JPH03294476A - Thin film forming apparatus - Google Patents

Abstract

PURPOSE:To stabilize the evaporation speed for a long period and to form uniform film by deflecting the electron beams generated with a hollow cathode by the magnetic field generated with an electromagnet, and heating and evaporating an evaporation material while scanning and irradiating the surface of the evaporation material. CONSTITUTION:The crucible 12 receiving the evaporation material 7 and a base plate 8 to be treated are oppositely disposed in a vacuum vessel 13 evacuated into vacuum. The electron beams 1 generated by the electric discharge through a hollow cathode 6 irradiates the evaporation material 7 to heat and evaporate. The vapor of this evaporation material 7 is, if necessary, reacted with the reaction gas supplied from a gas introduction pipe 14 to be deposited to form film on the base plate 8 impressed with biased voltage of high frequency wave from a high frequency wave electric power source 10 through an adjuster 9. In the above-mentioned thin film formation apparatus, the electromagnetic consisting of a coil 2 and an iron core 3 is disposed to deflect the electron beams 1 by its magnetic field so that the electron beams irradiate the surface of the evaporation material 7 while scanning. By this method, the evaporation speed of the evaporation material 7 is stabilized and the film homogeneous in the direction of film thickness is formed, and the adjustment of biased voltage is easy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a thin film forming apparatus used to form a thin film of metal nitride or metal oxide on a substrate to be processed.

[Summary of the invention]

A thin film forming apparatus equipped with an electromagnet that generates a magnetic field that deflects the electron beam generated by hollow cathode discharge and scans the surface of the residual material while irradiating it with the electron beam.

[Conventional technology]

Conventional technology only locally irradiates a narrow area of the surface of the evaporated material with the electron beam generated by hollow cathode discharge; it is not possible to deflect and scan the electron beam to irradiate a wide area of the surface of the evaporated material. Ta.

[Problems to be Solved by the Invention] For example, when trying to obtain a nitride thin film such as silicon nitride or aluminum nitride, or an oxide thin film such as silicon oxide or aluminum oxide, nitrogen gas or oxygen gas is will be introduced.

At this time, the evaporated substance such as silicon or aluminum, which has reached a high temperature in the crucible, is exposed to a nitrogen or oxygen atmosphere, so that it is significantly nitrided or oxidized. When the vaporized substance is nitrided or oxidized, its melting point increases. Therefore, the evaporated substance becomes difficult to melt, and only the narrow area that is directly irradiated with the electron beam becomes particularly high temperature, causing it to melt and evaporate.
Therefore, the evaporated material is not melted uniformly, and the electron beam may dig a hole in a part of the evaporated material. It becomes a substance state and becomes a nitride layer 20 and a local melted part. In this situation, only a portion of the evaporation material in the crucible can be evaporated, making the evaporation rate unstable and the deposition time shortened, making it impossible to form a film to the required thickness. .

Additionally, the electron beam could burrow deep into the evaporated material and destroy the crucible.

In the conventional technology, the electron beam generated by the hollow cathode discharge is only used to locally irradiate a narrow area on the surface of the evaporated material, so the above-mentioned problems tend to occur.

In addition, when applying a high frequency voltage as a bias to the substrate to be processed, with conventional technology, the evaporation rate of the evaporated substance is unstable, so the ion density in the atmosphere is not stable, making it difficult to properly match the high frequency impedance. During the process, Gu Cheng had to adjust the matching device.

[Means for solving the problem] By providing an electromagnet that generates a magnetic field capable of deflecting the electron beam generated by the hollow cathode, a relatively wide area of the surface of the evaporated substance is irradiated while scanning the electron beam. Solved the problem of locally irradiating and heating evaporated substances. As a result, regions that have begun to be nitrided or oxidized are also irradiated with the electron beam, heated and evaporated, making it difficult to form a significantly nitrided or oxidized layer.

[Effect]

In the presence of a magnetic field, the electron beam is deflected in its path by the Lorentz force. Therefore, by using an electromagnet to create a magnetic field that changes over time, it is possible to irradiate a wide area of the surface of the evaporated material while scanning the electron beam.

As a result, the electron beam is applied to a region that has begun to be nitrided or oxidized, and the region is heated and evaporated, making it difficult to form a significantly nitrided or oxidized layer.

〔Example〕

Embodiments of the present invention will be described using the drawings.

FIG. 1 is a front sectional view showing an outline of the embodiment.

Fig. 2(a), Fig. 2(b), and Fig. 3(a), Fig. 3(b) are diagrams showing an overview of the crucible and surroundings of the example.
In each figure, (a) is a plan view, and (b) is a front view.

An electromagnet that generates a magnetic field for deflecting the electron beam 1 is composed of a coil 2 and an iron core 3, and is driven by a low frequency oscillator 4 and a low frequency amplifier 5.

! The strength of the magnetic field generated by the magnet is 10 to several tens of Gauss near the hollow cathode 6. When the electron beam 1 is scanned by passing an alternating current through the electromagnet, the scanning amplitude and speed of the electron beam 1 can be changed by changing the magnitude and amplitude of the current.

Since the two t-magnets are arranged perpendicularly to each other as shown in FIG. 2 or 3, the electron beam 1 can be deflected and scanned two-dimensionally in any direction.

Aluminum nitride film,
When trying to form a silicon nitride film, the surface of the tea material 7 did not become significantly nitrided or the electron beam 1711 did not dig a deep hole into the tea material, unlike in the conventional method. Ta. FIG. 4(a) and FIG. 4(b) are cross-sectional views schematically showing the state of the trace material in the crucible in the example. FIG. 5 is a cross-sectional view schematically showing the state of evaporated substances in a crucible according to a conventional technique.

Furthermore, although a high frequency voltage was applied as a bias to the substrate 8 to be processed during the film formation, there was no need to adjust the matching device 9 as thoroughly as in the conventional technique.

FIG. 6 shows the results of Auger N-molecule spectroscopy of the aluminum nitride film formed in the example. FIG. 7 shows the results of Auger electron spectroscopy of an aluminum nitride film formed by the conventional technique. In the example, since the evaporation rate of aluminum is stable, -
Films with various compositions are formed.

Contrary to the above, it is also possible to obtain a compound film whose composition changes in the film thickness direction by temporally changing the discharge current of the hollow cathode discharge and the nitrogen gas flow rate during the treatment.

〔Effect of the invention〕

Because only a portion of the explosive material evaporates and no burrowing occurs, the deposition time is longer than with conventional techniques.

Also, there is no risk of breaking the crucible.

Compared to conventional techniques, the evaporation rate of evaporated substances becomes more stable.

Therefore, the formed film is homogeneous in the film thickness direction. Conversely, by controlling the amount of evaporation, it is also possible to obtain a compound film whose composition changes in the film thickness direction. In addition, when applying a high frequency voltage as a bias to the substrate to be processed,
Since the evaporation rate is stable, it is easy to match the impedance between the power source and the load.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view showing an outline of an embodiment of the present invention. Figures 2(a), 21D(b), and 3(
a) and FIG. 3(b) are diagrams showing the main parts around the crucible in the embodiment of the present invention. (a) is a plan view, (b)
) is a side view. FIG. 4(a) and FIG. 4(b) are cross-sectional views showing the state of the evaporated substance in the crucible in an embodiment of the present invention in different directions. FIG. 5 is a cross-sectional view showing the state of evaporated substances in a crucible according to a conventional technique. FIG. 6 is a characteristic diagram showing the results of Auger electron spectroscopy of the aluminum nitride film formed in the example. FIG. 7 is a characteristic diagram showing the results of Auger electron spectroscopy of an aluminum nitride film formed by a conventional technique. Electron beam coil iron core low frequency oscillator low frequency amplifier hollow cathode evaporation material 8゜9゜10゜11゜12゜13゜14゜15゜16゜17゜1B. 19゜20゜ Processing substrate matching device High frequency power supply Hollow cathode power supply Crucible Vacuum container Gas introduction tube Argon gas introduction tube Processing substrate holder Shutter heater Cooling water passage Nitride layer or more

Claims (1)

[Claims] (1) In a thin film forming apparatus that irradiates an evaporative substance with an electron beam generated by a hollow cathode discharge, heats and evaporates it, and forms a thin film on a substrate to be processed, the electron beam generated by a hollow cathode discharge is deflected and evaporated. A thin film forming apparatus characterized by comprising an electromagnet that generates a magnetic field capable of scanning a material surface and irradiating it with an electron beam.