A pretreatment device and manufacturing method for a new type of silicon carbide substrate

Abstract

The present invention provides a pretreatment device and manufacturing method for a novel silicon carbide substrate, including an intake pipeline, a reaction chamber, a heat insulation layer, a support component, a radio frequency heating component, a vacuum pumping component, an exhaust gas treatment pipeline, a heating substrate, and a substrate tray; the intake pipeline and the exhaust gas treatment pipeline are respectively located on two sides of the heat insulation layer, the radio frequency heating component is located at the bottom of the reaction chamber, the support component is located on the heating substrate and fixes the heating substrate to the inner bottom of the heat insulation layer, a groove is provided on the heating substrate, the substrate tray is located at the groove, and the vacuum pumping component is located outside the heat insulation layer; the substrate tray includes a base material, a structural layer, and a protective layer; the structural layer is located on the base material and has a standard morphology or a pattern support structure; the protective layer is located on the structural layer. The beneficial effects of the present invention are as follows: reducing substrate defects, improving the pretreatment before substrate epitaxial growth, performing large-batch and multi-batch processing without affecting the substrate treatment effect, reducing the epitaxial preparation time at the same time, and shortening the process flow.

Description

Technical Field

[0001] The present invention relates to semiconductor manufacturing equipment, and particularly to a pretreatment device and manufacturing method for a novel silicon carbide substrate. Background Art

[0002] The epitaxial growth process of the third-generation semiconductor material silicon carbide (SiC) consists of five parts: single crystal, epitaxy, device, module, and application. Among them, epitaxy is of crucial importance as the bridge connecting the single crystal and the device. However, due to the close-packed hexagonal crystal structure of 4H-type silicon carbide, special single crystal and substrate preparation processes, a large number of defects that are not conducive to subsequent epitaxial growth will be left in the substrate. Therefore, it is necessary to treat the substrate before epitaxial growth to reduce the number of defects in the substrate. Such a process is called "pretreatment of the silicon substrate".

[0003] The process methods for reducing defects in SiC single crystal substrates are mainly applied in the pretreatment stage and the epitaxial stage. General substrate pretreatment includes chemical mechanical polishing, deposition of a carbon protection layer, and high-temperature annealing in a protective atmosphere; while the epitaxial preparation stage includes in-situ / non-in-situ etching, design of a highly doped buffer layer, design of the epitaxial Si / C ratio, and growth interruption. The current silicon carbide substrate defect conversion process is usually located in the epitaxial stage. In this stage, in-situ etching with hydrogen and growth of a high-nitrogen buffer layer are used to prevent substrate defects from extending into the epitaxial layer. However, the above process steps not only prolong the entire silicon carbide epitaxial process flow, but also have a greater impact on the service life of the equipment, the background doping concentration in the epitaxial stage, and the actual production efficiency for single-wafer epitaxial equipment. Therefore, it is necessary to separately process the substrate treatment link and the actual epitaxial link in the current process flow, and perform large-batch and multi-batch processing without affecting the substrate treatment effect.

[0004] In the above pretreatment stage, it is necessary to perform annealing treatment on the single crystal substrate in a high-temperature environment. Therefore, graphite material is usually selected as the base material of the container in the above pretreatment process. However, in the actual annealing process, high temperature will cause adhesion between the inner surface of the graphite container and the substrate, which may in turn cause malignant events such as substrate scratching and fracture. Therefore, according to the relevant patent (CN102449185.B), the use of a tantalum container and the corresponding carburizing process can effectively reduce the adhesion phenomenon between the substrate and the container. However, a series of problems such as poor contact and easy detachment between the tantalum layer and the base material, and too thick or too thin tantalum layer thickness have also emerged. At the same time, the price of tantalum-based materials is not low, and it is necessary to balance the cost and the protection effect at the same time. Summary of the Invention

[0005] In order to solve the above technical problems, a pretreatment device and manufacturing method for a novel silicon carbide substrate are disclosed in the present invention. The technical solution of the present invention is implemented as follows:

[0006] A pretreatment device for a new type of silicon carbide substrate, comprising an intake pipeline, a heat insulation layer, a support component, a radio frequency heating component, a vacuum pumping component, an exhaust gas treatment pipeline, a heating substrate, and a substrate tray;

[0007] The intake pipeline and the exhaust gas treatment pipeline are respectively located on two sides of the heat insulation layer. The heat insulation layer is located on the inner side wall of the reaction chamber. The radio frequency heating component is located at the bottom of the reaction chamber. The support component is located on the heating substrate and fixes the heating substrate at the inner bottom of the heat insulation layer. A groove is provided on the heating substrate, and the substrate tray is located at the groove. The vacuum pumping component is located outside the heat insulation layer;

[0008] The substrate tray includes a base material, a structure layer, and a protective layer;

[0009] The structure layer is located on the base material and has a standard morphology or a pattern support structure; the protective layer is located on the structure layer.

[0010] Preferably, the number of the standard morphology or pattern support structures is 3, the height is 1 - 5 mm, and the width is 5 - 10 cm.

[0011] Preferably, the innermost ring of the standard morphology or pattern support structure forms a substrate placement groove, and the height of the substrate placement groove is 2 - 10 mm, and the diameter is 20.5 - 21 cm.

[0012] Preferably, the height of the substrate tray is 10 - 15 mm, and the diameter is 21 - 25 cm.

[0013] Preferably, the substrate tray further includes a tray edge, and the width of the tray edge is 0 - 1 cm.

[0014] Preferably, the material of the protective layer is selected from one of tantalum and niobium metals.

[0015] Preferably, the material of the protective layer is niobium metal, and the height of the protective layer is 3 - 5 mm.

[0016] Preferably, the types of the heating substrate include 6*8 inch, 8*6 inch, and 12*4 inch.

[0017] Preferably, the heating substrate includes a tray placement area and a silicon source placement hole; the tray placement area and the silicon source placement hole are rotationally symmetrically distributed on the heating substrate.

[0018] Preferably, the height of the heating substrate is 10 - 15 cm, and the diameter is 65 - 70 cm.

[0019] Preferably, the height of the silicon source placement hole is 0.5 - 2 cm, the diameter is 1 - 2 cm, and the angular distance between adjacent silicon source placement holes is 30 - 60 degrees.

[0020] Preferably, the heating substrate is a carbon-based substrate.

[0021] Preferably, the heating substrate is a graphite substrate.

[0022] A manufacturing method of a pretreatment device for a novel silicon carbide substrate includes the following steps;

[0023] Heating substrate preparation: Using cutting, grinding, and polishing machining tools, corresponding features are prepared on the surface of the heating substrate;

[0024] Substrate tray preparation: Before preparation, a three-dimensional model of the required standard topography or pattern support structure needs to be prepared in advance; Select a substrate that matches the size of the groove part of the heating substrate; Using traditional cutting, grinding, and polishing machining processes, the standard topography or pattern support structure is prepared on the surface of the substrate to form a substrate tray;

[0025] Substrate tray surface treatment: The surface of the substrate tray is purified;

[0026] Protective layer deposition: A protective layer is deposited on the surface of the purified substrate tray;

[0027] Carburizing treatment: The protective layer is carburized to form a composite protective layer;

[0028] Product assembly: All components are installed into a finished product.

[0029] Preferably, the protective layer material is niobium metal. Using chemical vapor deposition, TaCl5 and H2 are used as gas sources, and H2 is used as a carrier gas. A tantalum metal layer is deposited on the surface under the growth conditions of a temperature of 1000 - 1800 °C and a pressure of 100 - 500 Pa.

[0030] Preferably, the heating substrate with the substrate tray is placed in a closed reaction furnace made of graphite material and pumped to a vacuum degree less than 0.1 Pa. It is heated to 2000 - 2200 °C at a heating rate of 600 - 800 °C / h and held for 1.5 - 3 hours, and then cooled to room temperature at a cooling rate of 100 - 150 °C / h to obtain a tantalum carbide layer through a carburizing process.

[0031] Preferably, the carburizing process parameters for obtaining the carbon carbide layer: It is heated to 2150 °C at a heating rate of 700 °C / h and held for 2 hours, and then cooled to room temperature at a cooling rate of 140 °C / h.

[0032] Implementing the technical solution of the present invention can solve the technical problems existing in the prior art of substrate pretreatment; implementing the technical solution of the present invention can achieve the technical effects of reducing substrate defects, improving the pretreatment before substrate epitaxial growth, performing large-batch and multi-batch processing without affecting the substrate treatment effect, reducing the epitaxial preparation time, and shortening the process flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only one embodiment of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0034] Among them, the same components are denoted by the same reference numerals. It should be noted that the terms "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to the directions in the drawings, and the terms "bottom surface" and "top surface", "inner" and "outer" refer to the directions towards or away from the geometric center of a specific component, respectively.

[0035] Figure 1 It is a schematic cross-sectional structure diagram of a pretreatment device for a silicon carbide substrate;

[0036] Figure 2 It is a structural diagram of three types of heating substrates;

[0037] Figure 3 It is a cross-sectional view of a heating substrate;

[0038] Figure 4 It is a top view structural diagram and a cross-sectional view of a substrate tray;

[0039] Figure 5 It is a process flow diagram of a pretreatment device for a silicon carbide substrate.

[0040] In the above drawings, the reference numerals in each figure respectively represent:

[0041] 1, argon inlet pipeline

[0042] 2, reaction chamber

[0043] 3, heat insulation layer

[0044] 4, radio frequency heating coil

[0045] 5, support member

[0046] 6, heating substrate

[0047] 7, groove

[0048] 8, tail gas treatment pipeline

[0049] 9. Substrate tray Detailed implementation manners

[0050] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0051] Embodiment

[0052] In a specific embodiment, as Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 shown, a pretreatment device for a novel silicon carbide substrate includes an argon inlet pipeline 1, a reaction chamber 2, a heat insulation layer 3, a support member 5, a radio frequency heating coil 4, a vacuum pumping member (not marked in the figure), an exhaust gas treatment pipeline 8, a heating substrate 6 and a substrate tray 9;

[0053] The argon inlet pipeline 1 and the exhaust gas treatment pipeline 8 are respectively located on two sides of the heat insulation layer 3. The heat insulation layer 3 is located on the inner side wall of the reaction chamber 2. The radio frequency heating member 4 is located at the bottom of the reaction chamber 2. Through electromagnetic induction heating, without contacting the reaction chamber 2, the radio frequency heating coil 4 can adjust the position and the density. For example, it is centrosymmetric, with a dense central coil and a sparse peripheral coil. In this way, by controlling the position of the radio frequency heating coil 4 and the input power of the coil, the distribution and effect of the temperature field can be controlled. This adjustment method can be selected according to actual needs; the support member 5 is located on the heating substrate 6 and fixes the heating substrate 6 at the inner bottom of the heat insulation layer 3. A groove 7 is provided on the heating substrate 6. The substrate tray 9 is located at the groove 7. The vacuum pumping member is located outside the heat insulation layer 3; in this embodiment, the vacuum pumping member and the exhaust gas treatment pipeline 8 are on the same horizontal plane. Actually, the position can be adjusted according to needs, and a conventional vacuum pumping device can be used. The types of the heating substrate 6 include 6*8inch, 8*6inch and 12*4inch. The heating substrate 6 in this embodiment is 6*8inch.

[0054] The substrate tray 9 includes a base material, a structural layer, a protective layer and a tray edge. The width of the tray edge is 0.5 cm.

[0055] The structural layer is located on the base material and has a standard morphology or a pattern support structure; the protective layer is located on the structural layer.

[0056] The number of the standard morphology or pattern support structures is 3, the height is 1-5 mm, and the width is 5-10 cm.

[0057] The innermost ring of the standard topography or pattern support structure forms a substrate placement groove. The height of the substrate placement groove is 2 - 10 mm, and the diameter of the substrate placement groove 7 * 2 + 20 cm = the minimum substrate diameter. In this embodiment, the 6 * 8 inch specification is adopted, and the corresponding diameter of the substrate placement groove is 20.5 - 21 cm, and the height is 4 - 6 mm.

[0058] The height of the substrate tray 9 is 10 - 15 mm, and the diameter is 21.5 - 22 cm.

[0059] In this embodiment, the material of the protective layer is niobium metal, and the height of the protective layer is 3 - 5 mm.

[0060] The heating substrate 6 includes a tray placement area and silicon source placement holes; the tray placement area and the silicon source placement holes are rotationally symmetrically distributed on the heating substrate 6. The height of the heating substrate 6 is 10 - 15 cm, and the diameter is 65 - 70 cm. The height of the silicon source placement hole is 0.5 cm, the diameter is 2 cm, and the angular distance between adjacent silicon source placement holes is 60 degrees.

[0061] The heating substrate 6 is a carbon - based substrate. In this embodiment, the heating substrate 6 is a graphite substrate.

[0062] The heating substrate 6 in this embodiment supports large - batch and multi - batch processing of substrates. The heating substrate 6 evenly distributes the substrate trays 9 and has the characteristic of rotational central symmetry. At the same time, silicon source placement holes of corresponding specifications are distributed on the heating substrate 6 with a misaligned axis with respect to the position of the substrate trays 9. The hole distribution should also have the characteristic of rotational central symmetry, and the radial distribution characteristic should be symmetric about the position of the second marking line (Second marking line: the centers of the grooves 7 of the 6 heating substrates 6 are on the same circle, that is, the placement position of the substrate trays 9, not marked in the figure).

[0063] The size of the substrate tray 9 corresponds to the caliber of the groove 7 in the heating substrate 6. At the same time, the substrate tray 9 has a standard topography or pattern support structure, and a tantalum carbide / tantalum protective layer is introduced on the surface of the standard topography or pattern support structure. It can control substrate adhesion while effectively preventing the diffusion and infiltration of substrate elements or other impurity elements into the substrate. It effectively reduces the pedestal deformation phenomenon caused by the difference in thermal expansion coefficients between the substrate and the protective layer. By controlling the deposition time of tantalum metal and subsequent processing process parameters, the thickness of the tantalum layer can be effectively controlled. While conforming to the original substrate surface topography of the substrate tray 9, the protective layer thins the thickness of the tantalum composite layer in the prior art. Its special surface topography increases the contact area between the protective layer and the substrate and reduces the contact area with the substrate, reducing the phenomenon of substrate adhesion.

[0064] The manufacturing method of this embodiment includes the following steps;

[0065] Heating substrate 6 part: The size of the selected graphite block material should be selected according to the actual size of the silicon carbide reaction furnace cavity and the diameter of the substrate. In this example, the size of the selected graphite block substrate is; the diameter is 65 - 70 cm, and the height is 10 - 15 cm.

[0066] Heating substrate 6: Using machining tools such as cutting and grinding, grooves 7 are prepared on the surface of the substrate; the diameter of the grooves 7 should be determined according to the required substrate tray 9, and a margin of 5 - 10 mm should be reserved. In this embodiment, an 8-inch substrate is selected, and the width of the groove 7 should be 23 - 25 cm; the depth of the recessed part is 5 - 8 cm from the bottom of the substrate. A multi-stage gradient structure is prepared at the edge of the groove 7, and the gradient ratio is 1.5.

[0067] Silicon source placement holes: The distribution position, pore diameter, and pore depth of the silicon source placement holes in this embodiment are closely related to the substrate specifications. The solution provided in this example is that the distribution angle of the silicon source placement holes is rotated at an angle of 60°, and is rotationally symmetric about the center of the substrate. The first silicon source hole is located on the first scale line (the first scale line: the common circumscribed circle of the grooves 7 of 6 heating substrates 6), and the second silicon source hole is located on the third scale line (the third scale line: the common inscribed circle of the grooves 7 of 6 heating substrates 6). The aperture of the silicon source placement hole is 2 cm, and the depth is 0.5 cm.

[0068] Substrate tray 9 part: The structure should match the groove 7 of the heating substrate 6. The size is 22 - 23 cm, the height is 1 cm, and the edge step gradient ratio is 1.5.

[0069] Standard topography or pattern support structure: After three-dimensional modeling, the required support structure layer is prepared in the recess of the substrate tray 9. The height, width, and spacing of the pattern lines of the support structure layer should be determined by the actual required temperature field effect. According to the control standard of the actual temperature field, the heights of the pattern lines of the standard topography or pattern support structure may not be in the same plane. In order to achieve the temperature field uniformity on the surface of the substrate tray 9, all the pattern lines of the standard topography or pattern support structure should have central rotational symmetry. The design and preparation modes of the standard topography or pattern support structure include, but are not limited to, traditional machining techniques such as cutting and grinding, digital machining centers, and 3D printing.

[0070] After the above components are prepared, the surface of the substrate tray 9 needs to be purified. The auxiliary gases used include, but are not limited to, chlorine, hydrogen, etc. After the above surface treatment, the surface gray scale of the container drops below 20 ppm.

[0071] Preparation of the protective layer: Deposit a tantalum metal layer on the surface of the purified substrate tray 9 described above. The tantalum metal layer in this embodiment is prepared by chemical vapor deposition (CVD). The tantalum metal layer is deposited on the surface under the growth conditions of a temperature of 1000 - 1800 °C and a pressure of 100 - 500 Pa. In this example, TaCl5 and H2 are used as reactants and carrier gases, and the tantalum metal layer is deposited on the inner surface of the container prepared above under the growth conditions of a temperature of 1200 °C and a pressure of 200 Pa, and the effect is optimal under these growth conditions. To avoid the influence of the long-term heat treatment environment on the morphology of the protective layer, the deposition thickness is 3 - 5 mm.

[0072] Carburizing treatment: Perform carburizing treatment on the substrate tray 9 to form a tantalum carbide / tantalum composite protective layer. The specific method is to place the heated substrate 6 with the substrate tray 9 in a closed reaction furnace made of graphite material and evacuate it to a vacuum degree of less than 0.1 Pa. By setting the heating and cooling curves during the carburizing process, the thickness and surface flatness of the TaC protective layer can be controlled. This embodiment is carried out under the carburizing conditions (heating up to 2150 °C at a heating rate of 700 °C / h and holding for 2 hours, and then cooling down to room temperature at a cooling rate of 140 °C / h). Through the above carburizing process, a tantalum carbide layer with a coating thickness of 5 μm can be obtained.

[0073] It should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A manufacturing method of a pre-treatment device for a silicon carbide substrate, comprising the following steps: Heating substrate preparation: Using a cutting and polishing machining tool, corresponding features are prepared on the surface of the heating substrate. Substrate tray preparation: Before preparation, a three-dimensional model of the required standard topography or pattern support structure needs to be prepared in advance; a substrate matching the size of the groove part of the heating substrate is selected; using traditional cutting and polishing machining processes, the standard topography or pattern support structure is prepared on the surface of the substrate to form a substrate tray. Surface treatment of the substrate tray: The surface of the substrate tray is purified. Deposition of the protective layer: A protective layer is deposited on the surface of the purified substrate tray. Carburizing treatment: The protective layer is subjected to carburizing treatment to form a composite protective layer. Product assembly: All components are installed into a finished product. The pre-treatment device for the silicon carbide substrate includes an intake pipeline, a reaction chamber, a heat insulation layer, a support component, a radio frequency heating component, a vacuum pumping component, an exhaust gas treatment pipeline, a heating substrate, and a substrate tray. The intake pipeline and the exhaust gas treatment pipeline are respectively located on two sides of the heat insulation layer. The heat insulation layer is located on the inner side wall of the reaction chamber. The radio frequency heating component is located at the bottom of the reaction chamber. The support component is located on the heating substrate and fixes the heating substrate at the inner bottom of the heat insulation layer. Grooves are provided on the heating substrate. The substrate tray is located at the grooves. The vacuum pumping component is located outside the heat insulation layer. The substrate tray includes a substrate, a structure layer, and a protective layer. The structure layer is located on the substrate and has a standard topography or pattern support structure. The innermost ring of the standard topography or pattern support structure forms a substrate placement groove. At least one protrusion is formed outside the innermost ring of the standard topography or pattern support structure. The protrusion has central rotational symmetry. The protective layer is located on the structure layer. The heating substrate includes a tray placement area and a silicon source placement hole. The tray placement area and the silicon source placement hole are rotationally symmetrically distributed on the heating substrate.

2. The manufacturing method of a pretreatment device for a silicon carbide substrate according to claim 1, characterized in that: The types of the heating substrate include 6*8inch, 8*6inch, and 12*4inch.

3. The manufacturing method of a pretreatment device for a silicon carbide substrate according to claim 1, characterized in that: The height of the heating substrate is 10 - 15 cm, and the diameter is 65 - 70 cm. The height of the silicon source placement hole is 0.5 - 2 cm, and the diameter is 1 - 2 cm. The angular distance between adjacent silicon source placement holes is 30 - 60 degrees.

4. The manufacturing method of a pre-treatment device for a silicon carbide substrate according to claim 1, characterized in that: The heating substrate is a carbon-based substrate.

5. The manufacturing method of a pretreatment device for a silicon carbide substrate according to claim 4, characterized in that: The heating substrate is a graphite substrate.

6. The manufacturing method of a pretreatment device for a silicon carbide substrate according to claim 1, characterized in that: The height of the substrate placement groove is 2 - 10 mm, and the diameter is 20.5 - 21 cm. The height of the substrate tray is 10 - 15 mm, and the diameter is 21 - 25 cm. The number of protrusions of the standard topography or pattern support structure is 3, the height is 1 - 5 mm, and the width is 5 - 10 cm. The substrate tray also includes a tray edge, and the width of the tray edge is 0 - 1 cm. The protective layer material is selected from one of tantalum and niobium metals.

7. The manufacturing method of a pretreatment device for a silicon carbide substrate according to claim 6, characterized in that: The protective layer material is tantalum metal. Using the chemical vapor deposition method, TaCl5 and H2 are used as the gas sources, and H2 is used as the carrier gas. A tantalum metal layer is deposited on the surface under the growth conditions of a temperature of 1000 - 1800 °C and a pressure of 100 - 500 Pa.

8. The manufacturing method of a pretreatment device for a silicon carbide substrate according to claim 7, characterized in that: During the carburizing treatment, the heated substrate with the substrate tray is placed in a closed reaction furnace made of graphite material and evacuated to a vacuum degree of less than 0.1 Pa. It is heated to 2000 - 2200 °C at a heating rate of 600 - 800 °C / h and held for 1.5 - 3 hours, and then cooled to room temperature at a cooling rate of 100 - 150 °C / h to obtain a tantalum carbide layer through the carburizing process.

Images