JPS61270813A - Molecular beam epitaxial growth equipment - Google Patents

Abstract

PURPOSE:To change the state of growing a semiconductor thin film and the state of growing a hybrid film mixed with a molecular beam by preventing the mutual mixing of the molecular beams in the state of holding the vacuum of a growth chamber, by connecting to a rotary introduction part wherein a partition plate and a mask plate are attached to the outside of the growth chamber. CONSTITUTION:Cells 2, 3 which contain the first and the second materials 2a, 3a of the III group each are formed at a required position of the side wall of the growth chamber 1 of a molecular beam epitaxial growth equipment. A substrate 4 is held by a substrate holder 5 in a rotatable way at the position where the central axes of the cells 2, 3 are crossed. Further, a partition plate 6 which prevents the mutual mixing of the molecular beams of the III group in the growth chamber 1 and a mask plate 7 which limits the irradiation region with the molecular bean against the substrate 4 are integrally attached in a rotatable state. Further, a rotary introduction terminal 9 is attached to a flange 8 attached at the required position of the growth chamber 1 in a rotatable state and a supporter 10 in the growth chamber 1 is connected to the introduction terminal 9. So, the state of growing a semiconductor thin film and the state of growing a hybrid film mixed with the molecular beam are rapidly changed.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a molecular beam epitaxial growth apparatus, and more specifically, the present invention relates to a molecular beam epitaxial growth apparatus, in which layers of different thicknesses and types are alternately and periodically stacked on a substrate. The present invention relates to a molecular beam epitaxial growth apparatus capable of forming a periodic structure of a single-crystal a film used as a microwave device or a light-emitting/light-receiving device.

<Prior Art> Conventionally, epitaxial growth methods have been commonly used as a manufacturing method for compound semiconductor devices, especially optical devices, because of the ease of growing thin, uniform layers and controlling the composition ratio of component elements. Among them, the molecular beam epitaxial growth method (hereinafter abbreviated as MBE growth method) is known as a technique that has recently attracted particular attention.
Nikkei Electronics Yang 3G8,16 by Tsang
3 (1983), the MBE growth method and devices utilizing thin film periodic structures are described in detail.

According to this MBE growth method, by alternately and periodically stacking different types of ultra-thin film layers with a thickness of several tens of amps to several hundreds of amps on the light emitting part without forming alloy clusters,
It is now possible to manufacture a multi-quantum well laser as shown in FIG. 5. In the figure, (A) is p-type GaA
S, (B) is p-type Ga At -As, (C) is non-doped Qax (1x) As well, (D) is non-doped GaxA1 (1-x)
As barrier, (E) is n-type Qa Al (1-x)
As 1 (F) is an n-type Qa AS.

In the conventional MBE growth method for forming a periodic structure of a ■-V group compound semiconductor thin film, for example, as shown in FIG.
A substrate is held on a substrate holder (25) in the growth chamber (21), and the holding position is set at a position where the central axes of both cells (22) and (23) intersect. Then, the raw materials (22a) (
A cell shutter (22b) (23a) for controlling the irradiation of the molecular beam of the raw material evaporated from the substrate (20)
3b) is attached to both cells (22) and (23), and by alternately opening and closing the cell shutters (22bH23b) at a predetermined period, the molecular beams of one of the raw materials are selectively applied to the substrate (24). It is possible to alternately and periodically form compound semiconductor thin films of different types on the substrate (24) by irradiating the substrate (24).
(See Publication No. 11899).

Problems to be Solved by the Invention> In the above MBE growth method, while one cell shutter is open, the other cell shutter is occupied, but generally When growing by MBE, the raw material cells (22) (23) are usually 700 to 10
It is heated to a high temperature of 00°C. Therefore, while the cell shutters (22b) (23b) are closed, the raw material is heated and impure gas is generated, and if the impure gas is taken into the growing thin film, The electrical characteristics of am will be significantly deteriorated. Furthermore, apart from the above problem of impurity gas generation, the cell shutter (22b) (2
By closing 3b), the cell temperature itself is affected,
As a result, the cell shutter (22b) (23b
), it causes an overshoot in the intensity of the raw material molecular beam, making it difficult to control the film thickness of compound semiconductor thin films and the film composition in the case of mixed crystals. will decrease.

In addition, in order to grow an extremely thin semiconductor layer such as a monoatomic layer or a diatomic layer at a normal growth rate, it is necessary to significantly shorten the opening time of the cell shutters (22b) (23b). Considering the mechanical precision of 22b) and 23b, the open time error becomes large, making it difficult to grow a thin film with a constant period.

In order to solve this problem, the cell shutter is omitted and a partition plate for separating the flight line of the raw material and a mask plate are fixedly attached.

Therefore, it is possible to divide the growth chamber into multiple compartments, but each compartment is only irradiated with molecular beams from different raw materials, and only the superlattice structure can be grown. Therefore, mixed crystals cannot be grown at all.

Therefore, for example, if you try to grow a superlattice structure of 1nAs and GaAS directly on a substrate made of InP, as shown in FIG. 6, due to the unevenness of the surface of the InP substrate, as shown in FIG. , the X-ray diffraction half-width of the InAs-Ga AS superlattice is wide (~1GGG''), resulting in the disadvantage that only products with poor crystallinity can be obtained.

This invention was made in view of the above problems,
The purpose of the present invention is to provide a molecular beam epitaxial growth apparatus that can eliminate the inconvenience caused by opening and closing a cell shutter, and can easily and quickly switch between the growth of a compound semiconductor 4wJ film and the growth of a mixed crystal film. There is.

Means for Solving the Problems> In order to achieve the above object, the molecular beam epitaxial growth apparatus of the present invention includes a partition plate that separates the flight trajectory of each raw material with respect to the substrate, and a partition plate that separates the flight trajectory of each raw material with respect to the substrate. A mask in which a slit is formed to allow the flight of the growth chamber is connected to a rotating introduction section installed outside the growth chamber.

However, as for the above-mentioned partition plate and mask, the I
It is preferable that N is movably connected to the rotation introduction part, and the substrate is preferably supported rotatably about an axis perpendicular to the surface of the substrate.

Effect〉 If the molecular beam epitaxial growth apparatus has the above configuration,
By rotating the partition plate and the mask using the rotating introduction section, the molecular beams from each raw material are reliably separated by the partition plate in accordance with the rotational position, and the molecular beams are irradiated onto the substrate through the slits of the mask. Selecting a state in which the compound semiconductor iWwA can be grown by irradiating the substrate with molecular beams from each raw material without separating them, and a state in which the mixed crystal film can be grown by irradiating the substrate with molecular beams from each raw material without separating them. Can be done. This selection can be made by simply rotating the partition plate and the mask using the rotation introduction section, and the selection can be completed in a short time while maintaining the inside of the growth chamber at a high vacuum.

In particular, when the partition plate and the mask are connected to the rotation introduction part so as to be movable between a position corresponding to the center of the substrate and a position completely separated from the substrate, the growth of the compound semiconductor thin film, and It is preferable because the growth of the mixed crystal film can be selected reliably, and when the substrate is supported rotatably around an axis perpendicular to the surface of the substrate, the growth of the compound semiconductor thin film and the mixed crystal film can be controlled. This film has the advantage that it is possible to form a film extremely uniformly on a substrate, and that even if the film thickness is reduced, the above-mentioned uniformity is not impaired in any way.

<Example> Hereinafter, embodiments will be described in detail with reference to the accompanying drawings showing examples.

Fig. 1 is a schematic view of the inside of the MBE growth apparatus viewed from above, and Fig. 2 is a schematic perspective view showing the internal mechanism of the MBE growth apparatus. A cell (2) that stores the raw material (2a) and the second group raw material (3a)
1 (3) and both cells (2) +3
), the substrate (4) is rotatably held by a substrate holder (5) at a position where the central axes of (6), and a mask plate (force) that regulates the irradiation area of the molecular beam on the substrate (4) is rotatably attached within the unit.

To explain in more detail, a rotation introduction terminal (9) is rotatably attached to a flange (8) attached to a predetermined position of the growth chamber (1), and a rotation introduction terminal (9) is installed inside the growth chamber (1). The support rod □□□ passes through the flange (8) in an airtight manner and is connected to the rotation introduction terminal (9).

The support rod (2) has a substantially arc-shaped curved portion near the tip, and a partition plate (6) extending toward the side wall of the growth chamber (1) and a substrate (4) are attached to the arc-shaped curved portion. A mask plate ('7) which can be used as a mask is attached inside the body.

Then, on the mask plate (7), at a position directly facing the central axis of each cell (2) +31 with the partition plate (6) in between,
Slits (γa) (γb) are formed that allow the substrate (4) to be exposed in a fan shape at a predetermined central angle. Although the slits (7a) and (7b) are shown as having fixed opening areas, the opening areas can be changed by stacking two mask plates (7). You can also. Further, the distance between the substrate (4) and the mask plate (sword) is set within 2RIQ1.

With the above configuration, by rotating the partition plate (6) and the mask plate (sword) together with the support rod □□□ via the rotation introduction terminal (9), the partition plate (6) and the mask plate ( If the force is completely separated from the substrate (4),
Group 1 raw material (2a) stored in cell +2) (3)
, the molecular beam from the group II second raw material (3a) is simultaneously applied to the substrate (4).
), it is possible to grow mixed crystals.

In addition, the partition plate (6) and the mask plate (7) are connected to the substrate (
If the state corresponds to the center of cell (2) (
Molecular beams from the group ■ first raw material (2a) and the group ■ second raw material (3a) stored in the substrate (3) are separated from each other and transferred to the substrate (
4), a semiconductor thin film having a superlattice structure can be grown.

The above-mentioned growth operations can be switched while maintaining the high vacuum state in the growth chamber (1), and the switching can be done virtually instantaneously.

Thus, for example, in AS-Ga on an lnP substrate
When growing an AS superlattice, first, a partition plate (
6) and the mask plate (7) are completely separated from the substrate (4). ) is simultaneously irradiated onto the InP substrate (4), and the I
nGa-AS mixed crystal growth (se x
(1x) A mixed crystal such as A I I n (1-x) As may be grown by appropriately selecting the raw materials stored in the (2) +3), then the partition plate (6), and By placing the mask plate (7) in a state corresponding to the center of the substrate (4), the liquid from the liquid cylinder 1 raw material (2a) and ■liquid cylinder 2 raw material (3a) stored in the cell (21 (31) A semiconductor thin film (12) having an InAS-GaAs superlattice structure can be grown on the mixed crystal film (11) by irradiating the substrate (4) with molecular beams while being separated from each other. (See Figure 3).

The semiconductor thin film (12
) has a narrow X-ray diffraction half-width (~40") (see Figure 4), and its periodicity and crystallinity are comparable to those in the case where a semiconductor thin film with a superlattice structure is grown directly on the substrate (4). do,
Significantly improved. This is because the irregularities on the surface of the InP substrate (4) are smoothed by forming the mixed crystal film (11), and an In As-Qa AS superlattice is formed on this smooth surface. I'm there.

Note that the present invention is not limited to the above-described embodiments; for example, two or more partition plates (6) may be rotatably attached in accordance with the number of cells required to form a thin film periodic structure. In addition, when the partition plate (6) is rotated to a position corresponding to the center of the substrate (4), the Group II and Group V raw materials necessary for forming two types of semiconductor layers can be used. It is possible to form various semiconductor thin film periodic structures by attaching a plurality of cells each equipped with a partition plate (6) on both sides of the partition plate (6).Other than that, the gist of the present invention remains unchanged. It is possible to make design changes.

<Effects of the Invention> As described above, in this invention, the partition plate and the mask plate are connected to the rotation introduction section installed outside the growth chamber, so that molecular beams can be generated while maintaining the high vacuum inside the growth chamber. A state in which a compound semiconductor thin film is grown by preventing mutual mixing, and a state in which a mixed crystal film is grown by mixing molecular beams.
This has the unique effect of being able to be switched easily and quickly while maintaining a high vacuum inside the growth chamber.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the inside of the M8E growth apparatus viewed from above, Figure 2 is a schematic perspective view showing the internal mechanism of the MBE growth apparatus, and Figure 3 is a diagram showing the formation of a mixed crystal film and a semiconductor thin film on a substrate. Fig. 4 is a diagram showing X-ray diffraction data of the device in Fig. 3, Fig. 5 is a schematic diagram showing a multi-quantum well laser, and Fig. 6 is a conventional MBE growth apparatus. A schematic view, FIG. 7 is a vertical cross-sectional view showing a superlattice structure grown directly on a substrate, and FIG. 8 is a diagram showing X-ray diffraction data of the device shown in FIG. 7. (1) - Growth chamber, (2) (3) Cell, (2
a)...■Liquid cylinder 1 raw material, (3a)...■Liquid cylinder 2 raw material, (4)...Substrate, (6)...Partition plate, (force...
・Mass cutting board, (7a) (7b)...slit, (9
)...Rotating introduction terminal Patent applicant: Sumitomo Electric Industries, Ltd. Figure 5 Figure 7 Figure 6 Figure 8 Diffraction angle

Claims (1)

[Claims] 1. Cells in a growth chamber maintained under high vacuum The multiple types of raw materials stored in the It was flown in the direction and supported in the above growth chamber. The above raw materials are attached to the surface of the substrate, and the growth With molecular beam epitaxial growth equipment Therefore, the flight trajectory of each raw material relative to the substrate With a partition plate to separate the board and the board in place A pickpocket that allows the flight of raw materials to reach The mask with the cut formed thereon is placed in the above growth chamber. Connects to an externally mounted rotating introduction part. Molecular beam epitaxy characterized by le growth equipment. 2. The partition plate and mask are located at the center of the board. The location corresponds to the part and is completely separated from the board. Rotating introduction part that can be moved between positions of the above patent claims concatenated with Molecular beam epitaxial treatment as described in Range 1 growth equipment. 3. The substrate is centered on the axis perpendicular to the surface of the substrate. The above feature is rotatably supported as Molecular beam epitaxy according to claim 1 Kishal growth device.