CN100395373C - Growth Equipment for Chemical Vapor Deposition - Google Patents

Abstract

The chemical vapor deposition growth equipment adopts radio frequency induction heating, and a graphite reaction chamber is arranged in the middle of the radio frequency induction heater, and the graphite reaction chamber is placed in a vacuum quartz tube (1). ) is provided with a high temperature resistant pyrolysis BN casing (2) group. The BN casing group consists of 2-6 casings, and the distance between the casing wall and the casing wall and the quartz tube wall is 1mm-10mm. The multi-layer BN sleeve group is used as a radiation shield to effectively reduce the energy loss caused by heat radiation. BN material has low thermal conductivity and can achieve a temperature gradient above 100°C/mm, which has a good thermal insulation effect. A relatively high vacuum is maintained in the quartz tube, and vacuum is maintained between the BN sleeves and between the BN sleeve and the quartz tube, which helps to reduce heat loss.

Description

Growth Equipment for Chemical Vapor Deposition

technical field

The invention relates to the design of growth equipment for preparing CVD materials, in particular to the growth equipment for preparing CVD materials with pyrolysis BN casing group as heat preservation device.

Background technique

The third-generation semiconductors and wide-bandgap materials have excellent photoelectric properties and are widely used in the fields of communication and information. The chemical vapor deposition (CVD) method is one of the commonly used methods for epitaxially growing wide bandgap semiconductor thin film materials.

The epitaxial growth of thin film materials such as SiC and GaN is realized at high temperature. The growth temperature of SiC is 1300~1600°C, and that of GaN is 1000~1200°C. The heating device of the CVD material growth equipment used should have excellent Excellent thermal insulation performance, so that it can not only meet the requirements of material preparation, but also achieve the energy-saving goal of low energy consumption.

At present, most of the heating methods of epitaxial equipment for CVD materials used in the preparation of SiC thin film materials use radio frequency induction heating. Since the growth temperature is as high as 1300~1600°C, in order to avoid softening of the quartz tube, a high-temperature resistant high-purity insulation material is required between the quartz tube and the graphite reaction chamber heated by induction. In order to obtain high-quality epitaxial materials, it is also necessary to ensure that the During the high-temperature growth process, no impurities escape from the insulation material into the reaction chamber.

The traditional horizontal CVD equipment uses graphite felt to realize the function of high temperature resistance and heat preservation. The disadvantages of this method are:

1. Graphite felt is porous.

It is easy to absorb impurities, but it is not easy to clean, and it is not easy to adjust and combine assembly according to needs. After a certain period of use, it cannot be guaranteed that no impurities will escape during high temperature growth.

2. Graphite felt cannot support itself.

It is not easy to use in vertical CVD equipment, and CVD equipment without this configuration needs to have a larger size quartz chamber, and a water-cooled or air-cooled jacketed tube is attached to the quartz tube wall to ensure that the tube wall is at a constant temperature during the epitaxial growth process. lower temperature. Such devices are expensive and consume a lot of power.

Contents of the invention

The object of the present invention is to propose a design for the growth equipment for preparing CVD materials, especially the growth equipment for preparing CVD materials with pyrolysis BN casing set as the heat preservation device.

The object of the present invention is achieved like this: the epitaxy equipment of CVD material adopts radio frequency induction heating, and the middle of radio frequency induction heater is provided with graphite reaction cavity, and graphite reaction cavity is placed in the vacuum quartz tube, it is characterized in that quartz tube and induction heated A high temperature resistant pyrolysis BN sleeve set is arranged between the graphite reaction chambers.

The pyrolytic BN casing set includes at least two casings, for example, 2-6 casings constitute the casing set, and the distance between the casing walls and the distance between the casing walls and the quartz pipe walls is ≥1mm and less than 10mm. The thickness of the casing wall is 0.2-8 mm.

The invention is especially used for adopting pyrolysis BN casing group as the heat preservation device in the horizontal CVD material growth equipment.

The mechanism of the present invention is that the pyrolyzed BN material has remarkable characteristics such as high melting point, high heat insulation, high purity, high density, long life, difficult to absorb impurities, and easy cleaning. According to the material properties, the best solution is to use pyrolysis BN casing with a wall thickness greater than 5mm to reduce the temperature of the tube wall to below the conventional requirement of 600°C. However, the cost of this solution is extremely high, and the current processing level is still difficult to achieve.

The feature of the present invention's scheme is:

1. Use the multi-layer BN bushing group as a radiation shield to effectively reduce the energy loss caused by thermal radiation.

2. BN material has low thermal conductivity, can realize temperature gradient above 100°C/mm, and has good heat preservation effect.

3. The quartz tube maintains a relatively high vacuum, and there is a vacuum between the BN sleeves and between the BN sleeve and the quartz tube, so the thermal conductivity along the radial direction of the quartz tube is low, which helps to reduce heat loss.

4. Ensure that no impurities escape from the insulation material into the reaction chamber during the high-temperature growth process, and obtain high-quality epitaxial materials.

Description of drawings

Fig. 1 is the cross-sectional structure schematic diagram of the present invention, mark among the figure: quartz tube 1 (outer circle), three-layer BN sleeve pipe 2, graphite reaction chamber 3, epitaxial substrate growth platform 4 (central rectangle). The direction of the arrow indicates the direction of heat radiation, and the density of the arrow indicates the intensity of heat radiation

Detailed ways

As shown in the figure, the heating and heat preservation device includes the following structure:

The heating device adopts radio frequency induction heating, and a graphite reaction chamber is arranged in the middle of the radio frequency induction heater, and the graphite reaction chamber is placed in a vacuum quartz tube. A high temperature-resistant pyrolytic BN sleeve set is arranged between the quartz tube and the induction heated graphite reaction chamber.

RF induction heating furnace: power 30~40KW, frequency about 40KHZ.

Graphite reaction chamber (heating element): hollow, the size is designed according to the diameter of the epitaxial substrate.

Insulation device, BN casing group: the number of casings is greater than 2, three layers are selected in this embodiment, and two layers are also better for thicker pipes. When good insulation effect is required, pipes with four or more layers can be selected.

The length of the casing is 2-3 times the length of the heating element, the spacing between the casing and the distance between the casing and the quartz tube is ≥1mm, the space between the casings, the casing and the quartz tube are isolated and supported by BN rings, and the heating element (graphite) is placed in the inner casing Reaction chamber 3, epitaxial substrate growth platform 4) In the above reaction chamber, the outer tube is placed in the quartz tube.

The BN bushing wall thickness that the present invention scheme adopts selects the BN thickness that can realize at present processing level, and the processing method of present pyrolysis BN bushing is: the nitrogen that polymer precursor pyrolysis method prepares or the low-cost combustion synthesis process prepares Boron-based ceramics (used by Shanghai Institute of Ceramics, Institute of Composite Materials, Harbin Institute of Technology, etc.), currently the thickness of the casing wall of the pyrolytic BN casing is 0.2-2mm. Insulation is achieved through combination and assembly, which can ensure that no impurities escape during the high-temperature growth process, and meanwhile have satisfactory performance-price ratio and low manufacturing cost. The effect of thicker BN casing is better.

The advantage of the scheme of the present invention also includes:

1. Since the combination and adjustment of assembly can be conveniently implemented, this set of equipment can not only carry out epitaxial growth of SiC, GaN and other wide-bandgap semiconductor thin film materials at high temperature, but also realize Si-based materials (Si _{1 -x} G _x , Si _1-xy G _x C _y, etc.) epitaxial growth.

2. The effective heat preservation effect of the heat preservation device of the BN casing group can significantly reduce the power consumption of the CVD material growth equipment;

3. Pyrolytic BN can be self-supporting, and can be used in both horizontal CVD material growth equipment and vertical CVD material growth equipment, thus effectively reducing the manufacturing cost, technical difficulty and power consumption of vertical CVD material growth equipment .

The technical index that the scheme of the present invention has realized in the horizontal CVD material growth equipment:

High temperature growth temperature range: 800~1400°C, the temperature of the outer wall of the quartz tube during growth is <600°C (air cooling); low temperature growth temperature range: 550~850°C, the temperature of the outer wall of the quartz tube is less than 200°C (air cooling).

Claims (1)

1. The growth equipment of chemical vapor deposition adopts radio frequency induction heating, and a graphite reaction chamber is arranged in the middle of the radio frequency induction heater, and the graphite reaction chamber is placed in a vacuum quartz tube (1). A high temperature resistant pyrolytic BN casing (2) group is arranged between the graphite reaction chambers (3); the BN casing group consists of 2-6 casings, the distance between the casing wall and the distance between the casing wall and the quartz pipe wall It is 1mm-10mm; the thickness of the casing wall is 0.2-8mm; the length of the casing is 2-3 times the length of the graphite reaction chamber (3) of the heating element, and the casing wall, casing and quartz tube are isolated and supported by BN rings.

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