JPH03103393A - Vacuum film-forming device - Google Patents

Abstract

PURPOSE:To control element composition of film during film forming by irradiating the surface of substrate with electron rays from an electron gun at an acute angle, analyzing detected signal of emitted X ray by a control means and operating a shutter and a molecular beam evaporating source. CONSTITUTION:In a vacuum tank 11 made in an ultrahigh vacuum, molecular weight beam from a molecular beam evaporating source 15 is stuck to the surface of a substrate 12 to form a film. During growth of the film, when the surface of the substrate 12 is irradiated with electron rays from an electron gun 17, the electron beam is diffracted in the growing film on the surface of the substrate 12, bound electrons of atoms in the film are excited and X-rays are irradiated during relaxing. In the operation, when a slit 19 is transferred to a total reflection angle of X-rays and fixed, X-rays only from the surface adsorption layer of the growing film is passed through the slit 19 and detected by an X-ray detector 20. The detected signal is sent to a computer 21, element composition of the surface adsorption layer is analyzed and a signal to open and close a shutter 16 and a signal to control temperature of the evaporation source 15 are sent out.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a vacuum film forming apparatus capable of controlling the elemental composition of a film being formed.

(Prior Art) In a conventional vacuum membrane apparatus, for example, a molecular beam epitaxial apparatus as shown in FIG. 2, a substrate 3 is disposed above a molecular beam evaporation source 2 in a vacuum chamber l. . An electron gun 4 for reflection high-speed electron diffraction is attached to the left wall of the vacuum chamber 1, and an electron beam emitted from this electron gun 4 for reflection high-speed electron diffraction travels toward the substrate 3. A fluorescent screen 5 is attached to the right wall of the vacuum chamber 1, and a diffraction pattern etc. that can be observed by diffraction of electron beams on the surface of the substrate 3 is projected onto the fluorescent screen 5. A molecular beam flux monitor 6 is attached to the upper wall of the vacuum chamber 1, and each molecular beam intensity is measured by this molecular beam flux monitor 6. An energy analyzer of an electronic spectrometer 7 is mounted on the left wall of the vacuum chamber 1 so as to be located close to the substrate 3.

In the figure, 8 is a mass spectrometer, and 9 is a load lock chamber.

In such a molecular beam epitaxial apparatus, the molecular beams evaporated from the molecular beam evaporation source 2 adhere to the surface of the substrate 3, and a grown film is formed thereon, but the intensity of each molecular beam at this time is Measured by Molecular Beam East Monitor 6.

During and after film formation, when the substrate 3 is irradiated with an electron beam emitted from the reflection high-speed electron diffraction electron gun 4, the electron beam is reflected and diffracted on the surface of the substrate 3, and a diffraction pattern appears on the fluorescent screen 5. Becomes projected. Therefore, from the diffraction pattern projected on the fluorescent screen 5 and its intensity, information regarding the atomic arrangement on the film surface or near the film surface of the long film can be obtained during and after film formation.

On the other hand, if the substrate 3 is irradiated with an electron beam emitted from the reflection high-speed electron diffraction electron gun 4 only after film formation, the Auger electrons emitted from the atoms excited by this irradiation will be energized by the Auger electron spectrometer 7. It starts to break apart. Therefore, it becomes possible to measure the composition of the grown film formed on the surface of the substrate 3 after the deposition.

However, the elemental composition of the growing film during film formation in the above apparatus is controlled based on the partial pressure or total pressure of the molecular beam measured in advance by the molecular beam east monitor 6 before film formation.
This is done by determining the intensity of the molecular beam for each element that evaporates more.

(Problems to be Solved by the Invention) Conventional vacuum film deposition equipment controls the elemental composition of the growing film during film formation by the intensity of the molecular beam for each element determined before film formation as described above. Therefore, during film formation, the molecular beam evaporation source 2
When the intensity of the molecular beam that evaporates more fluctuates by increasing or decreasing, a problem arises in that the elemental composition cannot be controlled in response to this fluctuation. Furthermore, when determining the molecular beam intensity for each element to be evaporated before film formation, a molecular beam monitor 6 is used.
The partial pressure or total pressure of the molecular beam measured in
Since the amount of elements attached to the element does not necessarily correspond in a 1:1 ratio depending on the probability of attachment, a problem arises in which it is not desirable to use the molecular beam east monitor 6 to control the elemental composition.

In order to solve this problem, we will examine whether it is possible to solve this problem using the conventional equipment as it is.

First, in the case of the fluorescent screen 5, only information about the atomic arrangement of the grown film can be obtained, but no information about the elemental composition of the film can be obtained, so it cannot be used to control the elemental composition of the film.

Next, in the case of an Auger electron spectrometer, it is possible to measure the elemental composition of a film after deposition, so if you try to use it during film formation to measure the elemental composition of the film, Since it is disposed near the substrate 3, contamination due to adhesion of molecular beams evaporated from the molecular beam evaporation source 2 occurs, making it more likely to malfunction.

In addition, if you try to use it during film formation, the energy analyzer of the Auger electron spectrometer 7 will be connected to the molecular beam evaporation source 2 and the substrate 3.
As a result, the energy analyzer blocks the molecular beam, making it impossible to form a film.

Therefore, the Auger electron spectrometer 7 cannot be used during film formation, and therefore cannot be used to control the elemental composition of the film.

For this reason, the problem cannot be solved using conventional equipment.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a vacuum film apparatus that solves the conventional problems and makes it possible to control the elemental composition of a film by obtaining information about the elemental composition of the film during film formation. be.

(Means for Solving the Problems) In order to achieve the above object, the vacuum film forming apparatus of the present invention has a substrate held on a substrate holding stand in a vacuum chamber, and a molecular beam that can be ejected in the direction of this substrate. At least one molecular beam evaporation source and the molecular beam emitted from this molecular beam evaporation source,
This occurs when the electron beam from this electron gun is irradiated onto the growing film on the substrate surface. It is equipped with an X-ray detector that detects X-rays, and a control means that outputs an output signal that opens and closes a shutter or adjusts the temperature of a molecular beam evaporation source based on an input signal from the X-ray detector. It is characterized by this.

(Function) In this invention, the molecular beam ejected from the molecular beam evaporation source attaches to the surface of the substrate and forms a film there. When irradiated at an acute angle with respect to the surface of the substrate, the electron beam is diffracted by the growing film on the surface of the substrate, and bound electrons of atoms in the film are excited, and upon relaxation, X-rays are emitted. and,
Only the X-rays from the growing surface adsorption layer are detected by the X-ray detector located at its total internal reflection angle. The signal detected by the X-ray detector is sent to a control means to analyze the elemental composition of the surface adsorption layer, and also sends a signal to open and close the shutter and a signal to adjust the temperature of the molecular beam evaporation source. will be sent out. The elemental composition of the film can then be controlled by opening and closing a shutter or adjusting the temperature of the molecular beam evaporation source based on these sent out signals.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which a substrate 12 is held in a vacuum chamber 11 by a substrate holder 13. As shown in FIG. The substrate holding table l3 is a manibulator 14
In addition to being able to move in three-dimensional directions, it is also possible to rotate around a rotation axis, and furthermore, the inclination angle with respect to the incident direction of the electron beam can be adjusted. There are four molecular beam evaporation sources on the wall of vacuum chamber 11! 5 is attached, molecular beams are emitted from the molecular beam evaporation source 15 in the direction of the substrate 12, and are attached to the surface of the substrate 12 to grow a film. However, a shutter 16 for blocking the molecular beam is provided in the middle of the molecular beam adhering to the substrate 12. An electron gun (7) is attached to the wall of the vacuum chamber (11) so that the electron beam emitted from the electron gun (17) is irradiated onto the surface of the substrate (12) at an acute angle. A fluorescent screen l8 is also attached to the wall of the vacuum chamber l1 so that the diffraction pattern generated when the electron beam from the electron gun 17 is diffracted by the film on the surface of the substrate 12 is projected thereon. Become. Furthermore, near the wall of the vacuum chamber 11, there is a movable slit l that allows X-rays to pass through.
9 is provided. Furthermore, an X-ray detector 2oIJ< is disposed behind the slit 19. Therefore, X-rays generated when the surface of the substrate 12 is irradiated with an electron beam from the electron gun l7 pass through the movable slit 19 and are detected by the X-ray detector 20. The X-ray signal detected by the xi detector 20 is sent to the computer 21, which is a control means, where the elemental composition in the surface adsorption layer is analyzed, and the signal to open and close the shutter 16 and the molecular beam evaporation source are sent. A signal is now sent out to adjust the temperature of 15. Based on these signals, the shutter l6 is opened and closed, or the temperature of the molecular beam evaporation source 15 is adjusted, thereby controlling the elemental composition of the film.

In the figure, 22 is a liquid nitrogen shroud, 23 is an airlock chamber for substrate exchange, 24 is a gate valve that partitions the vacuum chamber 1 and the air opening vine chamber 23 for substrate exchange, and 25 is an airlock chamber 23 for substrate exchange. This is a rod for inserting the replaced substrate 12 into the vacuum chamber 1l. A molecular beam flux monitor is attached to the tip of the manipulator 14, and it is also possible to measure the molecular beam pressure by directing it toward the molecular beam evaporation source 15 through rotation of the manipulator 14. Similarly, although not shown, the substrate 12 can be stably heated at a temperature of about 800° C. or lower using a heater.

Next, the effect will be explained.

In the above embodiment, the molecular beams emitted from the molecular beam evaporation source 15 adhere to the surface of the substrate 12 in the vacuum chamber 11 evacuated to an ultra-high vacuum of 10-'' Torr or less, forming a film thereon. However, when the surface of the substrate 12 is irradiated with an electron beam from the electron gun 17 during film growth, the electron beam is diffracted by the growing film on the surface of the substrate 12, and the diffraction pattern appears on the fluorescent screen. At the same time, the bound electrons of atoms in the film are excited and emit X-rays during relaxation.At this time, the slit 19 is moved to the angle of total reflection of the X-rays and fixed there. Then, only the X-rays from the surface adsorption layer of the growing film pass through the slit l9 and reach the X-ray detector 2.
Detected at 0. The signal detected by the X-ray detector 20 is sent to the computer 21, where the elemental composition of the surface adsorption layer is analyzed, and the signal to open and close the shutter 16 and the temperature of the molecular beam evaporation source 15 are adjusted. A signal will now be sent out. Based on these signals, the shutter l6 is opened and closed or the temperature of the molecular beam evaporation source l5 is adjusted, thereby controlling the element composition of the film. Note that the slit l9 serves to shield the molecular beam from scattering toward the X-ray detector 20.

Next, the term "total reflection angle of X-rays" will be explained.

When an electron beam is irradiated at an acute angle to the sample surface, atoms on the sample surface are excited and emit X-rays during relaxation, but at this time, the angle θ between the emitted X-rays and the sample surface is changed. And at a certain angle θC, X1la from the surface adsorption layer
Detection sensitivity increases dramatically. This angle θC is called the total reflection angle of X-rays, and its value depends on the adsorbed species.

By the way, although the above embodiment uses four molecular beam evaporation sources 15, the number may be any number as long as it is one or more. Further, in the above embodiment, only the slit is moved to the position of the total reflection angle of the X-rays emitted from the adsorption layer, but both the slit and the X-ray detector may be moved.

Furthermore, although a computer is used as the control means in the above embodiment, a control means such as a sequencer may be used instead.

(Effect of the invention) This invention detects the X-rays generated when the electron beam from the electron gun irradiates the surface of the substrate at an acute angle with an X-ray detector, and analyzes the detected signal with a control means. Then, the control means sends a signal to open and close the shutter and a signal to adjust the temperature of the molecular beam evaporation source, and based on these signals, the shutter is opened and closed or the temperature of the molecular beam evaporation source is adjusted. This makes it possible to control the elemental composition of the film at the level of a single atomic layer based on information regarding the elemental composition of the surface adsorption layer during film growth.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing a conventional device. In the figure, 11...Vacuum chamber l2...Substrate l3...Substrate holding stand 15...Molecular beam evaporation source l6●...Shutter l7... Electron gun l9...Slit 20...Xva detector 21...Computer

Claims (1)

[Claims] 1. A substrate held on a substrate holding table in a vacuum chamber, at least one molecular beam evaporation source that can emit molecular beams in the direction of the substrate, and the molecular beams emitted from this molecular beam evaporation source attached to the substrate. There is a shutter that shields the surface of the substrate during the process, an electron gun that irradiates the electron beam at an acute angle to the surface of the substrate, and an X-ray that is generated when the electron beam from this electron gun is irradiated onto the growing film on the surface of the substrate. It is characterized by comprising an X-ray detector for detecting X-rays, and a control means for outputting an output signal for opening and closing a shutter and an output signal for adjusting the temperature of a molecular beam evaporation source based on an input signal from the X-ray detector. Vacuum film forming equipment.