CN104947182A

CN104947182A - Method for rapidly growing large-size high-purity semi-insulating silicon carbide single crystal

Info

Publication number: CN104947182A
Application number: CN201510417397.9A
Authority: CN
Inventors: 窦瑛; 徐永宽; 孟大磊; 张皓; 张政; 徐所成
Original assignee: CETC 46 Research Institute
Current assignee: CETC 46 Research Institute
Priority date: 2015-07-16
Filing date: 2015-07-16
Publication date: 2015-09-30

Abstract

The invention relates to a method for rapidly growing a large-size high-purity semi-insulating silicon carbide single crystal. According to the method, on one hand, through multiple times of gas replacements conducted on a growing chamber, the insulation of the growing chamber and air is achieved, the nitrogen content in the single crystal is reduced, on the other hand, the rapid-growth of the silicon carbide single crystal is achieved through improving temperature gradient between source powder and a seed crystal in a silicon carbide single crystal growing system of a PVT method and/or reducing pressure of the growing chamber, and the crystal forms of the high-purity semi-insulating silicon carbide single crystal comprise a 4H, 6H, 3C and 15R or an arbitrary combined crystal form of the four crystal forms. The method for rapidly growing the large-size high-purity semi-insulating silicon carbide single crystal has the advantages that resistivity of the silicon carbide single crystal is improved, the growth speed of the silicon carbide single crystal can reach 0.5 mm/h-2 mm/h, the growth speed exceeds the conventional speed for multiple times, and the productive rate of the silicon carbide single crystal is further improved.

Description

A kind of method of quick growing large-size high-purity semi-insulating silicon carbide monocrystalline

Technical field

The present invention relates to a kind of silicon carbide monocrystal growth method, particularly a kind of quick method preparing large size high-purity semi-insulating silicon carbide monocrystalline.

Background technology

Silicon carbide (SiC) material is the third generation semiconductor material continued since silicon (Si) and gallium arsenide (GaAs), there is the good characteristics such as broad stopband, high critical breakdown strength, high electronics saturation drift velocity, high heat conductance, become the ideal material making high temperature, high frequency, high-power, Flouride-resistani acid phesphatase device.

Semi-insulating silicon carbide mono-crystal comprises mixes the semi-insulating and high-purity semi-insulating two kinds of vanadium.When using the silicon carbide substrates making devices of vanadium doping, vanadium can be caught electric charge and be caused interior raw matrix effect, affects device performance, therefore preferably uses high-purity semi-insulating silicon carbide substrate.Meanwhile, high-purity semi-insulating silicon carbide substrate has more excellent heat conductivility, is conducive to further boost device performance.

A difficult problem for growth high-purity semi-insulating silicon carbide monocrystalline is exactly reduce the impurity in crystal, but owing to inevitably there is the impurity elements such as Al, B in source powder, crucible and heat-insulation system, N simultaneously in process of growth in air also can be incorporated in crystal in a large number, greatly affects the electric property of single-crystal silicon carbide.By the content using high-purity source powder, high purity graphite crucible and high-purity lagging material effectively can reduce Al, B, but be difficult to reduce by the N that air enters in growth room, become the principal element that restriction single-crystal silicon carbide realizes high-purity semi-insulating performance.

At present, domestic high-purity semi-insulating silicon carbide single crystal growing speed is slow, and production efficiency is lower, and cannot meet device producer to monocrystalline size at 3 ~ 4 inches, resistivity is greater than 10 ⁶Ω cm, nitrogen content is lower than 9 × 10 ¹⁶atom/cm ³the demand of large size silicon-carbide substrate.

Summary of the invention

In view of prior art Problems existing, the invention provides a kind of method of quick growing large-size high-purity semi-insulating silicon carbide monocrystalline, concrete technical scheme is, a kind of method of quick growing large-size high-purity semi-insulating silicon carbide monocrystalline, it is characterized in that: comprise the steps

(1), by SiC source powder be placed in plumbago crucible bottom, adopt the SiC seed crystal of diameter 3-4 inch to be placed in plumbago crucible top;

(2), first vacuumize, when the vacuum tightness in growth room reaches 5 × 10 before growth ^-5after mbar, substitution gas is passed in growth room, gas flow is 5 ~ 30mL/min, the time of passing into is 5 ~ 30min, passes into the substitution gas of same traffic, same time after the 30min of interval again, periodically repeats this process 2 ~ 5 times, air residual in displacement growth room, reach the object of denitrogenating, substitution gas can be the mixed gas of Ar, H2, CH4 or three, and blending ratio is 10 ~ 90% :10 ~ 90% :10 ~ 90%;

(3), adopt induction heating mode, crucible upper cover temperature is controlled at T ₁be 1900 ~ 2200 DEG C, powder position, source temperature controls at T ₂be 2300 ~ 2600 DEG C, growth pressure P is 0.1 ~ 10mbar, and crystal growth time is 30 ~ 100h;

(4), after crystal growth terminates, logical argon gas, under the protection of argon gas, progressively reduces power, makes the temperature of growing system slowly be down to room temperature.

Described high-purity semi-insulating silicon carbide monocrystalline crystal formation comprises the arbitrary combination crystal formation of 4H, 6H, 3C and 15R or these four kinds of crystal formations.

The invention has the beneficial effects as follows the nitrogen content reduced in single-crystal silicon carbide, improve the resistivity of single-crystal silicon carbide, silicon carbide monocrystal growth speed can reach 0.5mm/h ~ 2mm/h, exceeds conventional speeds several times, further increases the productive rate of single-crystal silicon carbide sheet.

Accompanying drawing explanation

Fig. 1 is PVT method SiC single crystal furnace structure diagrammatic cross-section.

Embodiment

Below in conjunction with embodiment, the present invention will be further described, as shown in Figure 1, the present invention's crystal growth equipment used is PVT method SiC single crystal stove, its primary structure comprises: insulation construction 1, coil 2, carborundum crystals 3, plumbago crucible 4, source powder 5, by coil 2 induction heating of plumbago crucible 4, source powder 5 is heated to sublimation temperature T ₂, set the temperature T of plumbago crucible 4 upper cover simultaneously ₁lower than the temperature of source powder 5, make the source powder 5 after distilling at seed crystal place crystalline growth, obtain carborundum crystals 3, outside plumbago crucible 4, have insulation construction 1.

Embodiment 1

Adopt induction heating type PVT method SiC single crystal stove to grow 3 inch silicon carbide silicon single-crystal, concrete steps are as follows,

(1) SiC source powder is placed in plumbago crucible bottom, SiC seed crystal is placed in plumbago crucible top, and SiC seed crystal diameter is 3 inches, and aufwuchsplate is carbon face, and the direction of growth is on-axis;

(2) plumbago crucible assembled is placed in high-frequency induction furnace;

(3) molecular pump is adopted to vacuumize high-frequency induction furnace, until the vacuum tightness in growth room reaches 5 × 10 ^-5below mbar;

(4) in growth room, H is passed into ₂and CH ₄mixed gas, the two ratio is 1 :1, gas flow is 10mL/min, and the time of passing into is 30min;

(5) after the 30min of interval, then the substitution gas with identical amount in step (4) is passed into;

(6) induction heater heats up, and controls crucible upper cover temperature T ₁be 2000 DEG C, powder position, source temperature T ₂be 2400 DEG C, growth pressure is 1mbar, and crystal growth time is 50h;

(7) after growth terminates; logical argon gas; under the protection of argon gas; progressively reduce power; make the temperature of growing system slowly be down to room temperature and obtain the 6H high-purity semi-insulating silicon carbide monocrystalline that length is greater than 3cm, diameter is greater than 3 inches; the speed of growth is greater than 0.6mm/h, and after cutting, grinding, polishing, resistivity is greater than 10 ⁶Ω cm.

Embodiment 2

The concrete implementation step difference from Example 1 of the present embodiment: the step in repetition embodiment 1 (5) four times, namely repeat to be filled with substitution gas totally five times, all the other steps of the present embodiment are identical with embodiment 1, do not repeat them here, obtain the 6H high-purity semi-insulating silicon carbide monocrystalline that length is greater than 3cm, diameter is greater than 3 inches, the speed of growth is greater than 0.6mm/h, and after cutting, grinding, polishing, resistivity is greater than 10 ⁸Ω cm, with the nitrogen content result nitrogen content in sims IMS-4F testing wafer lower than 9 × 10 ¹⁶atom/cm ³.

Claims

1. a method for quick growing large-size high-purity semi-insulating silicon carbide monocrystalline, is characterized in that: comprise the steps,

(2), first vacuumize, when the vacuum tightness in growth room reaches 5 × 10 before growth ^-5after mbar, substitution gas is passed in growth room, gas flow is 5 ~ 30mL/min, the time of passing into is 5 ~ 30min, pass into the substitution gas of same traffic, same time after the 30min of interval again, periodically repeat this process 2 ~ 5 times, air residual in displacement growth room, reach the object of denitrogenating, substitution gas can be Ar, H ₂, CH ₄or the mixed gas of three, blending ratio is 10 ~ 90% :10 ~ 90% :10 ~ 90%;

2. the method for a kind of quick growing large-size high-purity semi-insulating silicon carbide monocrystalline as claimed in claim 1, is characterized in that: described high-purity semi-insulating silicon carbide monocrystalline crystal formation comprises the arbitrary combination crystal formation of 4H, 6H, 3C and 15R or these four kinds of crystal formations.