JPS6411116B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for forming a thin film on the surface of a workpiece.

Conventionally, such devices as described above are based on reactive sputtering, CVD, plasma CVD, ion plating, and the like. In reactive sputtering, the target material is a solid substance, and the ions generated by glow discharge are used to knock out the target material and cause it to react with the gas that is generating the glow discharge. The ionized particles are hardly ionized,
The ionization rate of the gas causing the glow discharge is also
Since the content is as low as 0.1% or less, it was necessary to raise the temperature of the object to be treated in order to obtain a good quality film. For example, SiC
When producing a target material using Si as a target material and using C ₂ H ₂ or Ar as a reaction gas, the temperature of the object to be processed needs to be 600°C or higher. In addition, CVD requires a temperature of 1000°C or higher in order to cause the reaction gas to react on the object to be processed, and the deposition rate of the thin film differs in the initial, middle, and late stages, making it difficult to control the film thickness. Furthermore, plasma CVD can process at a lower temperature than CVD in order to ionize the reactive gas, but because the ionization rate of the reactive gas is low, the temperature of the processed material must be raised to 500°C or higher in order to obtain a high-quality film. No. In addition, in the case of ion plating, since the evaporation source is solid and limited, it is impossible to continuously create films with a thickness of 10 μm or more.

The present invention solves the above-mentioned problems, and aims to provide an apparatus that can increase the ionization rate and continuously form high-quality thin films even at low temperatures of the object to be processed.

The present invention will be explained below based on one embodiment shown in the drawings. In the figure, 2 is a vacuum tank, and 4 is a vacuum pump for this vacuum tank 2. An electron gun 6 is provided in the lower part of the vacuum chamber 2, and an object to be processed, such as hard carbon 8, is placed on the upper surface of the vacuum chamber 2.
is located. The electron gun 6 is for heating the object to be processed 8 with the electron beam 10 it generates.

30 upwards from near one edge of the object to be processed
Ionization electrodes 12 are arranged at a distance l1 of 100 mm to 100 mm (50 mm in this embodiment). This ionization electrode 12 is formed in a rectangular shape with a width of 3 cm and a length of 7 cm, and a positive DC voltage of 500 to 10 V (80 V in this embodiment) is applied. 14 is its DC power supply.

5 to 50 points downward from this ionization electrode 12.
Thermionic emission electrodes 16 are arranged at a distance l2 of mm. 18 is its AC power supply.

Between the ionization electrode 12 and the thermionic emission electrode 16, there are
At a distance l3 of 20 mm, and an ionization electrode 12
A reactant gas introduction pipe 20 is arranged so that the supply port is located at a distance l4 of 10 to 20 mm from the side wall of the vacuum chamber 2. A reaction gas (for example, C ₂ H ₂ , SiH ₄ and
(mixed with Ar in an appropriate ratio) is supplied from outside the vacuum chamber 2. 22 is a flow rate control valve for the reaction gas, and 24 is a stop valve thereof.

A magnetic field generator 26 made of, for example, a permanent magnet is arranged on the side of the electron gun 6, and generates a magnetic field directed in the front and back directions in the figure within an area 27 surrounded by a dotted line in the figure. This magnetic field is 30 to 500 Gauss, and is perpendicular to the electric field directed from the ionization electrode 12 toward the object to be processed (in the vertical direction in the figure). This is because if the magnetic field is less than 30 Gauss, the electrons cannot be caused to have a spiral motion, as will be described later, and if the magnetic field is more than 500 Gauss, the electron beam 10 will be affected.

150 to upward from the center of the workpiece 8
An ion gun 28 is placed at a distance l5 of 300 mm. This has a beam shape of 60mmφ, an acceleration voltage of 3KV, and a beam output of 20mA. In addition, a viewing window 29 is provided on the side wall of the vacuum chamber 2 so as to face each other.
30 is formed, the viewing window 29 is provided with a light emitting part 31 of an optical film thickness measuring device, and the viewing window 30 is provided with a light receiving part 32 of the optical film thickness measuring device. 33
is a temperature measuring device, which is used to measure the temperature of the object to be processed.

In the thin film forming apparatus configured as described above, the inside of the vacuum chamber 2 is first evacuated to a degree of vacuum of, for example, about 10 ^-6 Torr using the vacuum pump 4. Then, the object to be processed is heated to, for example, 300° C. by the electron gun 6, and thermionic electrons of 0.1 to 1 mA are emitted from the thermionic emission electrode 16. Furthermore, by adjusting the reaction gas stop valve 24 and the reaction gas flow rate control valve 22, the reaction gas introduction pipe 20
A reaction gas is supplied through the vacuum chamber 2 so that the pressure within the vacuum chamber 2 becomes 3×10 ⁻⁴ _Tprr .

In this state, the thermionic electrons emitted from the thermionic emission electrode 16 head toward the ionization electrode 12, but since the magnetic field by the magnetic field generator 26 is applied orthogonally to the electric field by the ionization electrode 12, the thermionic electrons The particles move toward the ionization electrode 12 in a spiral trajectory. Therefore, the probability of colliding with the reactive gas supplied between the ionization electrode 12 and thermionic emission electrode 16 and ionizing the reactive gas is higher than when only an electric field is applied. Further, since the electrons generated by ionizing the reactive gas similarly move toward the ionization electrode in a spiral trajectory, the ionization rate of the reactive gas becomes higher. The reaction gas ionized in this manner is directed toward the object to be processed 8 by the electric field generated between the ionization electrode 12 and the object to be processed 8, and forms a thin film of SiC on the object to be processed 8.

At this time, if ionized reaction gas is emitted from the ion gun 28 toward the object 8, a more stable thin film can be created.

Note that when the reactive gas is supplied so that the pressure inside the vacuum chamber 2 becomes 1×10 ^-3 _Tprr , the electron beam 10 from the electron gun 6 collides with the reactive gas, further promoting ionization of the reactive gas. Furthermore, the supply of the reaction gas and the evacuation of the vacuum chamber 2 are carried out in parallel so that the pressure within the vacuum chamber 2 is maintained at 3×10 ⁻⁴ _Tprr or 1×10 ⁻³ _Tprr . Furthermore, when creating an optical thin film, the workpiece 8 is irradiated with light from the light emitting part 31 of the optical thin film measuring instrument, and the reflected light is received by the light receiving part 32 of the optical thin film measuring instrument. By intermittently measuring the refractive index and absorption coefficient of the thin film on 8, a desired optical thin film can be obtained.

As described above, in the thin film forming apparatus according to the present invention, the ionization electrode 12 and the object to be processed 8 are relatively close to each other, and the ionization electrode 1
A thermionic emission electrode 16 is provided between the thermoelectron emission electrode 16 and the object to be processed 8 , and a reaction gas supply pipe 20 is opened between the thermionic emission electrode 16 and the ionization electrode 12 . Therefore, when the thermoelectrons emitted from the thermionic emission electrode 16 head towards the ionization electrode 12, they collide with the reaction gas supplied between the thermionic emission electrode 16 and the ionization electrode 12, and the reaction gas efficiently ionizes. Therefore, the density of the ionized reaction gas increases. The ionized reaction gas is directed toward the object to be processed 8 by the electric field between the ionization electrode 12 and the object to be processed 8, so that a film is efficiently formed on the object to be processed 8. For example, if ionization is performed not between the ionization electrode 12 and the workpiece 8, but between the ionization electrode and the opposite side of the workpiece, the workpiece may be heated to a considerably high temperature. A sufficient film cannot be formed unless the object is heated or a high negative voltage is applied to the object, but according to this invention, the object only needs to be heated to a relatively low temperature, and the reference potential A sufficient film can be formed just by connecting to the . Moreover,
In ion plating, solid metal is used as the evaporation source, so the evaporation source is limited, and when the evaporation source is exhausted, the evaporation source in the vacuum chamber 2 must be replaced, and the ion plating work is interrupted. However, in this device, the reactant gas source is provided outside the vacuum chamber 2, so it was not possible to continuously create a thin film with a thickness of 10 μm or more.
There is no need for internal replacement work, and thin films with a thickness of 10 μm or more can be created continuously.

[Brief explanation of the drawing]

The figure is a schematic configuration diagram of a thin film forming apparatus according to the present invention. 2... Vacuum chamber, 6... Electron gun (heating source), 8... Processing object, 12... Ionization electrode, 16... Thermionic emission electrode, 20... Reactive gas supply pipe (reactive gas supply passage), 26... Magnetic field generator .

Claims (1)

[Claims] 1. Between a vacuum chamber, a workpiece placed in the vacuum chamber and set to a reference potential, and a workpiece placed close to the workpiece and to which a positive voltage is applied. An ionization electrode forming an electric field, a thermionic emission electrode disposed between the ionization electrode and the object to be treated, and a supply port disposed between the thermionic emission electrode and the ionization electrode. a reaction gas supply passage for supplying a reaction gas to be ionized by the ionization electrode into the vacuum chamber from the outside; a heat source for heating the object to be processed; and a connection between the ionization electrode and the object to be processed. a magnetic field generator that generates a magnetic field orthogonal to the electric field between the ionization electrode and the object to be processed;
Equipped with a thin film forming device.