CN108977886A

CN108977886A - A kind of manufacturing method of SiC crystal

Info

Publication number: CN108977886A
Application number: CN201810950367.8A
Authority: CN
Inventors: 孙月静
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-08-20
Filing date: 2018-08-20
Publication date: 2018-12-11

Abstract

The present invention is a kind of method for manufacturing SiC single crystal, is control vapor transmission and temperature gradient in terms of main novel of the invention, wherein the transmission is limited in the central area of growth crystal, and crystal and its surrounding are in close under conditions of zero radial symmetry gradient.This leads to the growth interface of advantageous shape, such as flat or slightly convex towards source, reduced crystal stress and reduced defect concentrations in crystals.Other novel aspects of the invention include by distilling and densifying the source SiC in situ from the particle filtering steam for being originated from the source SiC.

Description

A kind of manufacturing method of SiC crystal

The present invention relates to SiC production technical field, in particular to a kind of manufacturing method of SiC crystal.

Background technique

In the past decade, SiC crystal growth and substrate manufacture achieve major progress.Currently, commercially available maximum SiC lining Bottom is 4H the and 6H SiC wafer that diameter is 100mm.150 millimeters of substrates just in exploitation, recently, limited amount 150 millimeters of N-shapeds Substrate can be tried out or be sampled.Be widely implemented the SiC substrate of 150mm diameter, and in the future, 200mm substrate will make SiC and The significant reduction of the cost of GaN base semiconductor devices.

Development stages 150mm N-shaped chip is well known in the art.However, the progress of the device based on SiC still by To commercially available high quality 150mm SiC substrate shortage and lack the obstruction of 200mm substrate.In SiC substrate Injurous defect includes: dislocation, micro-pipe, stacking fault, the field trash and carbon inclusion of extraneous polytype body.Stress in SiC substrate It is another to device performance and the harmful factor of technology.

Summary of the invention

The present invention is a kind of improved method of SiC sublimation crystal growth.It is control steam in terms of main novel of the invention Transmission and temperature gradient, wherein the transmission is limited in the central area of growth crystal, and crystal and its surrounding are in close Under conditions of zero radial symmetry gradient.This leads to the growth interface of advantageous shape, such as flat or slightly convex towards source, reduces Crystal stress and reduced defect concentrations in crystals.

Other novel aspects of the invention include by distillation and from the particle filtering steam for being originated from the source SiC come in situ fine and close Change the source SiC.As optional feature, the present invention is included the steps that from elemental constituent in-situ synthesis of SiC source.

Specific embodiment

Disclosed herein is a kind of methods for manufacturing SiC single crystal, comprising: (a) is there are temperature gradient in crystal seed Sublimation-grown SiC single crystal on surface, while the gradient is controlled to realize the gradient of substantially shallow radial crystal and its surrounding； (b) in step (a), the steam containing SiC is controlled by the way that the flux to be substantially limited in the central area of seed surface Flux.

SiC sublimation growth system, comprising: growth crucible is configured as with the SiC of SiC source material and spaced relationship crystalline substance Kind charging；Growth crucible is separated into source chamber by separating plate, the source when growth crucible is equipped with SiC source material where SiC source material Crystallisation chamber where area and SiC crystal seed, wherein when growth crucible is equipped with SiC crystal seed: the demarcation plate includes by second part The first central part surrounded, the second part are originated from the source SiC material to SiC crystal seed during the sublimation-grown on SiC crystal seed The permeability of the SiC bearing steam of material is lower than the first central part；It is 1 centimetre with the mass transfer ratio with SiC steam.

Demarcation plate can be made of at least one of the following: graphite, fire resistant compound, tantalum carbide or niobium carbide.Separation Plate can be spaced apart with SiC crystal seed, it is desirable that between 25% of the seed diameter below seed and 75%.Separate Plate may include tantalum carbide or niobium carbide coating, and the thickness of coating is between about 20 microns to 40 microns.The first of separating plate Central part may include channel, and the maximum gauge in each channel is between about 0.1mm and 1mm.

The flux of the source material of distillation to seed can be limited by separating plate, the separating plate have in sublimation process The steam of generation has significant different infiltrative different zones.Source material can be SiC.

By the flux filtration for the source material that will be distilled by separating plate, may be implemented from the logical of the source material of distillation Carbon particle is removed in amount to seed.

The center of the SiC single crystal grown in the direction of growth of SiC single crystal and the chip from the cutting of the SiC single crystal of growth Difference in thickness between diameter can be not greater than about 6mm.

This method may further include the chip for having one or more of property from the cutting of the SiC single crystal of growth: Chip is averaged micropipe density no more than about average 1cm-2；Or 2 × 2mm the square dies without micro-pipe extracted from chip Percentage not less than about 95%；Or the percentage for the 5 × 5mm square dies without micro-pipe extracted from chip is not small In about 90%；Or the average dislocation density of chip is not greater than about 10.4cm-2；Or the density of thread helix dislocation is not more than About 1000cm-2；Or basal plane dislocation density is not greater than about 300 cm/cms 3；Or the extraneous polytype inclusion enclave of zero density；Or one A or multiple carbon inclusion clouds, no more than about the 5% of total chip area；Or the grid curvature of edge-to-edge is not greater than about 0.15°；Or full width at half maximum (FWHM) (FWHM) × ray of no more than about 25 second of arcs reflects on the gross area of chip.

This method, which may further include to the first and second resistance heaters, applies the electrical power of sufficient degree with by earthenware Crucible temperature is increased to SiC sublimation temperature and generates temperature gradient inside crucible, comprising: the temperature gradient in seed chamber.Crucible, The seed chamber temperature gradient be controlled as its radial component be positive (that is, seed chamber center is colder, neighbouring sidewall of crucible is warmmer) and Amplitude is no more than 10K/cm, and in the source chamber of crucible, the source chamber temperature gradient is enough to divide original source material temperature gradient From distilling and condensing on plate, to form fine and close polycrystalline Si C body.

This method may further include the electrical power for keeping the first and second resistance heaters, so that fine and close polycrystalline SiC body distils and generates steam；Force in the polycrystalline Si C body distillation of the densification steam that generates pass through separating plate it is ventilative in Heart district domain；The steam for being forced through the permeable portion of separating plate is moved to the central area of seed and is condensate on the seed, Make crystal growth；And by crystal growth to required size.

All steps can carry out under the pressure of 1 to 100 support in the presence of an inert gas.

The 4H and many types of major diameter of 6H grown by the above method, high quality SiC substrate can have 100mm and The semi-conductor industry normal diameter of diameter between 200mm, including 100mm, 125mm, 150mm and 200mm.Substrate relative to Hexagon basal plane (0001) is orientated with " on axis ", i.e., chip is parallel towards (0001) face；Relative to hexagon basal plane (0001) 4 ° of angles are deviateed in substrate with " off-axis " orientation, i.e. wafer face and (0001) face, or less.

Space between source material and crucible bottom can form cavity inside crucible；First resistor heater is with interval The over top of crucible is arranged in the relationship opened；Second resistance heater have first part and second part, first part with Spaced relationship is arranged below crucible bottom, and second part is arranged on the outside of crucible side with spaced relationship.Source material and seed crystal It can be made of SiC.Second resistance heater has first part and second part, and first part is arranged with spaced relationship in earthenware Crucible bottom part down, second part are arranged on the outside of crucible side with spaced relationship.Source material and seed crystal can be made of SiC.The Two resistance heaters have first part and second part, and first part is arranged below crucible bottom with spaced relationship, and second Part is arranged on the outside of crucible side with spaced relationship.Source material and seed crystal can be made of SiC.

The present invention is a kind of improved SiC sublimation growth process, is suitable for high quality, the growth of great diameter SiC crystal.This Invention is intended to flat or slightly convex to generate by the flux of the source material of temperature gradient and distillation in control growing element Growth interface, wherein control gradient is in crystal to generate positive and substantially shallow gradient, and do not surpass around it The flux for the source material crossing 10K/cm and wherein distilling is controlled by limiting the vapor transmission from the source of crystal ingot to central area System.Furthermore there is disclosed the in situ fine and close of the source SiC of the steam for the SiC crystal for being supplied to growth from particle by distillation and filtering The optional fabricated in situ in change and the source SiC.

Above the embodiments of the present invention are described in detail, but the present invention is not limited to described embodiments.It is right For those skilled in the art, in the case where not departing from the principle of the invention and spirit, these embodiments are carried out more Kind change, modification, replacement and modification, still fall in protection scope of the present invention.

Claims

1. a kind of method for manufacturing SiC single crystal, comprising: (a) grows one on the surface there are crystal seed of the temperature gradient of distillation SiC single crystal；(b) in step (a), the temperature gradient is controlled, so that the radial symmetry gradient in crystal is positive and substantially Shallowly, and the central area by the way that the flux to be substantially limited in surface controls the flux of the steam containing SiC.

2. according to the method described in claim 1, wherein the central area of the seed surface is essentially around the crystal seed Center is between the 30% and 60% of the total surface area of the crystal seed.

3. according to the method described in claim 1, wherein step (b) includes being steamed by setting in the crystal seed and the SiC that contains The flux of the steam containing SiC is restricted to the central area of the seed surface by the demarcation plate between the source of vapour.

4. according to the method described in claim 3, wherein: the seed diameter interval about 25% of the demarcation plate and the crystal seed to 75%；The thickness of separating plate is about 4mm to 10mm.Wherein the demarcation plate perhaps not with the steam reaction containing SiC or packet Coating is included to avoid the contact between the demarcation plate and the steam containing SiC.

5. according to the method described in claim 3, wherein the demarcation plate includes around the first outside portion of the second interior section Point, second interior section substantially has more permeability to the steam containing SiC than first exterior section.Wherein, institute Demarcation plate is stated to be configured to substantially remove particle from the solder flux of the steam containing SiC.

6. according to the method described in claim 6, wherein: the second interior section of the demarcation plate accounts for the demarcation plate gross area 20% to 50%；Or isolation board is made of graphite, fire resistant compound, tantalum carbide or niobium carbide.

7. according to the method described in claim 1, wherein step (a) further includes there are in the case where at least one of following SiC single crystal described in sublimation-grown: in the thermoisopleth that the direction in the source towards the steam containing SiC protrudes above.

8. according to the method described in claim 1, further include from the SiC single crystal of the growth cutting have one of the following or Multiple chips: chip be averaged micropipe density be not greater than about 1/cm average value；Or 2 without micro-pipe extracted from chip The percentage not less than about 95% of × 2mm square dies；Or 5 × 5mm the square dies without micro-pipe extracted from chip Percentage not less than about 90%；Or the dislocation of chip averag density is not greater than about 104/cm；Or thread helix dislocation is close Degree is not greater than about 1000/cm；Or basal plane dislocation density is not greater than about 300 cm/cms 3；Or the extraneous polytype package of zero density Body；Or one or more carbon inclusion clouds, no more than about the 5% of total chip area；Or the grid curvature of edge-to-edge does not surpass Cross 0.15 °；Or full width at half maximum (FWHM) (FWHM) × ray of no more than about 25 second of arcs reflects on the gross area of chip.

9. a kind of SiC sublimation crystal growth system, comprising: growth crucible, be configured to spaced relationship fill SiC source material and SiC seed crystal；Growth crucible is separated into source chamber by separating plate, the source when growth crucible is equipped with SiC source material where SiC source material Crystallisation chamber where area and SiC crystal seed, wherein when growth crucible is equipped with SiC crystal seed: the demarcation plate includes by second part The first central part surrounded, the second part are originated from the source SiC material to SiC crystal seed during the sublimation-grown on SiC crystal seed The permeability of the SiC bearing steam of material is lower than the first central part；SiC wafer further include: grid curvature is not greater than about 0.2 °, 0.1 ° or 0.06 °.On the gross area of chip.Wherein, the SiC wafer further includes being no more than on the gross area of the chip About 50,30 or 20 second of arcs × ray reflection full width at half maximum (FWHM) (FWHM).

10. a kind of method for forming high quality Sic single crystal wafer, comprising: the distillation grown on SiC single crystal crystal seed, SiC single crystal Crystal ingot, diameter are enough chip of the cutting diameter between 100 and 200mm, wherein the sublimation-grown is there are controlled axis To the controlled flux with radial symmetry gradient and the source material that distils；It is cut into from the SiC boule with stacking fault area Combined area be no more than the chip gross area about 5%, 2% or 1% SiC wafer.