JP4797576B2 - Evaluation method of crystal defects - Google Patents

Description

  The present invention relates to a method for evaluating crystal defects formed in a semiconductor single crystal substrate.

Japanese Patent No. 3451955

  As a method for evaluating minute crystal defects in a semiconductor single crystal substrate while providing resolution in the depth direction, a method disclosed in Patent Document 1 is known. In this method, the main surface of the substrate is subjected to anisotropic etching with high selectivity such as reactive ion etching (RIE) at a certain thickness, and the remaining etching residue is detected to evaluate crystal defects. Is to do. Since the etching rate is different between the formation region of the crystal defect and the formation region (the former has a lower etching rate), when the anisotropic etching is performed, the main surface of the substrate has a crystal defect as a vertex. Conical protrusions remain. Crystal defects are emphasized in the form of protrusions by anisotropic etching, and even minute defects can be easily detected.

  However, the above Patent Publication 1 does not disclose a method for specifying the type of crystal defect from the defect emphasizing protrusion, and is not always satisfactory when considering application to substrate quality evaluation, manufacturing process management, and the like. It wasn't possible.

  An object of the present invention is to provide a crystal defect evaluation method capable of detecting a crystal defect with high accuracy based on the formation of a defect emphasizing protrusion and specifying a crystal defect type.

Means for Solving the Problems and Effects of the Invention

The present invention relates to a method for evaluating crystal defects formed in a semiconductor single crystal substrate, and in order to solve the above problems,
A method for evaluating crystal defects formed in a semiconductor single crystal substrate,
By subjecting the surface layer portion including the main surface of the semiconductor single crystal substrate to anisotropic etching with a selectivity higher than the etching rate with respect to the crystal defect formation region, the etching rate with respect to the crystal defect non-formation region An anisotropic etching step of forming a defect-enhanced protrusion on the main surface on which the top surface portion is formed;
A detection / evaluation step of detecting the top surface portion of the defect emphasizing projection portion with a laser scattering detection device and identifying the type of crystal defect based on the detected dimensional information of the top surface portion in this order. Carried out,
The semiconductor single crystal substrate is a silicon single crystal wafer, and based on the dimension information of the top surface portion of the defect emphasizing protrusion, the type of silicon oxide-based crystal defect is identified,
It is characterized by identifying whether a crystal defect is a COP or an OSF nucleus .

  According to the crystal defect evaluation method of the present invention, the top surface portion of the defect emphasizing protrusion can be detected by the laser scattering detection device, and the type of crystal defect can be identified by the dimensional information of the detected top surface portion. . As a result, information on the formation state and distribution of crystal defects on the substrate can be grasped together with information on the defect type, and feedback to substrate quality evaluation, manufacturing process management, etc. can be effectively achieved. Become.

  The semiconductor single crystal substrate can be a silicon single crystal wafer. In this case, based on the dimension information of the top surface portion of the defect emphasizing protrusion, the type of silicon oxide-based crystal defect (located on the top surface portion) can be identified. Silicon oxide-based crystal defects can easily provide etching selectivity with silicon forming the crystal bulk, and defect-enhanced protrusions can be formed relatively easily, and the types of silicon oxide-based crystal defects As a result, a significant difference occurs in the dimension of the defect emphasizing protrusion, and different types of crystal defects can be easily identified. In particular, the silicon oxide-based crystal defect is a COP (Cristal Originated Particle) or OSF (Oxidation Induced Stacking Fault) nucleus depending on whether it is the dimension of the top surface of the defect-enhancing protrusion. The OSF nuclei tend to be distributed in a ring shape in a form surrounding the crystal central axis on the main surface of the silicon single crystal substrate, so that both can be easily identified.

  As a result of the inventor confirming by experiment, when the dimension of the top surface portion of the defect emphasizing protrusion detected by the laser scattering detector exceeds 0.19 μm, the crystal defect can be identified as COP. When the thickness is less than 19 μm, the crystal defect can be identified as an OSF nucleus.

  Next, in the crystal defect evaluation method of the present invention, after the anisotropic etching step, prior to the detection / evaluation step, the main surface subjected to anisotropic etching adheres to the peripheral region of the defect emphasis protrusion. A by-product removing step for removing the by-product of the anisotropic etching can be performed. Thereby, when detecting a defect emphasis projection part, the detection noise originating in a by-product can be reduced significantly, and the detection accuracy of a crystal defect can be raised.

  The anisotropic etching process can be performed by wet etching using an etchant having selective etching properties for crystal defects. However, in order to form a more prominent defect emphasis protrusion, reactive ion etching is performed. It is desirable to adopt. Reactive ion etching is dry etching, and scattering and adhesion of by-products to the main surface of the substrate accompanying the etching are particularly remarkable, so that the ripple effect by application of the present invention is great.

  In the by-product removing step, the main surface of the semiconductor single crystal substrate subjected to anisotropic etching can be washed with a cleaning solution capable of removing by-products. According to this method, the by-product can be washed away with the cleaning liquid, and the effect of selectively removing only the by-product while leaving the defect emphasizing protrusion is excellent. When the semiconductor single crystal substrate is a silicon single crystal wafer, it is effective to use an ammonia-hydrogen peroxide aqueous solution as the cleaning liquid, and if a substance containing hydrofluoric acid is further used, The removal effect becomes more prominent.

  In the byproduct removal step, a method other than cleaning can be employed. For example, by-products can be removed by irradiating the main surface of the semiconductor single crystal substrate with an electron beam or ultraviolet rays. Since this method does not use a cleaning solution and can remove a by-product by a dry method, a step such as drying is unnecessary and is convenient. Further, by-products can be removed by heating the main surface of the semiconductor single crystal substrate to 200 ° C. or higher.

Embodiments of the present invention will be described below.
In this embodiment, a case where a silicon single crystal wafer is manufactured as a semiconductor single crystal substrate is taken as an example, but the present invention is not limited to this. First, a silicon single crystal ingot is manufactured by a known method such as CZ method or FZ method. The single crystal ingot thus obtained is cut into blocks having a certain resistivity range, and further subjected to outer diameter grinding. An orientation flat or an orientation notch is formed in each block after outer diameter grinding. The block thus finished is sliced by a slicer such as an inner peripheral cutting. Chamfering is performed on the outer peripheral edges of the silicon single crystal wafer after slicing by beveling.

  The silicon single crystal wafer after chamfering is lapped on both sides using loose abrasive grains to form a lapped wafer. Then, by immersing the lap wafer in an etching solution, both surfaces are chemically etched to form a chemically etched wafer. The chemical etching process is performed in order to remove a damaged layer generated on the surface of the silicon single crystal wafer in the previous machining process. After the chemical etching process, a mirror polishing process is performed to obtain a mirror wafer (silicon single crystal wafer).

  Crystal defects are formed in the obtained silicon single crystal wafer due to various factors. First, in the growth of a silicon single crystal, a defect due to crystal growth taken into the inside during crystal growth, that is, an internal defect called a Grown-in Defect is formed. The formation state of this grow-in defect differs depending on the growth rate of the single crystal and the cooling conditions of the single crystal pulled up from the silicon melt. For example, when a single crystal is grown with a relatively high pulling speed, shortage of silicon atoms in the single crystal is likely to occur. When this deficient portion aggregates, it appears on the surface in the form of a recess or a hole when the silicon single crystal is processed into a wafer shape. Thus, in this silicon single crystal, a shortage of silicon atoms occurs, and a point defect existing as a vacancy between atoms is called vacancy (abbreviation: V). In addition, a region in which a grown-in defect due to vacancies caused by vacancy agglomeration becomes dominant in the silicon single crystal is referred to as a V region. Such Grow-in defects due to vacancies include FPD (Flow Pattern Defects), COP (Crystal Originated Particles), and LSTD (Laser Scattering Tomography Defects), which are produced when a silicon single crystal is processed into a substrate (wafer). It is observed as an octahedral void defect on the wafer surface. The inner surface of the void is usually covered with silicon oxide, and a defect-enhanced protrusion by selective anisotropic etching can be easily formed and can be evaluated by the method of the present invention.

  On the other hand, when the single crystal growth is performed while suppressing the pulling rate of the silicon single crystal as much as possible, for example, the crystal growth rate is about 0.4 mm / min or less, an extra silicon atom is present between the lattices of the silicon single crystal. Point defects called interstitial-Si (interstitial-Si: interstitial silicon atoms (abbreviation: I)) tend to occur. In the region inside the silicon single crystal where interstitial silicon is dominant, L / D (Large Dislocation: an abbreviation for interstitial dislocation loop, a generic term for crystal defects such as LSPD and LFPD) Interstitial type silicon defects called as exist at low density. A region inside the silicon single crystal where the interstitial silicon is dominant is called an I region. However, this type of defect is not accompanied by generation of silicon oxide, and it is difficult to form a defect-enhanced protrusion by selective anisotropic etching, which is not suitable as an evaluation target by the method of the present invention.

  In addition, in the region where the single crystal growth condition is intermediate between the condition where the V region is dominant and the condition where the I region is dominant, there is no shortage of atoms or no extra atoms between the silicon atoms, or Even if it exists, it becomes a neutral state that is slight, and such a region inside the silicon single crystal is called an N region. Between the N region and the V region formed inside the silicon single crystal, there is a region where defects due to oxygen called OSF (Oxidation Induced Stacking Fault) and nuclei thereof exist at high density. Exists. When a silicon single crystal is processed into a wafer, the region is observed in a ring shape. Therefore, a region where the OSF of the silicon single crystal or its nuclei exist at high density is referred to as an OSF ring region. The core of the OSF is a crystal defect mainly composed of silicon oxide, and a defect-enhanced protrusion can be easily formed by selective anisotropic etching, and can be evaluated by the method of the present invention.

  In addition, the silicon single crystal wafer (mirror surface wafer) obtained as described above is further subjected to heat treatment (for example, 750 ° C. or higher and 1100 ° C. or lower) for forming oxygen precipitates for gettering prior to device formation. Can be applied. This oxygen precipitate is a kind of crystal defect called BMD (Bulk Micro Defect) and is generally smaller in size than a grown-in defect such as COP. This defect can also be easily formed with a defect-enhancing protrusion by selective anisotropic etching, and can be evaluated by the method of the present invention.

Based on the method of the present invention, crystal defects existing in the surface layer portion of the silicon single crystal wafer can be detected and evaluated as follows. First, in step 1 of FIG. 1, the natural oxide film formed on the surface of the silicon single crystal wafer 1 having the crystal defects P is removed by washing with a hydrofluoric acid aqueous solution or the like. Next, in step 2, anisotropic etching is performed on the main surface of the silicon single crystal wafer 1 from which the natural oxide film has been removed, for example, by reactive ion etching (RIE). Details of the anisotropic etching are known from Patent Document 1, but the outline is as follows. That is, as an etching gas, for silicon oxide crystal defects, for example, when etching is performed using a general magnetron RIE apparatus, a halogen-based mixed gas (for example, HBr / NF3 / He + O _2).
It is preferable to use a mixed gas). This halogen-based etching gas has a higher etching selectivity with respect to silicon oxide-based crystal defects in the order of F, Cl, and Br. Therefore, in order to generate more defect emphasis protrusions by detection sensitivity, that is, by this anisotropic etching, Br-based gas is most preferable, and Cl and F are in the following order.

  By performing the anisotropic etching at an appropriate depth (for example, 0.1 μm or more and 1 μm or less), the periphery of the crystal defect is etched off, a step is generated, and a defect emphasizing protrusion is formed. As a result, when the laser beam to be a probe is incident, the scattered light is likely to be generated at the top surface position of the defect emphasizing protrusion, and the crystal defects existing on the top surface portion can be easily identified. If the anisotropic etching depth is less than 0.1 μm, the crystal defect discrimination improving effect may not be sufficiently achieved. If the anisotropic etching depth exceeds 1 μm, the top surface portion dimension of the defect emphasizing protrusion is small. In some cases, the error increases in the dimensional measurement of crystal defects.

  As a result of the anisotropic etching, a conical defect emphasizing protrusion Q is exposed on the surface of the silicon single crystal wafer 1. However, at this stage, a large amount of anisotropic etching by-product CG adheres to the peripheral region of the defect-enhancing protrusion. The present inventor conducted an experiment to confirm the existence state of the by-product CG by observation with a scanning electron microscope (SEM), but the by-product on the sample was subjected to electron beam irradiation in the microscope during observation. I found it to shrink and eventually disappear. This is presumed to be a substance having a very high vapor pressure (e.g., SiOBr, SiBr, etc.) that evaporates and disappears when the temperature is increased under reduced pressure, unlike an oxide film attached to the silicon surface. Such a by-product can be almost completely dissolved and removed by a normal cleaning solution for a silicon substrate in a relatively short cleaning time.

Specifically, as shown in step 3, the silicon single crystal wafer 1 after etching is cleaned by immersing it in the cleaning liquid SC. As the cleaning liquid SC, an ammonia-hydrogen peroxide aqueous solution can be used, and in particular, the SC-1 cleaning liquid can be preferably used. The solution composition is 5% to 50% ammonia aqueous solution (NH ₃ concentration: 29% by weight) and 5% to 50% hydrogen peroxide solution (H ₂ O ₂ concentration: 31% by weight) by volume ratio. Hereinafter, the remaining water can be used. A specific cleaning liquid composition of SC-1 cleaning is, for example, volume ratio, aqueous ammonia solution: hydrogen peroxide water: water = 1: 1: 5. If a cleaning solution in which a part of water is replaced with a hydrofluoric acid aqueous solution is used, the cleaning removal effect of the by-product CG is further enhanced. In this case, it is appropriate to add a hydrofluoric acid aqueous solution (HF concentration: 50% by weight) in the range of 1% to 30%.

  The silicon single crystal substrate in which the defect emphasizing protrusions are formed by anisotropic etching and the etching by-products are removed by cleaning is formed on the side where the defect emphasizing protrusions are formed as shown in step 4. The surface is scanned with laser light, and the intensity of the scattered light RB from the defect emphasizing protrusion with respect to IB is measured for the incident light. At this time, if the by-product remains, as shown in FIG. 2A, the same scattered light peak as that of the defect-enhancing protrusion is generated even on the protrusion due to this by-product, and the true defect-enhancing protrusion It becomes indistinguishable from the scattered light peak derived from (that is, crystal defects).

  For example, the BMD (or its nucleus) in the wafer surface layer part is extinguished and diffused out of oxygen during the heat treatment for precipitating the BMD, and a so-called DZ (Denuded Zone) layer is formed in the surface layer part of the wafer. . The number of defects in the DZ layer is usually as small as about 5 to 20 wafers / wafer, and even when a part of the by-product, for example, about 10% cannot be removed, the number of the remaining by-products remains the actual crystal defects. It is almost equal to or more than the number, and is clearly unsuitable as a defect evaluation method.

  However, as shown in FIG. 2B, if the by-product is previously removed from the main surface of the anisotropically etched wafer by cleaning or the like, only the scattered light peak derived from the true defect-enhancing protrusion remains, and the crystal defect Detection accuracy can be increased. If the scattered light peak due to the defect emphasizing protrusion is detected, the coordinate data of the scanning position of the laser beam corresponding to this can be acquired as crystal defect detection point data.

  The by-product can be removed by irradiating with an electron beam in a vacuum atmosphere or evaporating by raising the temperature to 200 ° C. or higher (and lower than the melting point of the wafer).

  FIG. 3 is a block diagram showing an electrical configuration of the measurement apparatus 100 described above. The measuring device 100 is roughly composed of two elements, a detection device 150 and a data processing computer 200. The detection device 150 includes a control computer 111 and a measurement system 101 connected thereto. The control computer 111 is connected to an I / O port 108, a CPU 104, a ROM 105, a RAM 106 connected thereto, a hard disk drive (hereinafter abbreviated as HDD) 107 as a storage device, and a keyboard 109 and a mouse 110 as input devices. ing. The HDD 107 stores a control program 107a that controls the operation of the detection apparatus, a data capture program 107b for capturing defect emphasis protrusion detection data, and a data file 107c of the acquired defect emphasis protrusion detection data. Further, the RAM 106 is formed with work areas 106a and 106b for the control program 107a and the data fetch program 107b, and a data storage area 106c for the fetched defect emphasis protrusion detection data.

  Next, the measurement system 101 includes a laser beam probe (not shown) and a drive unit for scanning the laser beam probe on a main surface of a semiconductor wafer to be measured (hereinafter also simply referred to as a wafer). . In this embodiment, the scanning drive is performed by moving a holder (not shown) on which the wafer is mounted, but the laser beam probe side may be driven. Further, as the scanning method, either an XY scanning method or a spiral scanning method may be adopted, but in this embodiment, an XY scanning method is adopted. Therefore, the drive unit includes an X drive motor 113 and a Y drive motor 115 for independently driving the laser beam probe in the X direction and the Y direction, and a pulse generator (for detecting the servo control and rotation angle position of these motors). Hereinafter, it includes an X-PG 114 and a pulse generator 116 (hereinafter referred to as Y-PG). The X drive motor 113 and the Y drive motor 115 are each connected to the I / O port 108 of the control computer 111 via a motor driver (not shown), and are driven and controlled by executing the control program 107a.

  On the other hand, the laser light scattered on the wafer surface is detected by a scattered light detection unit (configured by a photomultiplier tube, a photodiode, a CCD sensor, or the like) 117 connected to the I / O port 108. The scattered light detection level output is input to the data interface 103. On the other hand, the outputs of the pulse generators 114 and 116 are input to the I / O port 108 via the data interface 103.

  The defect-enhanced protrusion detection data includes the level of scattered light generated at the defect-enhancing protrusion (mainly the top surface) as the laser beam enters the defect-enhancing protrusion, and the pixel coordinate value indicating the laser beam irradiation position. As a set of pixel data (hereinafter referred to as scattered light intensity mapping image data). That is, by mapping the detected scattered light level on the pixel plane corresponding to the main surface of the substrate, it is possible to image the top surface portion of the defect emphasizing protrusion, that is, the detection state of the crystal defect existing on the top surface portion. it can. In this case, the pixel setting value can be binarized or graded in multiple stages of three or more according to the scattered light detection level, and the obtained scattered light intensity mapping image data has the setting state of each pixel. Mapping can be performed as binary, grayscale or color image data described by a plurality of bits.

  For example, as shown in FIG. 4, the data interface 103 includes an X-counter 103a and a Y-counter 103b that counts up in response to pulse signals from the X-PG 114 and Y-PG 116, and analog detection from a scattered light detection unit. And an A / D converter 103c for digitizing the signal. The count output of each counter 103a, 103b uniquely gives the measurement position by the laser beam probe. The scattered light detection coordinate value from the X-counter 103a and the Y-counter 103b and the scattered light detection level value from the A / D conversion unit 103c are respectively input to the I / O port 108, and the scattered light intensity mapping image is displayed. It is taken in as pixel data to configure.

  The data processing computer 200 includes an I / O port 208, a CPU 201 connected thereto, a ROM 202, a RAM 203, an HDD 204 as a storage device, a mouse 206 and a keyboard 207 as input devices, and a monitor 205 as a display device. Are connected to the control computer 111 of the detection apparatus 150 via a communication line (or a communication network such as a LAN) 220 via the communication interfaces 209 and 112.

  The HDD 204 stores the scattered light intensity mapping image data file 204b acquired from the detection device 150 via the communication line 220, an analysis program 204a for performing analysis processing on the acquired scattered light intensity mapping image data, and the analysis result. The analysis result data file 204c shown is stored. The RAM 203 includes a work area 203a for the analysis program 204a, a storage area 203b for the acquired scattered light intensity mapping image data, a display memory 203c for displaying the analysis results in coordinate plots, and a storage area 203d for analysis result data. Is formed. Note that the functions of the data processing computer 200 can be integrated into the control computer 111 of the detection device 150.

  In the detection apparatus 150, first, wafer identification data such as the product number, lot number, and manufacturing date of the wafer to be measured is input. Next, the wafer is mounted on the holder of the apparatus, and if the mounting is completed normally, the measurement process is started. Then, the X drive motor 113 and the Y drive motor 115 are operated to move the holder position to a predetermined origin position on the (X, Y) coordinates, and the X-reset signal and Y-reset signal shown in FIG. As a result, the X-counter 103a and the Y-counter 103b are reset. Hereinafter, while scanning the irradiation position of the laser beam probe on the XY coordinate plane with the X direction as the horizontal direction and the Y direction as the vertical direction, each position is irradiated with the laser beam, and the scattered light intensity is measured. Then, the scattered light detection signal value is captured as a pixel setting value via the A / D conversion unit 103c in FIG. 4, and the counter values of the X-counter 103a and the Y-counter 103b at that time are the X coordinate data of the pixel. And Y coordinate data. The pixel data thus captured is stored in the scattered light intensity mapping image data storage area 106c of the RAM 106 of FIG. When the acquisition of pixel data for the entire surface of the wafer is completed, the set of pixel data is associated with the wafer identification data and stored in the HDD 107 as the scattered light intensity mapping image data file 107c.

  Next, FIG. 6 shows an example of the flow of defect analysis processing executed by the data processing program 204a in the data processing computer 200. First, in S51, wafer specific data of a wafer to be evaluated is input. This input may be performed by directly inputting the wafer specifying data using the keyboard 207 or by selecting a data file menu or icon displayed on the screen using the mouse 206. In S52, the scattered light intensity mapping image data file corresponding to the input wafer specifying data is read from the detection device 150 via the communication line 220. In S53, an area where pixels having scattered light intensity equal to or higher than a predetermined threshold level are gathered is separated by an image processing method known as the top face of each defect emphasizing protrusion, that is, an image area of a crystal defect. To do. In S54, as shown in FIG. 7, the representative point position (for example, the center of gravity position) G of each separated crystal defect image region 301 is calculated as the defect position.

  Next, it progresses to S55 and becomes a calculation process of a defect dimension. The dimension D of the crystal defect image region 301 separated as shown in FIG. 7 is measured on the image (for example, it can be calculated as the diameter of a circle having the same area as the separated top surface region). In S56, the type of the crystal defect is specified from the dimension, and is associated with the defect position information, and as shown in FIG. 5, a defect index is assigned to the analysis result data file 204C and stored / registered. For example, when the dimension D exceeds 0.19 μm, the crystal defect can be determined as a COP, and when it is less than 0.19 μm, the crystal defect can be determined as an OSF nucleus (boundary value 0. If it is exactly 19 μm, it is optional to determine whether it is a COP or an OSF nucleus, but it is necessary to determine in advance either one). Based on the stored contents of the analysis result data file 204c, the analysis result can be output in various forms. This output may be made visually by the monitor 205 of FIG. 3, or may be printed out by the printer 210. For example, when the count number of crystal defects of a specific type exceeds a predetermined limit value, the wafer or product lot can be judged as defective and can be selected from non-defective products.

  On the other hand, the right figure of FIG. 8 is a mapping result when SC-1 cleaning is performed after anisotropic etching is performed by RIE on the surface of a mirror-finished wafer obtained from a silicon single crystal ingot by the CZ method ( The left is before anisotropic etching). It was confirmed that minute defects having a size of less than 0.19 μm are distributed in a ring shape in the peripheral region of the wafer, while defects having a size exceeding 0.19 μm are present in the central region inside thereof. FIG. 9 shows the result of extracting and mapping only defects having a size of less than 0.19 μm (left) and defects having a size exceeding 0.19 μm (right) in order to make this tendency more easily understood. FIG. 10 shows an image obtained by observing some of defects having a size exceeding 0.19 μm in the central region with an SEM (magnification of 80000 times). It was confirmed that the void-shaped COP was hollow. On the other hand, FIG. 11 shows an image obtained by observing some of defects having a size of less than 0.19 μm existing in the surrounding region with an SEM (magnification of 160000 times). All were confirmed to be plate-like OSF nuclei.

Process explanatory drawing which concerns on an example of the evaluation method of the crystal defect of this invention. The figure explaining the influence of the by-product residue with respect to a crystal defect detection. Explanatory drawing by the effect by removing a by-product. The block diagram which shows an example of the apparatus for enforcing the crystal defect evaluation method of this invention. FIG. 4 is a circuit diagram showing a configuration example of a data interface in FIG. 3. Structure explanatory drawing of an analysis result data file. The flowchart which shows the flow of a defect analysis process. The conceptual diagram which shows the analysis content of a crystal defect image area | region. Mapping images (anisotropic) showing the results of defect detection using a laser scattering detector before (left) and after (right) anisotropic etching by RIE on the main surface of the mirror wafer Cleaning after reactive etching). FIG. 9 is a diagram illustrating a result of extracting and mapping only defects having a size of less than 0.19 μm (left) and defects having a size exceeding 0.19 μm (right) in FIG. An image obtained by observing some defects having a size exceeding 0.19 μm in the central region of the mirror wafer with an SEM. An image obtained by observing some of defects having a size of less than 0.19 μm existing in the peripheral region of the mirror surface wafer with an SEM.

Explanation of symbols

1 Silicon single crystal wafer (semiconductor single crystal wafer)
P Crystal defect Q Defect emphasis protrusion CG Byproduct

Claims (9)

A method for evaluating crystal defects formed in a semiconductor single crystal substrate,
The surface layer portion including the main surface of the semiconductor single crystal substrate is subjected to selective anisotropic etching in which the etching rate for the non-formation region of the crystal defect is higher than the etching rate for the formation region of the crystal defect, An anisotropic etching step of forming a defect-enhancing protrusion on the main surface, the top surface of which is formed by a crystal defect,
A detection / evaluation step of detecting the top surface portion of the defect emphasizing protrusion with a laser scattering detection device and identifying the type of the crystal defect based on the detected dimensional information of the top surface portion;
In this order ,
The semiconductor single crystal substrate is a silicon single crystal wafer, and based on the dimension information of the top surface portion of the defect emphasizing protrusion, identifying the type of silicon oxide based crystal defect,
A method for evaluating a crystal defect, comprising identifying whether the crystal defect is a COP or an OSF nucleus . In the detection / evaluation step, when the dimension of the top surface portion of the defect emphasizing protrusion exceeds 0.19 μm, the crystal defect is identified as a COP, and when it is less than 0.19 μm, the crystal defect is an OSF nucleus. The crystal defect evaluation method according to claim 1 , wherein the crystal defect is identified as After the anisotropic etching step, prior to the detection / evaluation step, the anisotropic etching by-product adhered to the peripheral region of the defect-enhancing protrusion on the main surface subjected to the anisotropic etching The method for evaluating crystal defects according to claim 1 or 2 , wherein a by-product removing step for removing the product is performed. The crystal defect evaluation method according to claim 3, wherein the anisotropic etching step is performed by reactive ion etching. In the by-product removing step, crystal defects according to the main surface of the semiconductor single crystal substrate of the anisotropic etching, to claim 3 or claim 4 and washed with the by-product removal is possible wash Evaluation method. Evaluation of crystal defects of claim 5, wherein the aqueous solution of hydrogen peroxide - before Symbol cleaning liquid ammonia. The crystal defect evaluation method according to claim 6 , wherein the cleaning liquid further contains hydrofluoric acid. Wherein the by-product removing step, by irradiating an electron beam or ultraviolet radiation on the main surface of the semiconductor single crystal substrate, method for evaluating crystal defects of claim 3 or claim 4 for removing the by-product. Wherein the by-product removing step, by heating the main surface of the semiconductor single crystal substrate to 200 ° C. or higher, the evaluation method of the crystal defects according to claim 3 or claim 4 for removing the by-product.