JPH062121A - Ion plating device - Google Patents

Abstract

(57) [Abstract] [Purpose] To prevent abnormal discharge while maintaining high plasma density in an ion plating device using a high frequency coil. [Structure] A crucible 2 is provided on the lower surface of a vacuum container 1, and a vapor deposition material 3 is accommodated in the crucible 2. The vapor deposition material 3 in the crucible 2 is heated and evaporated by the heater 4. A high-frequency coil 6 is arranged between the deposition target substrate 5 and the crucible 2 in the vacuum container 1. The high frequency coil 6 is connected to a high frequency power source 8 via a matching box 7. The high frequency coil 6 oscillates at a high frequency by the power supplied from the high frequency power source 8, the vapor deposition material evaporated from the crucible 2 is turned into plasma by the high frequency oscillation of the high frequency coil 6, and the ions therein are deposited as a thin film on the substrate 5 to be vapor deposited. A filter coil 9 is connected between the high frequency coil 6 and the matching box 7, and a bias resistor 10 is connected in series to the filter coil 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an evaporation source for evaporating and feeding a vapor deposition material to a substrate to be vapor-deposited provided in a vacuum chamber, a high frequency coil for ionizing vaporized vapor of the vapor deposition material, and supplying power to the high frequency coil. The present invention relates to an ion plating device including a high-frequency power supply for controlling the frequency and a matching box interposed between the high-frequency coil and the high-frequency power supply.

[0002]

2. Description of the Related Art A conventional ion plating apparatus of this type is shown in FIG. Reference numeral 1 denotes a vacuum container, and the gas in the vacuum container 1 is exhausted from the exhaust port 1a. There is a crucible 2 in the lower part of the vacuum container 1, and ITO or S is placed in the crucible 2.
A vapor deposition material 3 such as iO is stored. A heater 4 such as an electron gun is provided beside the crucible 2, and the vapor deposition material 3 in the crucible 2 is heated and evaporated by the heater 4. A vapor deposition substrate 5 is attached to the upper part of the vacuum container 1, and a high frequency coil 6 is disposed between the vapor deposition substrate 5 and the crucible 2. The high frequency coil 6 is connected to a high frequency power source 8 via a matching box 7. The high frequency coil 6 generates a high frequency voltage by the power supplied from the high frequency power source 8,
The vapor deposition material evaporated from the crucible 2 passes through the plasma generated by the high frequency voltage of the high frequency coil 6, is ionized, and is deposited on the substrate 5 to be vapor deposited as a thin film.

[0003]

In the conventional ion plating apparatus, the high-frequency coil 6 is abnormally discharged and the quality of the thin film deposited on the substrate 5 to be vapor-deposited is deteriorated. The abnormal discharge in the high-frequency coil 6 occurs because the high-frequency coil 6 has a high voltage because a self-bias voltage, which is a DC voltage, is generated in the high-frequency coil 6 in addition to the high-frequency voltage supplied from the high-frequency power source 8.

The principle of generating the self-bias voltage will be described below. A high-frequency voltage is applied to the high-frequency coil 6 by the power supplied from the high-frequency power source 8, and plasma is generated.
When the high frequency voltage is positive, electrons in the plasma flow into the high frequency coil 6, and when the high frequency voltage is negative, the ions in the plasma flow into the high frequency coil 6. Since the mobilities of electrons and ions are different, the amount of electrons flowing into the high frequency coil 6 is larger than the amount of ions flowing into the high frequency coil 6. Since the potential of the high frequency coil 6 is DC-directed by the matching capacitor 7a in the matching box 7, the high frequency coil 6 is set to a negative potential so that the inflow amount of electrons becomes equal to the inflow amount of ions in a steady state. Be self-biased. The above is the principle of generating the self-bias voltage.

An object of the present invention is to prevent abnormal discharge of the high frequency coil without deteriorating the quality of the deposited thin film.

[0006]

Therefore, according to the present invention,
An evaporation source that evaporates and feeds a vapor deposition material to a vapor deposition substrate provided in a vacuum chamber, a high frequency coil that ionizes vaporized vapor of the vapor deposition material, a high frequency power source that supplies power to the high frequency coil, a high frequency coil and a high frequency power source. In the ion plating device including a matching box interposed between the high frequency coil and the matching box, a filter coil for reducing only the self-bias voltage of the voltage applied to the high-frequency coil is connected between the high-frequency coil and the matching box. A voltage setter was connected in series with the filter coil.

[0007]

Since the filter coil cuts off the high frequency voltage, the high frequency voltage generated in the high frequency coil is the same as before. On the other hand, since the filter coil does not cut the DC voltage, the self-bias voltage generated in the high-frequency coil is reduced to the value set by the self-bias voltage setter.
The self-bias voltage setter is an electric resistance or a DC power supply.When the self-bias voltage setter is an electric resistance, the self-bias voltage is the product of the current value of the electron current flowing into the high frequency coil and the resistance value of the electric resistance. Become. When the self-bias voltage setting device is a DC power supply, the self-bias voltage has a value determined by the DC power supply.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying the present invention will be described below with reference to FIGS. As shown in FIG. 1, a filter coil 9 is connected between the high frequency coil 6 and the matching box 7, and a bias resistor 10 is connected in series to the filter coil 9, which is a characteristic feature of the present embodiment. The bias resistor 10 is grounded. Other configurations are shown in FIG.
Since it is the same as the conventional device of No. 1, the description of the configuration is omitted.

The impedance of the filter coil 9 is large enough to cut the high frequency voltage, and the bias resistor 10
Is a variable resistor whose resistance value can be adjusted. Figure 1
When the bias resistor 10 is removed from the above state, the high frequency coil 6 is grounded in terms of direct current. Therefore, of the high-frequency voltage and the self-bias voltage generated in the high-frequency coil 6, the high-frequency voltage that is an AC voltage is cut by the filter coil 9 and has the same magnitude as the conventional one, but the value of the self-bias voltage that is a DC voltage is zero. Becomes That is, the voltage generated in the high frequency coil 6 is reduced by the conventional self-bias voltage, and abnormal discharge is prevented.

In this state, the power supply is the same as in the conventional case, so the amount of plasma generated is the same as in the conventional case. However, a large amount of electrons in the plasma flow into the high-frequency coil 6 and flow out from the vacuum container 1, so that the plasma density decreases.
Therefore, an undesirable situation occurs in which the quality of the deposited thin film deteriorates.

When the bias resistor 10 is connected in series to the filter coil 9 as shown in FIG. 1, of the high frequency voltage generated in the high frequency coil 6 and the self bias voltage, the high frequency voltage which is an alternating voltage is cut by the filter coil 9. It is the same size as before. On the other hand, the self-bias voltage is a product value of the resistance value of the bias resistor 10 and the current value of the electron current flowing from the high frequency coil 6. Therefore, the self-bias voltage does not become zero, and the self-bias voltage can be changed by changing the resistance value of the bias resistor 10. Therefore, by adjusting the self-bias voltage, the inflow of electrons into the high-frequency coil 6 can be appropriately suppressed, and by suppressing this inflow, the self-bias voltage can be reduced while keeping the plasma density high. That is, by properly setting the resistance value of the bias resistor 10, it is possible to prevent the abnormal discharge while keeping the plasma density high.

In order to confirm the effect of this embodiment, a comparative experiment between the device of this embodiment and the conventional device was conducted. The graph of FIG. 2 shows the comparison results, where the horizontal axis represents the electron current value (unit mA) indicating the plasma density, and the vertical axis represents the self-bias voltage (unit V). The mark Δ indicates the measured value using the conventional device, and the mark ○ indicates the measured value using the device of this embodiment. As is clear from the comparison result of FIG. 2, the self-bias voltage is greatly reduced with the same plasma density as in the conventional device according to the present embodiment device.

As a result of investigating the number of abnormal discharges,
According to the device of this embodiment, the number of abnormal discharges can be reduced to 1/5 or less as compared with the conventional device. Of course, the present invention is not limited to the above-described embodiment, and if a control device 11 for monitoring the voltage and plasma density of the high frequency coil 6 and performing feedback control as shown in FIG. It is possible to perform fine control for preventing abnormal discharge while maintaining the same.

Further, as shown in FIG. 4, a variable DC power source 12 may be used instead of the bias resistor 10. In this case, the negative side of the DC power supply 12 is connected to the filter coil 9. This DC power supply 12 can also reduce the self-bias voltage, and by appropriately setting the size of the DC power supply 12, it is possible to prevent abnormal discharge while keeping the plasma density high.

JP-A-1-108371 discloses an apparatus for forming a thin film by generating plasma by discharge between a sample electrode and a counter electrode and applying ions to the sample on the sample electrode. There is. In this device, an L coupling (filter coil) is connected between the matching section (matching box) and the counter electrode, and a DC power supply is connected in series to the L coupling. This configuration is similar to the configuration of the embodiment of FIG. 4 of the present invention, but the series connection of the DC power supply to the L-coupling is done via the positive side of the DC power supply. That is,
This is because the conventional device disclosed in JP-A-1-108371 shifts the plasma potential to a positive potential, which is clearly different from the technical idea of the present invention.

[0016]

As described above in detail, according to the present invention, the filter coil is connected between the high frequency coil and the matching box, and the self-bias voltage setting device is connected in series with the filter coil. The high-frequency voltage of the voltage in 1 is kept unchanged from the conventional one and only the self-bias voltage is reduced, and the self-bias voltage setter regulates the degree of reduction of the self-bias voltage, thereby keeping abnormal plasma discharge while keeping the plasma density high. It has an excellent effect that it can be prevented.

[Brief description of drawings]

FIG. 1 is a front sectional view showing an embodiment embodying the present invention.

FIG. 2 is a graph showing a comparison of self-bias voltage reduction between the device of the present invention and the conventional device.

FIG. 3 is a front sectional view showing another example.

FIG. 4 is a front sectional view showing another example.

FIG. 5 is a front sectional view showing a conventional device.

[Explanation of symbols]

6 ... High frequency coil, 7 ... Matching box, 8 ... High frequency power supply, 9 ... Filter coil, 10 ... Bias resistor, 1
2 ... DC power supply.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsuhiko Shimizu 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd.

Claims (1)

[Claims] 1. A vaporization source for vaporizing and feeding a vapor deposition material to a vapor deposition substrate provided in a vacuum chamber, a high frequency coil for ionizing vaporized vapor of the vapor deposition material, and a high frequency power supply for supplying electric power to the high frequency coil. In an ion plating apparatus including a matching box interposed between a high frequency coil and a high frequency power source, a filter for reducing only a self-bias voltage of a voltage applied to the high frequency coil between the high frequency coil and the matching box. An ion plating device characterized in that a coil is connected and a self-bias voltage setting device is connected in series with a filter coil.