CN112067663B - Method and device for detecting resistivity of high-purity silicon carbide crystal - Google Patents
Method and device for detecting resistivity of high-purity silicon carbide crystal Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/041—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
Abstract
The application provides a method and a device for detecting the resistivity of a high-purity silicon carbide crystal, wherein the method comprises the following steps: irradiating the silicon carbide crystal by using a light source, detecting the light transmission wavelength of the silicon carbide crystal, comparing the light transmission wavelength with the standard color wavelength range, and judging whether the resistivity is qualified or not according to the comparison result; the standard color wavelength range is a numerical range of light transmission color wavelengths of standard silicon carbide crystals with qualified resistivity after being irradiated by the same light source. The resistivity detection method and device for the silicon carbide crystal provided by the application have the advantages of high accuracy, simple steps, strong operability, low requirements on the test environment, suitability for production sites, capability of reducing the workload and cost of the precise detection step, and improvement of the production efficiency, and particularly, reference for the preliminary evaluation of the resistivity of the high-purity silicon carbide crystal prepared by adopting a physical vapor transmission method.
Description
Technical Field
The application relates to the technical field of semiconductor performance parameter detection methods, in particular to a method and a device for detecting resistivity of high-purity silicon carbide crystals.
Background
For the conductive silicon carbide semiconductor crystal produced industrially, the quality, in particular the resistivity, is evaluated by the performance parameters such as resistivity, carrier concentration, microtube density, dislocation, inclusion and the like besides the conventional physical parameters such as weight, thickness, diameter and the like during characterization, and the resistivity is an important performance index for distinguishing different types of industrial silicon carbide products.
However, in the prior art, the performance of an industrial silicon carbide crystal product is evaluated by slicing, rounding, grinding and polishing an ingot, and a finished wafer product is detected in a laboratory by a precise detection instrument, but there is no method or instrument capable of primarily detecting the resistivity of the prepared silicon carbide crystal in the production process, for example, in a production field, so that the precision detection mode is adopted after each ingot is processed by slicing and other steps in the later period, the work of a detection department is increased, the depreciation rate of precision detection equipment is increased, and each precision detection equipment has a large volume, is expensive, has strict requirements on detection environment, and is not suitable for resistivity detection in the production process.
Therefore, the existing detection method of the resistivity of the silicon carbide crystal is not beneficial to improving the production efficiency, and the prior art fails to provide a detection method capable of preliminarily judging the resistivity of the prepared silicon carbide crystal in the production process.
Disclosure of Invention
In order to solve the problems, on one hand, the application provides a detection method for the resistivity of the high-purity silicon carbide crystal, which is simple to operate, convenient and quick, high in accuracy, beneficial to improving production efficiency, and particularly suitable for an industrial preparation site, and comprises the following steps of:
irradiating the silicon carbide crystal by using a light source, detecting the light transmission wavelength of the silicon carbide crystal, comparing the light transmission wavelength with the standard color wavelength range, and judging whether the resistivity is qualified or not according to the comparison result; the standard color wavelength range is a numerical range of light transmission color wavelength of the standard silicon carbide crystal with qualified resistivity after being irradiated by the same light source; when the light transmission wavelength is larger than the maximum value of the standard color wavelength range, judging that the resistivity is unqualified; when the transmission wavelength is larger than or equal to the minimum value and smaller than or equal to the maximum value of the standard color wavelength range, judging that the resistivity is qualified; and when the light transmission wavelength is smaller than the minimum value of the standard color wavelength range, precisely detecting the resistivity of the silicon carbide crystal and then judging.
According to the method for detecting the resistivity of the silicon carbide crystal, the transmittance wavelength of transmitted light of the industrially prepared silicon carbide crystal is detected, so that the resistivity of the industrially prepared silicon carbide crystal is preliminarily judged, the method can be used as a step in the production process, and the method is particularly suitable for detecting the high-purity silicon carbide crystal. The known silicon carbide crystal with qualified resistivity is defined as a standard silicon carbide crystal, and a numerical range of light transmission wavelengths which can be characterized by the standard silicon carbide crystal is defined as a standard color wavelength range. It is understood that, in order to make only the object to be detected differ in comparing the transmission wavelengths of the silicon carbide crystal to be detected and the standard silicon carbide crystal, the detection of the transmission wavelengths and the standard color wavelengths should be based on the same light source irradiation.
The precision test described in the present application is understood to be a test performed by using a precision instrument that can accurately obtain resistivity data, such as a resistivity tester. Preferably, the precision test is performed on the obtained wafer after slicing, rounding, grinding, polishing the silicon carbide ingot.
In the detection method, when the light transmission wavelength of the silicon carbide crystal to be detected falls within the standard color wavelength range, the resistivity of the crystal is judged to be qualified, the next slicing operation and other operations can be performed, and the precision test of the physical parameter performance such as the resistivity and the like is performed to obtain accurate data; when the transmission wavelength is larger than the standard color wavelength range, judging that the resistivity of the crystal is unqualified, and precisely testing the resistivity of the sliced wafer is not needed; when the light transmission wavelength is smaller than the standard color wavelength range, the wafer with qualified resistivity may be cut, and in order to improve the utilization rate, it is necessary to perform precise test and then judge according to the data. The detection method is characterized in that the qualitative detection of the prepared silicon carbide crystal sample can carry out preliminary classification screening on the prepared silicon carbide crystal, provides reference basis for resistivity evaluation of the silicon carbide crystal, and improves production efficiency.
It will be appreciated that light of different wavelengths can cause the human eye to feel different, i.e. to exhibit different colors, for example green light in the wavelength range 492-577nm, yellow light in the wavelength range 577-597nm, and orange light in the wavelength range 597-622nm. In the chemical field, however, the appearance of color may be considered as an intuitive representation of a particular chemical element, for example, some metal ions may cause selective absorption of visible light to color. And for the high-purity silicon carbide crystal, the silicon carbide crystal can selectively absorb, reflect and transmit light rays with a certain specific wavelength, and further display color. However, in the preparation of the silicon carbide crystal, the occurrence of impurities affects the light which can be transmitted through the silicon carbide, and the larger the concentration of the impurities is, the larger the influence is, so that the wavelength of the transmitted light of the silicon carbide crystal can reflect the content of the impurities in the silicon carbide crystal, the concentration of the impurities has an important influence on the resistivity, and the light-transmitting wavelength of the silicon carbide crystal can be used for detecting the resistivity of a product. Furthermore, the color of the silicon carbide single crystal is also related to the degree of the atomic packing rule, and the more excellent the packing degree is similar to that exhibited by diamond, the more the corresponding correlation data measurement tends to be normally qualified, so that the color of the silicon carbide single crystal can be used to reflect the product performance parameters thereof. In actual production, rough quality judgment can be performed by a method of manually observing the color of the crystal, but external factors influencing human color vision are more, and fine color differences are not easy to distinguish through manual observation, so that the manual mode has larger error and lower efficiency, and the method of the application has higher accuracy compared with the manual observation mode on the production site by detecting the light transmission wavelength as a judgment basis.
Further, the light source adopts a cold light source with the emission wavelength of 560-580 nm; the standard color wavelength range is 579-595nm.
The light emitted by the cold light source is faint yellow light visible to the naked eye, at this time, the standard color wavelength range and the light transmission wavelength of the crystal to be detected are both based on the numerical value under the cold light source, and the color displayed by the transmitted light is obtained by compositing the color of the light emitted by the cold light source with the color of the silicon carbide crystal.
Further, when the light transmission wavelength is less than 579nm and more than 570nm, precisely detecting the resistivity of the silicon carbide crystal and then judging; and when the light transmission wavelength is less than or equal to 570nm, judging that the resistivity is not qualified.
The arrangement provides a basis for rapidly judging that the resistivity is unqualified when the transmission wavelength is smaller than the minimum value of the standard color wavelength range, and the efficiency is further improved.
In one embodiment, the standard color wavelength range is 580-595nm, the resistivity is judged to be unqualified when the light transmission wavelength is more than 595nm or less than or equal to 570nm, the resistivity is judged to be qualified when the light transmission wavelength is more than or equal to 580 and less than or equal to 595nm, and the resistivity is judged to be numerical value after the light transmission wavelength is more than 570nm and less than 580 nm.
Further, the resistivity of the silicon carbide crystal is less than 10 after the silicon carbide crystal is qualified -6 ohm/cm。
Wherein, "processing" includes the steps of slicing, rounding, grinding and polishing. It will be appreciated that in this application, 10 - 6 ohm/cm is (1X 10) -6 )ohm/cm＝(10×10 -7 ) ohm/cm, i.e. when the resistivity of the silicon carbide wafer is less than (10X 10) -7 ) ohm/cm, is considered to be acceptable for resistivity.
Wherein, the experimental data of the application show that the measured crystal with the light transmission wavelength falling in the standard color wavelength range has the resistivity of the wafer measured after slicing of less than 10 -6 ohm/cm, when the transmittance is over 595nm, the resistivity is increased sharply and the standard requirement of the conductive silicon carbide product is not met, namely the detection method can be used as a preliminary judgment method for the resistivity numerical range of the silicon carbide wafer, and particularly, when the transmittance wavelength is measured to be 579-595nm, the resistivity can be judged to be less than 10 - 6 ohm/cm, while the prior art has failed to provide a detection method for silicon carbide crystals that determines the range of resistivity values by the transmission wavelength.
Further, the detection method of the light transmission wavelength comprises the following steps: the irradiation direction of the light source is directed to the side of the silicon carbide crystal, light transmitted through the silicon carbide crystal is received at the other side of the silicon carbide crystal, the tristimulus value of the transmitted light is detected, and the light transmission wavelength is obtained according to the tristimulus value.
After the tristimulus values are obtained, the light transmission wavelength can be obtained through inspection of a CIE 1931-color coordinate-tristimulus value table. The light source irradiates from the edge of the side part of the crystal, so that the light is convenient for the whole crystal to penetrate, and the crystal is also convenient for the artificial observation above the crystal to see whether the whole crystal is uniform in material quality. In one embodiment, the light source may be disposed at a position intermediate the sides of the crystal, and the light source may also be moved to test the transmission wavelength at a plurality of positions in the circumferential direction intermediate the sides thereof.
Further, the silicon carbide crystal employs an ingot having a thickness of at least 5 mm; the silicon carbide crystal is selected from one or two of 4H-type silicon carbide and 6H-type silicon carbide. Preferably, the silicon carbide crystals are useful in the preparation of conductive silicon carbide substrate materials. When the silicon carbide crystal with the specification and the parameters is used for detection, the detection result has higher accuracy.
Further, the silicon carbide crystal is prepared by adopting a physical vapor transmission method, and the physical vapor transmission method comprises the step of constructing a crystal growth temperature field by adopting step-by-step depressurization and heating under inert atmosphere.
It will be appreciated that the principle of the physical vapor transport method and the thermal field structure to be constructed are known to those skilled in the art, i.e. a silicon carbide seed crystal is placed on top of a graphite crucible, a silicon carbide powder is placed inside, and the silicon carbide powder sublimates to form a vapor phase component Si at high temperature m C n The gas phase component moves to a growth interface with relatively low temperature, namely a seed crystal, under the drive of an axial temperature gradient, and is adsorbed, migrated, crystallized and desorbed on the growth interface, so that the silicon carbide crystal is finally formed. And the process of the final silicon carbide crystal product can be influenced by controlling the temperature field, and the adjustment and the optimization can be performed.
Further, the step of step-by-step depressurization and heating to construct a crystal growth temperature field comprises the following steps: preserving heat for 2-8h at the pressure of 500mbar and the temperature of 1400-1800 ℃; preserving heat for 2-8h at the pressure of 250mbar and the temperature of 2000-2050 ℃; preserving heat for 2-8h at the pressure of 125mbar and the temperature of 2080-2150 ℃; the temperature is kept for 25 to 40 hours at the pressure of 60mbar and the temperature of 2100 to 2150 ℃.
In a preferred embodiment, the preparation method of the silicon carbide crystal comprises the following steps:
and (2) charging: filling silicon carbide powder into a graphite crucible, placing silicon carbide seed crystal on the top, sealing, filling into a crystal growth furnace, and reducing the pressure in the furnace body cavity to 10 -7 ～10 -9 After maintaining the pressure for 1 hour at mbar, inert gas is then introduced into the reaction chamber to raise the pressure to 500mbar. And (3) heating and growing crystals: keeping the pressure unchanged, heating to 1600 ℃ and preserving the heat for 3 hours; reducing the pressure to 250mbar, heating to 2030 ℃ and preserving the heat for 5 hours; reducing the pressure to 125mbar, heating to 2100 ℃ and preserving the heat for 5 hours, reducing the pressure to 60mbar, heating to 2130 ℃ and preserving the heat for 30 hours; during which each depressurization and temperature increase process is completed by 2 hours. And cooling and crystallizing to obtain the silicon carbide ingot.
The silicon carbide crystal prepared by adopting the physical vapor transmission method is a high-purity crystal, impurities are usually nitrogen or oxygen brought by a graphite crucible, the impurities are not easy to distinguish by a manual observation mode, and are not easy to detect by using the existing instrument on a production site, and the detection method provided by the application can rapidly judge the resistivity of the high-purity crystal through the light transmission wavelength, so that the method is a simple and feasible qualitative detection method.
In another aspect, the present application further provides a device for detecting resistivity of a high purity silicon carbide crystal, the device comprising:
the photosensitive detection module is used for receiving the light transmission induced to penetrate through the silicon carbide crystal and detecting the light transmission wavelength of the light transmission; and the judging module is used for comparing and judging the light transmission wavelength detected by the photosensitive detection module and the preset standard color wavelength range, and judging whether the resistivity of the silicon carbide crystal is qualified or unqualified or needs to be precisely detected according to the comparison result.
In one embodiment, the standard color wavelength range preset in the judging module is 579-595nm, preferably 580-595nm. In other embodiments, the device may be further adapted to detect other crystal resistivities suitable for use in the methods described herein, where the predetermined standard color wavelength range is set to be the light transmission range of the other standard crystal.
Further, the detection device also comprises a display module for outputting and displaying the light transmission wavelength and/or the tristimulus value of the light transmission detected by the photosensitive detection module and the result of the judgment of the silicon carbide crystal resistivity by the judgment module.
Optionally, the detection device further comprises a light source.
The following beneficial effects can be brought through this application:
the resistivity detection method and device for the silicon carbide crystal provided by the application have the advantages of high accuracy, simple steps, strong operability, low requirements on the test environment, suitability for production sites, capability of reducing the workload and cost of the precise detection step, and improvement of the production efficiency, and particularly, reference for preliminary evaluation of the resistivity of the high-purity silicon carbide crystal prepared by adopting a physical vapor transmission method.
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 embodiments of the application and together with the description serve to explain the application and do not constitute an undue limitation to the application. In the drawings:
FIG. 1 is a flow chart of one embodiment of a method for detecting resistivity of a high purity silicon carbide crystal;
FIG. 2 is a schematic diagram of one embodiment of a device for detecting resistivity of a high purity silicon carbide crystal;
in the figure: 1. a cold light source; 2. silicon carbide crystals; 3. a photosensitive detection module; 301. an optical receiver; 302. XYZ three stimulus sensor; 303. a color sensitive processor; 4. a judging module; 5. and a display module.
Detailed Description
In order to more clearly explain the general concepts of the present application, reference is made to the following detailed description, taken in conjunction with the accompanying drawings.
It should be noted that 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 as described herein, and therefore the scope of the present application is not limited to the specific embodiments disclosed below.
In addition, in the description of the present application, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," "circumferential," etc. indicate or refer to an azimuth or a positional relationship based on that shown in the drawings, and are merely for convenience of description and to simplify the description, and do not indicate or imply that the apparatus or element in question must have a specific azimuth, be configured and operated in a specific azimuth, and therefore should not be construed as limiting the present application.
In this application, unless specifically stated and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. However, it is noted that a direct connection indicates that two bodies connected together do not form a connection relationship by an excessive structure, but are connected to form a whole by a connection structure. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art as the case may be.
In this application, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," 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 present application. In this specification, schematic representations of the above terms are not necessarily directed 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.
Example 1
Embodiment 1 provides a resistivity detection method of a high purity silicon carbide crystal, as shown in fig. 1, comprising the steps of:
s1, irradiating a silicon carbide crystal by using a light source, wherein the light source adopts a cold light source with the wavelength of 560-580nm and is placed in the middle position close to the side edge of the silicon carbide crystal, so that the irradiation direction of the light source faces the silicon carbide crystal and light rays are transmitted through the whole crystal;
s2, detecting the transmission wavelength a of the silicon carbide crystal, wherein the transmission wavelength a is obtained by receiving transmitted light from the other side of the silicon carbide crystal, detecting the tristimulus value of the transmitted light and checking through a CIE 1931-color coordinate-tristimulus value table;
s3, comparing the light transmission wavelength a measured in the S2 with a standard color wavelength range, and judging whether the resistivity is qualified or not according to a comparison result, wherein the standard color wavelength range is a numerical range of light transmission color wavelengths possessed by standard silicon carbide crystals with qualified resistivity, for example, under the irradiation of the same cold light source, the standard color wavelength range is 580-595nm, when the measured light transmission wavelength a is more than 595nm, the resistivity is directly judged to be unqualified, when the light transmission wavelength a meets 580nm and less than or equal to a 595nm, the resistivity is directly judged to be qualified, and when the light transmission wavelength a is less than 580nm, further accurate detection is needed, such as detection of the resistivity by using a resistivity meter after slicing, grinding and polishing. Wherein the qualification of the resistivity is based on the wafer resistivity after slicing being less than 10 - 6 ohm/cm。
Preferably, in step S3, when the transmission wavelength a is less than 570nm, it may be determined that the resistivity is not acceptable.
The detection method can be suitable for preliminary qualitative judgment of the resistivity of the silicon carbide crystal in a production field, and can be used as a mode of preliminary detection of the resistivity in the production process to provide reliable reference for evaluation of the resistivity after slicing.
The high-purity silicon carbide crystal detected by the detection method is prepared by the following method:
and (2) charging: filling silicon carbide powder into a graphite crucible, placing silicon carbide seed crystal on the top, sealing, filling into a crystal growth furnace, and reducing the furnace body pressure to 10 -7 ～10 -9 After maintaining the pressure for 1 hour at mbar, inert gas is then introduced into the reaction chamber to raise the pressure to 500mbar.
And (3) heating and growing crystals: keeping the pressure unchanged, heating to 1600 ℃ and preserving the heat for 3 hours; reducing the pressure to 250mbar, heating to 2030 ℃ and preserving the heat for 5 hours; reducing the pressure to 125mbar, heating to 2100 ℃ and preserving the heat for 5 hours, reducing the pressure to 60mbar, heating to 2130 ℃ and preserving the heat for 30 hours; during which each depressurization and temperature increase process is completed by 2 hours.
And cooling and crystallizing to obtain the silicon carbide ingot with the thickness of 10 mm.
100 silicon carbide crystal ingot samples with the same thickness and purity are prepared by adopting the preparation method, the light transmission wavelength of 100 silicon carbide crystal ingot samples is measured by adopting the step S1 and the step S2 in the detection method, the statistical test result is obtained, the light transmission wavelength value of the silicon carbide crystal prepared by adopting the preparation method is between 569 and 597nm, at each wavelength point value appearing in the range, one silicon carbide crystal ingot sample is randomly selected, and after slicing, rounding, grinding and polishing are sequentially carried out, the resistivity of the silicon carbide crystal ingot sample is tested, wherein 3 crystal wafers are randomly selected for each crystal ingot sample for testing, and when the resistivity of the crystal wafers is tested, as each point on one crystal face has the resistivity and is different in distribution, the final resistivity data is the maximum value appearing on the crystal face, namely the least qualified value. The results obtained are shown in Table 1.
TABLE 1
As is clear from Table 1, when the light transmission wavelength of the crystal detected by the above detection method is within the range of 580-595nm, the maximum resistivity of the sliced wafer is less than 10 -6 ohm/cm, meets the standard of qualified resistivity, and the resistivity can reach 10 -7 ohm/cm、10 -8 ohm/cm even 10 -9 on the order of ohm/cm, a resistivity of up to 1.2X10 at a wavelength of 587nm -10 ohm/cm. And when the wavelength is more than 595nm, the resistivity of the silicon carbide composite material is increased sharply, and the resistivity requirement of the conductive silicon carbide product is not met. When the light transmission wavelength is less than 580nm, the sliced wafer has resistivity less than 10 -6 ohmWith both acceptable and unacceptable resistivity wafers (e.g., 575 nm) and wafer resistivities greater than 10 -6 ohm/cm (e.g., 577 nm), while at less than 570nm a sharp rise in resistivity also occurs. Therefore, in order to improve the utilization rate of the product, the silicon carbide crystal with the light transmission wavelength smaller than 580nm and larger than 570nm can be further precisely tested to screen out the wafer product with qualified resistivity.
Example 2
Embodiment 2 provides a device for detecting resistivity of high purity silicon carbide, which can implement the detection method as provided in embodiment 1, and as shown in fig. 2, when the device is used for detecting resistivity of silicon carbide crystal, it is necessary to place a cold light source 1 on the side of the silicon carbide crystal 2 and place the device on the other side of the silicon carbide crystal 2 through which light is transmitted, so as to receive and detect the transmitted light. Wherein the device comprises:
the photosensitive detection module 3 is used for receiving the light transmission induced to pass through the silicon carbide crystal 2 and detecting the light transmission wavelength of the light transmission; the judging module 4 is configured to compare and judge the light transmission wavelength detected by the light sensing detecting module 3 and the preset standard color wavelength range, and judge the resistivity of the silicon carbide crystal 2 according to the comparison result, preferably, the judgment of the resistivity is only performed in the judging module 4, and directly output the judgment result. In this embodiment, the standard color wavelength range preset in the judging module 4 is 580-595nm. The detecting device further comprises a display module 5, which is used for outputting and displaying the light transmission wavelength and/or tristimulus value of the light transmission detected by the photosensitive detecting module 3, and judging the result of the resistivity judgment of the silicon carbide crystal 2 by the judging module 4.
In a preferred implementation, the photosensitive detection module 3 may implement the light sensing reception by using the light receiver 301, the analysis detection of the light transmission tristimulus values by using the XYZ tristimulus sensor 302, and the conversion of the light transmission wavelength by using the color sensitive processor 303. Also, the judging module 4 may implement the functions of the module using various existing physical devices, such as a microcomputer, etc. The display module 5 may include a digital display screen, so as to display the tri-stimulus value X, Y, Z of the detected light transmission, the corresponding wavelength, and the "pass", "fail" or "continue detection" of the judging result on the digital display screen, and provide the operator with reference for data and judgment.
In other embodiments, the device may be further adapted to detect other crystal resistivities suitable for use in the methods described herein, where the predetermined standard color wavelength range is set to be the light transmission range of the other standard crystal.
The foregoing is merely exemplary of the present application and is not intended to limit the present application. Various modifications and changes may be made to the present application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc. which are within the spirit and principles of the present application are intended to be included within the scope of the claims of the present application.
Claims (8)
1. A method for detecting resistivity of high-purity silicon carbide crystals, which is characterized by comprising the following steps:
irradiating the silicon carbide crystal by using a light source, detecting the light transmission wavelength of the silicon carbide crystal, comparing the light transmission wavelength with the standard color wavelength range, and judging whether the resistivity is qualified or not according to the comparison result; the standard color wavelength range is a numerical range of light transmission color wavelength of the standard silicon carbide crystal with qualified resistivity after being irradiated by the same light source;
when the light transmission wavelength is larger than the maximum value of the standard color wavelength range, judging that the resistivity is unqualified; when the transmission wavelength is larger than or equal to the minimum value and smaller than or equal to the maximum value of the standard color wavelength range, judging that the resistivity is qualified; when the light transmission wavelength is smaller than the minimum value of the standard color wavelength range, precisely detecting the resistivity of the silicon carbide crystal and then judging;
the silicon carbide crystal adopts an ingot with the thickness of at least 5 mm; the silicon carbide crystal is selected from one or two of 4H-type silicon carbide and 6H-type silicon carbide;
the standard color wavelength range is 579-595nm;
when the light transmission wavelength is smaller than 579nm and larger than 570nm, precisely detecting the resistivity of the silicon carbide crystal, and then judging; and when the light transmission wavelength is less than or equal to 570nm, judging that the resistivity is not qualified.
2. The method according to claim 1, wherein the light source is a cold light source emitting light with a wavelength of 560-580 nm.
3. The method of any of claims 1-2, wherein the resistivity-acceptable silicon carbide crystal has a resistivity of less than 10 "6 ohm/cm after processing.
4. The method according to claim 1, wherein the method for detecting the transmission wavelength comprises the steps of: the irradiation direction of the light source is directed to the side of the silicon carbide crystal, light transmitted through the silicon carbide crystal is received at the other side of the silicon carbide crystal, the tristimulus value of the transmitted light is detected, and the light transmission wavelength is obtained according to the tristimulus value.
5. The method according to claim 1, wherein the silicon carbide crystal is prepared by a physical vapor transmission method, and the physical vapor transmission method comprises the step of constructing a crystal growth temperature field by step-wise depressurization and temperature increase under an inert atmosphere.
6. The method according to claim 5, wherein the step of step-down and step-up heating up to construct a crystal growth temperature field comprises: preserving heat for 2-8h at the pressure of 500mbar and the temperature of 1400-1800 ℃; preserving heat for 2-8h at the pressure of 250mbar and the temperature of 2000-2050 ℃; preserving heat for 2-8h at the pressure of 125mbar and the temperature of 2080-2150 ℃; the temperature is kept for 25 to 40 hours at the pressure of 60mbar and the temperature of 2100 to 2150 ℃.
7. A device for detecting resistivity of a high purity silicon carbide crystal according to claim 1, wherein the device comprises:
the photosensitive detection module is used for receiving the light transmission induced to penetrate through the silicon carbide crystal and detecting the light transmission wavelength of the light transmission;
and the judging module is used for comparing and judging the light transmission wavelength detected by the photosensitive detection module and the preset standard color wavelength range, and judging whether the resistivity of the silicon carbide crystal is qualified or unqualified or needs to be precisely detected according to the comparison result.
8. The detecting device according to claim 7, further comprising a display module for outputting and displaying the light transmission wavelength and/or tristimulus value of the light transmission detected by the light sensing detection module, and the result of the judgment of the silicon carbide crystal resistivity by the judgment module.
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| CN112899788B (en) * | 2021-01-14 | 2022-04-08 | 山东天岳先进科技股份有限公司 | Preliminary screening method and device for silicon carbide crystal ingot |
| CN114047383A (en) * | 2021-11-02 | 2022-02-15 | 中环领先半导体材料有限公司 | Automatic testing equipment and method for resistivity of single crystal silicon rod |
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