JPS5927383B2 - Ion beam thin film production equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thin film forming apparatus, particularly to a thin film forming apparatus using a field evaporation type ion source.

Generally, a traditional method for forming a thin film on a substrate is a vapor deposition method, but attempts have been made to form a thin film using an ion beam as a method that has advantages over this method.

That is, when using an ion beam, in principle, 1)
2) It is possible to form substances that can only be formed at high substrate temperatures at low substrate temperatures; 2) It is possible to suppress the amount of residual gas in the vacuum mixed into the thin film, resulting in a thin film with high purity;
3) Effects such as being able to improve the adhesion between the thin film and the substrate and improving the density of the thin film can be expected. However, the above-mentioned expected effects cannot necessarily be achieved using conventional ion beam generators. FIG. 1 shows a complicated conventional device configuration, which will be briefly explained and its shortcomings will be highlighted. Conventionally, a crucible-type ion beam generator has been used. That is, the substance in the crucible 1 is heated to a high temperature by the heater 2, evaporated and ionized, and the substance in the crucible 1 is heated to a high temperature of several KV to several tens of K by the high voltage power source 3.
After accelerating with a high electric field of V, it is focused to some extent by an electron lens system 4. In this device, since the crucible 1 is heated to a high temperature, impurity ions from the inner wall of the crucible, the heater, and the residual gas cannot mix into the output beam IB and directly irradiate the substrate. It must be subjected to mass analysis by a mass spectrometer 5 and directed to the substrate 6 with only the required components. Thereafter, the ion beam is decelerated in front of the substrate 6, and irradiated onto the substrate with an accelerating electric field of a power source T at a relatively low voltage, generally several tens to several hundreds of volts, to form a film. As described above, in an apparatus using a conventional crucible-type ion source, a large amount of impurity ions are inevitably generated from the ion source, and a mass spectrometer is required, resulting in an extremely large size of the entire apparatus. In view of this, the present invention aims to provide a small and simple thin film forming apparatus, and for this purpose, we first begin by searching for a highly functional ion beam generating apparatus.

As a result, it was decided to use a field evaporation type ion beam generator.

This field evaporation type ion beam generator itself has already been developed, and a substance to be ionized is attached to a needle-shaped anode with a tip radius of several μm provided in a heater, and the substance is left in a molten state heated by the heater. Ions are emitted by applying a strong electric field to the tip of the anode. Characteristics unique to this device include 1) small size, 2) simple structure, 3) large ion current per unit power consumption, 4) high brightness, and 5) difficulty in mixing with impurity ions. Although this invention is intended to take advantage of this feature as it is, the basic embodiment shown in FIG. 2 will be explained below. It is attached to a needle-like anode 10 provided in the.

Here, for ease of understanding, it is assumed that the substance 8 to be ionized is gold (AU). The gold as an ion source is kept at a positive potential of several tens to hundreds of volts by a power source 7 relative to ground or the substrate 6 on which the gold thin film is to be formed,
And it is maintained in a molten state by the heater 9.

In this state, when a negative high voltage of several KV is applied to the extraction electrode 11 from the high voltage power supply 3, gold ions are extracted. In order to focus this gold ion beam IB onto the substrate 6,
An electron lens system 13 is used, but this can take any simple configuration. In the case shown in the figure, the above-mentioned extraction electrode 11 and ground electrode 12 constitute an electron lens system, which creates an electric field directed toward the central axis of deceleration, and the trajectory of the ion beam IB is temporarily expanded. After focusing, it takes on a converging shape. By irradiating the substrate 6 with the gold ion beam focused in this manner, a desired gold thin film can be obtained, and in a trial example by the present applicant, it has become possible to achieve a focused diameter of 1 Tfnn or less.

This is partly due to the high brightness of the field evaporation type ion source. In other words, even with a simple electron lens system, the beam can be easily focused to a diameter of 1T1t1n or less, and a sufficient current density for forming a highly pure thin film can be obtained. In addition, because there is theoretically little room for impurity ions to enter, there is no need for large components such as conventional mass spectrometers.
The entire device can be significantly downsized.

Of course, the microwave oven system 13 can be designed in various configurations other than the embodiment shown in the second figure, and the electric potential can be maintained at a required relative potential difference between the ion source and the substrate. It is essentially the same even if both are set to a high potential.

As described in detail above, according to the present invention, the ion beam thin film forming apparatus, which was conventionally large and expensive, can be made smaller and simpler, and at the same time, the number of peripheral devices can be reduced.
This has the great effect of being inexpensive overall.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a conventional ion beam thin film forming apparatus, and FIG. 2 is a schematic diagram of a basic embodiment of the present invention. In the figure, 3 is a high voltage power supply, 6 is a substrate, 8 is a substance to be ionized, 9 is a heater, 10 is a needle electrode, and 13 is an electron lens system.

Claims (1)

[Claims] 1. It is characterized by comprising a field evaporation type ion beam generator and an electron lens system that focuses the ion beam generated by the device onto a substrate, and forms a thin film on the substrate with the focused ion beam. Ion beam thin film creation device.