CN117418305A

CN117418305A - Silicon carbide crystal growth equipment and growth method

Info

Publication number: CN117418305A
Application number: CN202311255203.0A
Authority: CN
Inventors: 伍艳; 张洁
Original assignee: Hunan Sanan Semiconductor Co Ltd
Current assignee: Hunan Sanan Semiconductor Co Ltd
Priority date: 2023-09-26
Filing date: 2023-09-26
Publication date: 2024-01-19

Abstract

The application discloses a silicon carbide crystal growth device and a growth method, wherein the silicon carbide crystal growth device comprises a crucible, a gas mixing device and a gasification device; wherein the crucible has a chamber for placing the source material and mounting the seed crystal; the gas mixing device is communicated with the cavity through a first pipeline, a first gas pipeline valve is arranged on the first pipeline, and the gasification device is communicated with the gas mixing device through a second pipeline and is used for placing and heating solid dopants; the device also comprises a third pipeline, one end of which is communicated with the gas mixing device, and the other end of which is used for being communicated with the carrier gas storage tank and/or the doping gas storage tank; in the silicon carbide crystal growth process, the rate of the mixed gas containing the doping gas and the carrier gas transmitted to the cavity of the crucible can be controlled through the first gas circuit valve, the release speed of the doping gas can be effectively controlled, the crystal doping uniformity is improved, and the electrical property of subsequent products is guaranteed.

Description

Silicon carbide crystal growth equipment and growth method

Technical Field

The application relates to the technical field of crystal growth, in particular to silicon carbide crystal growth equipment and a silicon carbide crystal growth method.

Background

In the crystal growth process, a physical gas phase transport method is generally adopted for crystal growth, so that the method is easy to manufacture and the crystal growth process is well controlled.

In practical operation, the research and development personnel of the application find that in order to realize different electrical properties after the crystal growth, in the crystal growth process, a diffusion mode is adopted to carry out doping in the crystal growth process, and the release of the doping concentration of the doping source is difficult to control, so that the crystal doping is uneven, and the electrical properties of subsequent products are affected.

Disclosure of Invention

The technical problem that this application mainly solves is to provide a carborundum (SiC) crystal growing device and growth method, can effectively control the doping concentration release rate of doping source, improves crystal doping uniformity.

In order to solve the technical problems, one technical scheme adopted by the application is as follows: providing a silicon carbide (SiC) crystal growth apparatus comprising a crucible, a gas mixing device, a gasification device, and a third conduit; wherein the crucible has a chamber for placing the raw material and mounting the seed crystal; the gas mixing device is communicated with the cavity through a first pipeline, and a first gas pipeline valve is arranged on the first pipeline; the gasification device is communicated with the gas mixing device through a second pipeline and is used for placing and heating solid dopants; one end of the third pipeline is communicated with the gas mixing device, and the other end of the third pipeline is used for being communicated with the carrier gas storage tank and/or the doping gas storage tank.

In order to solve the technical problems, another technical scheme adopted by the application is as follows: there is provided a silicon carbide (SiC) crystal growth method including the steps of: providing a silicon carbide (SiC) crystal growth apparatus, the silicon carbide (SiC) crystal growth apparatus comprising: a crucible having a chamber for holding a source material and mounting a seed crystal; the gas mixing device is communicated with the cavity through a first pipeline, and a first gas pipeline valve is arranged on the first pipeline; the gasification device is communicated with the gas mixing device through a second pipeline; one end of the third pipeline is communicated with the gas mixing device, and the other end of the third pipeline is communicated with the carrier gas storage tank and/or the doping gas storage tank; placing solid dopants into the gasification device, gasifying the solid dopants by the gasification device, and mixing the doping gases output by the gasification device with the carrier gases transmitted by the third pipeline by the gas mixing device; or mixing the doping gas conveyed by the third pipeline and the carrier gas conveyed by the third pipeline through the gas mixing device; and transmitting the mixed gas output by the gas mixing device into the chamber through the first gas circuit valve so as to realize doping in the silicon carbide (SiC) crystal growth process.

Different from the prior art, the silicon carbide (SiC) crystal growth equipment provided by the application can gasify the doping source to be gasified through the gasification device, and convey the gasified doping source to the gas mixing device through the second pipeline, and can also directly convey the doping gas which does not need to be gasified to the gas mixing device, so that the doping gas is conveyed to the chamber of the crucible for doping after being fully mixed with the carrier gas; the doping rate can be controlled and regulated through the first gas circuit valve, doping of different doping types can be performed simultaneously, the doping rate is controllable, the problem of inconsistent release rates of front and rear doping sources is avoided, the doping uniformity of the crystal growth is improved, and the electrical property of subsequent products is guaranteed.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art. Wherein:

FIG. 1 is a schematic structural view of a first embodiment of a silicon carbide (SiC) crystal growth apparatus of the present application;

FIG. 2 is a schematic structural view of a second embodiment of a silicon carbide (SiC) crystal growth apparatus of the present application;

FIG. 3 is a schematic view of an embodiment of a crucible of the present application;

FIG. 4 is a schematic view of the first embodiment of the mixing chamber of the present application;

FIG. 5 is a schematic view of the structure of a first embodiment of a curved plate of the present application;

FIG. 6 is a schematic view of a second embodiment of a mixing chamber of the present application;

FIG. 7 is a schematic view of a second embodiment of a curved plate of the present application;

FIG. 8 is a schematic structural view of a third embodiment of a silicon carbide (SiC) crystal growth apparatus of the present application;

fig. 9 is a flow chart of an embodiment of a method for silicon carbide (SiC) crystal growth in the present application.

In the drawing, a crucible 100, a through hole 101, a filter 102, a chamber 110, a gas mixing device 200, a premixing chamber 210, a mixing chamber 220, a curved plate 221, a wave plate 222, a gasification device 300, a gasification chamber 310, a first heater 320, a first pipeline p1, a first gas path valve v1, a second pipeline p2, a second gas path valve v2, and a third pipeline p3.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. It is to be understood that the specific embodiments described herein are for purposes of illustration only and are not limiting. It should be further noted that, for convenience of description, only some, but not all of the structures related to the present application are shown in the drawings. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments herein without making any inventive effort, are intended to be within the scope of the present application.

Reference in the application to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.

The terms "first," "second," and the like in this application are used for distinguishing between different objects and not for describing a particular sequential order. Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those listed steps or elements but may include other steps or elements not listed or inherent to such process, method, article, or apparatus.

In addition, although the terms "first," "second," etc. may be used several times in this application to describe various data (or various elements or various applications or various instructions or various operations) etc., these data (or elements or applications or instructions or operations) should not be limited by these terms. These terms are only used to distinguish one data (or element or application or instruction or operation) from another data (or element or application or instruction or operation). For example, the first position information may be referred to as second position information, and the second position information may be referred to as first position information, only that the two include different ranges, and the first position information and the second position information are all sets of various position and posture information, only that the two are not identical sets of position and posture information, without departing from the scope of the present application.

In the prior art, the crystal growth method mainly comprises a solution growth method, a pulling method, a crucible descending method, a physical vapor transport (physicalvapor transport, PVT) method and the like, and the physical vapor transport method has the advantages of easy equipment manufacture, better control of the crystal growth process, lower cost and the like, and becomes a commonly used method for growing silicon carbide single crystals at the present stage.

Doping techniques make it possible to achieve different electrical properties in silicon carbide (SiC) substrates, and doping techniques in crystal growth are largely divided into two categories, ion implantation and diffusion. The doping technique used for PVT growth is mainly diffusion, and the doping element enters the interior of the silicon carbide (SiC) lattice by diffusion. Silicon carbide (SiC) substrates exhibit different electrical properties by doping different elements in a single crystal of silicon carbide (SiC), and can be classified into conductive type (N-type) and semi-insulating type (P-type) according to electrical properties. The nitrogen (N2) is introduced in the crystal growth process, so that N-type doping can be easily realized, the relationship between the nitrogen (N) doping and the growth pressure is studied in detail at present, the relationship between the nitrogen doping and the temperature is complex, and although the nitrogen doping and the growth pressure are studied to a certain extent, the detailed mechanism is not fully understood.

The most common doping mode in the PVT crystal growth process is to use a solid compound to be placed in silicon carbide (SiC) powder, and the doping agent is decomposed and sublimated in the crystal growth process, so that doping is realized, however, the release rate of doping elements is not well controlled, the doping concentration is difficult to control, the release amount in the early growth stage is often larger than that in the later growth stage, and the crystal growth doping uniformity is further influenced.

Therefore, a silicon carbide (SiC) crystal growth apparatus is provided that can effectively control the doping concentration release rate of a doping source and improve the crystal doping uniformity.

Referring to fig. 1, fig. 1 is a schematic view showing a structure of a first embodiment of a silicon carbide (SiC) crystal growth apparatus of the present application.

As shown in fig. 1, a silicon carbide (SiC) crystal growth apparatus 10 includes: a crucible 100, a gas mixing device 200, and a gasification device 300; wherein the crucible 100 has a chamber 110 for placing a raw material and mounting a seed crystal, the chamber 110; the gas mixing device 200 is communicated with the chamber 110 through a first pipeline p1, a first gas path valve v1 is arranged on the first pipeline p1, and the gasification device 300 is communicated with the gas mixing device through a second pipeline p2 and is used for placing and heating the hot solid dopant; and a third pipeline p3, wherein one end of the third pipeline p3 is communicated with the gas mixing device 200, and the other end of the third pipeline p3 is used for being communicated with the carrier gas storage tank and/or the doping gas storage tank.

Wherein, the raw material is silicon carbide (SiC) source material, and the seed crystal is silicon carbide (SiC) single crystal seed crystal.

Specifically, a silicon carbide (SiC) source material is stored at the bottom of a chamber 110 in a crucible 100, a silicon carbide (SiC) single crystal seed crystal is arranged at the top of the chamber 110, under the action of heat generation and heat conduction of the crucible 100, the silicon carbide (SiC) source material is decomposed and sublimated, gas-phase substances such as silicon (Si) atoms, siC2 molecules and Si2C molecules are released, and the gas-phase substances are conveyed to a low temperature area under the driving of a vertical temperature gradient, namely conveyed to the silicon carbide (SiC) single crystal seed crystal at the top of the chamber 110, and then condensed at the silicon carbide (SiC) single crystal seed crystal to obtain a silicon carbide (SiC) crystal; and, in the process of producing silicon carbide (SiC) crystals, the gas mixing device 200 mixes the carrier gas and the doping gas, and transfers the mixed gas into the chamber 110 at a controllable preset rate, and the doping gas is transferred and adsorbed to the single crystal growth region at the top of the chamber 110 under the combined action of the vertical temperature gradient and the growth pressure, so that the doping gas is doped with the silicon carbide (SiC) crystals.

In some embodiments, the dopant gas may be obtained by gasifying the thermal-state dopant by the gasification device 300, that is, the gasification device 300 gasifies the thermal-state dopant source to obtain the dopant gas, and then the dopant gas is transferred to the gas mixing device 200 through the second pipeline P2, where the thermal-state dopant source may be a solid-state dopant source or a liquid-state dopant source, such as P-type doped trimethylaluminum (Al (CH 3) 3), vanadium tetrachloride (VCl 4), and the like.

In other embodiments, the dopant gas is a dopant source that does not require vaporization, such as N-type dopant source nitrogen (N2), and may be directly introduced into the gas mixing apparatus 200.

The carrier gas is a gas for conveying the doping gas to the accommodating cavity, does not react, and belongs to inert gases such as argon (Ar) or hydrogen (H2) and the like; the doping gas can be fully and uniformly mixed with the carrier gas, and when the doping gas is transmitted to the chamber 110, the output rate of the mixed gas can be controlled by adjusting the first gas circuit valve v1 on the first pipeline p1, so that the doping rate can be adjusted, the problem of inconsistent release rates of the front and rear doping gases in the crystal growth process is avoided, and the crystal growth doping uniformity is improved.

In some embodiments, the outside of the first pipe p1 is provided with heating means for heating the first pipe p 1; further, a heating device may be disposed on the outer side of the second pipeline p2, for heating the second pipeline p 2; further, a heating device may be disposed outside the gas mixing device 200 for heating the gas mixing device 200, and the pipe outside the crucible may be a metal pipe, and the pipe inside the crucible may be a graphite pipe; the heating temperature of the heating device is 20-300 ℃, so that the thermal movement of molecules can be accelerated, and the doped gas can be effectively prevented from condensing in each pipeline and the gas mixing device.

In this embodiment, the raw materials and the seed crystal are placed in the chamber 110 of the crucible 100, so that the raw materials and the seed crystal are separated from the doped gas, the doped gas and the carrier gas are mixed by the gas mixing device 200, and the mixed gas enters the chamber 110 at a controlled rate by the first gas circuit valve on the first pipeline p1, so as to realize the control of the doping concentration.

When the doping source is a doping gas, the second embodiment is referred to, and the same parts as those of the first embodiment will not be described again.

Referring to fig. 2, fig. 2 is a schematic structural view of a second embodiment of a silicon carbide (SiC) crystal growth apparatus of the present application.

As shown in fig. 2, a silicon carbide (SiC) crystal growth apparatus includes a crucible 100, a gas mixing device 200, and a gasification device 300; wherein the crucible 100 has a chamber 110 for placing a raw material and mounting a seed crystal, the chamber 110; the gas mixing device 200 is communicated with the chamber 110 through a first pipeline p1, a first gas path valve v1 is arranged on the first pipeline p1, and the gasification device 300 is communicated with the gas mixing device through a second pipeline p 2; and a third pipeline p3, wherein one end of the third pipeline p3 is communicated with the gas mixing device 200, and the other end of the third pipeline p3 is communicated with the carrier gas storage tank and the doping gas storage tank.

Referring to fig. 3, fig. 3 is a schematic structural view of an embodiment of a crucible in the present application.

As shown in fig. 3, the crucible 100 includes a chamber 110, a through hole 101 penetrating through the bottom wall is formed on the bottom wall of the crucible 100, the through hole 101 is communicated with the chamber 110, a first end of a first pipeline p1 is inserted into the through hole 101, a second end of the first pipeline p1 is communicated with the gas mixing device 200, a filter 102 is disposed in the through hole 101, and the filter 102 is located between the first pipeline p1 and the chamber 110.

In some embodiments, the thickness of the filter element 102 may be less than the thickness of the bottom wall of the crucible 100, such that the crucible 100 forms a recess at the filter element 102 through which the first pipe p1 may be connected to the crucible, while the material density of the filter element 102 is greater than the material density of the side wall of the crucible 100, and may be porous graphite, such that the mixed gas enters the chamber 110 of the crucible 100 after being filtered by the filter element 102; that is, the mixed gas after the doping gas and the carrier gas are sufficiently mixed is facilitated to enter the chamber in the crucible through the through hole.

In some embodiments, a heating chamber can be further arranged outside the crucible 100, the heating temperature of the heating chamber is generally 2000-2400 ℃, so that the crucible heats, and under the action of the heating and heat conduction of the crucible, the SiC source in the chamber of the crucible is decomposed and sublimated to release Si, si2C and SiC2 molecules; additionally, inert gas is filled between the heating chamber and the crucible 100; and the heating chamber is provided with an air inlet for inputting inert gas filled between the heating chamber and the crucible 100, and an air outlet for outputting byproducts and corresponding gas after crystal growth.

The inert gas input through the air inlet can be hydrogen, argon, helium and the like, and the flow range of the air inlet can be controlled to be 1 ml/min-20 l/min different from the effect of the carrier gas, so that the ventilation flow of the air inlet is large, the air inlet is used for introducing undoped gas, rapid inflation can be realized, and the effect of rapid cooling is achieved.

In some embodiments, a support is provided between the heating chamber and the crucible for supporting the entire crucible, and the first pipe p1 may be provided in the support to protect the first pipe p1.

In some embodiments, a pumping-out piece may be further disposed at the gas outlet of the heating chamber, and by-products and corresponding gases generated under the high-temperature condition of growing silicon carbide (SiC) crystals are desorbed from the corresponding growth interface of the crucible 100 and diffuse to the outside of the crucible 100, i.e., enter the heating chamber, so that the by-products and the corresponding gases may be pumped out of the heating chamber by the pumping-out piece; the pumping-out piece can be a vacuum pump, and after byproducts and corresponding gases generated in the crystal growing process are diffused into the heating chamber outside the crucible, the byproducts and the corresponding gases can be pumped out through the vacuum pump.

Specifically, under the high temperature conditions of growing crystals, the doping gas is cracked and reacts with hydrogen (H2) to produce byproducts such as: the effective molecules VCl2 in the doping gas are transported and adsorbed to the single crystal growth area under the combined action of the vertical temperature gradient and the crystal growth pressure to realize doping, and the byproduct HCl is desorbed from the interface of the growth area and diffused out of the crucible 100, namely diffused to the heating chamber, and is pumped out of the heating chamber by the pumping-out piece under the action of the pumping-out piece.

In some embodiments, a thermal barrier is also wrapped around the outer surface of crucible 100 to maintain the temperature inside the crucible.

With continued reference to FIG. 2, the gas mixing apparatus 200 includes a premixing chamber 210 and a mixing chamber 220, wherein the premixing chamber 210 is connected to the gasification apparatus 300 through a second pipeline p2 and is connected to one end of a third pipeline p 3; the mixing chamber 220 communicates with the premix chamber 210 and with the chamber 110 via a first conduit.

Because the doping source is doping gas and is stored in the doping gas storage tank, the second pipeline p2 is provided with a second gas valve v2, and the second pipeline p2 is closed through the second gas valve v2, that is, the premixing chamber 210 is not communicated with the gasification device 300.

In some embodiments, the premixing chamber 210 is provided with a plurality of air inlets, the third pipeline p3 has a plurality of pipelines, and is respectively communicated with the carrier gas storage tank through one part of the pipelines of the third pipeline p3 and is communicated with the doping gas storage tank through the other part of the pipelines of the third pipeline p 3; that is, the carrier gas storage tank conveys the carrier gas to the pre-mixing chamber 210 through a part of the channels of the third pipeline p3, the doping gas storage tank conveys the doping gas to the pre-mixing chamber 210 through another part of the channels of the third pipeline p3, so that the doping gas and the carrier gas are primarily mixed in the pre-mixing chamber 210, and the primarily mixed gas is conveyed to the mixing chamber 220.

In some embodiments, to achieve device integration, the growth device may further comprise a gas storage tank, i.e. the growth device may further comprise a carrier gas storage tank and a dopant gas storage tank.

In some embodiments, a plurality of curved plates are disposed within the mixing chamber 220 in order to provide better mixing of the dopant gas and the carrier gas.

Referring to fig. 4 and 5, fig. 4 is a schematic structural view of a first embodiment of the mixing chamber of the present application, and fig. 5 is a schematic structural view of a first embodiment of the curved plate of the present application.

As shown in fig. 4 and 5, a plurality of curved plates 221 are provided in the mixing chamber 220, and one end of the mixing chamber 220 is provided with an inlet and the other end is provided with an outlet, the inlet of the mixing chamber 220 communicates with the premixing chamber 210, and the outlet of the mixing chamber 220 communicates with the chamber through a first pipe p 1; the plurality of curved plates are sequentially arranged in the direction from the inlet of the mixing chamber 220 to the outlet of the mixing chamber 220, if any two adjacent curved plates are set to include a first curved plate and a second curved plate, the first end of the first curved plate is twisted by a first angle relative to the second end of the first curved plate, the first end of the second curved plate is twisted by a second angle relative to the second end of the second curved plate, and the twisting direction of the first curved plate is opposite to the twisting direction of the second curved plate, so that the gas primarily mixed in the premixing chamber is mixed again, and the mixing of the doping gas and the carrier gas is more sufficient.

The first angle may be 90 degrees, the second angle may be 90 degrees, the torsion direction of the first curved plate may be clockwise, the torsion direction of the second curved plate may be counterclockwise, or vice versa, the torsion direction of the first curved plate may be counterclockwise, the torsion direction of the second curved plate is clockwise, the gas primarily mixed in the premixing chamber is divided into two gas flows after entering the mixing chamber, and the two gas flows flow through the curved cells and turn in opposite directions to promote the mixing degree of the doping gas and the carrier gas. In some embodiments, the first angle may be 45 degrees, 60 degrees, or 80 degrees, and the second angle may be 30 degrees, 45 degrees, 60 degrees, or 85 degrees, which are not limited in this application.

The first curved plate and the second curved plate may be static curved plates, each static curved plate has a rectangular structure twisted by a preset angle, that is, twisted plates, as shown in fig. 5, and the end face of the second end of the first curved plate is opposite to and connected with the end face portion of the first end of the second curved plate, for example, the end faces are connected together by a central axis of the end faces, each two twisted plates form a unit cell, and a plurality of unit cells alternately form an internal member of the mixing chamber 220; the first inclined angle is formed between the length extending direction of the end face of the second end of the first curved plate and the length extending direction of the end face of the first end of the second curved plate, and the angle of the first inclined angle is more than 0 degrees and less than or equal to 90 degrees; further, when the doping gas and the carrier gas pass through the mixing chamber 220, a shearing stress is generated at the end surfaces of the first curved plate and the second curved plate when the end surfaces of the first curved plate and the second curved plate are in contact with each other, so that the doping gas and the carrier gas are mixed more sufficiently to obtain a mixed gas.

The doping gas and the carrier gas are divided into two flows after entering the mixing chamber 220, the two flows are turned around in opposite directions after flowing through the curved cells, and the two flows are divided again after flowing through the next cell, so as to generate mixed flow again, and the doping gas and the carrier gas are divided and mixed for many times, so that the doping gas and the carrier gas are fully mixed to form a mixed gas, and the mixed gas is conveyed into the chamber 110 in the crucible 100 according to the corresponding first speed by controlling the first gas circuit valve v1 of the first pipeline p1, so that doping is realized in the growth process of silicon carbide (SiC) crystals.

In other embodiments, in order to provide better mixing of the dopant gas and carrier gas, the mixing chamber 220 has a plurality of corrugated plates disposed side by side as curved plates.

Referring to fig. 6 and 7, fig. 6 is a schematic structural view of a second embodiment of the mixing chamber of the present application; fig. 7 is a schematic structural view of a second embodiment of a curved plate in the present application.

As shown in fig. 6, the plurality of curved plates in the mixing chamber 220 may be a plurality of wave plates 222 arranged in parallel, each extending in a direction from an inlet of the mixing chamber 220 to an outlet of the mixing chamber 220, with a gap between any two adjacent wave plates.

The two adjacent wave plates include a first wave plate and a second wave plate, the first wave plate and the second wave plate are mirror-symmetrical, the wave plates of two-to-two mirror images form a unit cell, a plurality of unit cells form an internal structure of the mixing chamber 220, and a mixing principle of the doping gas and the carrier gas is similar to that of the structure of fig. 4.

In some embodiments, each wave plate is provided with a plurality of through holes, so that the doping gas and the carrier gas can be subjected to the mixing principle of the structure shown in fig. 4, and the doping gas and the carrier gas can be fully mixed by complete convergence, mixing and flow division.

In some embodiments, the silicon carbide (SiC) crystal growth apparatus further includes a controller electrically connected to the second gas circuit valve and to the first heater for controlling opening and closing of the second gas circuit valve and for controlling opening and closing of the first heater; the controller can also be electrically connected with the first air passage valve to realize automatic control of the first air passage valve, namely, the controller can further realize control and adjustment of the concentration of the doping gas by controlling the air inlet rate of the first air passage valve, so that the concentration of the doping gas in the chamber is kept in a preset range, and the preset range is a corresponding concentration range of the doping gas which can be completely doped.

In this embodiment, for the case that the doping source is the doping gas, the doping gas and the carrier gas are directly conveyed to the premixing chamber through the third pipeline p3, after the preliminary mixing of the premixing chamber and the thorough mixing of the mixing chamber are performed on the doping gas and the carrier gas, the mixed gas is obtained, and then the rate of the mixed gas entering the chamber 110 is controlled through the first pipeline v1 on the first pipeline p1, so that the doping concentration is controlled, the doping concentration corresponding to the doping gas can be controlled in the silicon carbide (SiC) crystal growth process, the doping uniformity of the crystal is improved, and the electrical property of the subsequent product is ensured.

When the doping source is a thermal-setting dopant, referring to the third embodiment, the same parts as those of the first embodiment and the second embodiment will not be described in detail.

Referring to fig. 8, fig. 8 is a schematic structural view of a third embodiment of a silicon carbide (SiC) crystal growth apparatus of the present application.

As shown in fig. 8, a silicon carbide (SiC) crystal growth apparatus includes a crucible 100, a gas mixing device 200, a gasification device 300; wherein the crucible 100 has a chamber 110 for placing a raw material and mounting a seed crystal, the chamber 110; the gas mixing device 200 is communicated with the chamber 110 through a first pipeline p1, a first gas path valve v1 is arranged on the first pipeline p1, and the gasification device 300 is communicated with the gas mixing device through a second pipeline p2 and is used for placing and heating the hot solid dopant; and a third pipeline p3, wherein one end of the third pipeline p3 is communicated with the gas mixing device 200, and the other end of the third pipeline p3 is communicated with the carrier gas storage tank.

With continued reference to fig. 8, the gas mixing device 200 includes a premixing chamber 210 and a mixing chamber 220, the premixing chamber 210 is connected to the gasification device 300 through a second pipeline P2, at this time, the second pipeline P2 is opened, and the premixing chamber 210 is connected to one end of a third pipeline P3; the mixing chamber 220 communicates with the premix chamber 210 and with the chamber 110 via a first conduit.

In some embodiments, the pre-mixing chamber 210 is provided with a plurality of gas inlets, which are respectively connected to the carrier gas storage tank through the third pipeline p3 and the gasification device 300 through the second pipeline p2, that is, the gasification device 300 conveys the doping gas to the pre-mixing chamber 210 through the second pipeline p2, and the carrier gas storage tank conveys the carrier gas to the pre-mixing chamber 210 through the third pipeline p3, so that the doping gas and the carrier gas are primarily mixed in the pre-mixing chamber 210, and the primarily mixed gas is conveyed to the mixing chamber 220.

In some embodiments, the gasification device 300 includes a gasification chamber 310 and a first heater 320, wherein the first heater 320 is disposed outside the gasification chamber 310 and surrounds the gasification chamber 310, and the gasification chamber 310 is in communication with the gas mixing device 200 through a second pipeline p2, that is, the gasification chamber 310 is in communication with the premixing chamber 210 in the gas mixing device 200 through the second pipeline p2, and a second gas path valve v2 is disposed on the second pipeline p2, so as to turn on and off the second pipeline p2 by controlling the opening and closing of the second gas path valve v2, and to monitor the flow value of the gas flowing through the second pipeline p 2.

The second air path valve v2 may be a one-way valve, which can effectively prevent the gas in the premixing chamber 210 from flowing back to the gasification chamber 310, and the first heater 320 may be a water bath heater, an oil bath heater, or other heaters with heating effects, which are used for ensuring heating uniformity.

Specifically, the heating of the gasification chamber by the first heater 320 may allow the thermal-state dopant to be sufficiently decomposed into the dopant gas.

The principle of the embodiment is as follows, and is applicable to the situation that a doping source needs to be gasified, for example, doping metal elements of vanadium (V) and aluminum (Al) in SiC monocrystal; in the Chemical Vapor Deposition (CVD) technology, a gas mixing device is heated firstly, when the gas mixing device is heated to a preset temperature, carrier gas is introduced into the gas mixing device, the carrier gas carries precursor vapor in the Chemical Vapor Deposition (CVD) to enter a cavity of a crucible, cracking reaction occurs under the action of the corresponding temperature, and related gas byproducts and unreacted precursor vapor leave the cavity through the action of diffusion; under the action of crucible heating and heat conduction, the SiC source is decomposed and sublimated to release Si, si2C and SiC2 molecules, and the molecules decomposed by the SiC source are transported to the seed crystal under the driving action of vertical temperature gradient and are condensed at the seed crystal to obtain SiC monocrystal; in addition, when the crystal growth condition is reached, the gasification device is heated to a preset heating temperature, the heating temperature interval is set according to sublimation temperatures of different doping sources (for example, VCl4 is used as a vanadium doping source to set the heating temperature to 15-25 ℃), the heating temperature is specifically set to be +0-10 ℃), after the doping source in the gasification device reaches a certain gasification amount, corresponding doping gas enters the gas mixing device through the second pipeline under the action of pressure to be mixed, the mixed gas is transmitted into a cavity of the crucible through the first pipeline, and the obtained flow is fed back to the controller through the first gas circuit valve on the first pipeline, so that the controller adjusts according to the flow of the doping gas and adjusts the heating temperature of the gasification device.

In this embodiment, for the doping source of the thermosetting dopant, the thermosetting dopant is heated by the gasification device to be fully decomposed, so as to obtain gasified doping gas, and the doping gas is output to the premixing chamber, after the preliminary mixing of the premixing chamber and the full mixing of the mixing chamber are performed on the doping gas and the carrier gas, the mixed gas is obtained, and then the rate of the mixed gas entering the cavity 110 of the crucible 100 is controlled by the first gas circuit valve on the first pipeline p1, so that the doping concentration is controlled, the doping concentration corresponding to the doping gas can be controlled in the silicon carbide (SiC) crystal growth process, the uniformity of crystal doping is improved, and the electrical property of the subsequent product is ensured.

Also included in the present application is a method of silicon carbide (SiC) crystal growth.

Referring to fig. 9, fig. 9 is a flow chart illustrating an embodiment of a method for growing silicon carbide (SiC) crystals in the present application.

As shown in fig. 9, the method comprises the following steps:

s11, providing a silicon carbide (SiC) crystal growth apparatus, the silicon carbide (SiC) crystal growth apparatus comprising: the crucible is provided with a chamber, and the chamber is used for placing raw materials and installing seed crystals; the gas mixing device is communicated with the cavity through a first pipeline, and a first gas pipeline valve is arranged on the first pipeline; the gasification device is communicated with the gas mixing device through a second pipeline; and one end of the third pipeline is communicated with the gas mixing device, and the other end of the third pipeline is communicated with the carrier gas storage tank and/or the doping gas storage tank.

The crucible is used for providing a crystal growth environment, a cavity is arranged in the crucible, raw materials are placed at the bottom of the cavity, and seed crystals are arranged on the top or the side wall of the cavity, namely, the seed crystals are not in direct contact with the raw materials; it will be appreciated that the crucible may be adapted to allow the crystal growth environment to reach predetermined growth conditions, such as growth temperature, growth pressure, etc.

Wherein the crystal growth temperature is 2000-2400 ℃, and the crystal growth pressure is 1-100 torr.

In some embodiments, the gasification device includes a gasification chamber and a first heater disposed outside the gasification chamber, the first heater disposed around the gasification chamber, and the first heater 320 heats the gasification chamber to enable the thermal state dopant to be sufficiently decomposed into the dopant gas; the gasification chamber is communicated with the gas mixing device through a second pipeline, a second gas circuit valve is arranged on the second pipeline, and the second gas circuit valve can be used for conducting or blocking the second pipeline and monitoring the flow value of the gas flowing through the second pipeline.

In some embodiments, the silicon carbide (SiC) crystal growth apparatus further comprises: the controller is electrically connected with the second air passage valve and the first heater, and based on the flow value monitored by the second air passage valve, the controller can control the working state of the first heater, namely, based on the flow value monitored by the second air passage valve, the controller controls the opening and closing of the first heater and the temperature regulation after the opening.

Specifically, when the flow value monitored by the second gas circuit valve reaches a first condition, reducing the heating power of the first heater until the temperature of the gasification chamber is reduced from the first temperature to a second temperature; and when the flow value monitored by the second gas circuit valve reaches a second condition, increasing the heating power of the first heater until the temperature of the gasification chamber is increased from the first temperature to a third temperature.

Wherein the absolute value of the difference between the first temperature and the second temperature is less than or equal to 5 ℃; the absolute value of the difference between the third temperature and the first temperature is less than or equal to 5 ℃; the first temperature is higher than the sublimation temperature of the solid-state dopant, the absolute value of the difference between the first temperature and the sublimation temperature of the solid-state dopant is lower than or equal to 30 ℃, and the temperature is adjusted to accelerate the thermal movement of molecules, promote the further uniform mixing of the carrier gas and the doping gas, avoid abnormal heating, and enable the adjustment range of the temperature to be relatively stable.

The first condition is that the flow value monitored by the second air circuit valve is larger than or equal to a first flow value, specifically, the flow value monitored by the second air circuit valve is continuously larger than or equal to the first flow value and the duration reaches a first time, and the absolute value of the fluctuation amplitude of the flow value in the continuous first time is smaller than the first amplitude; the first duration is 5-30 minutes, the first amplitude is 3ml/s, the first flow value is determined based on the doping concentration, namely, the flow value is adjusted according to the doping concentration, so that the doping concentration in the cavity is kept in a range capable of being fully doped, and the doping concentration in the cavity can be further accurately controlled.

The second condition is that the flow value monitored by the second air circuit valve is smaller than the first flow value, specifically, the flow value monitored by the second air circuit valve is continuously smaller than the first flow value and the duration reaches the second duration, and the absolute value of the fluctuation amplitude of the flow value in the continuous second duration is smaller than the second amplitude; wherein the second duration is 5-30 minutes and the second amplitude is 3ml/s; the corresponding limiting conditions are set, so that the doping concentration can be controlled more accurately.

S12, placing the solid dopant into a gasification device, gasifying the solid dopant by the gasification device, and mixing the dopant gas output by the gasification device with the carrier gas transmitted by a third pipeline by a gas mixing device; alternatively, the doping gas transferred through the third pipeline and the carrier gas transferred through the third pipeline are mixed by a gas mixing device.

Wherein the doping gas refers to a gas that can be doped with silicon carbide (SiC) crystals, and the carrier gas refers to a gas that can transport the doping gas to the chamber.

Specifically, when the doping source is a solid-state dopant, the solid-state dopant is placed in a gasification device, the solid-state dopant is gasified into doping gas by the gasification device, the doping gas is further conveyed to a gas mixing device, and the carrier gas is conveyed to the gas mixing device, and the doping gas and the carrier gas are fully mixed by the gas mixing device; or when the doping source is the doping gas which does not need to be gasified, the doping gas and the carrier gas are directly conveyed to the gas mixing device through different pipelines of the third pipeline, and then the doping gas and the carrier gas are fully mixed through the gas mixing device.

And S13, transmitting the mixed gas output by the gas mixing device into the chamber through a first gas circuit valve so as to realize doping in the growth process of the silicon carbide (SiC) crystal.

In order to maintain uniform doping during growth of silicon carbide (SiC), a dopant gas having a specific concentration during growth is required, and therefore, the mixed gas needs to be transferred into a chamber in which the silicon carbide (SiC) crystal grows at a specific rate to achieve uniform doping during growth of the silicon carbide (SiC) crystal.

Specifically, after the doping gas and the carrier gas are fully mixed, the output rate of the mixed gas is regulated through a first gas circuit valve on the first pipeline, and the mixed gas is transmitted into the chamber according to the corresponding rate, so that the doping is realized in the growth process of the silicon carbide (SiC) crystal.

In this embodiment, provide crystal growth environment through the crucible to place raw materials and installation seed crystal in the cavity of crucible, rethread gas mixing arrangement carries out intensive mixing with doping gas and carrier gas, and then through the rate of first gas circuit valve control gaseous mixture entering crucible's cavity, make the release rate of doping gas controllable, thereby it is controllable to realize doping concentration, can effectively avoid the crystal in-process to mix inhomogeneous, improve long brilliant doping uniformity, and be applicable to the condition of different doping sources, the range of application is wide.

The technical scheme provides silicon carbide (SiC) crystal growth equipment, which comprises a crucible, a gas mixing device, a gasification device and a third pipeline; wherein the crucible has a chamber for placing the raw material and mounting the seed crystal; the gas mixing device is communicated with the cavity through a first pipeline, and a first gas pipeline valve is arranged on the first pipeline; the gasification device is communicated with the gas mixing device through a second pipeline and is used for placing and heating solid dopants; one end of the third pipeline is communicated with the gas mixing device, and the other end of the third pipeline is communicated with the carrier gas storage tank and/or the doping gas storage tank; the method is suitable for corresponding doping gases obtained from different doping sources, the doping gases and the carrier gas are fully mixed, and the rate of the mixed gas conveyed to the cavity is controlled through the first gas circuit valve, so that the release speed of the doping gases is controllable, the doping concentration is controllable, the non-uniformity of doping in the crystal growth process can be effectively avoided, and the uniformity of crystal growth doping is improved.

In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices may be implemented in other manners. For example, the system embodiments described above are merely illustrative, e.g., the division of the modules or units is merely a logical functional division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted, or not performed.

The foregoing description is only of embodiments of the present application, and is not intended to limit the scope of the patent application, and all equivalent structures or equivalent processes using the descriptions and the contents of the present application or other related technical fields are included in the scope of the patent application.

Claims

1. A silicon carbide crystal growth apparatus, comprising:

a crucible having a chamber for holding a source material and mounting a seed crystal;

the gas mixing device is communicated with the cavity through a first pipeline, and a first gas pipeline valve is arranged on the first pipeline;

the gasification device is communicated with the gas mixing device through a second pipeline and is used for placing and heating solid dopants;

and one end of the third pipeline is communicated with the gas mixing device, and the other end of the third pipeline is communicated with the carrier gas storage tank and/or the doping gas storage tank.

2. The apparatus of claim 1, wherein the gas mixing device comprises:

the premixing chamber is communicated with the gasification device through the second pipeline and is communicated with one end of the third pipeline;

and the mixing chamber is communicated with the premixing chamber and is communicated with the chamber through the first pipeline.

3. The apparatus of claim 2, wherein the mixing chamber has a plurality of curved plates.

4. A device according to claim 3, wherein the mixing chamber is provided with an inlet at one end and an outlet at the other end, the inlet of the mixing chamber being in communication with the premixing chamber, the outlet of the mixing chamber being in communication with the chamber via the first conduit;

the plurality of curved plates are sequentially arranged in the direction from the inlet of the mixing chamber to the outlet of the mixing chamber, any two adjacent curved plates comprise a first curved plate and a second curved plate, the first end of the first curved plate is twisted by a first angle relative to the second end of the first curved plate, the first end of the second curved plate is twisted by a second angle relative to the second end of the second curved plate, and the twisting direction of the first curved plate is opposite to the twisting direction of the second curved plate.

5. The apparatus of claim 4, wherein an end face of the second end of the first curved plate is opposite to and connected to an end face portion of the first end of the second curved plate, and wherein a first angle is formed between a length extension direction of the end face of the second end of the first curved plate and a length extension direction of the end face of the first end of the second curved plate, and wherein the first angle is greater than 0 degrees and less than or equal to 90 degrees.

6. The apparatus of claim 5, wherein the first angle is equal to 90 degrees, the second angle is equal to 90 degrees, the twist direction of the first curved plate is clockwise, and the twist direction of the second curved plate is counter-clockwise; the first included angle is equal to 90 degrees.

7. The apparatus of claim 4, wherein the plurality of curved plates are a plurality of corrugated plates arranged in parallel, each corrugated plate extends in a direction from an inlet of the mixing chamber to an outlet of the mixing chamber, each corrugated plate is provided with a plurality of through holes, and a gap is formed between any two adjacent corrugated plates.

8. The apparatus of claim 7, wherein any two adjacent wave plates include a first wave plate and a second wave plate, the first wave plate being mirror-symmetrical to the second wave plate.

9. The apparatus of claim 1, wherein the gasification device comprises a gasification chamber and a first heater, the first heater is arranged outside the gasification chamber, the first heater is arranged around the gasification chamber, the gasification chamber is communicated with the gas mixing device through the second pipeline, a second gas circuit valve is arranged on the second pipeline, and the second gas circuit valve can conduct or block the second pipeline and can monitor the flow value of the gas flowing through the second pipeline;

The apparatus further comprises:

and the controller is electrically connected with the second air circuit valve and the first heater.

10. The apparatus of claim 9, wherein the second air passage valve is a one-way valve;

and/or the number of the groups of groups,

the first heater is a water bath heater or an oil bath heater.

11. The apparatus according to claim 1, characterized in that the outside of the first pipe and/or the outside of the second pipe and/or the outside of the gas mixing device is provided with heating means.

12. The apparatus of claim 1, wherein a through hole penetrating the bottom wall is formed in the bottom wall of the crucible, the through hole is in communication with the chamber, a first end of the first pipe is inserted into the through hole, a second end of the first pipe is in communication with the gas mixing device, and a filter is disposed in the through hole and is located between the first pipe and the chamber.

13. A method for growing a silicon carbide crystal, comprising:

providing a silicon carbide crystal growth apparatus, wherein the silicon carbide crystal growth apparatus comprises: a crucible having a chamber for holding a source material and mounting a seed crystal; the gas mixing device is communicated with the cavity through a first pipeline, and a first gas pipeline valve is arranged on the first pipeline; the gasification device is communicated with the gas mixing device through a second pipeline; one end of the third pipeline is communicated with the gas mixing device, and the other end of the third pipeline is communicated with the carrier gas storage tank and/or the doping gas storage tank;

Placing solid dopants into the gasification device, gasifying the solid dopants by the gasification device, and mixing the doping gases output by the gasification device with the carrier gases transmitted by the third pipeline by the gas mixing device; or mixing the doping gas conveyed by the third pipeline and the carrier gas conveyed by the third pipeline through the gas mixing device;

and transmitting the mixed gas output by the gas mixing device into the chamber through the first gas circuit valve so as to realize doping in the silicon carbide crystal growth process.

14. The method of claim 13, wherein the gasification device comprises a gasification chamber and a first heater, the first heater is arranged outside the gasification chamber, the first heater is arranged around the gasification chamber, the gasification chamber is communicated with the gas mixing device through the second pipeline, a second gas circuit valve is arranged on the second pipeline, and the second gas circuit valve can conduct or block the second pipeline and can monitor the flow value of the gas flowing through the second pipeline;

the apparatus further comprises: the controller is electrically connected with the second air passage valve and the first heater;

The method further comprises the steps of:

and controlling the working state of the first heater based on the flow value monitored by the second air circuit valve.

15. The method of claim 14, wherein the controlling the operating state of the first heater based on the flow value monitored by the second air circuit valve comprises:

when the flow value monitored by the second gas circuit valve reaches a first condition, reducing the heating power of the first heater until the temperature of the gasification chamber is reduced from a first temperature to a second temperature, wherein the first condition is that the flow value monitored by the second gas circuit valve is larger than or equal to the first flow value;

and when the flow value monitored by the second gas circuit valve reaches a second condition, increasing the heating power of the first heater until the temperature of the gasification chamber is increased from the first temperature to a third temperature, wherein the second condition is that the flow value monitored by the second gas circuit valve is smaller than the first flow value.

16. The method of claim 15, wherein an absolute value of the difference between the first temperature and the second temperature is less than or equal to 5 ℃;

the absolute value of the difference between the third temperature and the first temperature is less than or equal to 5 ℃;

The first temperature is greater than a sublimation temperature of the solid-state dopant, and an absolute value of a difference between the first temperature and the sublimation temperature of the solid-state dopant is less than or equal to 30 ℃.

17. The method of claim 16, wherein the first condition is: the flow value monitored by the second gas circuit valve is continuously greater than or equal to a first flow value, the duration reaches a first time, and the absolute value of the fluctuation amplitude of the flow value in the continuous first time is smaller than a first amplitude;

the second condition is: the flow value monitored by the second gas circuit valve is continuously smaller than the first flow value, the duration reaches a second duration, and the absolute value of the fluctuation amplitude of the flow value in the second duration is continuously smaller than a second amplitude.

18. The method of claim 17, wherein the first duration is 5-30 minutes and the first amplitude is 3ml/s;

the second duration is 5-30 minutes and the second amplitude is 3ml/s.

19. The method of claim 15, wherein the first flow value is determined based on a doping concentration.