JPH04160158A - Vacuum apparatus with atomic absorption device - Google Patents

Abstract

PURPOSE: To drastically lessen the adhesion of the evaporated matter to a translucent glass window existing on an optical path connecting a light projector and a light receiver by providing this glass window with a structure consisting of plural pipes on the side of the window to be exposed to vacuum so as to satisfy specific conditions.

CONSTITUTION: The concn. of vapor is detected by the light projector 3 and the light receiver 4 at the time of executing deposition on a substrate 9 by heating an evaporation source 7 in vacuum within a vacuum chamber 10. At this time, the surface on the side to be exposed to the vacuum of the translucent glass window 2 existing on the optical path 5 existing on the light projector 3 and the light receiver 4 is provided with the honeycomb-shaped structure 1 formed by welding the plural pipes. The structure 1 is so formed as to satisfy the relation L/D>l>h when the horizontal distance from the bottom end in the aperture of the pipe of the lowermost part to the evaporation source 7 is defined as l, the perpendicular distance as (h), the max. length in the perpendicular direction in the apertures of the pipes as D and the length of the pipes as L. In addition, the structure is so formed that the ratio of the sectional area shielding the optical path 5 attains ≤75%. As a result, the adhesion of the evaporated matter on the glass window 2 is drastically lessened and the vacuum vapor deposition apparatus having the excellent accuracy and reliability is obtd.

COPYRIGHT: (C)1992,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vacuum apparatus equipped with an atomic absorption spectrometer for thin film production or elemental analysis in vacuum.

[Conventional technology]

Sensor technology vow, 10. No. 8 (July 1990
As shown in the previous issue, vacuum equipment equipped with a film deposition controller that detects the vapor concentration of elements during vacuum deposition using atomic absorption spectrometry has been announced. This vacuum apparatus can control the evaporation rate by using an attached atomic absorption device, and by using a plurality of light absorption devices, it is possible to control the composition of multiple elements in simultaneous vapor deposition and alternate vapor deposition.

FIG. 5 shows the configuration of a conventional vacuum evaporation apparatus equipped with an atomic absorption device. In the figure, 2 is a transparent glass window, 3 is a projector, 4 is a light receiver, 7 is an evaporation source, 8 is an electron beam gun, 9 is a substrate to be evaporated, 10 is a vacuum chamber,
15 is an anti-stick cylinder, 16 is an electron beam power source, 17 is a computer, 18 is a system controller, and 19 is a detector.

In this apparatus, the deposition rate is controlled by an atomic absorption device consisting of a light emitter 3 and a light receiver 4 in a vacuum chamber l.

This can be controlled by measuring the amount of vapor of the element being evaporated from the evaporation source within the evaporation source and controlling the power of the electron beam power source 16 or the like for heating the evaporation source.

In this atomic absorption device, if evaporated matter adheres to the transparent glass window 2 on the optical axis, the amount of light decreases and an erroneous signal is obtained.
was attached to the transparent glass window 2.

[Problem to be solved by the invention]

However, the anti-adhesive cylinder 15 that has been used in the past has little effect in preventing the adhesion of evaporated matter, so if it is used continuously, it may cause the vacuum of the transparent glass window 2 on the optical path connecting the emitter 3 and the receiver 4. Evaporated matter adheres to the exposed surface. Therefore, the amount of light from the projector 3 changes over time, which tends to cause errors in measurement.

Therefore, in the conventional technology, it is necessary to shorten the deposition time or perform calibration during measurement, and there is a problem that the atomic absorption spectrometer cannot be used continuously for a long time.

In addition, in the conventional anti-adhesive cylinder 15 consisting of a single pipe, if the diameter of the pipe is made small in order to increase the effect of preventing adhesion of evaporated matter, the detection sensitivity will decrease due to a decrease in the amount of light, and alignment of the optical axis will become difficult. There was a problem.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to significantly reduce the adhesion of vapor deposits to a light-transmitting glass window without reducing detection sensitivity or making it difficult to align optical axes.

[Means to solve the problem]

To achieve this purpose, Mokubo's vacuum equipment with atomic absorption device is an atomic absorption device equipped with an emitter and a light receiver to detect the vapor concentration of the elements that make up the substance heated and evaporated in vacuum. In a vacuum apparatus having a plurality of pipes, the opening of the lowest pipe is located on or near the surface of the transparent glass window on the side exposed to vacuum on the optical path connecting the emitter and the receiver. When the horizontal distance to the lower end is 1 and the vertical distance is h, the ratio of the maximum vertical length D of the opening of the pipe to the length L of the pipe (L/
D) is equipped with a structure that satisfies the relationship of L/D>l/h (1) and has a cross-sectional area ratio of 75% or less that blocks the optical path. Features.

[Effect]

It is known that the vapor of an evaporated substance heated and evaporated in a vacuum moves in a spherical and widespread manner around the evaporation source unless it collides with residual gas.

Therefore, as shown in Figure 4, for a pipe whose maximum vertical opening length is D and length L, the horizontal distance from the evaporation source to the lower end of the pipe opening is β, and the vertical distance is h. Sometimes, the light-transmitting glass window 2 is
If the pipe is attached to the side exposed to vacuum (1), the evaporated matter flying directly from the evaporation source 7 will be blocked by the wall of the pipe and will not reach the glass window.

In addition, since general vacuum evaporation is performed at a pressure of 10-4 to 1O-6 Torr, residual gas cannot be ignored, and some evaporated atoms and molecules collide with the residual gas and move in various directions. There is. Therefore, it is necessary to prevent even one molecule of these atoms from adhering to the transparent glass window 2.

In the present invention, by providing a plurality of pipes, it is possible to increase the frequency of collisions between the pipe wall surface and one molecule of these atoms, and it is possible to prevent evaporated substances from adhering to the transparent glass.

Note that some vacuum devices have the evaporation source 7 placed above, but this corresponds to the case where Fig. 4 is turned upside down.
In this case, the vertical opening length is also reduced, and by attaching a structure consisting of two or more pipes of length L to the vacuum side of the light-transmitting glass window so as to satisfy the relationship of equation (1), the evaporated material can be removed. Prevents adhesion to glass windows.

In the present invention, when a structure consisting of a plurality of pipes is installed, the cross-sectional area of the structure is adjusted so as not to block more than 75% of the light intensity from the projector, so the detection sensitivity decreases due to the decrease in light intensity. does not occur. Furthermore, since the diameter of the entire optical path does not change even after the structure is attached, adjustment of the optical axis is easy.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. In the figure, components having the same functions as those of the conventional example shown in FIG. 5 are designated by the same reference numerals, and the explanation thereof will be omitted.

In the figure, l is a vacuum pump.

In FIG. 1, a honeycomb-like structure 1 made of a plurality of rectangular pipes welded is provided on an optical path 5 connecting a light emitter 3 and a light receiver 4. One pipe has dimensions such that the maximum vertical opening length D is 4 mm and the length is 5 Q mm, and 40 pipes are welded together. The value of L/D was set to eight times β/h, and the cross-sectional area of the structure was such that 10% of the optical path was blocked.

Copper was used as a deposition source and was evaporated by irradiating an electron beam from an electron beam gun. At this time, the amount of light input from the projector 3 changed depending on the concentration of the evaporated copper vapor. Similar to the conventional device, this change in the amount of light was transformed into a change in electrical signals by the light receiver 4 and the detector, and was input manually to the computer through a system controller having an interface function with the computer. The computer converted the input signal into a deposition rate, compared it with the set value of the deposition rate, determined the amount of increase or decrease in the electron beam power, and controlled the power of the electron beam power source through the system controller. This enabled vapor deposition at a constant evaporation rate (2 persons/5 ec).

In this embodiment, by installing the honeycomb structure 1, the second
Optical path 5 of atomic absorption with evaporated molecules whose course is bent by collision with residual gas, such as the evaporated atoms 20 shown in the figure.
(See FIG. 1) Even atoms that were not parallel to the surface no longer adhered to the light-transmitting glass window 2. In addition, in Figure 2, 12
is a screw for fixing the transparent glass window 2 to the holder 14;
13 is an O-ring for maintaining airtightness.

FIG. 3 shows the results of a comparison of the time dependence of the output signal in the atomic absorption apparatus of the conventional apparatus and the apparatus of the present invention when copper is evaporated at an evaporation rate of 2 persons/sec. In the conventional device, the atomic absorption signal decreased by about 10% in about 10 minutes, but in the device of the present invention, the decrease was less than 1%. After a further 30 minutes, a decrease of 30% or more was observed in the conventional device, but the decrease was as small as 2% or less in the device of the present invention.

Therefore, the vacuum device equipped with an atomic absorption device of the present invention can be used continuously and with little error for vapor deposition of not only copper but also other types of metal materials and ceramic materials, and almost no calibration is required during measurement. .

In this example, a vacuum device equipped with an atomic absorption device was used for thin film production, but an unknown material was heated and vaporized in vacuum.
It is clear that the vacuum apparatus of the present invention is also effective when chemically analyzing this using an atomic absorption spectrometer.

Further, although only a rectangular pipe is used in this embodiment, the shape of the pipe is not limited to this, and a plurality of circular, triangular, hexagonal, etc. pipes may be used.

It is clear that the same effect as in this embodiment can be obtained also when a bundled structure is attached to a light-transmitting glass window.

〔Effect of the invention〕

As described above, according to the present invention, the adhesion of evaporated matter to the glass window on the optical path of the atomic absorption device is significantly reduced. Therefore, almost no measurement error occurs due to a decrease in the amount of incident light from the projector of the atomic absorption device, and there is no need to calibrate during measurement or shorten the deposition time. For this reason, the present invention is applied to equipment that uses signals from an atomic absorption device to control the film deposition rate using a computer, or that uses multiple emitters and receivers to deposit thin films made of multiple components while controlling the composition. By doing so, a vacuum evaporation apparatus with excellent accuracy and reliability can be manufactured.

Further, by applying the present invention to an apparatus that analyzes the components of an unknown material by heating and evaporating it in a vacuum, it is possible to obtain an apparatus with excellent accuracy and reproducibility.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the configuration of an embodiment of a vacuum apparatus with an atomic absorption device according to the present invention, FIG. 2 is an enlarged view of the main parts of the present invention, and FIG.
Figure 4 is a graph showing the effects of the present invention in comparison with a conventional device, Figure 4 is an explanatory diagram showing the behavior of evaporated atoms and residual gas molecules in the present invention, and Figure 5 is a graph showing the effects of the conventional vacuum apparatus equipped with an atomic absorption device. FIG. 2 is a schematic diagram showing the configuration. 1: Honeycomb structure 2: Transparent glass window 3: Floodlight
4: Photoreceiver 5: Optical path 6: Evaporated material 7: Evaporation source 8: Electron beam gun 9: Substrate
10: Vacuum chamber l: Vacuum pump
12: Screw] 3: O-ring 14: Holder 20: Evaporation atom patent applicant Yaskawa Electric Co., Ltd. (and one other person) representative
Masato Kobori Figure 5 Figure 1 Figure IIB Figure 4 hours 1 intervention Figure 2 Figure 4. Soft

Claims (1)

[Claims] 1. In a vacuum apparatus having an atomic absorption device equipped with a light emitter and a light receiver for detecting the vapor concentration of an element constituting a substance heated and evaporated in vacuum, a light-transmitting device on an optical path connecting the light emitter and the light receiver. It consists of a plurality of pipes on the surface or near the surface of the glass window exposed to vacuum, where the horizontal distance from the evaporation source to the lower end of the opening of the lowest pipe is l, and the vertical distance is h. The ratio (L/D) of the vertical maximum length D of the opening of the pipe to the length L of the pipe satisfies the relationship L/D>l/h, and the ratio of the cross-sectional area that blocks the optical path is 75 % or less of a structure.