阅读说明：本技术 碳化硅晶体的生长方法 (Method for growing silicon carbide crystal ) 是由 狄聚青 刘运连 薛帅 于 2021-09-23 设计创作，主要内容包括：本公开提供一种碳化硅晶体的生长方法,包括步骤：将碳化硅粉装入开口向上的坩埚中；将坩埚装入碳化硅炉中并安装在第一旋转机构且由加热机构包围；将籽晶置于安装在第一旋转机构的上方的第二旋转机构上,以使籽晶覆盖在坩埚的开口但坩埚的开口间隔开且不使籽晶在第二旋转机构的驱动下在水平内旋转时受到坩埚干涉；启动加热机构加热坩埚,待碳化硅粉开始升华时,第一旋转机构和第二旋转机构启动,第一旋转机构带动坩埚在水平面内旋转,第二旋转机构带动籽晶在水平面内旋转,坩埚和籽晶的旋转方向相反,以使升华的碳化硅粉附着在籽晶的面对坩埚的开口的表面上进行晶体生长。由此,在不增加碳化硅炉内的气体压力下提高生长速度,降低缺陷,提高质量。(The present disclosure provides a method for growing silicon carbide crystals, comprising the steps of: silicon carbide powder is filled into a crucible with an upward opening; the crucible is loaded into a silicon carbide furnace, is arranged on a first rotating mechanism and is surrounded by a heating mechanism; placing the seed crystal on a second rotating mechanism installed above the first rotating mechanism so that the seed crystal covers the opening of the crucible but the opening of the crucible is spaced apart and the seed crystal is not interfered by the crucible when being driven by the second rotating mechanism to rotate in the horizontal direction; the heating mechanism is started to heat the crucible, when the silicon carbide powder begins to sublimate, the first rotating mechanism and the second rotating mechanism are started, the first rotating mechanism drives the crucible to rotate in the horizontal plane, the second rotating mechanism drives the seed crystal to rotate in the horizontal plane, and the rotating directions of the crucible and the seed crystal are opposite so that the sublimated silicon carbide powder is attached to the surface of the seed crystal, facing the opening of the crucible, to perform crystal growth. Therefore, the growth speed is improved, the defects are reduced and the quality is improved under the condition that the gas pressure in the silicon carbide furnace is not increased.)

1. A method of growing a silicon carbide crystal, comprising the steps of:

silicon carbide powder (200) is filled into a crucible (1) with an upward opening (11);

the crucible (1) is arranged in a silicon carbide furnace (2), is arranged on a first rotating mechanism (3) and is surrounded by a heating mechanism (4);

placing the seed crystal (300) on a second rotating mechanism (5) installed above the first rotating mechanism (3) so that the seed crystal (300) covers the opening (11) of the crucible (1) but the opening (11) of the crucible (1) is spaced apart and the seed crystal (300) is not interfered by the crucible (1) when being driven by the second rotating mechanism (5) to rotate horizontally;

the crucible (1) is heated by starting the heating mechanism (4), when silicon carbide powder (200) begins to sublimate, the first rotating mechanism (3) and the second rotating mechanism (5) are started, the first rotating mechanism (3) drives the crucible (1) to rotate in the horizontal plane, the second rotating mechanism (5) drives the seed crystal (300) to rotate in the horizontal plane, and the rotating directions of the crucible (1) and the seed crystal (300) are opposite, so that the sublimated silicon carbide powder (200) is attached to the surface (300a) of the seed crystal (300) facing to the opening (11) of the crucible (1) to perform crystal growth.

2. The method of growing a silicon carbide crystal according to claim 1,

the rotation speed of the crucible (1) and the seed crystal (300) is kept the same at all times.

3. The method of growing a silicon carbide crystal according to claim 2,

the seed crystal (300) alternately rotates forwards and backwards in the crystal growth process;

the crucible (1) holding is changed along with the rotation direction change of the seed crystal (300), so that the rotation directions of the crucible (1) and the seed crystal (300) are kept opposite at any time.

4. The method of growing a silicon carbide crystal according to claim 3,

the time of the seed crystal (300) rising from rest to the maximum rotating speed R is T, the rotating speed is gradually reduced to 0 within the time T after the time T is kept at the maximum rotating speed R; then, reversing within the time T, keeping the rotating speed at the maximum reverse rotating speed R for the time T, and gradually reducing to 0 within the time T;

the crucible (1) holding is changed along with the rotation direction change of the seed crystal (300), so that the rotation directions of the crucible (1) and the seed crystal (300) are kept opposite at any time.

5. The method for growing a silicon carbide crystal according to claim 4,

1≤R≤20rpm，1≤T≤3min，0≤t≤3min。

6. the method for growing a silicon carbide crystal according to claim 4,

as the crystal grows, the rotation speed R 'of the seed crystal (300) and the crucible (1) is gradually reduced and satisfies the following relation with the time t': r ═ R (1-t'/2 t)₁) Wherein, t₁The length of time for crystal growth.

7. A method for growing silicon carbide crystals according to claim 1 wherein the gas pressure in the silicon carbide furnace (2) is between 1 mbar and 50 mbar before the heating mechanism (4) is activated to heat the crucible (1).

8. A method for growing silicon carbide crystals according to claim 7 wherein the gas pressure in the silicon carbide furnace (2) is 10 mbar before the heating mechanism (4) is activated to heat the crucible (1).

Technical Field

The disclosure relates to the field of crystal preparation, and in particular relates to a method for growing silicon carbide crystals.

Background

The silicon carbide (SiC) crystal has the outstanding characteristics and advantages of high thermal conductivity, high breakdown field strength, high saturated electron drift rate, high bonding energy, high chemical stability, radiation resistance, lattice constant and thermal expansion coefficient similar to those of GaN and the like, is an ideal material for manufacturing high-temperature, high-frequency, high-power and radiation-resistant electronic devices, and is widely applied to the fields of aerospace, electronic power, photoelectric devices and the like.

At present, most of the crystal growth methods of silicon carbide are gas phase transportation methods. The method sublimes silicon carbide powder into gas-phase Si and Si at high temperature₂Molecular fragments such as C and SiC. These molecular fragments are transported to the surface of the seed crystal and recombined into a single crystal of silicon carbide.

In the process of crystal growth, the gas pressure in the silicon carbide furnace is usually several millibars to dozens of millibars, and the gas flow is slow, so that the growth speed of the silicon carbide crystal is influenced. And under the condition of increasing the gas pressure in the silicon carbide furnace, the sublimation speed of the silicon carbide powder is reduced, and the growth speed of the crystal is also reduced. Meanwhile, due to the existence of the temperature gradient of the crucible and the seed crystal, the growing interface of the silicon carbide crystal is not a flat interface, so that the silicon carbide crystal has poor uniformity and high dislocation.

Disclosure of Invention

In view of the problems in the background art, an object of the present disclosure is to provide an apparatus and a method for manufacturing a dome window, which can increase the growth rate of silicon carbide, reduce crystal defects, and improve the quality of a silicon carbide crystal without increasing the gas pressure in a silicon carbide furnace.

Thus, in some embodiments, a method of growing a silicon carbide crystal comprises the steps of: silicon carbide powder is filled into a crucible with an upward opening; the crucible is loaded into a silicon carbide furnace, is arranged on a first rotating mechanism and is surrounded by a heating mechanism; placing the seed crystal on a second rotating mechanism installed above the first rotating mechanism so that the seed crystal covers the opening of the crucible but the opening of the crucible is spaced apart and the seed crystal is not interfered by the crucible when being driven by the second rotating mechanism to rotate in the horizontal direction; the heating mechanism is started to heat the crucible, when the silicon carbide powder begins to sublimate, the first rotating mechanism and the second rotating mechanism are started, the first rotating mechanism drives the crucible to rotate in the horizontal plane, the second rotating mechanism drives the seed crystal to rotate in the horizontal plane, and the rotating directions of the crucible and the seed crystal are opposite so that the sublimated silicon carbide powder is attached to the surface of the seed crystal, facing the opening of the crucible, to perform crystal growth.

In some embodiments, the rotational speeds of the crucible and seed crystal are maintained the same at all times.

In some embodiments, the seed crystal alternately undergoes forward and reverse rotation during crystal growth; the crucible holding is changed as the rotation direction of the seed crystal is changed to constantly keep the rotation directions of the crucible and the seed crystal opposite.

In some embodiments, the seed crystal is raised from rest to the maximum rotation speed R for T, the rotation speed is kept for T at the maximum rotation speed R, and then is gradually reduced to 0 within T time; then, reversing within the time T, keeping the rotating speed at the maximum reverse rotating speed R for the time T, and gradually reducing to 0 within the time T; the crucible holding is changed as the rotation direction of the seed crystal is changed to constantly keep the rotation directions of the crucible and the seed crystal opposite.

In some embodiments, 1 ≦ R ≦ 20rpm, 1 ≦ T ≦ 3min, and 0 ≦ T ≦ 3 min.

In some embodiments, as the crystal grows, the rotation rate R 'of the seed crystal and crucible is gradually reduced and satisfies the following relationship with time t': r ═ R (1-t'/2 t)₁) Wherein, t₁The length of time for crystal growth.

In some embodiments, the gas pressure within the silicon carbide furnace is between 1 mbar and 50 mbar prior to activating the heating mechanism to heat the crucible.

In some embodiments, the gas pressure within the silicon carbide furnace is 10 mbar prior to activating the heating mechanism to heat the crucible.

The beneficial effects of this disclosure are as follows: need not to increase the inside gas pressure of carborundum stove, all rotate but rotation direction is opposite through seed crystal and crucible, when adopting gaseous phase transport method growth carborundum crystal, form great gaseous flow in the sublimed gaseous phase of carborundum powder, be favorable to transporting the surface that the sublimed carborundum powder of crucible reaches the seed crystal near for the carborundum crystal growth rate on the surface of seed crystal. Meanwhile, as the seed crystal and the crucible rotate, the influence of temperature gradient in the seed crystal and the crucible on the uniformity of the crystal is inhibited, the uniformity of a temperature field is improved, crystal defects (such as micropipe defects, screw dislocations, basal plane dislocations and FWHM) are reduced, the resistivity of the crystal is low, and the difference of the resistivity of the whole piece is small, so that the high-quality silicon carbide crystal can be obtained.

Drawings

FIG. 1 is a schematic view of one embodiment of an apparatus for growing a silicon carbide crystal according to the present disclosure.

Wherein the reference numerals are as follows:

apparatus for growing 100 silicon carbide crystals

1 crucible

11 opening

2 silicon carbide furnace

3 first rotating mechanism

4 heating mechanism

5 second rotating mechanism

200 silicon carbide powder

300 seed crystal

300a surface

Detailed Description

The accompanying drawings illustrate embodiments of the present disclosure and it is to be understood that the disclosed embodiments are merely examples of the disclosure, which can be embodied in various forms, and therefore, specific details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure.

First, an apparatus for growing a silicon carbide crystal will be described.

Referring to fig. 1, an apparatus 100 for growing a silicon carbide crystal includes a crucible 1, a silicon carbide furnace 2, a first rotating mechanism 3, a heating mechanism 4, and a second rotating mechanism 5.

The crucible 1 is used for containing silicon carbide powder 200. The first rotating mechanism 3, the heating mechanism 4, and the second rotating mechanism 5 are provided in the silicon carbide furnace 2. The first rotating mechanism 3 is used for driving the crucible 1 to rotate in the horizontal plane. The heating mechanism 4 is used for heating the crucible 1 containing the silicon carbide powder 200. The second rotating mechanism 5 is located above the first rotating mechanism 3. The second rotating mechanism 5 is used for driving the seed crystal 300 to rotate in the horizontal plane.

Next, a method for growing a silicon carbide crystal is described with reference to FIG. 1.

The method for growing silicon carbide crystals comprises the steps of: silicon carbide powder 200 is filled into the crucible 1 with an upward opening 11; the crucible 1 is loaded into a silicon carbide furnace 2 and is installed on a first rotating mechanism 3 and surrounded by a heating mechanism 4; placing the seed crystal 300 on a second rotating mechanism 5 installed above the first rotating mechanism 3 so that the seed crystal 300 covers the opening 11 of the crucible 1 but the opening 11 of the crucible 1 is spaced apart and so that the seed crystal 300 is not interfered with the crucible 1 while rotating horizontally by the second rotating mechanism 5; the heating mechanism 4 is started to heat the crucible 1, when the silicon carbide powder 200 begins to sublimate, the first rotating mechanism 3 and the second rotating mechanism 5 are started, the first rotating mechanism 3 drives the crucible 1 to rotate in the horizontal plane, the second rotating mechanism 5 drives the seed crystal 300 to rotate in the horizontal plane, and the rotating directions of the crucible 1 and the seed crystal 300 are opposite, so that the sublimated silicon carbide powder 200 is attached to the surface 300a, facing the opening 11 of the crucible 1, of the seed crystal 300 to perform crystal growth.

In the method for growing the silicon carbide crystal, the gas pressure in the silicon carbide furnace 2 does not need to be increased, and the seed crystal 300 and the crucible 1 rotate but rotate in opposite directions, so that when the silicon carbide crystal is grown by adopting a gas phase conveying method, a large gas flow is formed in a gas phase sublimated by the silicon carbide powder 200, the silicon carbide powder 200 sublimated nearby the crucible 1 can be conveyed to reach the surface 300a of the seed crystal 300, and the growth speed of the silicon carbide crystal on the surface 300a of the seed crystal 300 is accelerated. Meanwhile, as the seed crystal 300 and the crucible 1 both rotate, the influence of the temperature gradient in the seed crystal 300 and the crucible 1 on the uniformity of the crystal is inhibited, the uniformity of the temperature field is improved, crystal defects (such as micropipe defects, screw dislocations, basal plane dislocations, and FWHM) are reduced, the resistivity of the crystal is low, and the difference of the resistivity of the whole piece is small, so that the high-quality silicon carbide crystal can be obtained.

On the basis that the seed crystal 300 and the crucible 1 both rotate but in opposite directions, further, the rotation speeds of the crucible 1 and the seed crystal 300 are constantly kept the same. Under this condition, the gas flow can be sufficiently agitated.

In some examples, the seed crystal 300 alternately undergoes forward and reverse rotation during crystal growth; the crucible 1 holding is changed as the rotation direction of the seed crystal 300 is changed to constantly keep the rotation directions of the crucible 1 and the seed crystal 300 opposite. The design of positive and negative rotation can make gas fully stir, avoids appearing local air current static.

Specifically, the time that the seed crystal 300 is raised from rest to the maximum rotating speed R is T, the rotating speed is gradually reduced to 0 within the time T after the time T is kept at the maximum rotating speed R; then, reversing within the time T, keeping the rotating speed at the maximum reverse rotating speed R for the time T, and gradually reducing to 0 within the time T; the crucible 1 holding is changed as the rotation direction of the seed crystal 300 is changed to constantly keep the rotation directions of the crucible 1 and the seed crystal 300 opposite. According to actual needs, the forward rotation and the reverse rotation can be repeated continuously.

In some examples, 1 ≦ R ≦ 20rpm, 1 ≦ T ≦ 3min, and 0 ≦ T ≦ 3 min. A maximum speed R exceeding 20rpm will cause turbulence in the gas phase, seriously affecting the gas phase stability, and in this interval T and T, an effective stirring can be achieved.

In some examples, as the crystal grows, the maximum rotation rate R of the seed crystal 300 and the rotation rate R 'of the crucible 1 gradually decrease and satisfy the following relationship with the time t': r ═ R (1-t'/2 t)₁) Wherein, t₁The length of time for crystal growth. As the crystal grows, the silicon carbide powder 200 in the crucible 1 gradually decreases, the sublimation amount of the silicon carbide powder 200 increases, and the rotation speed needs to be reduced to realize stable crystal growth.

In some examples, the gas pressure within silicon carbide furnace 2 is 1 mbar to 50 mbar before heating mechanism 4 is activated to heat crucible 1.

In some examples, the gas pressure within the silicon carbide furnace 2 is 10 mbar before the heating mechanism 4 is activated to heat the crucible 1.

Finally, the test procedure of the method for growing silicon carbide crystals is explained.

In the following description of the embodiments and comparative examples, a simplified description compared to the foregoing is employed and reference numerals of corresponding parts are omitted for the sake of brevity.

Example 1

Silicon carbide powder is filled into the crucible, the silicon carbide furnace is sealed (at the moment, the gas pressure in the silicon carbide furnace is 10 mbar), the heating mechanism is started, and crystal growth is started when the silicon carbide powder begins to sublimate. The seed crystal and the crucible are kept at the same rotating speed and opposite directions at any time. The seed crystal is raised to the maximum rotating speed of 20rpm from rest within 3min, the seed crystal is kept for 3min at the maximum rotating speed of 20rpm, and the rotating speed is gradually reduced to 0rpm within 3 min. Then, the rotation speed is reversed within 3min, the rotation speed reaches 20rpm, the rotation speed is kept for 3min at the maximum reverse rotation speed of 20rpm, and the rotation speed is gradually reduced to 0rpm within 3 min. The rotation speed R 'of the seed crystal and the crucible is gradually reduced along with the growth of the crystal, and the following relation is satisfied with the time t': r '═ R (1-t'/200). And after the crystal grows for 100 hours, naturally cooling to obtain the 6-inch silicon carbide crystal.

Silicon carbide crystals prepared in example 1, free of micropipe defects, with a TSD of 300cm^-2BPD of 45cm^-2The FWHM is 15arcsec, the crystal resistivity is more than 1E11 omega cm, and the difference of the whole sheet resistivity is within 5 percent.

Example 2

Silicon carbide powder was charged into the crucible, the silicon carbide furnace was closed (at this time, the gas pressure in the silicon carbide furnace was 10 mbar), the heating mechanism was started, and crystal growth was started. The seed crystal and the crucible are kept at the same rotating speed and opposite directions at any time. The seed crystal is raised to the maximum rotating speed of 1rpm from rest within 1min, and the rotating speed is gradually reduced to 0rpm within 1 min. Then, the rotation speed is reversed within 1min and reaches 1rpm, and then the rotation speed is gradually reduced to 0rpm within 1 min. The rotation speed R 'of the seed crystal and the crucible is gradually reduced along with the growth of the crystal, and the following relation is satisfied with the time t': r ═ R (1-t'/100). After the crystal grows for 50 hours, the temperature is naturally reduced to obtain 4 inches of silicon carbide crystal.

Silicon carbide crystals prepared in example 2, free of micropipe defects, with a TSD of 250cm^-2BPD of 20cm^-2The FWHM is 10arcsec, the crystal resistivity is more than 1E11 omega cm, and the difference of the whole sheet resistivity is within 4 percent.

Example 3

Silicon carbide powder was charged into the crucible, the silicon carbide furnace was closed (at this time, the gas pressure in the silicon carbide furnace was 10 mbar), the heating mechanism was started, and crystal growth was started. The seed crystal and the crucible are kept at the same rotating speed and opposite directions at any time. The seed crystal is raised from static state to the maximum rotation speed of 25rpm within 1min, and the rotation speed is gradually reduced to 0rpm within 1 min. Then, the rotation speed is reversed within 1min to reach 25rpm, and then gradually reduced to 0rpm within 1 min. The rotation speed R 'of the seed crystal and the crucible is gradually reduced along with the growth of the crystal, and the following relation is satisfied with the time t': r ═ R (1-t'/100). After the crystal grows for 50 hours, the temperature is naturally reduced to obtain 4 inches of silicon carbide crystal.

Silicon carbide crystals prepared in example 3, free of micropipe defects, with a TSD of 600cm^-2BPD of 80cm^-2The FWHM is 50arcsec, the crystal resistivity is more than 1E11 omega cm, and the difference of the whole sheet resistivity is within 25 percent.

Example 4

Silicon carbide powder was charged into the crucible, the silicon carbide furnace was closed (at this time, the gas pressure in the silicon carbide furnace was 10 mbar), the heating mechanism was started, and crystal growth was started. The seed crystal and the crucible are kept at the same rotating speed and opposite directions at any time. The seed crystal is raised to the maximum rotating speed of 20rpm from rest within 5min, the seed crystal is kept for 3min at the maximum rotating speed of 20rpm, and the rotating speed is gradually reduced to 0rpm within 5 min. Then, the rotation speed is reversed within 5min, the rotation speed reaches 20rpm, the rotation speed is kept for 3min at the maximum reverse rotation speed of 20rpm, and the rotation speed is gradually reduced to 0rpm within 5 min. The rotation speed R 'of the seed crystal and the crucible is gradually reduced along with the growth of the crystal, and the following relation is satisfied with the time t': r '═ R (1-t'/200). And after the crystal grows for 100 hours, naturally cooling to obtain the 6-inch silicon carbide crystal.

Silicon carbide crystals prepared in example 4, free of micropipe defects, with a TSD of 400cm^-2BPD of 50cm^-2The FWHM is 30arcsec, the crystal resistivity is more than 1E11 omega cm, and the difference of the whole sheet resistivity is within 15%.

Example 5

And (3) putting silicon carbide powder into the crucible, sealing the silicon carbide furnace, starting the heating mechanism, and starting crystal growth. The seed crystal and the crucible are kept at the same rotating speed and opposite directions at any time. The seed crystal is raised to the maximum rotating speed of 20rpm from rest within 3min, the seed crystal is kept for 5min at the maximum rotating speed of 20rpm, and the rotating speed is gradually reduced to 0rpm within 3 min. Then, the rotation speed is reversed within 3min, the rotation speed reaches 20rpm, the rotation speed is kept for 5min at the maximum reverse rotation speed of 20rpm, and the rotation speed is gradually reduced to 0rpm within 3 min. The rotation speed R 'of the seed crystal and the crucible is gradually reduced along with the growth of the crystal, and the following relation is satisfied with the time t': r '═ R (1-t'/200). And after the crystal grows for 100 hours, naturally cooling to obtain the 6-inch silicon carbide crystal.

Silicon carbide crystals prepared in example 5, free of micropipe defects, with a TSD of 380cm^-2BPD of 80cm^-2The FWHM is 40arcsec, the crystal resistivity is more than 1E11 omega cm, and the difference of the whole sheet resistivity is within 20 percent.

Example 6

Silicon carbide powder was charged into the crucible, the silicon carbide furnace was closed (at this time, the gas pressure in the silicon carbide furnace was 10 mbar), the heating mechanism was started, and crystal growth was started. The seed crystal and the crucible are kept at the same rotating speed and opposite directions at any time. The seed crystal is raised to the maximum rotation speed of 20rpm from rest within 5min, kept for 5min at the maximum rotation speed of 20rpm, and gradually reduced to 0rpm within 5 min. Then, the rotation speed is reversed within 5min, the rotation speed reaches 20rpm, the rotation speed is kept for 5min at the maximum reverse rotation speed of 20rpm, and the rotation speed is gradually reduced to 0rpm within 5 min. The rotation speed R 'of the seed crystal and the crucible is gradually reduced along with the growth of the crystal, and the following relation is satisfied with the time t': r '═ R (1-t'/200). And after the crystal grows for 100 hours, naturally cooling to obtain the 6-inch silicon carbide crystal.

Silicon carbide crystals prepared in example 6, free of micropipe defects, with a TSD of 500cm^-2BPD of 90cm^-2FWHM is 40arcsec, crystal resistivity is larger than 1E11 omega cm, and the whole sheet resistivity difference is within 25%

Comparative example 1

Silicon carbide powder was charged into the crucible, the silicon carbide furnace was closed (at this time, the gas pressure in the silicon carbide furnace was 10 mbar), the heating mechanism was started, and crystal growth was started. Only the crucible rotates, the rotation process of the crucible is the same as that of the embodiment 1, and the seed crystal is still. And after the crystal grows for 100 hours, cooling to obtain the silicon carbide crystal.

Silicon carbide crystal prepared in comparative example 1, which had micropipe defect of 10cm^-2TSD of 800cm^-2BPD of 100cm^-2FWHM is 120arcsec, crystal resistivity is more than 1E10 omega cm, and the difference of the whole sheet resistivity is 5Within 0%.

The corresponding test procedure is described below.

(1) Micropipe defect testing

The silicon carbide single crystal micro-pipeline defect research, 15 th stage 2011, pages 68-69,185, is tested and counted by referring to the chapter aright, scientific introduction.

(2) TSD (Threading Screw Dislocation) and BPD (basic Plane Dislocation) tests

Referring to a dislocation density detection method of a silicon carbide single crystal polished wafer, the Mitsuncura Tianhe union group standard of the innovation of the wide bandgap semiconductor technology,https://www.docin.com/p-2175184945.htmltesting is carried out;

(3) FWHM (full width at half maximum) test

XRD rocking curve testing was performed using a Bruker D8 Discover high resolution X-ray diffractometer.

(4) Crystal resistivity and bulk resistivity differential test

The crystal resistivity was measured by resistivity surface scanning using a non-contact resistivity tester, OREMA-WT.

Table 1 and table 2 list the parameters and product test performance for some of the above examples and comparative examples.

TABLE 1 parameters for examples 1-6 and comparative example 1

TABLE 2 Properties of the products of examples 1-6 and comparative example 1

As seen from examples 1-6 and comparative example 1, micropipe defects were eliminated and TSD, BSD, FWHM, crystal resistivity, and bulk resistivity differences were significantly reduced by moving the crucible and seed crystal in opposition to each other.

It is seen from a comparison of example 3 with example 2 that the rotation rate is too high, causing a drastic increase in the TSD, BPD, FWHM and the overall resistivity difference.

As seen from the comparison of example 4 with example 1, T is too large and TSD, BSD, FWHM and the global resistivity difference are all significantly increased.

As seen from the comparison of example 6 with example 4 and from the comparison of example 5 with example 1, t is further excessive and TSD is further increased. From a comparison of example 6 and example 5, it is seen that T is further increased and the TSD, BPD and sheet resistivity differences are further increased.

Based on the above, 1. ltoreq. R.ltoreq.20 rpm, 1. ltoreq. T.ltoreq.3 min, 0. ltoreq. t.ltoreq.3 min, R '═ R (1-T'/2T)₁)。

The above detailed description is used to describe a number of exemplary embodiments, but is not intended to limit the combinations explicitly disclosed herein. Thus, unless otherwise specified, various features disclosed herein can be combined together to form a number of additional combinations that are not shown for the sake of brevity.