JPS62279862A - Apparatus for forming membrane - Google Patents

Abstract

PURPOSE:To uniformize a film thickness by freely controlling the collision quality of air to the surface of a substrate while dispensing with the rotational driving of a substrate holding member, by making the jet direction of air from an air jet device movable. CONSTITUTION:For example, in a molecular beam epitaxial growth monocrystal membrane forming apparatus, the center axis of a molecular beam cell takes the motion shown by two-dotted chain lines 201, 202 around a ball 24 while keeping a constant angle theta around a shaft 200 and an air jet direction is moved along a conical surface of a vertical angle 2theta. Therefore, if the molecular beam cell main body 10 is allowed to position at the central part of the bottom wall 21 of a vacuum container directing to the front surface of a substrate, the control of a film thickness can be performed ideally without rotating a substrate holding member.

Description

[Detailed description of the invention] 3. Detailed description of the invention (industrial application field) This invention relates to an improvement in a thin film forming apparatus that forms a thin film on a substrate surface using the gas as a raw material.

(Prior Art) In a conventional thin film forming apparatus, as shown in FIG. It has a structure that is fixed to the side of the container or the bottom of the vacuum container. 4 is an exhaust hole.

(Problem to be Solved by the Invention) In the conventional apparatus having the above configuration, in order to form a thin film with a uniform thickness on the surface of the substrate 2 with the gas injected into the vacuum container 1, it is necessary to It was necessary to rotate around a predetermined axis, for example, 2a. This rotation rotationally drives the substrate holding member 7 containing a heating mechanism (not shown), which has the disadvantage of inevitably making the apparatus bulky.

This disadvantage becomes even more pronounced in the following devices. That is, in a normal thin film forming apparatus, the air molecules injected from the gas injection device must be vacuumed many times before being exhausted from the exhaust hole or captured by the gas trapping mechanism. It repeatedly collides with the walls of the container, increasing the amount of time it spends floating inside the vacuum container. The drifting time is strongly influenced by the internal pressure of the vacuum chamber, the structure of the vacuum chamber, especially the arrangement and structure of the substrate section (substrate and substrate holding member), and the configuration and position of the exhaust hole opening or gas trapping mechanism. . The long time the gas floats around causes the following problems. That is, the organometallic gas HIJ is trimethyl gallium (hereinafter referred to as TMG).
),) Monocrystalline thin film A1 using remethylaluminum (hereinafter referred to as TMA) and arsine (AH3)
/GaAs heterostructure, in this heterostructure, as is well known, A l x Ga 1-X
The X value of the composition ratio of AS and GaAs and the steepness of the change in the structure of the interface are particularly important.
G and arsine are ejected to first make GaAsji',
Next, TMA is injected as a gas to form AlGaA with a desired X value.
When attempting to deposit the s layer, first a constant flow rate T
MA is injected to the interface °C 11th A', Ga
Even if the As composition ratio can be set to the desired X value, the X value of the AlGaAs composition ratio in subsequent layers inevitably tends to a larger value, which is an unpleasant phenomenon.

This is because the TMA repeatedly collides with the walls of the vacuum chamber as described above and floats in the vacuum chamber for a long time, and it takes a long time for the partial pressure to settle to a predetermined steady partial pressure value by evacuation, during which time the TMA repeatedly collides with the substrate surface. Therefore, the composition ratio X inevitably shifts.

A similar problem occurs when the supply of TMA is stopped, and the X value of the composition ratio changes slowly at the corresponding interface after the time of stopping, and the sharpness of the change in the structure of the interface is lost.

These phenomena also exist when forming thin films other than those mentioned above, and are used in types of semiconductor devices (high mobility electronic devices, semiconductor (lasers, etc.), this is a major reason why they are unable to achieve the desired performance, resulting in serious problems.

In order to solve this problem, as shown in FIG.
The direction 5 of the gas injection of the gas injection devices 3e, 3f, 3g
By arranging the substrate so that the direction 5a in which the gas reflects on the substrate surface and moves toward the opening of the exhaust hole (or the gas trapping mechanism) 4, drift is eliminated, and the substrate is A single crystal single film forming apparatus in which the substrate holding member 7 is configured in the shape of a polygonal pyramid has been considered so that a large number (21 to 26) of substrates can be loaded and processed at once.
In the case of this device, when attempting to rotate each substrate and rotate the substrate holding member 7 around the polygonal pyramid axis 40,
The rotational drive mechanism becomes even more extensive.

(Objective of the Invention) An object of the present invention is to provide a thin film forming apparatus that solves the above problems and can eliminate or greatly simplify rotational driving of a substrate holding member.

(Means for Solving the Problems) The present invention 2 is 11 Vacuum, introducing a gas into a container, or generating a gas in a vacuum container, and using the gas as a raw material in the vacuum container to produce a substrate. In a thin film forming device that forms a thin film on a surface, the thin film forming device is configured such that the direction of gas jetting is movable, or simply, the angle between the gas jetting direction and a predetermined axis is kept constant. The above object has been achieved by a thin film forming apparatus configured to rotate the direction of the jet around the predetermined axis.

(Function) In the present invention, since the direction of the gas jet from the gas jet device is movable, the film thickness can be ideally controlled by making the gas collide with the substrate surface according to a predetermined program. I can do it. In addition, when devising the structure of a thin film forming apparatus, it is necessary to keep the angle between the direction of gas injection and a predetermined axis constant, and to rotate the direction around the predetermined axis.
By adopting this advanced configuration, it is possible to achieve the same effect as rotating the substrate holding member.

(Example) FIG. 1 shows a cross-sectional view of a gas injection device (molecular beam cell) used in an apparatus for forming a single crystal thin film grown by molecular beam epitaxy according to an example of the present invention. This type generates gas in a vacuum container and injects it. Reference numeral 10 is a molecular beam cell body made of, for example, PBN, which accommodates a melted source material 12.

13 is the liquid level. In the molecular beam cell main body 10, a guide ring 18 is fixed in reflectors 15 and 16 with paper, and a spiral heater wire 14 introduced via a lead wire 29 and an insulated tube 17 surrounds the guide ring 18. surrounding. The lower part of the reflector IS is fixed to a cell fixing plate 23, and the cell fixing plate 23 is attached to the bottom wall 2 of the vacuum container 1.
1 with a bellows 22. The cell fixing plate 2
3 is also attached with a ball 24 and an operating rod 25, and a bearing 27 that engages with the ball 24 is fixed to the vacuum container. . The operating rod 25 is inserted into the hole 260 of the operating disk 26 that rotates around the shaft 200.
ing.

Due to the above configuration, the central axis of this molecular beam cell maintains a constant angle θ around the axis 200 using the ball 24 as a fulcrum.
201 and 202, the direction of the gas jet is moved along a conical surface with an apex angle of 2θ. This molecular beam cell is placed at the center 3 on the front side of the substrate 2 in FIG.
It is clear that the rotation of the substrate holding member 7 can be omitted in the apparatus shown in FIG. 4 if the substrate holding member 7 is placed at the position C (indicated by a dashed line).

Even when the molecular beam cell is placed at a position 3d away from the center, the practical purpose can be achieved by appropriately tilting the direction of the rotation axis 200 such as 200d.

What is shown in FIG. 2 is a diagram of the gas injection device section of the embodiment of the thin film forming apparatus of the present invention, in which gas is introduced from outside the vacuum container and is injected. An injection pipe 36 is connected to the pipe base 32 via a bellows 33.
is connected, and two balls 34 and 44 are fixed to the injection pipe 36.

Each ball 34 and 44 engages a bearing 37 fixed to the operating rod 35 and a bearing 47 fixed to the side wall 31, respectively. With this configuration, by operating the operating rod 35 (the operating drive device is not shown), the injection pipe 36 is
The direction 301 of the gas jet is set to the axis 300 of the introduction pipe base 32.
It becomes possible to orient the ball 44 in a desired direction using the ball 44 as a fulcrum. If this gas injection device is placed in the positions 3g, 3e, and 3f of the thin film forming apparatus shown in FIG. 3, it is unnecessary to rotate the substrate holding member 70, as described above, and no explanation is required.

(Effects of the Invention) According to the present invention, the amount of gas colliding with the substrate surface can be freely controlled, and the thickness of the thin film, uniformity of the film quality, etc. can be controlled.
The same effect as rotating the substrate holding member can be obtained.

[Brief explanation of the drawing]

1 and 2 are schematic sectional views of the gas injection device section of the embodiment of the thin film forming apparatus of the present invention. Figures 3 and 4' show a single crystal single crystal thin film forming apparatus of the present invention.
1 is a schematic illustration of an example implementation. 1... Vacuum container, 2... Substrate, 3
8~3g... Gas injection device, 4...
Exhaust hole, 5, 5a...Advancing direction of the injected gas, 7...Substrate holder, 10...Molecular beam cell body, 24.34', 4
4... Ball, 25.35... Operating rod, 22.33... Bellows, 36...
...Injection pipe.

Claims (4)

[Claims] (1) Introducing a gas into a vacuum container or generating a gas in a vacuum container, and using the gas as a raw material in the vacuum container,
A thin film forming apparatus for forming a thin film on a substrate surface, characterized in that the direction of jetting the gas is configured to be movable. (2) Claim 1 characterized in that the angle between the direction of gas injection and the predetermined axis is kept constant, and the direction of the injection is rotated around the predetermined axis. The thin film forming apparatus described above. (3) The thin film forming apparatus according to claim 1 or 2, wherein the gas injection device introduces gas from outside the thin film forming apparatus. (4) Claim 1 or 2, wherein the gas injection device generates and injects gas within the thin film forming device.
Thin film forming apparatus as described in .