JPS6150326A - Semiconductor crystal growing device - Google Patents

Abstract

PURPOSE:To enable to grow a crystal layer, having uniform film thickness, on the whole surface of a substrate in a short period of time by a method wherein the molecular beam, evaporated from a vertical molecular beam element reservoir part, is radiated by the help of the action of a molecular beam reflection accelerating plate, a radiant aperture part and the like. CONSTITUTION:The molecular beam source element reservoir part 1 and the molecular beam source element 2 evaporating from the above-mentioned reservoir part 1 are reflection-accelerated in the direction of the substrate to be crystal-grown. The molecular beam reflection accelerating plate 4, which can be moved in the arbitrary direction for a normal, and a radiant aperture part 6 with which the direction of the above-mentioned molecular beam is controlled are provided. The temperature of the molecular beam reflection accelerating plate 4 is maintained higher than that of the molecular beam source element reservoir part 1, and the molecular beam source element is set in such a manner that its incidence angle and radiation angle are equalized. The film thickness of the crystal layer can be made uniform by moving periodically or irregularly the molecular beam reflection accelerating plate 4 in vertical and horizontal directions or in a circular manner by the help of the action of a driving part 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to molecular beam epitaxial growth (molecular beam epitaxial growth).
The present invention relates to a semiconductor crystal growth apparatus suitable for performing an ar beam epitaxy (MBE) method.

[Conventional technology]

Generally, in order to obtain a good crystal layer by applying the MBE method, it is necessary to stabilize the molecular beam.

By the way, in order to stabilize the molecular beam, the radiation area, radiation position, and radiation direction of the molecular beam must always be constant and uniform.

FIG. 2 is an explanatory diagram of the main parts of a conventional example of a semiconductor crystal growth apparatus that implements the MBE method.

In the figure, 1 indicates a molecular beam source element reservoir portion made of boron nitride (BN), 2 indicates a molecular beam source element, 3 indicates a heater, and 7 indicates a crystal growth substrate.

The element reservoir portion 1 in the illustrated semiconductor crystal growth apparatus is
It varies depending on the target element, but about 400['C]
It is heated by a heater 3 to a temperature selected within a range of about 1,500 ('C) to about 1,500 ('C), and the resulting molecules fly out and deposit on the substrate 7.

[Problem that the invention seeks to solve]

In the semiconductor crystal growth apparatus shown in FIG. 2, the element reservoir section 1 having a trumpet-shaped nozzle is arranged obliquely, so the surface of the molecular beam source element 2 is obliquely aligned with respect to the axis of the element reservoir section 1. It has become.

Therefore, the absolute majority direction of the molecular source is not necessarily parallel to the direction toward the substrate 7, and as a result, the molecular beam intensity has a distribution within the plane of the substrate 7, and the growth occurs in a random manner. In this case, the thickness of the crystal layer has a Gaussian distribution as shown by the broken line in the figure.

Furthermore, as the number of growth increases, the molecular beam source element 2 is consumed, so not only its position, that is, the height, but also the distance between the substrates 7 changes, and furthermore, the surface area changes. As a result, the direction and intensity of the molecular beam change accordingly, further promoting non-uniformity in the thickness of the grown crystal layer.

As described above, the molecular beam emitted by the conventional semiconductor crystal growth apparatus is not stable.

It is possible to form a crystal layer with a uniform thickness by relaxing the non-uniformity of the thickness of the growing crystal layer for a sufficiently long time and allowing the crystal to grow where the molecular beam radiation spreads. However, this increases the crystal growth time, which is not preferable from a practical point of view.

Furthermore, for the same purpose, attempts have been made to emit molecular beams evenly over the entire surface of the substrate by rotating or revolving the substrate 7 during crystal growth, but this mechanism is quite complex. If such a mechanism could be made unnecessary, the configuration of this type of device would be extremely simplified and the cost would be reduced.

Furthermore, as described above, since the element reservoir portion 1 is arranged diagonally, the amount of the element 2 that can be accommodated in the curve of the outer shape is small and must be replenished frequently.

The present invention can grow a crystal layer with a uniform thickness over the entire surface of the substrate in a sufficiently short time from a practical point of view, can accommodate a large amount of elements, and has a simple mechanism. A semiconductor crystal growth apparatus is provided.

[Means for solving problems]

The semiconductor crystal growth apparatus according to the present invention includes a cylindrical molecular beam source element reservoir section that is arranged upright, and a molecular beam source element that evaporates from the molecular beam source element reservoir section in the direction of the crystal growth substrate. The method comprises a molecular beam reflection accelerator plate that performs reflection acceleration and is movable in any direction with respect to the normal line, and a radiation aperture portion that regulates the direction of the molecular beam from the molecular beam reflection acceleration plate, The temperature of the molecular beam reflection accelerator plate is maintained higher than that of the molecular beam source element storage portion, and its position is set so that the incident angle and emission angle of the molecular beam source element with respect to the normal line are equal. It is something.

[Effect]

When the above method is adopted, the radiation position and intensity of the molecular beam made of the molecular beam source element evaporated from the molecular beam source element reservoir part arranged upright is always stable, and the stability depends on the number of times the crystal grows. Therefore, the thickness of the crystal layer grown on the crystal growth substrate is extremely uniform, and the reproducibility in each growth is also good. In addition, since the molecular beam source element storage portion is arranged upright, the storage capacity of the molecular beam source element is much larger than that of the conventional one.

Furthermore, since the crystal growth substrate is fixed and the molecular beam reflection accelerator plate is movable, the mechanism is extremely simple.

〔Example〕

FIG. 1 is a cutaway side view of essential parts of one embodiment of the present invention, and FIG.
The same parts as those described with respect to the figures are indicated by the same symbols.

In the figure, 4 is a molecular beam reflection accelerator plate made of boron nitride;
5 is the driving part of the molecular beam reflection accelerator plate 4, 6 is the radiation aperture part, θ1 is the molecular beam incidence angle with respect to the normal line of the molecular beam reflection accelerator plate 4, and θ2 is the molecular beam radiation with respect to the normal line of the molecular beam reflection accelerator plate 4. angle, θ3 is the elevation angle or depression angle of the substrate 7 seen from the molecular beam reflection acceleration plate 4, and θ4 is the substrate 7 seen from the molecular beam reflection acceleration plate 4.
The radiation aperture angle and A indicate the surface area of the molecular beam source element 2, respectively.

In order to grow a crystal layer using this embodiment, the molecular beam source element 2 is heated and evaporated in the element reservoir 1, and the vapor of the molecular beam source element 2 is transferred in the form of molecular beams to the molecular beam reflection accelerator. The crystal growth principle itself is essentially the same as that of the prior art.

Now, as explained above, when growing a crystal layer using this embodiment, θ1-62. It is necessary to satisfy the relationship θ4>θ3, and this is one condition that enables good emission of molecular beams.

In addition to the above conditions, if the temperature in the element reservoir part 1 is T1, the temperature in the molecular beam reflection accelerator plate 4 is T2, and the temperature in the radiation aperture part 6 is T3, then T3≧72>TI
It is also necessary to satisfy the following conditions, and as long as this condition is satisfied, the evaporated molecular beam source element 2
Otherwise, it does not adhere to the radiation aperture portion 6.

When each of the above conditions is satisfied, the radiation amount and radiation position of the molecular beam are proportional to the surface area A of the molecular beam element 2, so the intensity and radiation direction of the molecular beam are extremely stable.

As is clear from the figure, the element reservoir portion 1 in the present invention
Although it has a cylindrical shape and tends to be placed vertically, compared to the conventional example shown in Fig. 2, which is trumpet-shaped and placed at an angle,
The capacity of the molecular beam source element 2 is extremely large, and even if the molecular beam source element 2 is consumed as the number of growth increases, its surface area A is always constant, and therefore the intensity of the molecular beam is It is always stable regardless of how the source element 2 is consumed.

As mentioned above, the stability of the molecular beam derived from the structure of the semiconductor crystal growth apparatus in the present invention is as described above. It is necessary to make sure that there is no

Furthermore, the radiation angle of the molecular beam varies greatly depending on the shape of the molecular beam reflection accelerator plate 4. When the molecular beam reflection acceleration plate 4 is a flat surface, the emitted molecular beam is proportional to the surface area of the molecular beam source element 2 viewed from the molecular beam reflection acceleration plate 4. When the distance between the molecular beam reflection acceleration plate 4 and the substrate 7 is short, it is necessary to make the molecular beam reflection acceleration plate 4 convex toward the molecular beam side in order to widen the molecular beam radiation angle. If the distance is long, it is necessary to make the molecular beam reflection accelerator plate 4 concave toward the molecular beam side in order to narrow down the molecular beam radiation angle.

The intensity of a molecular beam is usually large at the center of the radiation angle,
It becomes smaller towards the outer periphery. Therefore, in the past, as explained above, the substrate 7 was rotated and revolved, but in the present invention, the molecular beam reflection accelerator plate 4 is moved vertically, horizontally, horizontally, or vertically with respect to the normal direction by the action of the driving part 5. By periodically or irregularly moving the circular shape, it is possible to make the thickness of the crystal layer uniform. In order to drive the molecular beam reflection accelerator plate 4, there is no need for a complicated gear mechanism to rotate or revolve the substrate 7, and it can be easily realized by using magnetic force using an electromagnet or the like. can.

As can be understood from the above, in the present invention, the radiation direction and radiation intensity of the molecular beam can be arbitrarily changed depending on the shape and motion condition of the molecular beam reflection accelerator plate 4. A crystal layer having a uniform thickness can be grown while fixing the substrate 7. Therefore, the substrate 7 can be easily supported, and the installation direction can be arbitrarily selected.

〔Effect of the invention〕

In the semiconductor crystal growth apparatus of the present invention, there is provided a molecular beam source element reservoir section that is cylindrical and arranged upright, and a molecular X source element evaporated from the molecular beam source element reservoir section that is reflected and accelerated toward the crystal growth substrate. and a molecular beam reflection accelerator plate that is movable in any direction with respect to the normal line, and a radiation aperture portion that regulates the direction of the molecular beam from the molecular beam reflection acceleration plate. The temperature of the accelerator plate is maintained higher than that of the molecular beam source element storage portion, and its position is set so that the angle of incidence and emission angle of the element of the molecular beam source with respect to the normal are equal.

According to this configuration, the molecular beam consisting of the molecular beam source element evaporated from the upright molecular beam source element reservoir section is affected by the molecular vAS,
It is possible to uniformly irradiate the crystal growth substrate and grow a crystal layer having a uniform thickness over the entire surface without requiring measures such as increasing the distance between the element reservoir and the crystal growth substrate. . In addition, since the molecular beam source element reservoir is upright, even if the number of growth increases and the molecular beam source element is consumed, its surface area remains unchanged, and the direction and intensity of the molecular beam do not change. Since the capacity of the molecular beam source element is large, there is no need for frequent replenishment. Furthermore, the crystal growth substrate is fixed and only the molecular beam reflection accelerator plate moves, so the mechanism is extremely simple.

[Brief explanation of the drawing]

FIG. 1 is a cutaway side view of a main part of an embodiment of the present invention, and FIG. 2 is an explanatory diagram of a main part of a conventional example. In the figure, 1 is the molecular beam source element reservoir, and 2 is 1
Molecular beam source element, 3 is a heater, 4 is a molecular beam reflection acceleration plate, 5 is a driving part, 6 is a radiation aperture part, θ1 is a molecular beam incidence angle with respect to the normal to molecular beam reflection acceleration Fi4, and θ2 is also a molecular beam radiation angle, θ3 is the elevation angle or depression angle of the group Fi7 seen from the molecular beam reflection acceleration plate 4, θ4 is the radiation aperture angle with respect to the substrate 7 seen from the molecular beam reflection acceleration plate 4, and A is the surface area of the molecular beam source element 2. ing. Patent Applicant Fujitsu Co., Ltd. Representative Patent Attorney Shoji Aitani Representative Patent Attorney Hiroshi Watanabe - Figure 2

Claims (1)

[Claims] A cylindrical molecular beam source element reservoir section is arranged upright, and the molecular beam source element evaporated from the molecular beam source element reservoir section is reflected and accelerated in the direction of the substrate to be crystal grown, and at an arbitrary angle relative to the normal. It is equipped with a molecular beam reflection acceleration plate that can move in the direction of the molecular beam reflection acceleration plate, and a radiation aperture portion that regulates the direction of the molecular beam from the molecular beam reflection acceleration plate, and the temperature of the molecular beam reflection acceleration plate is adjusted according to the molecular beam source. 1. A semiconductor crystal growth apparatus characterized in that the element reservoir portion is maintained at a higher level than that of the element reservoir portion, and the position thereof is set so that the incident angle and the emission angle of the molecular beam source element with respect to the normal line are equal.