CN-121629501-B - Method for growing off-angle silicon carbide single crystal by liquid phase method

Abstract

The invention relates to a method for growing off-angle silicon carbide single crystals by a liquid phase method, belonging to the technical field of silicon carbide single crystal production. The method comprises the steps of arranging the wedge-shaped seed crystal on the wedge-shaped seed crystal support to form a positive crystal direction seed crystal surface, then growing silicon carbide on a positive crystal direction seed crystal surface by a liquid phase method to obtain an ingot comprising the wedge-shaped seed crystal and the silicon carbide growing crystal, taking the ingot off the wedge-shaped seed crystal support, and performing multi-line cutting by taking the inclined surface of the wedge-shaped seed crystal as a reference to obtain the off-angle silicon carbide single crystal. According to the method, the wedge-shaped seed crystal and the wedge-shaped seed crystal support form a positive crystal orientation seed crystal surface for liquid phase growth, and then the off-angle silicon carbide single crystal is obtained through multi-wire cutting.

Inventors

• ZHANG GUANGYU
• ZHANG ZESHENG
• WANG GUOBIN

Assignees

• 北京晶格领域半导体有限公司

Dates

Publication Date

20260512

Application Date

20260203

Claims (7)

1. 1. A method for growing a silicon carbide single crystal at an off-angle by a liquid phase method, characterized in that the method is performed by an apparatus for growing a silicon carbide single crystal by a liquid phase method, the apparatus comprising a wedge-shaped seed crystal holder and a wedge-shaped seed crystal, the method comprising the steps of: (1) Setting the wedge-shaped seed crystal on the wedge-shaped seed crystal support to form a forward crystal direction seed crystal surface, and then growing silicon carbide on the forward crystal direction seed crystal surface by a liquid phase method to obtain an ingot comprising the wedge-shaped seed crystal and a silicon carbide growing crystal, wherein the silicon carbide growing crystal is in a forward crystal direction; the wedge-shaped seed crystal support comprises a positive angle part and a deflection angle part, wherein the positive angle part is vertically connected with a seed rod, and the inclined surface of the deflection angle part is bonded with the inclined surface of the wedge-shaped seed crystal through a bonding agent, so that the lower surface of the wedge-shaped seed crystal forms a positive crystal direction seed crystal surface which is vertical to the seed rod; (2) Taking the ingot off from the wedge-shaped seed crystal support, and performing multi-line cutting by taking the inclined surface of the wedge-shaped seed crystal included in the ingot as a reference to obtain a deflection angle silicon carbide single crystal; In the step (2), after multi-line cutting is performed based on the inclined surface of the wedge-shaped seed crystal included in the ingot, a new wedge-shaped seed crystal can be obtained, and the new wedge-shaped seed crystal is recycled in the step (1).
2. 2. A method as set forth in claim 1 further comprising the step of rounding the silicon carbide grown crystal comprising the ingot from step (1) prior to removing the ingot from the wedge-shaped seed holder.
3. 3. The method according to claim 1, characterized in that: The inclination angle of the wedge-shaped seed crystal support and the inclination angle of the wedge-shaped seed crystal are not more than 4 degrees.
4. 4. The method according to claim 1, characterized in that: the length of the seed crystal rod is 400-500 mm.
5. 5. The method according to claim 4, wherein: The seed rod is connected with a seed rod rotary lifting device.
6. 6. The method according to claim 1, characterized in that: The thickness of the positive angle part is 5-25 mm.
7. 7. The method according to any one of claims 1 to 6, characterized in that: in the step (2), when multi-wire cutting is performed, the cutting angle error is not more than 0.2 degrees.

Description

Method for growing off-angle silicon carbide single crystal by liquid phase method Technical Field The invention belongs to the technical field of silicon carbide single crystal production, and particularly relates to a method for growing an off-angle silicon carbide single crystal by a liquid phase method. Background Silicon carbide (SiC) is one of extremely important third-generation semiconductor materials, and has characteristics of a specific large forbidden bandwidth, high critical breakdown field strength and the like, so that the SiC is an ideal material for manufacturing high-frequency, high-power, radiation-resistant and illumination integrated devices, and is widely applied to various fields of new energy automobiles, 5G communication, aerospace and the like. For silicon carbide materials, in order to meet the requirements of downstream device fabrication, the quality of the midstream epitaxy is often required to reach a certain standard, and the epitaxy end has limitations on the angle in addition to the quality requirement of the substrate end. In the silicon carbide single crystal growth technology, a physical vapor transport method (PVT method) can directly adopt an off-angle growth mode due to the vapor phase growth characteristic, and the off-angle epitaxial substrate can be obtained by regulating and controlling the thermal field gradient without liquid phase participation and meniscus control problem. However, the liquid phase method has irreplaceable advantages in preparing silicon carbide single crystals, such as lower dislocation density, higher crystal purity, and better doping uniformity. However, when silicon carbide grows by a liquid phase method, the consistency of the quality of grown crystals can be ensured only by keeping the forward crystal growth, because the high-quality growth of crystals depends on the stability of a melt and a solid phase interface, if the forward crystal growth is carried out by adopting the forward crystal growth, the mass transfer and the thermal field distribution on two sides of the solid-liquid interface are seriously uneven, the shape of a meniscus is distorted, the phenomena that one side grows at a high speed, the other side grows slowly and even part of crystals are separated from the melt occur, the growth continuity is seriously damaged, one end of each crystal is thin and the other end of each crystal is thick, the same meniscus cannot be kept after the crystal is grown, the growth quality is poor and the like. At present, no effective means is available in the prior art to meet the requirements of the growth stability of the liquid phase method and the preparation of the off-angle single crystal. In addition, although the forward silicon carbide single crystal is grown by a liquid phase method and then the forward silicon carbide single crystal can be obtained by subsequent cutting, when the forward ingot is cut by the forward angle, a large amount of waste materials which cannot be used for processing the substrate are generated at the upper end and the lower end of the ingot due to insufficient geometric dimensions, namely, the parts of which the upper end and the lower end do not meet the dimensions cannot be effectively utilized, so that resource waste is caused, and the typical process of the forward angle cutting of the liquid phase silicon carbide single crystal comprises ingot, rolling circle, crystal orientation, double-sided single-line cutting or flat grinding and forward multi-line cutting, wherein the single-line cutting link of the forward angle is generally provided with two methods, namely (a) manufacturing a special single-line cutting die and then cutting by using the single-line cutting die, the method can realize cutting, but the cost is increased, the single-line cutting die is mostly disposable, the customization and the consumption of the die are continuously pushed to high production cost, and (b) the ingot is bonded in a forward angle mode, and the method relies on high-end single-line cutting equipment with complicated space posture adjusting capability to cut the cutting tool under the angle, and the strict method has the requirement of increasing the precision of the equipment and the cost is avoided. Therefore, the existing method for cutting the front crystal orientation growth and the back deflection angle is complex in cutting process, and has the problems of low material utilization rate, high cost and the like. In summary, it is highly desirable to provide a method for growing off-angle silicon carbide single crystals by a liquid phase process. Disclosure of Invention In order to solve one or more technical problems in the prior art, the invention provides a method for growing an off-angle silicon carbide single crystal by a liquid phase method. The invention provides a method for growing a silicon carbide single crystal with an off-angle by a liquid phase method, which is carried out by adopting a device fo