CN111411396A - A kind of preparation method of transparent colored silicon carbide polycrystalline plate - Google Patents

Abstract

The invention discloses a preparation method of a transparent colorful silicon carbide polycrystalline plate, which comprises the steps of fixing the back of a substrate on the inner side of an upper cover at the top of a graphite crucible by using a patterned silicon carbide single crystal or polycrystalline substrate sheet, putting a silicon carbide raw material at the bottom of the graphite crucible, putting the graphite crucible into a high-temperature growth furnace, enabling the bottom of the graphite crucible to be positioned in a high-temperature region and the top of the graphite crucible to be positioned in a lower-temperature region, thus forming a temperature gradient in the axial direction of the graphite crucible, growing a silicon carbide polycrystalline block on the patterned silicon carbide substrate by adopting a physical vapor transport method, and cutting, grinding and polishing to obtain the transparent colorful silicon carbide polycrystalline plate. The preparation method is simple, and compared with the traditional silicon carbide ceramic, the transparent colorful silicon carbide polycrystalline plate has the advantages of better compactness, high component purity and higher heat conductivity.

Description

A kind of preparation method of transparent colored silicon carbide polycrystalline plate

technical field

The invention relates to a preparation method of silicon carbide polycrystalline, in particular to a preparation method of a transparent colored silicon carbide polycrystalline plate.

Background technique

Silicon carbide materials have important applications in two main fields. One is the single crystal form of silicon carbide. Mainly used in the semiconductor field, as a third-generation semiconductor material, it has the characteristics of wide band gap, high thermal conductivity, large saturation electron drift rate and large breakdown voltage, as well as low dielectric constant and excellent chemical properties. stability. The above characteristics make it have important application value in high temperature, high frequency, high power and radiation resistant devices. The material properties of silicon carbide make its devices focus on application integration and miniaturization. The other type is the form of silicon carbide ceramics. Silicon carbide ceramics have excellent mechanical properties, high flexural strength, excellent corrosion resistance, excellent oxidation resistance and high wear resistance. The structure and properties of silicon carbide ceramic materials make it still have excellent mechanical properties under high temperature conditions. Therefore, the silicon carbide ceramic device can work stably at a very high temperature, and its working temperature can reach more than 1500 ℃. And silicon carbide ceramics have excellent thermal conductivity, which has been widely used in aerospace, power electronics and communication equipment fields.

The harsh use environment also has higher requirements on materials. The limitations of traditional silicon carbide ceramic materials in terms of compactness and uniformity of thermal conductivity limit their application. Although silicon carbide single crystal material is more superior in performance, its preparation technology is difficult and high cost. At present, the largest size silicon carbide single crystal material product on the market is 6 inches in diameter, and there is no larger size product for sale. Current silicon carbide ceramic products usually use rare earth oxides as sintering aids to improve the compactness of silicon carbide ceramics, but affect their mechanical properties.

SUMMARY OF THE INVENTION

Purpose of the invention: In view of the above problems, the present invention provides a method for preparing a transparent colored silicon carbide polycrystalline plate. By using a graphite crucible as a growth vessel, the graphite crucible is composed of a graphite crucible cover and a graphite crucible cavity; using patterned silicon carbide Single crystal or polycrystalline substrate, fix the back of the substrate on the inside of the graphite crucible cover, put the silicon carbide raw material at the bottom of the graphite crucible, and put the graphite crucible into the high temperature growth furnace, so that the bottom of the graphite crucible is located in the high temperature area, and the top is located in the lower In the temperature zone, a silicon carbide polycrystalline block is grown on a patterned silicon carbide substrate by a physical vapor transport method; wherein, the thickness of the patterned silicon carbide single crystal or polycrystalline substrate is 0.2-1 mm, and the thickness of the patterned silicon carbide single crystal or polycrystalline substrate is 0.2-1 mm. During the growth of the block, the growth temperature is 1800°C-2400°C, the growth pressure is maintained at 1-5kPa, the growth time is more than 30 hours, and the axial temperature gradient of the graphite crucible is in the range of 3°C-8°C per centimeter.

Technical scheme: in order to solve the above-mentioned technical problems, the technical scheme adopted in the present invention is:

A preparation method of a transparent colored silicon carbide polycrystalline plate, comprising the following steps:

Step 1, preparation device: use a graphite crucible as a growth vessel, and the graphite crucible is composed of a graphite crucible cover and a graphite crucible cavity;

Step 2. Place the raw material: use the patterned silicon carbide single crystal or polycrystalline substrate sheet, fix the back of the patterned silicon carbide single crystal or polycrystalline substrate sheet on the inside of the graphite crucible cover, and put the silicon carbide raw material at the bottom of the graphite crucible, Put the graphite crucible into the high temperature growth furnace, so that the bottom of the graphite crucible is located in the high temperature area, and the top is located in the lower temperature area;

Step 3. Growing a silicon carbide polycrystalline block: using a physical vapor transport method to grow a silicon carbide polycrystalline block on the patterned silicon carbide substrate; wherein, the thickness of the patterned silicon carbide single crystal or polycrystalline substrate sheet 0.2-1mm. During the growth of silicon carbide polycrystalline block, the growth temperature is 1800℃-2400℃, the growth pressure is maintained at 1-5kPa, the growth time is more than 30h, and the axial temperature gradient of the graphite crucible is in the range of 3℃-8℃. centimeter.

Further, in the step 1, the graphite crucible is in the shape of a cylindrical shell, and the graphite crucible cover is closed and connected to the graphite crucible cavity through threads.

Further, in the step 2, the opening depth of the patterned silicon carbide single crystal or polycrystalline substrate sheet is 10 μm-50 μm, the pattern width is 10 μm-50 μm, and the pattern spacing is 10 μm-50 μm.

Further, in the step 2, the thickness of the patterned silicon carbide single crystal or polycrystalline substrate sheet is 0.2-0.8 mm.

Further, in the step 2, the silicon carbide raw material is pure silicon carbide powder with a purity greater than 99%.

Further, in the step 3, the growth time is 40-100h.

Further, in the step 3, the axial temperature gradient of the graphite crucible ranges from 3°C to 8°C per centimeter.

Further, in the step 3, in the growth method, the carrier gas is a mixed gas of an inert gas and nitrogen.

The beneficial effects are as follows: the present invention provides a preparation method of a transparent colored silicon carbide polycrystalline plate, the preparation method is simple, and by using a patterned silicon carbide single crystal or polycrystalline substrate, the obtained transparent colored silicon carbide polycrystalline plate not only The color is bright, and the density and thermal conductivity are better than traditional silicon carbide ceramics, and its purity is higher and the uniformity is good, which can promote the wider application of silicon carbide materials, and its economic cost is much lower than that of single crystal materials.

Description of drawings

Fig. 1 is the working schematic diagram of the present invention.

Among them, 1, patterned silicon carbide substrate, 2, graphite crucible, 3, silicon carbide raw material, 4, heating coil, 5, heat insulating material.

Detailed ways

In order to make those skilled in the art better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to specific embodiments. The embodiments described below are exemplary, only used to explain the present invention, and should not be construed as a limitation of the present invention.

In view of the above problems existing in the prior art, the present invention provides a method for preparing a transparent colored silicon carbide polycrystalline plate. By using a graphite crucible as a growth vessel, the graphite crucible is composed of a graphite crucible cover and a graphite crucible cavity; using a graph Silicon carbide single crystal or polycrystalline substrate, fix the back of the substrate on the inside of the graphite crucible cover, put the silicon carbide raw material at the bottom of the graphite crucible, put the graphite crucible into the high temperature growth furnace, so that the bottom of the graphite crucible is located in the high temperature area, and the top Located in a lower temperature region, a silicon carbide polycrystalline block is grown on a patterned silicon carbide substrate by a physical vapor transport method; wherein, the thickness of the patterned silicon carbide single crystal or polycrystalline substrate is 0.2-1 mm, and the thickness of the patterned silicon carbide single crystal or polycrystalline substrate is 0.2-1 mm. During the growth of the silicon polycrystalline block, the growth temperature is 1800°C-2400°C, the growth pressure is maintained at 1-5kPa, the growth time is more than 30 hours, and the axial temperature gradient of the graphite crucible is in the range of 3°C-8°C per centimeter.

In order to solve the above-mentioned technical problems, the technical solution adopted in the present invention is: as shown in Figure 1, a preparation method of a transparent colored silicon carbide polycrystalline plate, comprising the following steps:

1. By using a graphite crucible 2 as a growth vessel, the graphite crucible 2 is wrapped with a thermal insulation material 5, and the graphite crucible is made of high-purity graphite, which is composed of a graphite crucible cover and a graphite crucible cavity, and the graphite crucible cover is connected with the graphite crucible cavity through threads. seal. According to the specific embodiment of the present invention, a graphite crucible with a suitable diameter can be selected in the range of 2-10 inches for the size requirement of preparing the silicon carbide polycrystalline plate.

2 Use the patterned silicon carbide single crystal or polycrystalline substrate sheet 1, fix the back of the substrate sheet on the inside of the graphite crucible cover, put the silicon carbide raw material at the bottom of the graphite crucible 3, put the graphite crucible into the high temperature growth furnace, make the bottom of the graphite crucible In the high temperature zone, the top is in the lower temperature zone.

According to specific embodiments of the present invention, the crystal form, material and specific shape of the patterned open-pore structure of the patterned silicon carbide single crystal or polycrystalline substrate are not particularly limited. According to some specific embodiments of the present invention, the material of the patterned silicon carbide single crystal or polycrystalline substrate sheet is silicon carbide single crystal wafer and polycrystalline wafer, and the crystal form is 2H-, 4H-, 6H-, 15R- or other α Type structure silicon carbide wafers. The shape of the openings of the patterned silicon carbide single crystal or polycrystalline substrate sheet includes, but is not limited to, stripe, wavy, cone, triangular pyramid, arc, square, and inverted trapezoid; the patterned silicon carbide The opening depth of the opening structure of the single crystal or polycrystalline substrate sheet is 10 μm-50 μm, the pattern width is 10 μm-50 μm, and the pattern spacing is 10 μm-50 μm. According to a specific embodiment of the present invention, the thickness of the patterned silicon carbide single crystal or polycrystalline substrate is 0.2-1 mm.

According to the specific embodiment of the present invention, the fixing manner between the patterned silicon carbide single crystal or polycrystalline substrate and the inner side surface of the upper cover of the crucible is not particularly limited. According to some specific embodiments of the present invention, the patterned silicon carbide single crystal or polycrystalline substrate is fixed on the inner side of the upper cover of the crucible by means of bonding. The patterned substrate surface is placed opposite the silicon carbide feedstock. The silicon carbide raw material 3 is placed on the inner bottom of the graphite crucible 2. According to the specific embodiment of the present invention, the purity of the silicon carbide raw material is 99.5%, and the closed graphite crucible is put into the heating furnace. According to a specific embodiment of the present invention, after the graphite crucible is placed in a heating furnace, the furnace cavity is sealed and evacuated, and an inert gas is introduced. According to a specific embodiment of the present invention, the inert gas is argon. The heating coil 4 of the heating furnace is heated around the furnace cavity, and a suitable thermal field is obtained by adjusting the position of the graphite crucible up and down. centimeter.

3. The silicon carbide polycrystalline block is grown on the patterned silicon carbide substrate by the physical vapor transport method. According to a specific embodiment of the present invention, the growth temperature of the silicon carbide polycrystalline block is 1800°C-2400°C, the growth pressure is maintained at 1-5kPa, the growth time is 50-120 hours, and the axial temperature gradient range of the graphite crucible is 3°C -8°C per cm.

Thus, the present invention provides a method for preparing a transparent colored silicon carbide polycrystalline plate. By using a patterned silicon carbide single crystal or polycrystalline substrate sheet, the graphite crucible is put into a heating furnace to grow silicon carbide crystals. The growth temperature is 1800℃-2400℃, the growth pressure is 1-5kPa, and the obtained silicon carbide polycrystal can be cut, ground and polished to obtain a transparent colored silicon carbide polycrystal plate.

In the description of this specification, description with reference to the terms "embodiment," "specific embodiments," "some embodiments," etc. means that a particular feature, material, structure, or characteristic described in connection with the embodiment or example is included in the present invention at least one embodiment of . In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment. Furthermore, the particular features, materials, structures or characteristics described may be combined in any suitable manner in one or more embodiments.

Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope is defined by the claims and their equivalents.

Specific Example 1

First, the 3-inch-diameter silicon carbide polycrystalline substrate that has been patterned and corroded is glued to the inner measuring surface of the graphite crucible cover with graphite. The bottom of the graphite crucible cavity is put into the silicon carbide raw material with a purity of 99.6%, and the graphite crucible cover is screwed tightly. It is tightly wrapped with thermal insulation felt and placed in the heating furnace, the silicon carbide raw material is controlled to be placed in the high temperature area, the graphite crucible cover is placed in the low temperature area, and the axial temperature gradient of the graphite crucible is controlled to be 3°C/cm. Pump the vacuum to less than 1.5 × 10 ^-2 Pascals, fill with argon to make the pressure in the furnace 20 Torr, heat up to the growth temperature of 2150 ° C, grow for 80 hours, program control to cool down to room temperature, open the heating furnace, and open the graphite crucible, that is, Silicon carbide polycrystals with a thickness of 12 mm can be obtained on the graphite crucible cover, and transparent colored silicon carbide polycrystalline plates can be obtained by cutting, grinding and polishing, with a total thickness of 0.9 mm and a diameter of 76 mm.

Silicon carbide crystal growth usually inherits the crystal structure of the seed crystal, but it is also related to the growth surface of the seed crystal. The light yellow 4H-crystal can grow on the (000-1) plane, the green 6H-crystal and the brown 15R- The crystal form can be grown on the (11-20) plane or the (1-100) plane. Therefore, the present invention selects the patterned silicon carbide crystal substrate, which can provide different growth surfaces with dispersed multiple regions. Thus, a transparent colored silicon carbide polycrystalline plate can be obtained.

Claims (8)

1. A preparation method of a transparent colorful silicon carbide polycrystalline plate is characterized by comprising the following steps: the method comprises the following steps:

step 1, preparing a device: a graphite crucible is used as a growth container, and the graphite crucible consists of a graphite crucible cover and a graphite crucible cavity;

step 2, placing raw materials: using a patterned silicon carbide single crystal or polycrystalline substrate slice, fixing the back of the patterned silicon carbide single crystal or polycrystalline substrate slice on the inner side of a graphite crucible cover, putting a silicon carbide raw material at the bottom of the graphite crucible, putting the graphite crucible into a high-temperature growth furnace, and enabling the bottom of the graphite crucible to be located in a high-temperature region and the top of the graphite crucible to be located in a lower-temperature region;

step 3, growing the silicon carbide polycrystalline block: growing a silicon carbide polycrystalline block on the graphical silicon carbide substrate by adopting a physical vapor transport method; the thickness of the graphical silicon carbide single crystal or polycrystalline substrate slice is 0.2-1mm, the growth temperature is 1800-2400 ℃ in the growth process of the silicon carbide polycrystalline block, the growth pressure is kept at 1-5kPa, the growth time is more than 30h, and the axial temperature gradient range of the graphite crucible is 3-8 ℃ per centimeter.

2. The method of claim 1, wherein the step of preparing a transparent colored silicon carbide polycrystalline plate comprises: in the step 1, the graphite crucible is in a cylindrical shell shape, and the graphite crucible cover is connected with the graphite crucible cavity in a sealing manner through threads.

3. The method of claim 1, wherein the step of preparing a transparent colored silicon carbide polycrystalline plate comprises: in the step 2, the opening depth of the patterned silicon carbide single crystal or polycrystalline substrate slice is 10-50 μm, the pattern width is 10-50 μm, and the pattern interval is 10-50 μm.

4. The method of claim 1, wherein the step of preparing a transparent colored silicon carbide polycrystalline plate comprises: in the step 2, the thickness of the patterned silicon carbide single crystal or polycrystalline substrate slice is 0.2-0.8 mm.

5. The method of claim 1, wherein the step of preparing a transparent colored silicon carbide polycrystalline plate comprises: in the step 2, the silicon carbide raw material is pure silicon carbide powder with the purity of more than 99%.

6. The method of claim 1, wherein the step of preparing a transparent colored silicon carbide polycrystalline plate comprises: in the step 3, the growth time is 40-100 h.

7. The method of claim 1, wherein the step of preparing a transparent colored silicon carbide polycrystalline plate comprises: in the step 3, the axial temperature gradient range of the graphite crucible is 3-8 ℃ per centimeter.

8. The method of claim 1, wherein the step of preparing a transparent colored silicon carbide polycrystalline plate comprises: in the step 3, in the growth method, the carrier gas is a mixed gas of an inert gas and nitrogen.

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