JPH03274267A - Film forming device - Google Patents

Abstract

PURPOSE:To surely and easily uniformize the thickness of a film over the whole surface of a substrate by variably controlling the speed of a pulse motor for a rotating jig fixed to the substrate in accordance with the angle of the substrate to the film forming material source through the pulse frequency. CONSTITUTION:A polygonal carrousel-type jig 6 is erected on a turntable 5 in a vacuum vessel 1 provided with evacuating ports 3 and 4, and plural substrates (not shown in the figure) are mounted on the substrate mounting surfaces 6a and heated to a specified temp. by a halogen lamp 10. A couple of targets 7 provided with a magnet 13 on the rear and a shutter 8 on the front are arranged on the periphery. The jig 6 is rotated by a pulse motor 21, a sputtering gas is introduced from a port 2 to sputter the target 7, and a film is formed on the substrate. In this film forming device, the speed of the motor 21 is variably controlled by a controller 24 in accordance with the angle of the substrate to the target 7. The basic rotational speed of the jig 6 is varied by the controller 24 in accordance with the rotating position detected by an encoder 22.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a film forming apparatus for forming a film on a substrate using a film forming material in a vacuum chamber.

(Conventional technology) Conventionally, this type of film-forming equipment includes a sputtering equipment that irradiates a film-forming material (target) with ions to form a film of the film-forming material on a substrate. Vapor deposition apparatuses such as a thermal evaporation apparatus that performs vapor deposition on a substrate by evaporation, and an ion blating apparatus that performs vapor deposition by ionizing evaporated particles of a film-forming material are generally known.

It is also known that such a film forming apparatus uses a rotating jig that has a plurality of substrate mounting surfaces arranged in the circumferential direction and rotates so that each substrate mounting surface sequentially faces a target or evaporation source of the film forming material. It is being

In other words, examples of the rotating jig mentioned above for sputtering equipment include a carousel type in which a plurality of substrate mounting surfaces are arranged in a rectangular tube shape on a turntable in a vacuum chamber, and There are dome-shaped ones arranged in a conical or pyramidal shape, and drum-shaped ones in which a plurality of substrate mounting surfaces are arranged in a rectangular tube shape and rotated with the axis horizontal. In a carousel type sputtering apparatus, a target is disposed around the outer periphery of the sputtering apparatus, in a dome type sputtering apparatus, a target is disposed below the sputtering apparatus, and in a drum type sputtering apparatus, a target is disposed inside the sputtering apparatus. and,
Such a rotating jig is also provided in a vapor deposition apparatus, but it is usually rotated at a constant speed when forming a film on a substrate.

(Problem to be Solved by the Invention) Generally, in a film forming apparatus, a film with an uneven thickness is formed on the substrate in accordance with the flight angle distribution of the film forming material. When used, the rotation of the substrate also affects the film thickness distribution on the substrate. For example, in the case of a carousel type sputtering system, the rotation of the substrate also affects the film thickness distribution, so the central part of the substrate is the thickest.
It becomes thinner as it moves away from the center to both sides.

That is, as shown in FIG. 7, the film thickness T at point P of the substrate 40 is such that the sputtered particles are deposited while the point P passes through the angle AOB, and the emissivity R from the target 7 and the substrate surface are 7 and the cosine eO8β of the angle β, then if the distance from the target 7 to the point P is ignored, it becomes Tm,jRcosβdt. Since θ−ωt, T−(1/ω) x, jRcos(θg+a−θ)dθ −(2R/(IJ) ・cos a ・sin θ.

-(R/ω) (W/r) and the perpendicular line drawn to the substrate 40, ω is the rotational angular velocity of the substrate 40, θ0 is half of the angle AOB, α0 is half the spread angle of the substrate 40, W is the width of the target 7, and r is from the rotation center O. This is the distance to the edge of the substrate 4o.

Therefore, in the case of a carcell type jig with a hexagonal cross section, Do-
Since it is 30°, T” (R/(JJ) ・(W/ r) ・1.1
5cos 2a. In addition, in the case of a carcell type jig with an octagonal cross section, αo = 22.5°, so Tm (R/ω) (W/ r) ・1.08co
s 2a, and the film thickness distribution of the sputtered film is the thickest at the center of the substrate 40 and becomes thinner as it moves away from the center on both sides.

The fact that the rotation of the rotating jig affects the film thickness distribution of the substrate is the same not only for the carousel type but also for the dome type or drum type. Also,
When a plurality of substrates are attached to one substrate mounting surface at intervals in the rotational direction, the film thickness of each substrate differs depending on the mounting position on the substrate mounting surface.

Therefore, the present applicant has previously developed a film forming apparatus in which a rotating jig is rotated in a vacuum chamber and a film forming process such as sputtering is performed on a substrate attached to the substrate mounting surface. The rotational speed of the rotating jig is determined by changing the rotational speed of the rotating jig when the substrate faces approximately the center of the film forming material supply source such as a target in the rotating direction of the rotating jig, and when the substrate faces both ends of the supply source in the rotating direction of the rotating jig. We proposed a method that minimizes unevenness in film thickness caused by substrate rotation by providing a control means that controls the speed at a variable speed by relatively changing the speed from time to time (patent application). Hei 1-
201075 specification and drawings).

The purpose of this invention is to further advance the above proposal,
By embodying the rotating jig driving means and its control means, the above proposal can be realized more reliably and easily. There is a particular thing.

(Means for Solving the Problem) In order to achieve this object, in the invention according to claim (1), the drive means for the rotating jig is constituted by a pulse motor (stepping motor), and the control means includes: A predetermined function waveform signal corresponding to time is output from the waveform generation circuit, and the pulse frequency output to the pulse motor is changed by the pulse generation circuit according to the signal from the waveform generation circuit.

That is, the present invention includes a deposition material supply source that is disposed in a vacuum detection unit and supplies a deposition material to a substrate, and a plurality of substrate mounting surfaces that are rotatably supported in a vacuum chamber and that attach substrates in a circumferential direction. and a rotating jig that rotates so that each substrate mounting surface sequentially faces the supply source, and the film is formed on the substrate on the substrate mounting surface while rotating the rotating jig. A film deposition system is assumed.

and a pulse motor that rotationally drives the rotating jig;
A control means for variably controlling the rotational speed of the pulse motor in accordance with the orientation of the substrate with respect to the target is provided.

Furthermore, the control means includes a first signal generation circuit that generates a first signal at a constant level that sets the basic rotational speed of the rotating jig, and a second signal that changes the rotational speed of the rotating jig according to time. The output signal level of the second signal generation circuit generated based on a predetermined function and the first signal generation circuit is corrected according to the output signal level of the second signal generation circuit, and the frequency is adjusted according to the corrected signal level. and a pulse generation circuit that outputs a pulse signal having a pulse signal to the pulse motor.

In the invention according to claim (2), the rotational speed of the rotating jig is variably controlled by a digital signal.

Specifically, in the film forming apparatus based on the above premise, the control means for variably controlling the rotational speed of the pulse motor according to the orientation of the substrate with respect to the film forming material supply source controls the rotational speed pattern of the rotating jig. a storage means for storing data related to the data, an arithmetic circuit for processing the data stored by the storage means and outputting a signal, and receiving an output signal of the arithmetic circuit and generating a pulse signal having a frequency corresponding to the signal level. The present invention is characterized by a configuration including a pulse generation circuit that outputs output to the pulse motor.

The rotational speed pattern of the rotating jig is a pattern that changes with predetermined characteristics over time, and this data is expressed, for example, as the circumferential speed (number of pulses per unit time) for the number of pulses in one rotation of the rotating jig. Man-powered.

(Function) With the above configuration, in the invention according to claim (1), the first signal generating circuit of the control means outputs the first signal at a constant level for setting the basic rotation speed of the rotating jig, and the second signal The generation circuit outputs a second signal that changes the rotational speed of the rotating jig, and the pulse generation circuit corrects the signal level of the first signal according to the output signal level of the second signal, and adjusts the corrected signal level. A pulse signal having a frequency corresponding to the pulse motor is outputted to the pulse motor to control the rotation speed of the pulse motor. That is, the correction signal generated by the correction in the pulse generating circuit is a signal that changes from the first signal as a reference depending on the change in the signal level of the second signal. Therefore, the pulse signal corresponding to this correction signal level has a pulse frequency (number of pulses per unit time) of the second
The characteristics change according to the signal, and by outputting this pulse signal to the pulse motor, the rotation speeds of the motor and the rotating jig are variably controlled in accordance with the second signal.

Therefore, by setting the second signal according to a predetermined function, it is possible to perform control such as slowing down the rotation speed of the substrate so that, at a constant speed, more particles are deposited in areas where the film thickness is thinner than in other areas. Therefore, it is possible to reliably and easily equalize the film thickness.

In the invention according to claim 2, data regarding the rotational speed pattern of the rotating jig is stored in advance in the storage means,
The arithmetic circuit processes the data stored in the storage means and outputs a signal, and the pulse generation circuit that receives this signal outputs a pulse signal having a frequency corresponding to the signal level to the pulse motor, The motor is controlled.

Therefore, by simply inputting and storing the above data in advance, the rotational speeds of the pulse motor and the rotating jig can be variably controlled, and the same effects as the invention according to claim (1) can be obtained.

(First example) Embodiments of the present invention will be described below based on the drawings.

3 and 4 show a sputtering apparatus as a film forming apparatus according to a first embodiment of the present invention, 1 is a vacuum chamber, this vacuum chamber 1 includes a sputtering gas introduction boat 2, an exhaust gas for evacuation. Boat 3 and Exhaust boat 4 for snow and ivy
are each opened. A turntable 5 is provided at the center of the bottom of the vacuum chamber 1 with its axis vertical, and on top of the turntable 5 are a plurality of board mounting surfaces 6a, 6a, .
A car cell type jig 6 (rotating jig) in which... is arranged in a polygonal (in this example, octagonal) cross section is installed upright, and this car cell jig 6 is rotated by a turntable 5. Possibly supported. Further, in the vacuum chamber 1, a pair of targets 7.7, which serve as film forming material supply sources, are disposed on the sides of the outer periphery of the carousel type jig 6, and are opposed to each other in the diametrical direction of the vacuum chamber 1. ing.

Further, a target shunter 8°8 driven by a motor 9 is rotatably supported on the ceiling plate of the vacuum chamber 1, and a halogen lamp heater 10 is mounted on the inner periphery of the side wall of the vacuum chamber 1. .10, . . . are arranged.

Further, as shown in FIG. 4, the target 7 is sealed in a support member 11 fixed to the peripheral wall of the vacuum chamber 1 and held in a holder 12, and a plurality of magnets 13, ．． ... are arranged at intervals. Further, the peripheral wall of the vacuum chamber 1 includes a fixed wall 1a provided with both exhaust boats 3.4 for evacuation and for sputtering gas,
It is composed of a movable wall 1b rotatably supported by the fixed wall 1a via a hinge 14, and by rotating the movable wall 1b, the vacuum 11 is opened and closed, and the circuit board 40 is attached to the cal-cell. The mold jig 6 is put in and taken out.

The car cell type jig 6 (turntable 5) is driven by a pulse motor 21 as a driving means disposed below the vacuum chamber 1.
Driven by. This pulse motor 21 has a rotor 2
It consists of a stator 1a and a stator 21b, and its operation is controlled by receiving a control signal from a control device 24. Further, this motor 21 is attached with an encoder 22 that detects the rotational position of the rotor 21a, and by feeding back the output signal of this encoder 22 to the control device 24, the pulse motor 21 is driven and controlled. It has become.

The control bag @24 variably controls the rotational speed of the pulse motor 21 according to the orientation of the substrate 40 attached to the substrate mounting surface of the jig 6 with respect to the target 7, and its configuration will be explained with reference to FIG. Specifically, this control device 24 includes first and second level controllers 25 and 26, and a function generating circuit 27 that manually generates a predetermined function based on the signal output from the second level controller 26. has. The above second level controller 2
5 is a voltage generating circuit that generates a voltage signal (first signal) with an adjustable constant level vl, as shown in FIG. A first signal generating circuit is configured to generate a constant level signal for setting a basic rotational speed.

On the other hand, the second level controller 26 selects a speed change waveform for changing the rotational speed of the car cell type jig 6 or adjusts the size of the speed change waveform, and is composed of a voltage generation circuit. .

Further, the function generation circuit 27 is connected to the second level controller 2
It consists of a voltage input type waveform generation circuit that manually generates the voltage signal output from 6 and generates a sine wave voltage signal as shown in FIG. When 6 has an octagonal cross section, a speed change waveform signal is generated by a function of 8 cycles per rotation.

Here, in order to make the film thickness uniform on the substrate 40,
The function generated by the function generation circuit 27 is a sine wave, and the reason for this will be explained. Now, as shown in FIG. 7, the correction coefficient when changing the rotational speed of the substrate 40 is K.
(β) and θ for simplicity. −α. If the proportionality constant is ignored, then the deposition of sputtered particles per unit time on the substrate 40 is fi! At the tip C in the rotational direction of the substrate 40, the j amount T is T (C) -fK (β)・cosβdβ At the center Q of the substrate 40, T (Q) −jK (β)・eO3βdβ in the rotational direction of the substrate 40. At the rear end, T (D) −fK (
β)・cosβdβ. Therefore, K(β)=1/c
If osβ, then T (C) −T (Q) −T (
D). In other words, the rotational speed of the turntable 5 is
The preset average value corresponds to the above K(β)=1/cosβ. In other words, it is faster when the substrate 40 is facing approximately the center of the target 7 in the rotational direction of the carousel type jig 6, and slower when the substrate 40 is facing both ends of the target 7 in the rotational direction. When controlled by a sinusoidal amplitude (for example, ±10%), the film thickness becomes uniform.

In this embodiment, the function generating circuit 27 generates a
A second signal generation circuit is configured to generate a variable speed waveform signal (second signal) for changing the rotational speed of the cell type jig 6 based on a predetermined function depending on time.

The respective output signals of the first level controller 25 and the function generating circuit 27 are manually input to a pulse generating circuit 28. As shown in FIG. 2(C), this pulse generating circuit 28 operates in a function generating circuit 27 in response to a voltage signal (first signal) of a constant level v1 outputted from the first level controller 25.
The variable speed waveform voltage signal (second signal) outputted from the converter is increased by a voltage level corresponding to its amplitude, and then corrected, and a pulse signal having a pulse frequency corresponding to the corrected waveform signal is output. It has become.

Note that it is also possible to correct the voltage signal from the function generation circuit 27 by lowering and subtracting the voltage signal from the function generation circuit 27 by the voltage level corresponding to the amplitude of the voltage signal from the second level controller 26, or by adding both signals as they are. .

In addition to the sine wave, the speed change waveform signal may include, for example, a triangular wave shown in FIG. 5(a), a rectangular wave shown in FIG.
The trapezoidal wave shown in c), the deformation of the trapezoidal wave shown in figure (d), and the trapezoidal wave shown in figure (d).
There are variations of the sine wave shown in e), and variations of the triangular wave (sawtooth wave) shown in Figure (f). In other words, when forming a film using a sputtering device, in addition to making the film thickness uniform, the functions of the sputtered film, such as the strength and direction of the magnetic field for magnetic disks and magnetic tapes, the transparency and electrical resistance for transparent conductive films for liquid crystals, etc. are required, and it is preferable to select the variable speed waveform according to the requirements of the functions of these membranes.

The output signal of the pulse generating circuit 28 is input to a servo driver 23 for driving the pulse motor 21, and the feedback signal from the encoder 22 is input to the driver 23. With the above configuration, the control device 24 controls the rotation speed of the turntable 5, that is, the substrate 40, depending on the amount of sputtered particles deposited on the substrate 40.
Feedback control is performed so that it remains approximately constant over the entire surface of 0.

Next, the operation of the above embodiment will be explained.

The carcell type jig 6 with the substrate 40 attached thereto is placed in the vacuum chamber 1 and placed on the turntable 5. The vacuum chamber 1 is then evacuated from the exhaust boat 3 by a large vacuum pump.
After lowering the internal pressure, the turntable 5 is rotated by the operation of the pulse motor 21, and at the same time, sputter gas is introduced from the introduction boat 2, and vacuum is pumped from the sputter gas exhaust boat 4 using a small vacuum pump. Sputtering is performed under a constant temperature condition using a heater 10 while evacuating the chamber 1 to a constant vacuum pressure.

In the case of cono sputtering, the pulse motor 21 is controlled by the control bag fW24, and in the control device 24, a voltage signal of a constant level for setting the basic rotational speed of the carousel type jig 6 is outputted from the first rubel controller 25. , from the function generation circuit 27 to the second level controller 2
6, and outputs a sinusoidal voltage signal that changes the rotational speed of the carousel type jig 6. Then, in the pulse generation circuit 28, the sine waveform voltage signal from the function generation circuit 27 is added to the voltage signal from the first level controller 25 to generate a correction voltage signal, and a pulse signal having a frequency according to the correction signal level is generated. is output.

The correction voltage signal is a signal that changes from the voltage signal from the first rubel controller 25 in accordance with changes in the signal level of the sine waveform signal. Therefore, the pulse signal corresponding to this correction signal level has a characteristic that its pulse frequency (the number of pulses per unit time) changes according to the sine waveform signal. This pulse signal is input from the pulse generation circuit 28 to the pulse motor 21 via the driver 23, whereby the rotational speed of the pulse motor 21 is controlled in a sine curve shape in response to the sine wave from the function generation circuit 27. . Therefore, the pulse motor 21
As a result of controlling the rotational speed of the turntable 5, the rotational speed of the turntable 5 becomes faster when the substrate 40 faces approximately the center of the target 7, but in this state, many sputtered particles are deposited at the center of the substrate 40. As the rotation speed increases, the deposition of sputtered particles at the center of the substrate 40 is suppressed. On the other hand, the rotational speed of the substrate 40 becomes slow when the substrate 40 faces both ends of the target 7, but in this state, there are few or no sputtered particles deposited at the center of the substrate 40; Sputtered particles are deposited on either end of the substrate 40, and the slower the rotation speed, the more sputtered particles are deposited on both ends of the substrate 40. This reduces the difference in the sputtering film thickness between the center portion and both ends of the substrate 40, thereby making it possible to reliably and easily make the sputtering film thickness uniform.

In the above embodiment, the level controllers 25 and 26 were configured with voltage generation circuits, and the function generation circuit 27 and pulse generation circuit 28 were configured with voltage input types, but the current generation circuit and current input type were configured. May be used.

(Second Embodiment) FIG. 6 shows a second embodiment. The same parts as in FIG. 1 are given the same reference numerals and detailed explanations are omitted)
The rotational speed of the carousel type jig 6 is variably controlled by digital signals.

In this embodiment, the control device 24' for the pulse motor 21 includes a data input device 29, and a CPU 30 as an arithmetic circuit that processes data input manually by the human power device 29 and outputs a signal corresponding to the data. , and a memory 31 that exchanges signals with the CPU 30 and stores the input data.

The two human-powered devices have numeric keys for inputting numerical data manually, and data regarding the rotational speed pattern of the carousel type jig 6 is inputted through this input device 29. Specifically, the rotational speed pattern of the carousel type jig 6 is a pattern in which the rotational speed changes, for example, into a sine wave with the passage of time while maintaining a constant rotational speed, and the input data is For example, when the carcell type jig 6 is rotated one rotation from the reference position so that the rotational speed pattern of the jig 6 becomes a sine wave, the rotation angle from the reference position (therefore, the pulse motor 21 The pulse frequency is inputted by sequentially setting the pulse frequency for the number of pulses inputted in the pulse frequency. This input data is processed by the CPU 30 and then stored in the memory 31.

The output of the CPU 30 is input to a D/A converter 32, and the converter 32 converts the input data processed by the CPU 30 into an analog signal. and,
The output signal of this converter 32 is input to the pulse generation circuit 28, and the data regarding the rotation speed pattern of the carousel type jig 6 is converted into a sine wave voltage signal by the D/A converter 32, and this voltage signal is converted into a sine wave voltage signal. A manually operated pulse generation circuit 28 generates a pulse signal having a pulse frequency corresponding to a sine wave.

The control device 24' is equipped with a counter 33 that measures the number of pulses output from the pulse generation circuit 28 to the pulse motor 21 based on a signal from the driver 23.
By transmitting and receiving signals between this counter 33 and the CPU 30, the rotational state of the pulse motor 21, that is, the actual rotational pattern of the carousel type jig 6 is monitored.

Therefore, in this embodiment, when data regarding the rotational speed pattern of the car-cell type jig 6 is manually inputted by the manual device 29, this data is stored in the memory 31. When the sputtering apparatus is in operation, the above data is called by the CPU 30, and after being processed by the CPU 30, it is converted into a sine wave voltage signal by the D/A converter 32, and the pulse generation circuit 28 converts the voltage signal into a sine wave voltage signal. A pulse signal having a frequency corresponding to the level is generated, and this pulse signal is output to the pulse motor 21, thereby controlling the motor 21. Therefore, the same effects as in the first embodiment can be obtained.

In this embodiment, the data is entered manually using an input device, but data of a plurality of predetermined rotational speed patterns may be stored in a memory and selected.

When this second embodiment is compared with the first embodiment, in the first embodiment, the functions set in the function generation circuit 27 are determined in advance, and it is only necessary to select from among them.
Variable control of the speed of the cell type jig 6 can be achieved simply and easily at low cost.

On the other hand, in the second embodiment, the speed change waveform of the jig 6 can be arbitrarily set and the rotation pattern can be freely changed without any restrictions, although the data requires manual labor. But it is advantageous. Therefore, the structure of the two-prize example may be selected as necessary.

The above embodiment is an example applied to a sputtering apparatus having a carousel type jig 6 having an octagonal cross section, but the present invention is applicable not only to other sputtering apparatuses such as dome type or drum type, but also to vapor deposition apparatuses. It goes without saying that the present invention can also be applied to other film forming apparatuses such as the present invention.

(Effect of the invention) As described above, according to the inventions according to claims (1) and (2), when the rotation speed of the rotating jig in the film forming apparatus is made variable, the driving means is a pulse motor. configure,
Since the pulse motor is controlled by variable pulse frequency control, it is easier to control the pulse motor when the substrate faces both ends of the supply source than when it faces approximately the center of the supply source. is controlled so that it is relatively slow, thereby suppressing the increase in particle deposition in the center of the substrate.
By increasing the amount of particles deposited on both ends of the substrate, it is possible to reliably and easily equalize the film thickness of the entire substrate.

[Brief explanation of drawings]

1 to 5 show a first embodiment of the present invention, FIG. 1 is a block diagram of a control device, FIG. 2 is a diagram showing output signals in a predetermined circuit of the control device, and FIG. 3 is a diagram showing sputtering. A vertical cross-sectional view of the device; FIG. 4 is a partially cutaway plan view of the device;
FIG. 5 is a diagram showing a modification of the output signal of the pulse generation circuit. FIG. 6 is a diagram corresponding to FIG. 1 showing the second embodiment. FIG. 7 is a schematic plan view showing the relationship between the substrate and the target. 1... Vacuum chamber 6... Car cell type jig (rotating jig) 6a... Substrate mounting surface 7... Target (film forming material supply source) 21... Pulse motor 24.24' ... Control device (control means) 25 ... Second level controller (first signal generation circuit) 26 ... Second level controller 27 ... Function generation circuit (second signal generation circuit) 28 ...
・Pulse generation circuit 29...Data input device 30...CPU (calculating means) 31...Memory (storage means) 40...Substrate gruel 3 section (a) 1...Vacuum tank 6... Car-cell type jig (rotating jig) 6a...Substrate mounting surface 7...Target (film forming material supply source) 21...Pulse motor 24.24'...Control device (control means) 25 ...First level controller (first signal generation circuit) 26...Second level controller 27...Function generation circuit (second signal generation circuit) 28...
・Two pulse generation circuits...Data input device 30...CPU (computation means) 31...Memory (storage means) 40...Substrate B placement time time second section

Claims (2)

[Claims] (1) A film-forming material supply source that is arranged in a vacuum chamber and supplies materials to be deposited on a substrate, and a plurality of substrate mounting surfaces that are rotatably supported within the vacuum chamber and that attach substrates in a circumferential direction. and a rotating jig that rotates so that each substrate mounting surface sequentially faces the supply source, and the film is formed on the substrate on the substrate mounting surface while rotating the rotating jig. The film apparatus includes a pulse motor that rotationally drives the rotating jig, and a control means that variably controls the rotational speed of the pulse motor depending on the orientation of the substrate with respect to the film-forming material supply source, the control means comprising: A first signal generation circuit that generates a first signal at a constant level to set the basic rotational speed of the rotating jig, and a second signal that changes the rotational speed of the rotating jig based on a predetermined function according to time. a second signal generating circuit that corrects the output signal level of the first signal generating circuit according to the output signal level of the second signal generating circuit, and transmits a pulse signal having a frequency corresponding to the corrected signal level to the pulse motor. A film forming apparatus characterized by comprising a pulse generating circuit that outputs a pulse. (2) A film-forming material supply source that is arranged in a vacuum chamber and supplies materials to be deposited on the substrate, and a plurality of substrate mounting surfaces that are rotatably supported within the vacuum chamber and that attach the substrates in the circumferential direction. and a rotating jig that rotates so that each substrate mounting surface sequentially faces the supply source, and the film is formed on the substrate on the substrate mounting surface while rotating the rotating jig. The film apparatus includes a pulse motor that rotationally drives the rotating jig, and a control means that variably controls the rotational speed of the pulse motor depending on the orientation of the substrate with respect to the film forming material supply source, the control means comprising: a storage means for storing data regarding the rotational speed pattern of the rotating jig; an arithmetic circuit for processing the data stored by the storage means and outputting a signal; and receiving an output signal from the arithmetic circuit and responding according to the signal level. and a pulse generation circuit that outputs a pulse signal having a frequency to the pulse motor.