SU852976A1 - Device for producing multilayer semiconduction structures by liquid epytaxy - Google Patents

Description

The invention relates to semiconductor electronics and can be used to make multilayer semiconductor structures used to create semiconductor devices.

Structures are known with which multilayer semiconductor structures are fabricated by liquid epitaxy. In this case, either one substrate is successively placed in different solutions 1, or the solutions are successively forced through the space above the substrate 2.

A device is known consisting of a housing, a moving block of solutions, pressure 3. The substrates are located in the lower part of the device and are arranged parallel to each other, forming one long channel between them. The piston is located under the solution block. The space in front of the piston is associated with a thin expanding channel with a gap between the substrates. When one of the containers is aligned with a hole in the space in front of the piston, the solution enters this space, then is forced through the channel and into the gap between the substrates. From this solution grows the first layer of the structure. The space in front of the powder is then filled with the following solution, which is likewise pressed through the channel and into the gap between the substrates, squeezing out the previous spent solution. Last on a special channel falls into the collection. From the solution between the substrates, the next layer of the structure grows. At the end of growth, a solution of Ga-GaAs with a large amount is injected into the gap between the substrates.

10 amount of aluminum. When the system is cooled to room temperature, this solution drops a layer close in composition to AlAs, which is then removed in 15 hydrochloric acid. There is also a shift of the solution from the substrate at the end of growth.

However, this device has the following disadvantages. The device is intended only for the manufacture of structures based on GaAs, AlAs and their solid solutions, since the end of growth due to covering the surface of the structure with an AlAs layer followed by its etching in acid is unacceptable for most other structures and layers. For example, covering in this way a solid solution (InGa) As corrodes the surface of this compound. Most often, films and structures with a so-called “growth surface,” ie, a surface freed from the solution immediately after growth, are required at high temperatures. Such, for example, are the requirements for the surface of the structures used in the manufacture of photo-emitters with negative electron affinity. Although, in the well-known method, such a solution shift is provided, but it is carried out from half of the substrates. The second half in this case turns out to be ballast. In the manufacture of some multilayer structures, a mechanical shift of the spent solution is necessary after the end of growth of one of the intermediate layers. Thus, for example, in the manufacture of structures in which adjacent layers differ sharply in properties (e.g., n-n-structures for Gunn generators, where the decrease in doping level during the transition from layer + to layer n should be 10 times), To squeeze out the previous solution, it is then necessary to expend a large amount of the washing solution. The presence of an intermediate mechanical shift would significantly reduce the amount of washing solution. However, such a possibility in a known method is not provided. The aim of the invention is to more fully remove the melt from the gap between the substrates and improve productivity. This goal is achieved in that the device is equipped with a cassette made in the form of a frame with grooves for accommodating substrates installed in the growth chamber with the possibility of moving, and a set of horizontal plates rigidly fixed in the growth chamber opposite the holes in the frame between the slots. In FIG. 1 shows the housing in axonometry; in fig. 2 is a fragment; in fig. 3 - ejector; in fig. 4 - substrate cassette; in fig. 5 - container for melts. The device comprises a housing / placed in the grooves 2, an ejector S having plates 4. A cassette 5 with substrates 6 is also placed in the housing. So that the substrates do not fall out of it during the forward movement of the cassette, they are locked with clips 7 and 5. In the housing there is a space 9 for dosing the solution, connected by means of a small hole 10 with the space // in front of the cassette. A space 12 is placed in the space 9 which can be moved. The whole body is closed by a guide 3 with a solution block M consisting of several containers (5) for solutions. Each tank has a hole in the bottom. In the guide there is also a hole located above the space for dosing solution 9 Below the cassette in the device case there is a container 16 for collecting the waste solution. Bracket 7 is also a press with which it moves the cassette inside the assembled device during operation. The device works as follows. By moving the block of solutions 14, the hole in one of the containers 15 containing the solution is aligned with the hole in the guide 13. The solution from the tank enters the dispensing space 9 before the piston 12. The amount of solution entering this space is determined by the free volume in front of the reservoir. The piston 12 slides over the solution and pushes it into the space // in front of the cassette 5 through the opening 10. The brackets 7 and 5 form the side walls of this space. The upper wall is formed by the guide 13. Before the solution is removed through the hole. 10, the cassette 5 is installed so that it closes the space 11, separating it from the collection of waste solutions. After the solution has been forced into space 11, the cassette with the help of staples 7 slides onto the solution until it stops against a wall having an opening 10. The entire solution is forced into the gaps between the substrates. The main part of the solution falls through the right side of the cassette into the container 16. From the solutions on the substrates, the layer grows. Removal of the spent solution is made by pushing the cassette onto the plates 4. The plates pass through the gaps between the substrates and the spent solution through the left side of the cassette enters the container 16. If the surface of the grown layer is not exposed, the cassette does not slide onto the plates 4 . The next solution is delivered to the ill space in front of it in the manner described. When the cassette is pulled over this solution, it also falls into the gaps between the substrates, pushing out the spent solutions. Thus, the device allows the change of solutions both by pushing them out using plates and pushing them out with each other without contacting the surface of the grown film with the atmosphere of amnula. Both ways of changing solutions can be applied when growing the same structure. The end of the fabrication process is carried out by shifting the last solution by pushing the cassette onto the plate system 4. The cassette 5 is provided with slots in which rectangular or circular substrates are placed. The distances between the grooves determine the thickness of the solution located in the gap between the substrates. The thickness of the plates, which serve as ejector pushers of spent solutions, is determined by the thickness of the gaps between the substrates, taking into account the thickness of the fabricated structure.

The proposed device allows the growth of multilayer structures for heterolasers and hetero-light diodes on a GaAs, AlAs basis, as well as other n + nn + compounds and other structures for VHF devices; p-GaAs (GaAlAs) GaP and other structures for photo-emitters with negative electron affinity.

Since the substrate cassette is located in the middle but the height of the device, the dimensions of the substrates are close to the internal diameter of the reactor used.

Claims (3)

Invention Formula A device for obtaining multilayer semiconductor structures by liquid epitaxy, comprising a housing inside which a growth chamber is placed with substrates installed horizontally in it with a gap, connected with channels to the melt feed chamber equipped with a piston and to the spent melt chamber and mounted on the housing horizontal movement of the container with tanks for melts having a hole in the bottom, different from the fact that, in order to completely remove the melt from the gap between the substrates and increase productivity, the device is equipped with a cassette made in the form of a frame with grooves for placing substrates installed in the growth chamber with the possibility of moving, and a set of horizontal plates rigidly fixed in the growth chamber opposite the holes in the frame between the grooves. Sources of information taken into account in the examination: 1. J. Gryst, Growth. 1974, v. 27, p. 97. 2.Jap. J. of Appl. Phys. 1976, v. 15, N 5, p. 887. 3.Kristall und Technik, 1976, v. 11, N 10, p. 1013 (prototype). Ouz-i 2 ibz FIG. 2