A non-destructive measurement method for silicon carbide defect density

Abstract

A non-destructive measurement method for silicon carbide defect density comprises the following steps: performing XRD detection on a silicon carbide sample to be tested to obtain a rocking curve, and further obtaining the half-height width of the silicon carbide sample to be tested; performing XRD detection on a standard sample to obtain a rocking curve, and further obtaining the half-height width of the standard sample; calculating according to a defect density calculation formula to obtain the silicon carbide defect density; the defect density calculation formula is: dislocation density = (half-height width of the silicon carbide sample to be tested - half-height width of the standard sample) 2 / (4.35×b 2 )×10 ‑4 ; Wherein, b is the Burgers vector of the defect. Based on a thorough study of the relationship between the defect density of silicon carbide, residual stress and the rocking curve, the present invention can non-destructively measure the defect density of silicon carbide by measuring the half-width of the rocking curve, and further calculate the residual stress by the peak position of the rocking curve, thereby realizing rapid and accurate measurement of the defect density of silicon carbide without damaging the substrate material, with high efficiency and low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor defect detection, and more specifically, to a non-destructive measurement method for silicon carbide defect density. Background Art

[0002] Silicon carbide is an inorganic substance with the chemical formula SiC. The industrial production of silicon carbide substrate materials is mainly based on physical vapor sublimation. This method requires sublimating silicon carbide powder in a high-temperature vacuum environment, and then controlling the temperature field to allow the sublimated components to grow on the surface of the seed crystal to obtain silicon carbide crystals. Silicon carbide is a semiconductor that exists in nature in the form of an extremely rare mineral moissanite. Since 1893, it has been mass-produced as powder and crystals for use as abrasives, etc. Among non-oxide high-tech refractory raw materials such as C, N, and B, silicon carbide is the most widely used and economical one, which can be called corundum or refractory sand.

[0003] As a power semiconductor material, the defect density of silicon carbide directly affects the reliability and yield of silicon carbide power devices. In order to evaluate the quality of the substrate material, its defect density needs to be measured. The existing method for measuring the defect density of silicon carbide mainly uses high-temperature alkali corrosion to expose defects such as dislocations, and then observes the defect morphology and quantity under an optical microscope to achieve the measurement of defect density. See Figures 1-2 shown.

[0004] However, the above-mentioned traditional measurement methods cause irreversible damage to the substrate material. As we all know, 4H silicon carbide substrate materials are expensive. The use of traditional measurement methods will damage the substrate material, greatly increasing the cost. In addition, the observation of defect morphology and quantity under an optical microscope will be affected by problems such as inconsistent measurement results in different selected areas. For example, the defect density at the edge of the sample to be measured will be significantly higher than that in other selected areas. Therefore, the traditional measurement method also has the problem of low efficiency. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a non-destructive measurement method for silicon carbide defect density, which can achieve rapid and accurate measurement of silicon carbide defect density without damaging the substrate material, with high efficiency and low cost; and the residual stress can be further calculated.

[0006] The present invention provides a non-destructive measurement method for silicon carbide defect density, comprising the following steps:

[0007] Perform XRD detection on the silicon carbide sample to be tested, obtain the rocking curve, and further obtain the half-height width of the silicon carbide sample to be tested;

[0008] Perform XRD test on the standard sample to obtain the rocking curve, and further obtain the half-height width of the standard sample;

[0009] According to the defect density calculation formula, the silicon carbide defect density is obtained;

[0010] The defect density calculation formula is:

[0011] Dislocation density = (half-height width of the silicon carbide sample to be tested - half-height width of the standard sample) 2 / (4.35×b 2 )×10 -4 ;

[0012] Where b is the defect's Burgers vector.

[0013] Preferably, the silicon carbide sample to be tested is a hexagonal silicon carbide substrate material.

[0014] Preferably, the selected points for XRD detection of the silicon carbide sample to be tested are the center point and points offset by 10 mm to 40 mm above, below, left and right of the center point.

[0015] Preferably, by performing XRD detection on different selected points of the silicon carbide sample to be tested, the rocking curves of the corresponding selected points are obtained, and the half-height widths of the corresponding selected points are further obtained, and the average value is calculated to obtain the half-height width of the silicon carbide sample to be tested.

[0016] Preferably, the selected points for XRD detection of the standard sample are the center point and points offset by 10 mm to 40 mm above, below, left and right of the center point.

[0017] Preferably, by performing XRD detection on different selected points of the standard sample, the rocking curves of the corresponding selected points are obtained, and the half-height widths of the corresponding selected points are further obtained, and the average value is calculated to obtain the half-height width of the standard sample.

[0018] Preferably, the error introduced by the self-broadening of the calibration instrument is calibrated by subtracting the half-width of the standard sample from the half-width of the silicon carbide sample to be measured.

[0019] Preferably, the half-width at half-height of the silicon carbide sample to be tested minus the half-width at half-height of the standard sample is ≥ 0.3 arc seconds.

[0020] Preferably, for SiC, the value of b is 10.053×10 -10 .

[0021] Preferably, the residual stress of silicon carbide is calculated based on the rocking curve measurement results.

[0022] The present invention provides a non-destructive measurement method for silicon carbide defect density, comprising the following steps: performing XRD detection on a silicon carbide sample to be tested, obtaining a rocking curve, and further obtaining the half-height width of the silicon carbide sample to be tested; performing XRD detection on a standard sample, obtaining a rocking curve, and further obtaining the half-height width of the standard sample; calculating according to a defect density calculation formula to obtain the silicon carbide defect density; the defect density calculation formula is: dislocation density = (half-height width of the silicon carbide sample to be tested - half-height width of the standard sample) 2 / (4.35×b 2 )×10 -4 ; Wherein, b is the Burgers vector of the defect. Compared with the prior art, the present invention, based on a full study of the relationship between the defect density of silicon carbide, residual stress and the rocking curve, can non-destructively measure the defect density of silicon carbide by measuring the half-height width of the rocking curve, and further calculate the residual stress by the peak position of the rocking curve, thereby realizing a fast and accurate measurement of the defect density of silicon carbide without damaging the substrate material, with high efficiency and low cost; and the residual stress can be further calculated. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a low-magnification optical microscope photograph of the defect density of silicon carbide measured by the prior art;

[0024] Figure 2 This is a high-magnification optical microscope photograph of the defect density of silicon carbide measured by the existing technology;

[0025] Figure 3 is the XRD rocking curve of Si001 surface in Example 1;

[0026] Figure 4 This is the XRD rocking curve of the SiC 0004 surface, where the silicon carbide surface adopts a 4° bevel cutting process. DETAILED DESCRIPTION

[0027] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] The present invention provides a non-destructive measurement method for silicon carbide defect density, comprising the following steps:

[0029] Perform XRD detection on the silicon carbide sample to be tested, obtain the rocking curve, and further obtain the half-height width of the silicon carbide sample to be tested;

[0030] Perform XRD test on the standard sample to obtain the rocking curve, and further obtain the half-height width of the standard sample;

[0031] According to the defect density calculation formula, the silicon carbide defect density is obtained;

[0032] The defect density calculation formula is:

[0033] Dislocation density = (half-height width of the silicon carbide sample to be tested - half-height width of the standard sample) 2 / (4.35×b 2 )×10 -4 ;

[0034] Where b is the defect's Burgers vector.

[0035] The present invention first performs XRD detection on the silicon carbide sample to be tested to obtain a rocking curve, and further obtains the half-height width of the silicon carbide sample to be tested.

[0036] In the present invention, the silicon carbide sample to be tested is preferably a hexagonal silicon carbide substrate material. The present invention has no special restrictions on the source of the hexagonal silicon carbide substrate material, and commercially available products familiar to those skilled in the art can be used. At present, the existing technology for measuring the defect density in silicon carbide substrate materials mainly uses high-temperature alkali corrosion to expose defects such as dislocations, and then observes the defect morphology and quantity under an optical microscope, which not only causes irreversible damage to the material but also has low efficiency. At the same time, due to the high price of silicon carbide substrate materials, the damage is also costly. The core purpose of the present invention is to provide a non-destructive measurement method for the defect density of hexagonal silicon carbide substrate materials in response to the above technical problems.

[0037] In the present invention, the selected point for XRD detection of the silicon carbide sample to be tested is preferably the center point and the point where the center point is offset by 10mm to 40mm. In a preferred embodiment of the present invention, the selected point for XRD detection of the silicon carbide sample to be tested is the center point and the point where the center point is offset by 25mm.

[0038] In the present invention, XRD detection is performed on different selected points of the silicon carbide sample to be tested to obtain the rocking curve of the corresponding selected point, further obtain the half-height width of the corresponding selected point, calculate the average value, and obtain the half-height width of the silicon carbide sample to be tested.

[0039] The present invention has no special limitation on the instrument and method for the XRD detection, and conventional XRD detection can be performed using instruments well known to those skilled in the art.

[0040] Afterwards, the present invention performs XRD detection on the standard sample to obtain a rocking curve, and further obtains the half-height width of the standard sample.

[0041] In the present invention, the standard sample is preferably a silicon wafer. The present invention has no special restrictions on the source of the silicon wafer, and commercially available products known to those skilled in the art can be used.

[0042] In the present invention, the selected point for XRD detection of the standard sample is preferably the center point and the center point offset by 10mm to 40mm. In a preferred embodiment of the present invention, the selected point for XRD detection of the standard sample is the center point and the center point offset by 25mm.

[0043] In the present invention, XRD detection is performed on different selected points of the standard sample to obtain the rocking curve of the corresponding selected point, further obtain the half-height width of the corresponding selected point, calculate the average value, and obtain the half-height width of the standard sample.

[0044] In the present invention, the error introduced by the self-broadening of the calibration instrument is calibrated by subtracting the half-height width of the standard sample from the half-height width of the silicon carbide sample to be tested. In addition, the half-height width of the silicon carbide sample to be tested minus the half-height width of the standard sample is preferably ≥ 0.3 arc seconds; otherwise, the defect density calculation formula may not be applicable because the difference between the two is too small.

[0045] The present invention fully studies the relationship between the defect density of silicon carbide and the rocking curve, and improves the general calculation formula based on specific experiments and data, including the selection of the constant 4.35 in the formula; and after measuring multiple groups of samples to be tested, it can be seen from the data results that: when the half-width at half height of the sample to be tested deviates from the instrument broadening, it is accurate to estimate the defect density using the rocking curve, but when it is close to the instrument broadening, the square term makes the error larger, and other factors such as measurement need to be excluded.

[0046] On this basis, the defect density calculation formula provided by the present invention is actually a corrected defect density calculation formula; and the calculated result of the corrected defect density calculation formula is preferably ≥20cm -1 Otherwise, there are also cases where the defect density calculation formula is not applicable.

[0047] In the present invention, the defect density calculation formula is:

[0048] Dislocation density = (half-height width of the silicon carbide sample to be tested - half-height width of the standard sample) 2 / (4.35×b 2 )×10 -4 ;

[0049] Where b is the defect's Burgers vector; for SiC, the value of b is preferably 10.053×10 -10 .

[0050] The nondestructive measurement method of silicon carbide defect density provided by the present invention obtains a rocking curve through XRD detection, and according to the rocking curve measurement result, the silicon carbide residual stress can be further calculated as an additional technical effect; for details, refer to the technical solution provided by Chinese patent CN114858324A, which will not be repeated in the present invention.

[0051] The present invention provides a non-destructive measurement method for silicon carbide defect density, comprising the following steps: performing XRD detection on a silicon carbide sample to be tested, obtaining a rocking curve, and further obtaining the half-height width of the silicon carbide sample to be tested; performing XRD detection on a standard sample, obtaining a rocking curve, and further obtaining the half-height width of the standard sample; calculating according to a defect density calculation formula to obtain the silicon carbide defect density; the defect density calculation formula is: dislocation density = (half-height width of the silicon carbide sample to be tested - half-height width of the standard sample) 2 / (4.35×b 2 )×10 -4 ; Wherein, b is the Burgers vector of the defect. Compared with the prior art, the present invention, based on a full study of the relationship between the defect density of silicon carbide, residual stress and the rocking curve, can non-destructively measure the defect density of silicon carbide by measuring the half-height width of the rocking curve, and further calculate the residual stress by the peak position of the rocking curve, thereby realizing a fast and accurate measurement of the defect density of silicon carbide without damaging the substrate material, with high efficiency and low cost; and the residual stress can be further calculated.

[0052] In order to further illustrate the present invention, the following examples are used for detailed description. The silicon wafers used in the following examples of the present invention are provided by Shin-Etsu Chemical of Japan, and the model is high-purity single crystal silicon wafers; the SiC used is provided by Shandong Tianyue, and the model is high-purity 4H silicon carbide; the model of the XRD tester used is Malvern Panalytical X'Pert MRD.

[0053] Example 1

[0054] A non-destructive measurement method for silicon carbide defect density comprises the following steps:

[0055] (1) The width of the measuring instrument:

[0056] High-quality silicon wafers are used as standard samples to calibrate the error introduced by the instrument's own broadening.

[0057] The specific steps are:

[0058] Measure the XRD rocking curve of the Si001 surface to obtain the half-height width FWHM_Si (rad); take multiple points evenly on each wafer. For a 4-inch wafer, take the center point and the points offset by 25 mm up, down, left, and right. Calculate the average value of the half-height width FWHM_Si (rad) based on the results of the above multiple points, which is 15.16 arc seconds (see Figure 3 shown).

[0059] (2) XRD rocking curve test of the sample to be tested:

[0060] Measure the rocking curve of SiC 0004 surface and obtain the half-height width FWHM_SiC (rad); take multiple points evenly on each wafer. For 4 inches, take the center point and the points offset by 25mm up, down, left and right; see Figure 4 As shown, 1 is the center point, 2 is 25 mm above the center point, 3 is 25 mm below the center point, 4 is 25 mm to the left of the center point, and 5 is 25 mm to the right of the center point.

[0061] (3) Defect calculation:

[0062] Substitute the test results obtained in step (1) and step (2) into the defect density calculation formula, calculate the average value based on the defect density results of multiple points, and obtain the defect density of the sample to be tested.

[0063] Defect density calculation formula:

[0064] Dislocation density / cm -1 =(FWHM_SiC-FWHM_Si) 2 / (4.35×b 2 )×10 -4 ;

[0065] Where b is the defect's Burgers vector, and for SiC, its value is 10.053×10 -10 .

[0066] (4) Residual stress calculation:

[0067] According to the technical solution provided by Chinese patent CN114858324A, the residual stress of the sample to be tested is calculated based on the above test results.

[0068] The test data is shown in Table 1.

[0069] Table 1

[0070]

[0071]

[0072] Comparative Example 1

[0073] The traditional silicon carbide wafer dislocation density test is adopted - silicon carbide KOH corrosion test.

[0074] Testing standards:

[0075] 1. GB_T 30868-2014 "Chemical etching method for determination of microtube density of silicon carbide single wafer";

[0076] 2. T / CASA 013-2021 "Dislocation density detection method for silicon carbide wafers: KOH corrosion combined with image recognition method".

[0077] After testing, the average defect density obtained in Comparative Example 1 is 200.4 cm -1 The defect densities at each point are: 294, 149, 294, 150, 115 (cm -1 ).

[0078] In summary, the technical solution provided by the present invention is based on a full study of the relationship between the defect density of silicon carbide, residual stress and rocking curve. The defect density of silicon carbide can be non-destructively measured through the half-width of the rocking curve of the 0004 crystal plane, and the residual stress can be further calculated through the peak position of the rocking curve. The rapid measurement method helps to improve detection efficiency and reduce production costs.

[0079] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A non-destructive measurement method for silicon carbide defect density, characterized in that: The following steps are involved: Performing XRD detection on the silicon carbide sample to be tested to obtain a rocking curve, and further obtaining the half-height width of the silicon carbide sample to be tested; the silicon carbide sample to be tested is a hexagonal silicon carbide substrate material; Perform XRD test on the standard sample to obtain the rocking curve, and further obtain the half-height width of the standard sample; According to the defect density calculation formula, the silicon carbide defect density is obtained; The defect density calculation formula is: Dislocation density = (half-height width of the silicon carbide sample to be tested - half-height width of the standard sample) 2 / (4.35×b 2 )×10 -4 ; Where b is the defect's Burgers vector.

2. The non-destructive measurement method of silicon carbide defect density according to claim 1, characterized in that: The selected points for XRD detection of the silicon carbide sample to be tested are the center point and the points offset by 10 mm to 40 mm above, below, left and right of the center point.

3. The non-destructive measurement method of silicon carbide defect density according to claim 2, characterized in that: By performing XRD detection on different selected points of the silicon carbide sample to be tested, the rocking curve of the corresponding selected point is obtained, and the half-height width of the corresponding selected point is further obtained. The average value is calculated to obtain the half-height width of the silicon carbide sample to be tested.

4. The non-destructive measurement method of silicon carbide defect density according to claim 1, characterized in that: The selected points for XRD detection of the standard sample are the center point and the points where the center point is offset by 10 mm to 40 mm above, below, left and right.

5. The non-destructive measurement method of silicon carbide defect density according to claim 4, characterized in that: By performing XRD detection on different selected points of the standard sample, the rocking curve of the corresponding selected point is obtained, and the half-height width of the corresponding selected point is further obtained. The average value is calculated to obtain the half-height width of the standard sample.

6. The non-destructive measurement method of silicon carbide defect density according to claim 1, characterized in that: The error introduced by the self-broadening of the instrument is calibrated by subtracting the half-height width of the standard sample from the half-height width of the silicon carbide sample to be measured.

7. The non-destructive measurement method of silicon carbide defect density according to claim 6, characterized in that: The half-width of the silicon carbide sample to be tested - the half-width of the standard sample ≥ 0.3 arc seconds.

8. The non-destructive measurement method of silicon carbide defect density according to claim 1, characterized in that: For SiC, the value of b is 10.053×10 -10 .

9. The non-destructive measurement method of silicon carbide defect density according to claim 1, characterized in that: According to the rocking curve measurement results, the residual stress of silicon carbide is calculated.

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