CN211497869U - Annealing treatment device for crystals - Google Patents

Abstract

The utility model provides an annealing treatment device of crystal, the device includes: the crucible is used for placing crystals needing annealing treatment; the first heater comprises a plurality of first heating rings which are concentrically arranged, and the first heating rings are distributed above the crucible; the second heater comprises a plurality of second heating rings which are concentrically arranged, and the plurality of second heating rings are distributed below the crucible; and a third heater disposed at a side surface of the crucible. The utility model discloses set up the heater that is located crucible top, below, both sides respectively, and set up a plurality of heaters of crucible top, below into a plurality of heating ring structures, through the suitable power of adjusting every heating ring, can control the crucible temperature and evenly reduce to the edge from the center, and control crucible lower part temperature and be higher than the temperature on the crucible upper portion of corresponding part, different or opposite axial temperature gradient in the time of can obtaining with crystal growth can realize residual thermal stress's basic elimination.

Description

Annealing treatment device for crystals

Technical Field

The utility model relates to an annealing treatment device of crystal belongs to the technical field of annealing treatment after the crystal growth.

Background

Silicon carbide is one of the third generation wide bandgap semiconductor materials following silicon and gallium arsenide, and is widely applied to the fields of power electronics, radio frequency devices, photoelectronic devices and the like because of its excellent properties such as large forbidden bandwidth, high saturated electron mobility, strong breakdown field, high thermal conductivity and the like. High quality crystals are the cornerstone of semiconductor and information industry development, and the level of their fabrication limits the fabrication and performance of downstream devices. Although Physical Vapor Transport (PVT) growth of silicon carbide crystals has advanced sufficiently in recent years, excessive residual stress is a problem to be solved for large-size single crystal silicon carbide, and particularly for silicon carbide single crystals larger than or equal to 6 inches, the following consequences can be caused by too much stress: ingot cracking, wafer cracking, crack edge chipping, and large surface profile.

CN204417642U discloses a heating device for preparing silicon carbide crystals, which is characterized in that a top heater is additionally arranged above a crucible, the temperature above the crystals is actively adjusted by the top heater, so that the temperature gradients of the inner radial direction and the axial line of the crystals are greatly reduced or turned over compared with the growth process of the crystals, the residual thermal stress in the cooled crystals is greatly reduced, and the crystals are not cracked due to overhigh internal stress. The number of the top heaters is 1 or 2, the power of the top heaters is set to be proper, so that the central temperature of the crystal is higher than the edge temperature, or the top temperature of the crystal is higher than the lower temperature, but the radial temperature gradient of the crystal cannot be changed, the intelligent control of the temperature gradient cannot be realized, the stress in the crystal cannot be completely eliminated, and the device is only suitable for in-situ annealing of the crystal and can reduce the yield of the crystal growing furnace.

SUMMERY OF THE UTILITY MODEL

In order to solve the above problems, the present invention provides an annealing treatment device for a crystal, which controls the radial and axial temperature gradients in a crucible by separately installing heaters above, below and around the crucible, thereby substantially eliminating the internal stress of the crystal.

The technical scheme adopted by the application is as follows:

the utility model provides an annealing treatment device of crystal, the device includes:

the crucible is used for placing crystals needing annealing treatment;

the first heater comprises a plurality of first heating rings which are concentrically arranged, and the first heating rings are distributed above the crucible;

the second heater comprises a plurality of second heating rings which are concentrically arranged, and the plurality of second heating rings are distributed below the crucible;

and a third heater disposed at a side surface of the crucible.

Preferably, the first heater and the second heater are symmetrically arranged at both ends of the crucible.

Preferably, the first heating rings are concentrically arranged with the upper part of the crucible center as the center of a circle, and the second heating rings are concentrically arranged with the lower part of the crucible center as the center of a circle.

Preferably, the number of the first heating rings or the second heating rings is 3-6, and the distance between every two adjacent first heating rings or the second heating rings is equal.

Preferably, the third heater comprises a plurality of third heating rings arranged axially concentrically.

Preferably, the first heater, the second heater and the third heater are all graphite heaters.

Preferably, the temperatures of the first heating rings, the second heating rings and the third heaters are respectively controlled by a temperature control device, and the temperatures of the first heating rings, the second heating rings and the third heaters corresponding to the crucible areas are respectively measured by a temperature measuring device.

Preferably, the device further comprises an insulating layer, and the insulating layer is arranged on the periphery of the first heater, the second heater and the third heater.

Preferably, the height of the crucible is less than its diameter.

Preferably, the crucible is a graphite crucible, and the graphite crucible comprises a crucible body and a crucible cover covering the crucible body;

the crucible body is communicated with a vacuum system;

the bottom center in the crucible body is provided with a base which can be adjusted up and down, and the base is used for placing crystals to be annealed.

The utility model has the advantages that:

(1) the utility model discloses set up the heater of crucible top, below, both sides respectively, and set up a plurality of heaters of crucible top, below into the heating ring structure, adjust the suitable power of every heating ring, control crucible temperature evenly reduces to the edge from the center to and control crucible lower part temperature is higher than the temperature on the crucible upper portion of corresponding part, different or opposite axial temperature gradient in the time of can obtaining with crystal growth can realize residual thermal stress's basic elimination.

(2) The utility model discloses use solitary crucible to carry out annealing treatment, for the normal position annealing that uses long brilliant stove, can not reduce the productivity of long brilliant stove.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:

FIG. 1 is a schematic sectional view of an annealing apparatus according to the present invention;

FIG. 2 is a schematic cross-sectional view of an embodiment of an annealing apparatus according to the present invention;

fig. 3 is a top view of the heating device of the present invention;

fig. 4 is a schematic sectional view of the heating device of the present invention;

FIG. 5 is a schematic structural view of the annealing apparatus of the present invention;

fig. 6 is a high-resolution XRD pattern of sample 1 of the present invention;

wherein, 1, a crucible; 2. a first heating ring; 3. a second heating ring; 4. a third heating ring; 5. a temperature control device; 6. a temperature measuring device; 7. a heat-insulating layer; 8. and (4) crystals.

Detailed Description

The present application will be described in detail with reference to examples, but the present application is not limited to these examples.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application, however, the present application may be practiced in other ways than those described herein, and therefore the scope of the present application is not limited by the specific embodiments disclosed below.

In addition, in the description of the present application, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the referred devices or elements must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application.

The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.

In this application, unless expressly stated or limited otherwise, the terms "mounted," "connected," "coupled," and the like are to be construed broadly and include, for example, fixed or removable connections or integral parts; the connection can be mechanical connection, electrical connection or communication; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.

In this application, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through intervening media. In the description herein, reference to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Unless otherwise specified, the raw materials and reagents in the examples of the present invention were purchased commercially.

The utility model discloses an annealing treatment device of crystal can be used to the annealing treatment of silicon carbide crystal, but is not limited to the annealing treatment of silicon carbide crystal, the utility model discloses use silicon carbide crystal to explain this annealing treatment device's structure and application method as the example.

Example 1: the utility model is used for annealing processing apparatus of carborundum crystal, its concrete structure as follows:

as shown in fig. 1 to 3, the crystal annealing device of the present invention comprises a crucible 1, the crucible 1 is used for placing a crystal 8 to be annealed, and a first heater, a second heater and a third heater for heating the crucible 1; the first heater comprises a plurality of first heating rings 2 which are concentrically arranged, and the plurality of first heating rings 2 are distributed above the crucible 1; the second heater comprises a plurality of second heating rings 3 which are concentrically arranged, and the plurality of second heating rings 3 are distributed below the crucible 1; and a third heater provided on a side surface of the crucible 1.

The utility model discloses set up the heater respectively in the top of crucible 1, below and side, utilize the first heating ring 2 of the top of crucible 1 to heat 1 top of crucible, can realize the radial temperature gradient of crucible 1, can obtain the radial temperature gradient different or opposite with crystal growth, can show the radial stress that reduces the crystal. The utility model discloses still utilize second heating ring 3, realize the temperature difference of the temperature of 1 top of temperature and crucible below the crucible 1, and utilize the third heating ring 4 of 1 side of crucible, realize 1 axial temperature gradient of crucible, can obtain the axial temperature gradient different or opposite with crystal growth, can show the axial stress that reduces the crystal. Because each heating ring is independently arranged, the temperature of different heating rings can be respectively controlled, and the temperature control of partial area of the crucible 1 is realized. In the process of crystal growth, the temperature of the growth surface is higher than that of the seed crystal surface, and the temperature of the center of the crystal on the same plane is lower than that of the edge of the crystal, so that the annealing temperature in the crucible can be controlled to be different from or opposite to the growth temperature gradient according to the temperature gradient of crystal growth, the crystal can be in a radial and axial temperature gradient completely different from the growth during annealing, and the internal stress generated in the crystal growth stage can be eliminated through the reverse temperature gradient in the annealing stage.

In a preferred embodiment, the first heater and the second heater are symmetrically disposed at both ends of the crucible. The first heater and the second heater are symmetrically arranged, so that the temperature of the heaters in partial areas of the crucible and areas corresponding to points can be conveniently adjusted and controlled.

In a preferred embodiment, the first heating rings are concentrically arranged around the upper part of the crucible center, and the second heating rings are concentrically arranged around the lower part of the crucible center. When the silicon carbide crystal grows, the axial temperature gradient of the central area is larger than that of the edge area, so that the growth speed of the central area of the silicon carbide crystal is higher than that of the edge area, and the growth interface of the silicon carbide crystal is in a slightly convex shape. Therefore, the first heating ring and the second heating ring are concentrically arranged by taking the upper part/the lower part of the center of the crucible as the circle center, so that the axial temperature gradient of the central area of the crystal is smaller than that of the edge area in the crystal annealing process.

In a preferred embodiment, the number of the first heating ring 2 and/or the second heating ring 3 is 3 to 6, and more preferably 4 to 5. Because the first heating ring 2 and the second heating ring 3 are distributed in an up-and-down symmetrical manner, the number of the first heating ring 2 and the second heating ring 3 is the same. The first heating ring 2 is a group of concentrically arranged circular ring structures, the heating ring at the center of the circular ring can be approximately a solid circular structure, and the number of the heating rings cannot be too small due to the arrangement of radial temperature gradients. As shown in the figure, the number of the first heating ring 2 and/or the second heating ring 3 is 4. To achieve a more uniform radial temperature gradient, the spacing between adjacent first heating rings 2 or second heating rings 3 is set to be equal.

In one embodiment, the third heater is a heating coil wound around two sides of the crucible or a heating ring surrounding two sides of the crucible. As shown in fig. 2, in a preferred example, said third heater comprises a plurality of third heating rings 4 arranged axially concentrically. The number of the third heating rings 4 can be 1, 2 or 3, and the height of the crucible is low, so long as the crystal to be annealed can be placed in the crucible. The number of the third heating rings 4 does not need to be set too much. As shown in the figure, the number of the third heating rings 4 is 2, the temperature of 2 third heating rings 4 can be set to be the same or different, the temperature of the third heating ring arranged below can be slightly higher than the temperature of the third heating ring arranged above, the temperature of the third heating ring 4 is in the middle value of the temperature of the first heating ring 2 and the second heating ring 3, and the trend of temperature reduction inside the crucible from bottom to top is formed. In order to achieve a more uniform axial temperature gradient, a plurality of third heating rings are evenly distributed in the axial direction of the crucible, and the size of the plurality of third heating rings is equal, for example, two third heating rings are respectively arranged at 1/3 and 2/3 of the height of the crucible.

In a preferred embodiment, as shown in fig. 2, the apparatus further comprises an insulating layer 7, and the insulating layer 7 is disposed at the periphery of the first heater, the second heater and the third heater. In a specific example, the heat insulating layer 7 is a graphite felt, and the first heater, the second heater and the third heater are arranged on the inner side of the heat insulating layer 7, so that the first heater, the second heater and the third heater are only used for heating the inside of the crucible 1, heat heated by the first heater, the second heater and the third heater is not diffused outwards, and the temperature in the crucible can be accurately controlled.

In one embodiment, as shown in fig. 5, the heating temperatures of the first heating rings 2, the second heating rings 3 and the third heaters are respectively controlled by a temperature control device, and the temperatures of the first heating rings 2, the second heating rings 3 and the third heating rings 4 corresponding to the crucible areas are respectively measured by a temperature measuring device.

The utility model discloses in, every heating ring temperature is temperature control device 5 regulation respectively, controls the heating temperature of different crucible subregion, and the temperature after the heating obtains through temperature measuring device 6. In a specific example, the temperature control device 5 and the temperature measuring device 6 can be integrally arranged together, the temperature measuring device 6 is electrically connected with the temperature control device 5, and the temperature measuring device 6 and the temperature control device 5 are controlled by a general controller; the temperature measuring device 6 comprises a pyrometer which is arranged on a partial region of the crucible 1 and is used to measure the temperature of the partial region of the crucible.

In a preferred embodiment, the first heating ring 2, the second heating ring 3 and the third heating ring 4 are made of graphite. The graphite heating ring has good stability and high thermal conductivity, and can ensure that the interior of the heated crucible is in a relatively stable temperature field.

In a preferred embodiment, the height of the crucible 1 is smaller than its diameter. The utility model discloses a crucible 1 is when using, through on putting into the base of the crucible body from crucible body top with the crystal that will need annealing, adjusts the base and can be located the approximate central point of crucible with the crystal that needs annealing and puts for the central point that the crystal that needs annealing is in the inside temperature field of crucible puts, more is favorable to the elimination of crystal internal stress. Because the crucible only is used for annealing the crystal, still need be used for crystal growth's difference with the crucible of normal position annealing treatment, the utility model discloses crucible 1 highly as long as be applicable to the thickness of crystal can, consequently, the crucible of setting highly is less than its diameter.

In a specific embodiment, the crucible 1 is a graphite crucible, the graphite crucible comprises a crucible body and a crucible cover covering the crucible body, an adjustable base is arranged at the bottom of the crucible body, and a crystal to be annealed is placed on the base; the crucible body is communicated with a vacuum system. The height of the crucible 1 is smaller than its diameter.

The bottom center in the crucible 1 body of the utility model is provided with a vertically adjustable base, the adjusting structure for the base can be an adjusting structure which is conventionally used in the field, in one example, the base can be connected with the adjusting structure, the adjusting structure comprises a support bar, a ball screw, a screw nut and a motor, one end of the support bar is fixedly connected with the base, and the other end passes through the bottom center of the crucible and is connected with the screw nut; the ball screw is in threaded fit with the screw nut, and the motor drives the ball screw to rotate through the coupler.

The utility model discloses a crucible body intercommunication has vacuum system, and vacuum system is used for to the inside evacuation of crucible or ventilate with the inside atmospheric pressure that resumes of crucible. The vacuum system may be a vacuum system conventionally used in the art, and in one embodiment, the vacuum system includes a vacuum pump, a vacuum gauge and a gas release valve, which are respectively connected with the inside of the crucible 1 through pipes. The vacuum pump is used for vacuumizing the interior of the crucible 1, the vacuum gauge is used for detecting the vacuum condition in the interior of the crucible 1, and the air release valve is used for ventilating to restore the interior of the crucible to one atmospheric pressure.

Example 2: annealing treatment method for crystal

According to an embodiment of the present application, a method of performing a crystal annealing process using the apparatus of example 1 includes:

(1) a preparation stage: putting a crystal (6 inches) to be annealed into a crucible 1, vacuumizing and introducing inert gas (Ar gas) to control the pressure in the crucible 1 to be 200-900 mbar and the flow rate of the Ar gas to be 50-500 ml/min;

(2) a heating stage: as shown in FIG. 4, all the heating rings are controlled to start synchronous heating at the same time, the heating is carried out to T1 (1700-2300 ℃), and the temperature is kept for 1-10 h;

in the crystal growth process, the temperature of the growth surface is higher than that of the seed crystal surface, and the temperature of the center of the crystal is lower than that of the edge of the crystal on the same plane, so that in this stage, the temperature T1 in the previous step is used as a starting point, the heating power of all the first heating ring 2 and the second heating ring 3 is controlled, the temperature at the center is controlled to be the highest, the temperature is uniformly reduced to the edge, but the heating temperature of the corresponding parts above and below is kept the same (the temperature of A1 is the same as that of B1, the temperature of A2 is the same as that of B2, the temperature of A3 is the same as that of B3, and the temperature of A4 is the same as that of B4), the radial temperature gradient X is controlled, wherein X is 5-50 ℃, namely the temperature of A4 and B4 is controlled to be T1, the temperature of A3 is higher than A4, the temperature of A2 is higher than the temperature of A3, the A1 is higher than the temperature of the A2, the;

on the basis, the heating temperature of the second heating ring below the crucible along the axial direction is controlled to be Y higher than the temperature above the crucible, wherein Y is 10-100 ℃. That is, when A4 is T1, the temperature of B4 is controlled to be Y higher than A4, B3 is controlled to be Y higher than A3, B2 is controlled to be Y higher than A2, and B1 is controlled to be Y higher than A1. Controlling the temperature of the third heating ring on the side surface of the crucible to enable the heating temperature of the third heating ring to be between A4 and B4, namely when A4 is T1, the temperature of S1 is T1+1/3Y, and the temperature of S2 is T1+ 2/3Y;

then keeping the temperature (the temperature gradient completely opposite to that during crystal growth) for 1-10 h;

(3) cooling and ventilating stages: controlling the power of all heating rings with the temperature higher than T1 to cool the partial region, wherein the temperature of all positions of the crucible is T1 in the cooling process, and then all regions are cooled to the room temperature at the speed of 50-250 ℃/h by taking T1 as a starting point; introducing Ar gas until the air pressure in the furnace chamber is kept level outside, and taking out the annealed crystal.

Specific implementation conditions are shown in table 1:

table 1 annealing process parameters of samples of the present invention

In addition, 2 comparative examples were provided, and in comparative example 1, the second heating ring above the crucible and the third heating ring below the crucible were not provided, and the remaining parameter settings were the same as those of sample 1, and comparative sample 1 was obtained after annealing. In comparative example 2, the number of the second heating rings and the third heating rings was two, the temperature difference between the two second heating rings and the two third heating rings was 10 ℃, the remaining parameters were set to be the same as those of sample 1,

the crystal quality of all samples of samples 1 to 6 and comparative samples 1 to 2 was examined. The thicknesses of four points of the crystal are respectively measured by a vernier caliper after the crystal growth is finished, the crystal quality is measured by high-resolution XRD, the high-resolution XRD image of the sample 1 is shown in figure 6, and the test results of all the samples are shown in table 2.

TABLE 2 results of crystal quality measurements for all samples

As shown in the results of Table 2, the geometric parameters of the wafer after annealing treatment in the embodiment of the present invention are ideal, the variation range of Warp (Warp) is 16-19 μm, the variation range of Bow (Bow) is 10-14 μm, and the variation range of Total Thickness Variation (TTV) is 4-5 μm, which is far smaller than the industrial standard, and the obtained wafer has no edge breakage and crack. Compared with the example 1, the heating rings above and below the crucible are not arranged in the comparative example 1, the heating rings arranged in the comparative example 2 are too small in number, the radial and axial temperature gradient change cannot be formed, the Warp, Bow and TTV values of the obtained wafer are large, the edge breakage and the cracking of the wafer are caused, and the quality is poor. Therefore, the utility model discloses a set up a plurality of heating rings that are located crucible top and crucible below, form radial and axial temperature gradient's change, can eliminate basically and reduce the stress in the crystal, show the quality that has improved the crystal.

The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the system embodiment, since it is substantially similar to the method embodiment, the description is simple, and for the relevant points, reference may be made to the partial description of the method embodiment.

The above description is only an example of the present application, and the protection scope of the present application is not limited by these specific examples, but is defined by the claims of the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the technical idea and principle of the present application should be included in the protection scope of the present application.

Claims (10)

1. An apparatus for annealing a crystal, the apparatus comprising:

the crucible is used for placing crystals needing annealing treatment;

the first heater comprises a plurality of first heating rings which are concentrically arranged, and the first heating rings are distributed above the crucible;

the second heater comprises a plurality of second heating rings which are concentrically arranged, and the plurality of second heating rings are distributed below the crucible;

and a third heater disposed at a side surface of the crucible.

2. The apparatus of claim 1, wherein the first and second heaters are symmetrically disposed at opposite ends of the crucible.

3. The apparatus of claim 1, wherein the first plurality of heating rings are concentrically arranged about a center above a center of the crucible and the second plurality of heating rings are concentrically arranged about a center below the center of the crucible.

4. The crystal annealing device according to claim 1, wherein the number of the first heating ring or the second heating ring is 3 to 6, and the distance between two adjacent first heating rings or second heating rings is equal.

5. The crystal annealing apparatus of claim 1, wherein the third heater comprises a plurality of third heating rings arranged axially concentrically.

6. The crystal annealing apparatus of claim 1, wherein said first heater, second heater and third heater are all graphite heaters.

7. The apparatus of claim 1, wherein the temperatures of the first heating rings, the second heating rings, and the third heaters are controlled by temperature control means, and the temperatures of the first heating rings, the second heating rings, and the third heaters in the crucible regions are measured by temperature measuring means.

8. The crystal annealing apparatus according to claim 1, further comprising an insulating layer provided around the first heater, the second heater, and the third heater.

9. The crystal annealing apparatus of claim 1, wherein the height of the crucible is less than its diameter.

10. The crystal annealing apparatus of claim 1, wherein the crucible is a graphite crucible comprising a crucible body and a crucible cover covering the crucible body;

the crucible body is communicated with a vacuum system;

the bottom center in the crucible body is provided with a base which can be adjusted up and down, and the base is used for placing crystals to be annealed.

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