the relative spectrum sN(f).
Detect. Then, the controller 52 calculates the film thickness d of the plating layer 30 of the workpiece 22 from the detected frequency f and the pre-stored function d-C/f. The calculated film thickness d is displayed on the display 42, and is also displayed on the plating controller 28 (;
is input.

The plating controller 28 compares the desired film thickness dL inputted in advance with the film thickness d sent from the controller 52. The formation and measurement of the plating layer 30 are continued until d≧dL, and when dadL is reached,
The plating controller 28 stops the operation of the power supply drive circuit 26. Note that if the film thickness d of the plating layer 30 has not reached the desired film thickness dL even after the preset supply time has elapsed, the plating controller 28 operates the power supply drive circuit 26 until d≧d. Continue.

Through the above steps, the plating work is completed, and a plating layer 30 having a thickness of dL is formed on the surface of the substrate 24.

After the plating work is completed, the first and second transducers 32, 34 and the attitude control device 36 are immersed in a water tank (not shown) and cleaned by the elevating mechanism 38 and the transport mechanism 40.

According to the thin film forming apparatus configured as described above, the film thickness is 4
The plating work can be performed while the thickness of the plating layer is fixed by /I-1 using the -1 constant device 12, and the thickness of the plating layer can be adjusted to an accuracy of <$11. There is no need to interrupt plating work for measurement, and work efficiency can be improved.

Note that this invention is not limited to the embodiments described above, and can be modified in various ways within the scope of this invention.

For example, the plating equipment itself is not limited to electroplating equipment.
An electroless plating device may also be used. Similarly, the material of the base of the workpiece and the material of the plating layer can be variously modified as necessary.

[Effects of the Invention] As described above, according to the thin film forming apparatus of the present invention, plating can be performed while measuring the thickness of the plating layer, and a plating layer with an accurate thickness can be formed. .

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway side view showing the entire thin film forming apparatus according to an embodiment of the present invention, FIG. 2 is a diagram showing the reflected wave spectrum of the reference substrate, and FIG. 3 is a diagram showing the thin film forming apparatus described above. FIG. 4 is a flowchart showing the operation, FIG. 4 is a diagram showing the reflected wave spectrum of the workpiece, and FIG. 5 is a diagram showing the relative spectrum. 10... Plating device main body, 12... Film thickness measuring device,
18...2! /Ii! ! Base, 16... Anode,
22... Workpiece, 24... Base, 26... Power supply drive circuit, 28... Plating controller, 30...
Plating layer, 32... first transducer, 34...
...Second transducer, 50...Spectrum analyzer, 52...Controller. Applicant's agent Patent attorney Takehiko Suzue Figure 4 Figure 5

Claims (1)

[Scope of Claims] A plating apparatus main body having a plating tank containing a plating solution and forming a plating layer on the surface of a workpiece placed in the plating solution; a film thickness measuring device for measuring the film thickness of the plating layer, the film thickness measuring device comprising: ultrasonic irradiation means for irradiating ultrasonic waves at a predetermined incident angle to the plating layer through the plating solution; a receiving means for receiving the ultrasonic waves reflected by the plating layer; a spectrum forming means for forming a reflected wave spectrum of the workpiece from the ultrasonic waves received by the receiving means; a subtraction means for subtracting the reflected wave spectrum of the reference base that does not occur from the reflected wave spectrum of the workpiece to form a relative spectrum; a detection means for detecting a frequency of a minimal reflection intensity portion on the relative spectrum; calculation means for calculating the film thickness of the plating layer from the frequency determined, and the plating apparatus main body operates the plating apparatus main body according to the set desired film thickness and calculates the film thickness of the plating layer calculated as described above. The plating apparatus is characterized by comprising a plating apparatus control means that compares the thickness with the desired film thickness and stops the operation of the plating apparatus main body when the calculated film thickness reaches the desired film thickness. Thin film forming equipment.