JPS6141766A - Method and device for sputtering - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method and apparatus for forming a composite thin film.
In particular, the present invention relates to a precise and simple method for forming a composite thin film of any composition and an apparatus therefor.

[Background of the invention]

The sputter metallization method is widely used to obtain thin films used in industrial optics, decoration, precision machinery, and the like. There are many expectations for new materials and functional devices based on alloyed and composite thin films, and research is actively progressing at research institutions both domestically and internationally. Conventionally, when creating a composite thin film by sputter metallization, it has been common to form a target with the same composition as the composite thin film and perform sputtering. but,
In this method, some targets cannot be alloyed or composited, and even if they can be composited, the processability is poor and it is often impossible to create a target.

Unfortunately, in conventional sputter metallization methods, targets cannot be alloyed or composited, and even if they can be alloyed or composited, they often cannot be processed into a target of a predetermined shape.

The conventional method for deciding such issues is to
It is known to form a composite thin film by sputtering a target into four parts A-B-A-B as shown in FIG. 3 (%I4 Publication No. 9074 of 1980). However, in this method, since the sputtering rate is different between the target human material and B material, the area ratio of human material and BqIIJ material is set to 1:1.
Even if the ratio is 1, it is not possible to form a coated thin film of 1:1. Since the cis batter rate varies depending on the substance, the composition of the thin film is adjusted by varying the area ratio of the divided areas. Therefore, it is not easy to create a split target and the component v4:! The problem is that i is difficult. On the other hand, as shown in FIG. 14, in a conventional composite sputtering apparatus, an auxiliary target (divided target) 4 is interposed between a main target 2 and a substrate 3 in a closed container 1. The high end is connected to the positive power supply f6 via the variable resistor 5, and discharge energy is applied in a controlled manner to form a composite thin film on the substrate 3 (Japanese Patent Publication No. 15203/1983). In addition,
7 is a cathode, 8 is an anode, and 9 is an insulating material. This sputtering apparatus was developed for the purpose of improving the non-uniform thickness distribution of thin films formed by commonly used sputtering methods and vacuum evaporation methods.

That is, as shown in the figure, the film thickness is adjusted by varying the resistance of the auxiliary target 4 via a variable resistor 5 to change the discharge voltage (current).

This discharge 1rIL flow has a fixed resistance value due to the resistance of each auxiliary target, and even if the current flowing through each main target 2 is set, it is not possible to obtain a thickness with good reproducibility. The reason for this poor reproducibility is that since each target is discharged at the same time, the glow discharges interfere with each other in a strange way.

Furthermore, since the voltage applied to each target is different, the energy of Ar ions used for sputtering varies greatly depending on the position of the target. This difference in Ar ion energy means that even if the film can be formed to a certain thickness, the density will vary depending on the position of the film. This is the cause of the large difference in the

This clearly appears as an etching difference when etching is performed after forming a thin film, so it is often not practical.

On the other hand, Cr-N1 alloy thin films are used as resistors. In order to create such a Cr--Ni alloy thin film using a conventional method, a target is created by melting Cr and Ni, casting, and rolling in this order.

Therefore, when changing the alloy components, Cr
Because targets must be created by melting-casting-rolling various compositions of Ni and Ni, extensive experiments must be performed to create thin films of appropriate alloy resistance.

Furthermore, materials that cannot be melted and rolled, such as MO-si and Mo-8i0x, must be molded from powder and then sintered to create a target.

Even in this case, there was a problem in that in order to form an R4 film suitable for the purpose, it was necessary to sinter with various compositions. Furthermore, when the powder is molded and sintered, oxidation and nitrogen gas are mixed into the sintered body, making it impossible to obtain a dense composite thin film with good properties.

Furthermore, when adding trace elements to the main ingredients,
In order to increase the value of the variable resistor 5 connected to the auxiliary target, there was a problem in that the voltage decreased to a value below which sustains the glow discharge, and the discharge stopped.

[Purpose of the invention]

An object of the present invention is to provide a composite sputtering method and a sputtering apparatus that can easily and accurately create an alloyed or composite thin film with an arbitrary composition ratio, and can make the film thickness distribution uniform. be.

[Summary of the invention]

The first invention is a sputtering method for forming a composite thin film having an arbitrary composition ratio with high precision, and its characteristics are that a target serving as a cathode is divided into a plurality of parts, and each divided target is An arbitrary composite thin film is formed by forming each of the thin film composition elements, setting the pulse discharge time and peak voltage corresponding to the composition ratio of the composite, and applying the pulse discharge time and peak voltage to each divided target sequentially at high speed. Further, the second invention is characterized in that the device for directly implementing the sputtering method for producing the composite thin film described above is equipped with a pulse application device that sequentially switches and applies a pulse discharge voltage to each divided target.

Examples of the present invention will be described in detail below.

<Example 1> FIG. 1 is an explanatory configuration diagram showing an example of a sputtering apparatus of the present invention. In the figure, this sputtering device has a cathode target 12 and an anode 12 facing each other in a closed container 11.
are installed respectively, and a support stand 14 made of insulating material is installed.
The target 12 placed thereon is divided into four parts with an insulating material 15 interposed therebetween.

The e terminal of the high voltage power supply device 18 is connected to each of the divided targets 122 to 12 d via a switching transistor 16 , 17 , and the e terminal is connected to the positive electrode 13 via the sealed container 11 .

A pulse generator 19 is connected to the bases of the switching transistors 16 and 17, respectively.
The switching transistors 16 and 17 are opened and closed by pulse signals from the pulse generator ft19, and a sputtering voltage having a predetermined pulse discharge time and peak voltage is applied to each of the divided targets 12a to 12dlCIa. On the other hand, the positive electrode 13 supports a substrate on which a composite thin film is formed.

Using the sputtering device configured in this way, CR-
An example of forming a Ni composite thin film on a substrate is shown below.

First, the divided targets 12a and 12C are made of Cr, and the applied Subaru voltage is constant as the pulse discharge time tl and the pulse peak voltage t''Vo.On the other hand, the divided targets 12b and 12d are made of Ni and the applied Subaru voltage is constant as tl and pulse peak voltage t"V o. The pulse voltage is set to t2, the pulse discharge time is t2, and the pulse peak voltage is Vo.
By changing the current conduction ratio tL/11+tz variously, thin films of arbitrary compositions were formed on the substrate.

The sputtering conditions were the energization shown in Table 1.

Figure 2 is a pulse waveform diagram showing an example of sputtering voltage applied to each divided target.
, if the discharge time of Ni is t2, the energization ratio is ti/lt
+t2.

FIG. 3 is a graph showing the relationship between the energization ratio (t2/11+ti) and the composition ratio of the alloy thin film. Therefore, it has been found that a Cr--Ni alloy thin film having an arbitrary composition can be obtained by changing the pulse @.

As shown in FIG. 4, the film thickness distribution of the Cr--Ni alloy thin film obtained in this example shows a glass distribution similar to the generally used sputtering method or vapor deposition method. still,
For other three-element alloys, the current carrying ratio (h/lt+tz)
It was confirmed that there is a proportional relationship between the alloy composition and the alloy composition.

<Example 2> In this example, as shown in Fig. 5, the glass distribution of the film thickness was improved when creating an alloy thin film of (::r-Ni) using a target divided into eight parts. .

Each target divided into 8 parts Cr(1), N1(1), Cr
(2) and N1 (2) are sequentially applied with sputtering voltages shown in FIG. That is, the energization time of the targets N i (1) and Cr (1) on the outside from the center is made longer than on the targets N1 (2) and Cr (2) on the inside. As shown in FIG. 7, the Cr--Ni valley all-gold thin film formed in this way has a significantly improved film thickness distribution compared to the method using a four-part target. This can be used as a conductor or resistor for liquid crystal displays, etc., which require At film to be uniformly deposited over a large area. When increasing the size of this liquid crystal display, it is important to form a uniform thin film over a large area by arbitrarily controlling the film thickness.

<Example 3> This example uses target persons 1 to 4, B1 to B4.01 to C4t-, which are divided into 12 equal parts as shown in FIG.
Furthermore, an AA film with a wide area of uniform thickness was created. Target is 350w x 250 A4 board t-1
A glass substrate (300W) was used as the substrate.
X200m) was used. Further, the discharge sequence applied to the targets Person 1 to Person 4, Bl-B4, and C1 to C4 divided into 12 equal parts is shown in FIG. As shown in FIG. 10, the Aj thin film created by such a discharge sequence has a significantly improved Gaussian distribution of film thickness. The dotted line X in the figure represents the film thickness distribution of the conventional method.
represents the thickness distribution of the At film according to the present invention. The sputtering method according to the present invention is also effective for depositing a uniform film over a large area.

<Embodiment 4> FIG. 11 is a principle block diagram showing another embodiment of the sputtering apparatus of the present invention, which is characterized by a pulse application device.

That is, to explain by assigning the same reference numerals to the same parts as in FIG. 1, this pulse application device is equipped with a high voltage, high frequency power source 20, 21 and an impedance matching device! 22 and 23 are connected respectively, and the stain pressure, depending on the material shape of the load target, etc.
This prevents the current phase from being significantly shifted and the efficiency from decreasing. The switching of the high frequency was controlled by stopping the oscillation of the high voltage high frequency power supply 20, 21 using a signal from the pulse oscillator 24. In the aforementioned DC pulse method, no discharge occurs unless the target is a conductor such as a metal, but this sputtering device uses a high frequency (15.5 MHz) to process insulators such as ceramics and composites of insulators and metals. can be formed into a thin film.

This apparatus was used to create a Mo-8ii film resistor.

Mo-8i thin films are used as heating resistors in thermal heads of printers, fax machines, and the like. Incidentally, Si is a semiconductor, and 81 alone exhibits high resistance, and is an insulator, so it is difficult to discharge with direct current pulses. The sputtering conditions are: high frequency voltage peak value 3kl/, atmospheric pressure A r
2 x 10-1 Torr.

The test was conducted under the condition that the distance between the electrodes was 30 m. Schematic diagrams of the waveforms are shown in FIGS. 12(a) and 12(b). Although it is not possible to obtain any solid solution in the phase diagram of MO and Si, the present invention
By changing the discharge time of 3i and the discharge time of 3i, it was possible to obtain a resistor with an arbitrary composition.

For sputtering conductors and insulators, the same effect can be obtained with DC pulse discharge when using a VC conductor as shown in Figure 12 (Q).Also, both the DC pulse method and the high frequency pulse method can reduce the peak voltage (power) by approximately Although the amount of sputtering was controlled by controlling the pulse width at a constant value, the peak power voltage may be changed as long as the discharge sustaining voltage is within the range.

In the present invention, each divided target is made of a single metal, and the power supplied to each target is switched at high speed according to the alloy or composite composition, film thickness, etc. to prevent glow discharge interference between targets. By changing the discharge pulse width to thin the film, a thin film of any composition can be easily formed with high accuracy. Furthermore, since it is not sintered, oxides and nitrogen gas are not mixed in, so a dense film with good properties can be obtained.

In the present invention, the targets are divided into smaller parts and the power supplied to each target is switched at high speed to prevent interference between the targets, so that a reproducible film thickness can be obtained.

Furthermore, since the pulse peak power (voltage) is kept constant and the average power is controlled by the pulse width, the instantaneous ion energy at each position is almost constant. Therefore, a high-quality thin film can be obtained with the same film quality at each position.

In the present invention, since the power is controlled by the pulse width, the peak value does not change even if the average power is lowered, so the discharge continues and trace components can be easily added. Furthermore, since there is no interference between targets, thin films with good reproducibility can be formed. Furthermore, since the present invention performs sequential pulse discharge, it is possible to prevent abnormal discharge between targets, making it possible to create a composite thin film of a metal and a non-conductor such as ceramic with good reproducibility.

〔Effect of the invention〕

As described above, the present invention has the remarkable effect that an alloy or composite thin film of any composition can be easily obtained with high precision and a uniform film thickness.

[Brief explanation of the drawing]

FIG. 1 is an explanatory configuration diagram showing an example of the sputtering apparatus of the present invention, FIG. 2 is a pulse waveform diagram showing an example of the sputtering voltage applied to each divided target according to the present invention, and FIG. 3 is a diagram showing the energization ratio of each pulse. A diagram showing the relationship with the composition ratio of the alloy thin film, FIG. 4 is a glass distribution diagram of the film thickness of the Ni-Cr alloy thin film,
Figure 5 is a plan view showing a target divided into 8 parts, Figure 6 is a pulse waveform diagram showing an example of sputtering voltage applied to an 8 divided target, and Figure 7 is a plan view of a target divided into 8 parts.
Figure 8 is a plan view showing an example of a 12-divided target, Figure 9 is a pulse waveform diagram showing an example of sputtering voltage applied to a 12-divided target, and Figure 10 is a diagram showing the conventional method and this book. 11 is an explanatory configuration diagram showing another embodiment of the sputtering apparatus of the present invention; FIG. 12 is a waveform diagram of high-frequency pulse voltage; FIG. The figure is a plan view of a conventional four-split target, and FIG. 14 is an explanatory configuration diagram showing an example of a conventional sputtering apparatus. 11...Airtight container, 12...Target, 13...
-Anode, 16.17...Switching transistor, 18...High voltage power supply device.

Claims (1)

[Claims] 1. A sputtering method in which a high voltage is applied between a cathode target and an anode substrate to generate a glow discharge, and metal particles scattered from the target are compositely deposited on the substrate. dividing into a plurality of targets, and forming each divided target with the composite compositional element,
A composite sputtering method characterized by forming a composite thin film by setting pulse discharge times and peak voltages corresponding to the composition ratio of the composite and sequentially switching and applying the pulses to each divided target at high speed. 2. The composite sputtering method according to claim 1, wherein the pulse discharge is a direct current pulse, a high frequency pulse, or a mixed pulse of high frequency and direct current. 3. In a sputtering apparatus comprising a reduced pressure vessel in which a cathode target and an anode substrate are placed facing each other, and a power supply device that applies a discharge high voltage between the cathode target and the anode substrate, the cathode target is , is divided into a plurality of targets via an insulating material, each formed of different metal elements, and a power supply device is connected in parallel to each divided target via a switching element, and receives a pulse signal from a pulse generator. 1. A sputtering apparatus characterized in that a pulsed sputtering voltage is applied by sequentially switching each switching element at high speed based on .