JPS63230865A - Formation of thin metallic film - Google Patents

Abstract

PURPOSE:To form high quality vapor-deposited films at a low degree of vacuum by continuously increasing the quantity of electric current supplied to a heating source from a low value to a desired value without generating rush current when vapor of a metal is generated with the heating source. CONSTITUTION:A vacuum chamber 1 is evacuated to about 1X10<-2>Torr by a rotary pump 4, further evacuated to about 1X10<-3>Torr by the pump 4 and a mechanical booster pump 3 and finally evacuated to about 3-4X10<-4>Torr by the pumps 4, 3 and a diffusion pump 2. Electric current is then supplied from an AC power source 10 to filaments 5 through a current regulator 9 to evaporate the metal 5 for vapor deposition and to form thin metallic films on substrates 8. At this time, the quantity of electric current supplied to the filaments 5 is continuously increased from a low value to the value required to form the films without generating rush current. Thus, no gas is emitted and vapor deposition can be carried out without causing defects.

Description

Detailed Description of the Invention [Industrial Fields of Application] The present invention is directed to the production of a gold pAM film in a vacuum by a vacuum evaporation method, an ion plating method, a sputtering method, a plasma chemical vapor deposition method (plasma C/VD method), etc. The present invention relates to a method for efficiently forming a metal thin film by preventing the generation of rush current of a heating filament in the metal and suppressing the generation of released gas when performing surface treatment by forming a metal on the surface of a base material.

[Prior Art] Physical vapor deposition methods (PVD methods) such as vacuum evaporation methods, ion plating methods, and sputtering methods; thermal CVD methods;
Chemical vapor deposition methods (CVD method) such as photoCVD method and plasma CVD method
D method) is known.

All of these are methods in which gas phase metals such as metal atoms, metal molecules, or metal ions are generated and deposited on the surface of a substrate in one step.

[Problems to be Solved by the Invention] However, if gaseous components that easily react with metals, such as oxygen and water vapor, remain in the vacuum chamber, defective vapor deposition of single metals may occur, or only defective vapor deposited films may be obtained. Normally, the degree of vacuum in the room must be maintained at 7X10-4 Torr or higher. The time it takes to reach this degree of vacuum by evacuation becomes significantly longer when humidity is high, and the time required differs several times between dry winter and high humidity seasons.

In addition, gas containing water vapor, etc. is generated from the vacuum chamber walls and base material due to the radiant heat of the heating source used to generate gas phase metals (atoms, molecules, ions), which may react with metals or form metal thin films. It may be sorbed and cause poor deposition. This is the gold y &
This is because the presence of the film releases gases such as water vapor in the atmosphere that have been adsorbed onto it, and furthermore, water vapor or gases specific to plastics are released from the plastic base material.

The conventional method is characterized in that the current applied to the filament is added in stages during the vapor deposition process.If the set current value of the filament current during vapor deposition is 100, first, a current of 50 is applied in the preheating stage. After holding the current for a certain period of time, the current is increased to 100 and vapor deposition is started.

During these operating steps, the filament current was increased to 50.
100, an inrush current occurs in both cases. Due to this instantaneous excessive current, the radiant heat of the filament increases exponentially, and gas is rapidly generated from the substrate and the walls of the vacuum chamber, resulting in a decrease in the degree of vacuum in the vacuum chamber, making it unsuitable for vapor deposition. It becomes a state. Therefore, it was necessary to wait until the degree of vacuum rose to a certain level. In addition, if vapor deposition is performed at a low vacuum level, uneven gloss may occur on the vapor-deposited surface of the base material, the surface may become dark black due to coating with oxides, or vapor deposition defects may occur such as a decrease in the adhesion of the vapor-deposited metal. There was a problem.

The main component of the gas generated from the walls of this vacuum chamber is water vapor.
Gold Ba deposited on the wall of the vacuum chamber during previous deposition
The membrane is the source. This is because this vapor-deposited film is considered to be amorphous and has very high activity and easily absorbs water vapor in the atmosphere.

Furthermore, when the base material is a plastic such as acrylic resin, carbonyl chloride resin, or polycarbonate resin, a considerable amount of gas is released in a vacuum due to the composition of the plastic. The main component of this released gas is also water vapor. There is also data that shows that acrylic resin releases 2000 times more gas than stainless steel.

Therefore, when depositing on plastic, a system must be designed that can exhaust a large amount of water vapor in a short period of time. Another problem when handling plastic is that it has a lower heat resistance than glass 2 stainless steel (usually 100 to 300 degrees Celsius), and it is necessary to consider the effects of radiant heat from the filament. It will be done.

In this way, if residual gas and released gas can be removed from the vacuum chamber, a good deposited film can be obtained, and there is no risk of a sudden drop in the degree of vacuum in the vacuum chamber due to the sudden generation of released gas. , it is expected that good vapor deposition will be possible even with a lower degree of vacuum than in the past.

[Means for Solving the Problems] The present inventors have made extensive studies to solve the above problems, and as a result, have completed the present invention.

That is, the present invention provides a method for forming a metal thin film on the surface of a substrate by generating a vapor phase metal in the presence of a heating source in a vacuum chamber, in which the amount of current supplied to the heating source is changed from a low amount of current to form a metal thin film. This is a method for forming a gold fFA thin film characterized by suppressing the generation of inrush current and continuously increasing the current amount up to the amount required for .

Note that the degree of vacuum in the vacuum chamber herein refers to the degree of vacuum at a location in the vacuum chamber near the exhaust port of the exhaust system, and unless otherwise specified, the degree of vacuum refers to this degree of vacuum. On the other hand, the degree of vacuum around the base material refers to the degree of vacuum in a place close to the base material, and compared to the degree of vacuum inside the vacuum chamber, it is particularly susceptible to the effects of gas released from the base material, and the degree of vacuum changes greatly. .

Hereinafter, the present invention will be explained in more detail with reference to the drawings using a vacuum evaporation method as an example. It can be applied to metal thin film formation.

FIG. 1 is a diagram of a vacuum evaporation apparatus according to an embodiment of the present invention, and FIG. 2 is a diagram showing an example of the state of a filament and deposited metal in a vacuum chamber.

FIG. 3 is a graph showing changes in filament current over time during vacuum deposition in one embodiment of the present invention.

In Fig. 1, inside the vacuum chamber 1, there is a filament 5 placed to be heated by passing an electric current, and a deposition table 1716 placed on the filament 5 (see Fig. 2), which can be rotated around the filament 5. A base material mounting bracket 7 and a base material 8 placed thereon are set.

Current is supplied to the filament 5 from an AC power source 10 through a current regulator 9.

To perform vacuum evaporation, as a preparation, the inside of the vacuum chamber 1 is first evacuated to about I x 10'T Orr using the rotary pump 4, and then further evacuated to about Ix 10-3 Torr using the mechanical booster pump 3. Diffusion pump 2 is added to the top of the tank and evacuated to 3-4X 1O-4T Orr.

Next, a current is applied to the filament 5. Here, it is important to gradually and continuously increase the current 1+f1 with respect to time.

Although this cannot be determined unconditionally depending on the scale of the device and other conditions, for example, if the deposition setting current is 1000A,
Preferably, a current is passed through the filament 5 in the range of 100 A/sec.

FIG. 3 is a graph showing changes in filament current over time during vapor deposition according to the present invention. In the present invention, the filament current is gradually and continuously increased over time. In this case, an example is shown in which the current is increased linearly until the time of vapor deposition, and no rush current to the filament occurs as seen in the prior art. As a result, there is no generation of released gas, and therefore no decrease in the degree of vacuum occurs, and the vapor deposition can be performed immediately without causing any defects in the vapor deposition.The current can be continuously applied. In addition to the straight line as shown in Figure 3, the term "gradually rising" includes a method of raising in a curve, a substantially continuous method of raising in the form of minute steps, etc. Any method that does not substantially generate an inrush current may be used.

The device to gradually increase the current is not particularly limited as long as it is an adjusting device that can adjust the current flowing through the filament to gradually increase it and substantially cut the inrush current of the filament, but current adjustment using a thyristor can be used. An example is a vessel.

When the filament current reaches the deposition set value, the deposited metal 6 is evaporated and attached to the base material 8, that is, the deposition is performed.

The deposition setting value of the filament current cannot be determined unconditionally depending on the equipment or deposition conditions, but it is, for example, 100 to 1
The range is 0000△.

The M-wearing time is usually about 10 to 30 seconds, but can be changed as appropriate depending on the type of substrate and purpose.

In addition, in order to smooth the vapor deposition surface and improve the optical properties of the vapor deposition surface, the substrate surface may be polished or a synthetic resin may be applied to the substrate surface before vapor deposition to smooth the surface. good.

Especially when manufacturing electronic parts, polishing and cleaning treatment is necessary to improve the electrical properties.

In addition, it is possible to preheat the base material to strengthen the adhesion with the deposited metal, but if the base material is plastic, the heat resistance is low, and the filament is 1/1
@Di It is not necessarily necessary due to the influence of heat.

[Example] Below, the present invention will be explained in more detail with reference to Examples.

Acrylic resin base material (5caX 3nX 2ttua
, 100 pieces) were vapor-deposited using the apparatus shown in FIG. 1, using aluminum as the vapor-deposited metal 6, and using stranded tungsten as the filament 5 to evaporate the aluminum 6. First, use rotary pump 4 to vacuum chamber 1.
Evacuate the interior to IX 1O-2T orr, and use a mechanical booster pump to increase IX 1O-3T.
Orr, and 3X 10' To with diffusion pump 2
Exhausted to rr.

Here, to heat the filament 5 used for vapor deposition,
A current regulator 9 incorporating a thyristor was used.

Set this current regulator 9 to set the filament current to 25A.
J: sea urchin gradually rises at 1/sec. 40 seconds after starting the filament current, the filament current reaches 100.
From when the voltage became 0A, 1000A was maintained for 10 seconds and the substrate 8 was deposited. Thereafter, the filament current was reduced to zero to complete the deposition.

As a result, no decrease in the degree of vacuum around the base material 8 was observed from preheating to the start of vapor deposition, and it was confirmed that almost no released gas was generated.

After the vapor deposition was completed, the vacuum chamber 1 was opened to the atmosphere, and the substrates 8 were taken out and examined. As a result, all the substrates 8 were found to be in a good vapor deposition state.

[Effect of the invention] The effects of the present invention are as follows.

■When comparing the degree of vacuum inside the vacuum chamber, the present invention has a degree of vacuum of 3 to 4.
Vapor deposition can be started at about x 10-4 Torr, and vapor deposition can be started at a lower degree of vacuum compared to 1x10 to Torr in the conventional method.

(2) As a result, according to the present invention, the time required to reach a desired degree of vacuum is shortened, for example, from 40 minutes to 1 minute, making it possible to streamline the work of serving sake.

■Conventionally, due to the positional relationship between the base material and the filament, a large amount of released gas was distributed, especially in the upper and lower parts of the vacuum chamber, due to the influence of radiant heat caused by the heating of the filament due to the rush current, and in these positions, defective products due to evaporation of the base material were generated. The base material was installed only in the middle part where defective products are relatively less likely to occur.

However, according to the present invention, since the width heat generated by the filament is small, the base material is not affected by its position with the filament, and as a result of the small amount of released gas, the base material can be installed from the top to the bottom inside the vacuum chamber. The effective deposition volume of the vacuum T can be increased from 60% to 80%.

■Furthermore, compared to the conventional method, in the present invention there is no inrush current to the filament, so the 11113 ratio of the filament is smaller, and therefore, the average number of times one filament is used is eight times in the past, but with the present invention, the average number of times one filament is used is eight. The average number of uses is 20 times, which increases the effect by nearly 3 times! ? It will be done.

[Brief explanation of drawings]

FIG. 1 is a diagram of a device according to an embodiment of the present invention, and FIG.
A diagram showing an example of the state of the filament J3 and the vapor-deposited metal in the vacuum chamber. FIG. 3 is a graph of the time course of the filament current during vapor deposition in one embodiment of the present invention. 1... Vacuum chamber, 2... Diffusion pump, 3... Mechanical booster pump, 4... Rotary pump, 5
... filament, 6... vapor deposited metal, 7... base material mounting jig, 8... base material, 9... current regulator, 10.
··AC source.

Claims (1)

[Claims] 1. In a method for forming a metal thin film on the surface of a substrate by generating a vapor phase metal in the presence of a heating source in a vacuum chamber, the amount of current supplied to the heating source is changed from a low current amount to a metal thin film. A method for forming a metal thin film, characterized by suppressing the generation of inrush current and continuously increasing the current amount up to the amount required for forming the thin film. 2. Forming the metal thin film according to claim 1, in which the amount of current is continuously increased at a rate of 0.5 to 10% A/sec with respect to the deposition set current value using a current regulator using a thyristor. Method. 3. The metal thin film according to claim 1 or 2, wherein the method for forming the metal thin film is any one selected from vacuum evaporation, ion plating, sputtering, and plasma chemical vapor deposition. How to form.