RU130996U1 - REACTOR FOR PRODUCTION OF PRODUCTS CONTAINING A SILICON SUBSTRATE WITH A SILICON CARBIDE FILM ON ITS SURFACE - Google Patents

Abstract

1. A reactor for the manufacture of products containing a silicon substrate with a silicon carbide film on its surface, characterized in that it has a housing with an internal volume heated to 950-1400 ° C and equipped with a nozzle for supplying a gas mixture comprising carbon monoxide and silicon-containing gas, and outlet pipe for gaseous reaction products, a gas-permeable chamber is located inside the casing, which serves as a barrier for the passage of silicon-containing gas molecules, with a substrate holder located in it, made possible STI parallel installation of silicon wafers podlozhek.2. The reactor according to claim 2, characterized in that the gas-permeable chamber is made of porous graphite.

Description

A reactor for manufacturing products that belong to a new class of semiconductor materials and semiconductor nanomaterials and which can be used to create a new generation of semiconductor and nano-semiconductor devices is claimed.

For a number of applications, for example, in semiconductor technology, micro- and optoelectronics, and a new, rapidly developing field of nanoelectronics, thin films of silicon carbide and films of silicon nano-carbide on various substrates can be used. Among them, silicon substrates are of interest.

RU 2162117 describes a reactor for epitaxial growing of monocrystalline silicon carbide by chemical vapor deposition on the growth surface of a substrate. The reactor contains a chamber with one or two diametrically located substrates installed in it, has channels for separately supplying a reagent containing silicon and a reagent containing carbon and a means for heating the chamber walls to the chamber, which allows maintaining the temperature of the chamber walls in the range of 1800-2500 ° C. The inner surface of the reactor chamber is made of a solid solution of tantalum carbide and silicon in tantalum. The space between the body and the outer walls of the chamber is filled with a porous graphite heat insulator. The substrates are mounted on graphite pedestals, which are coaxially mounted on the drive shafts. The shafts are connected to mechanisms providing the substrates with rotational and translational movements along their axes. The disadvantage of this device is the complexity of its design and low productivity, because at the same time, films can be grown on one or only two substrates, as well as high synthesis temperatures above 1700 ° C.

The CVD reactor described in patent RU 2394117 [Patent RU 2394117, publ. July 10, 2010, Option 5, presented in FIG. 3 of the patent specification]. In the reactor, the synthesis of heteroepitaxial films of silicon carbide on a silicon substrate is carried out by chemical vapor deposition. A substrate holder is installed in the reactor vessel, made of a single piece of graphite in the form of two cones connected together. Substrate holders are secured in a container with a holder. The container is placed inside a graphite heater, heated by an inductor. Sections of heaters are located in the reactor around the central current lead. Holes are made in the central water-cooled current lead through which the products of the reaction of silicon carbide formation are removed. Hydrogen is supplied into the heaters through the second current leads, which are fixed in the outer reactor vessel. Substrate holders are mounted radially on a multi-tier carousel, which allows more efficient use of radiation from each heater.

The main disadvantage of the prototype of the inventive reactor is the design complexity, the presence of rotating elements that operate at elevated temperatures and low pressures, which makes special demands on the sealing nodes. In addition, it should be noted that the operation of the reactor is based on the principle of deposition from the gas phase, and, consequently, the method implemented during the operation of the reactor has the disadvantage of low quality films.

The inventive utility model aims to significantly increase productivity and simplify the manufacture of an article containing a silicon carbide film on the surface of a silicon substrate, as well as to improve the quality of the silicon carbide film obtained in the reactor.

The claimed technical result is the provision of the possibility of manufacturing in one technological cycle a large number of products containing a silicon substrate with an epitaxial silicon carbide film with high crystallographic perfection without defects such as etching pits.

The inventive reactor for the manufacture of products containing a silicon substrate with a silicon carbide film on its surface, has a body with an internal volume heated to 950-1400 ° C, and is equipped with a pipe for supplying a gas mixture including carbon monoxide and silicon-containing gas, and a pipe for outputting gaseous reaction products . A gas-permeable chamber is located inside the casing, which serves as a barrier for the passage of silicon-containing gas molecules, with a substrate holder located in it, made with the possibility of parallel (on the edge) installation of silicon wafer plates. It is preferable to use a gas-permeable chamber, the walls of which are made of porous graphite. The ratio of wall thickness and porosity of the gas-permeable chamber is chosen from the condition of ensuring structural strength, as well as from the condition of creating the necessary developed contact surface that provides thermal decomposition of silane, or other silicon-containing gas, when it passes, more precisely, products of its thermal decomposition, through the chamber walls at a given temperature and pressure in the internal volume of the reactor.

In order to better demonstrate the distinctive features of the utility model, as an example, not having any restrictive nature, the implementation options are described below. Examples of implementation are illustrated by the Figures, which show:

Figure 1 - diagram of the inventive reactor used for the manufacture of samples according to the Examples described below.

Figure 2 - image of the surface of the sample product (size 20 × 20 μm) made according to Example 1 (with the addition of silane in the gas mixture) obtained by a scanning probe microscope.

Figure 3 - image of the surface of the sample (size 20 × 20 μm), manufactured under conditions similar to Example 1, but without the addition of silane, obtained by a scanning probe microscope.

Figure 1 shows a schematic representation of the inventive reactor, where the following notation is introduced: 1 - walls of the reactor, 2 nozzle for supplying a gas mixture, including carbon monoxide and silicon-containing gas, 3 - nozzle for withdrawing gaseous reaction products, 4 - walls of a gas-permeable chamber, 5 - in parallel mounted silicon wafers; 6-gas-permeable chamber lid.

The reactor operates as follows. Substrates, which are plates of single-crystal silicon, cut out taking into account the crystallographic orientation, are placed in the internal volume of the reactor in a special cartridge, which is a gas-permeable chamber made of graphite. Silicon substrates are installed parallel to each other with a gap of 1-10 mm and heated in vacuum at a residual gas pressure of 10 ^-2 -10 ^-3 Pa to a temperature of 500-800 ° C. Then, carbon monoxide CO and a silicon-containing gas (silane) or its mixture with an inert gas are pumped through the reactor. The temperature is increased to 950-1400 ° C and the samples are kept for 1-80 minutes. The pressure in the reactor is maintained within the range of 20-600 Pa, and the temperature in the indicated range. After the formation of the silicon carbide layer and cooling, the obtained products are recovered.

The pressure and temperature range is determined by the rate of the chemical reaction. At lower pressures (less than 20 Pa) and temperatures (less than 950 ° C), the speed is so low that silicon carbide is practically not formed. At higher values (pressure above 600 Pa and temperature above 1400 ° C) - the speed is so great that the silicon carbide film has a block structure, and the blocks are misoriented relative to each other (i.e. the film is not single-crystal). The inert gas used additionally acts as a carrier gas, which ensures the delivery of reagents to the reactor.

Example 1. As substrates, two, three, four, five, six or more single crystal silicon wafers of any grade, with a diameter of 35, 56, 60, 76 mm, 100 mm, 150 mm or more with a surface orientation of (111), (100 ), (110), (210), (310), (311), (510) or any other orientation. These silicon substrates, mounted on an edge, are placed in a graphite gas-permeable chamber at a distance of 2 mm from each other, the chamber is placed in a reactor, air is pumped out, heating is carried out to 800 ° C, and carbon monoxide is supplied at a pressure of 150 Pa in the reactor. Then the internal volume of the reactor is heated to a temperature of 1250 ° C and silane SiH _{4 is} fed, maintaining a pressure of 150 Pa in the reactor. After holding the substrates under the indicated conditions for 10 minutes, the gas supply is stopped, the gaseous reaction products are pumped out and the reactor is cooled, after which the graphite chamber with the substrates is removed from the reactor. The presence of a silicon carbide film formed on silicon substrates is recorded by optical microscopy, ellipsometry or electron diffraction.

Adding silane to the gas mixture eliminates defects such as etching pits in the obtained silicon carbide films (Figs. 2, 3). The rms roughness of the silicon carbide films made with the addition of silane was 5–10 nm.

Example 2. As substrates, two, three, four, five, six or more single crystal silicon wafers of any grade with a diameter of 35, 56, 60, 76 mm, 100 mm, 150 mm or more with a surface orientation of (111) with a deviation from the base are used plane (111) to 0 °, (100), (110), (210) or any other orientation. These silicon substrates are placed in a graphite gas-permeable chamber at a distance of 2 mm from each other, the chamber is placed in the reactor, air is pumped out, heated to 800 ° C and carbon monoxide is supplied at a pressure of 80 Pa in the reactor, then the internal volume is heated to a temperature of 950 ° C-1380 ° C and serves a stream of silane-diluted silane SiH ₄ , maintaining a pressure of 80 Pa in the reactor. After holding under the indicated conditions for 15 minutes, the gas supply is stopped, the gaseous reaction products are pumped out and the reactor is cooled, after which the graphite chamber with the substrates is removed from the reactor. The presence of a silicon carbide film formed on silicon substrates is recorded by optical microscopy, ellipsometry or electron diffraction.

The structure and characteristics of the obtained samples are similar to the structure and characteristics of the samples described in Example 1. The use of dilution of silane with argon can improve the safety of work and make the process used more environmentally friendly.

Example 3. As substrates, 50 wafers of single crystal silicon of various grades with a diameter of 76 mm or 100 mm are used. This silicon substrate is placed in a graphite gas-permeable chamber with a size of 100 * 100 * 150 mm at a distance of 1 mm from each other (Figure 1), the chamber is placed in a reactor, air is pumped out, heating is carried out to 850 ° C and carbon monoxide is supplied at a pressure in the reactor 170 Pa, then the furnace is heated to a temperature of 1270 ° C and a stream of silane SiH4 diluted with argon is fed, maintaining a pressure of 170 Pa in the reactor. After holding under the indicated conditions for 15 minutes, the gas supply is stopped, the gaseous reaction products are pumped out and the reactor is cooled, after which the chamber with the substrates is removed from the reactor. The presence of a silicon carbide film formed on silicon substrates is recorded by optical microscopy.

Example 4. As substrates, two, three, four, five, six or more wafers of monocrystalline silicon of various grades with a diameter of 35, 56, 60, 76 mm, 100 mm, 150 mm or more with a surface orientation deviated by 2 °, 4 ° are used , 6 °, 8 °, 10 ° or 12 ° or any other degree lying between 2 ° and 14 ° from the base plane (111). These silicon substrates are placed in a graphite gas-permeable chamber at a distance of 5 mm from each other, the chamber is placed in the reactor, air is evacuated, heated to 800 ° C and carbon monoxide is supplied at a pressure of 80 Pa in the reactor, then the internal volume is heated to a temperature of 950 ° C-1300 ° C and serves a stream of silane-diluted silane SiH ₄ , maintaining a pressure of 100 Pa in the reactor. After holding under the indicated conditions for 5 minutes, the gas supply is stopped, the gaseous reaction products are pumped out and the reactor is cooled, after which the graphite chamber with the substrates is removed from the reactor. The presence of a silicon carbide film formed on silicon substrates is recorded by optical microscopy, ellipsometry or electron diffraction.

Example 5. As substrates, two, three, four, five, six or more single crystal plates of various grades with a diameter of 35, 56, 60, 76 mm, 100 mm, 150 mm and more with a surface orientation deviated by 2 °, 4 °, are used 6 °, 7 °, 8 °, 10 ° or any other degree lying between 2 ° and 10 ° from the reference plane (100). These silicon substrates are placed in a graphite gas-permeable chamber at a distance of 10 mm from each other, the chamber is placed in the reactor, air is pumped out, heating is carried out to 800 ° C and carbon monoxide is supplied at a pressure of 200 Pa in the reactor, then the internal volume is heated to a temperature of 1000 ° C-1270 ° C and serves a stream of silane-diluted silane SiH ₄ , maintaining a pressure of 200 Pa in the reactor. After holding under the indicated conditions for 3 minutes, the gas supply is stopped, the gaseous reaction products are pumped out and the reactor is cooled, after which the graphite chamber with the substrates is removed from the reactor. The presence of a silicon carbide film formed on silicon substrates is recorded by optical microscopy, ellipsometry or electron diffraction.

The structure and characteristics of the obtained samples are similar to the structure and characteristics of the samples described in Example 1.

The principal difference of the claimed reactor from other known reactors is the use of a gas-permeable chamber with silicon substrates parallel to each other with a gap of 1-10 mm, as well as the addition of silicon-containing gas to the gas mixture, which quickly decomposes at temperatures of 950-1400С. Through the walls of the gas-permeable chamber, CO freely participates directly in the formation of the film by chemical reaction with it of the surface layers of silicon substrate. For silicon-containing gas (molecules), the walls of the chamber are a barrier, but when silicon-containing gas comes in contact with the heated walls of the chamber, it decomposes (dissociates), and the decomposition products pass through the pores of the chamber and affect the film formation process: they are used to "heal" the shrink pores, formed during the chemical reaction of the surface layers of silicon substrate with carbon monoxide, and to prevent evaporation of the upper layers of the activated complex.

Silicon formed during the dissociation of a silicon-containing gas, adsorbed on the surface of the substrate and the growing film, reduces the surface tension of the resulting silicon carbide, and allows you to get not only the surface of silicon carbide with the release of carbon atoms, but also the crystalline surface of silicon carbide, on the outside of which there are silicon atoms. By supplying silicon atoms to the reaction zone, it is possible to achieve high crystallographic perfection and the absence of defects of the type of etching pits.

The arrangement of silicon substrates parallel to each other at a distance of 1 mm to 10 mm plays an important role in stabilizing the surface of the substrates at the stage of their heating to a temperature of 800 ° C, at which the supply of CO and silicon-containing gas to the reaction zone begins. At temperatures above 600 ° С, the active reconstruction of the upper silicon atoms, the silicon substrate, begins near the surface. Some of these atoms can evaporate and thereby destroy the upper smooth layer of the substrate, since heating occurs in vacuum at a residual gas pressure of 10 ^-2 -10 ^-3 Pa. Evaporating from two neighboring substrates located nearby, silicon into a narrow gap (1-10 mm) creates an excess equilibrium pressure of silicon vapor in it, i.e. such a pressure at which atoms evaporate as much as they settle back onto the substrates. The distance between the substrates is chosen so that the mean free path of the silicon atom at a given residual gas pressure is comparable with the distance between the substrates and is not less than the latter.

Thus, the use of a reactor of a given design provides the ability to synthesize silicon carbide films simultaneously on a large number of silicon substrates, which can significantly increase the performance of the process for producing silicon carbide films on silicon substrates, improve their crystalline quality and reduce their cost. The reactor, unlike the prototype, does not have moving parts, and, therefore, does not require the use of a special drive and sealing units. This increases the reliability of the design and a significant simplification of the design of the substrate holders with their versatility in relation to the size of the substrates and their shape.

Claims (2)

1. A reactor for the manufacture of products containing a silicon substrate with a silicon carbide film on its surface, characterized in that it has a housing with an internal volume heated to 950-1400 ° C and equipped with a nozzle for supplying a gas mixture comprising carbon monoxide and silicon-containing gas, and outlet pipe for gaseous reaction products, a gas-permeable chamber is located inside the casing, which serves as a barrier for the passage of silicon-containing gas molecules, with a substrate holder located in it, made possible STI parallel installation of plates of silicon wafers. 2. The reactor according to claim 2, characterized in that the gas-permeable chamber is made of porous graphite.

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