JP2005158961A - Unit and method for crystal defect inspection - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently inspect a specimen for crystal defects. <P>SOLUTION: The crystal defect inspection apparatus comprises a liquid tank 10 containing an etchant 2, a measuring instrument 30 for determining the amount etched away from a specimen 1 in the etchant 2, a controller 32 for receiving and comparing the etched amount with a prescribed value and for outputting a takeout signal in case the etched amount is equal to or more than the prescribed value, an elevator 20 that takes the specimen 1 out of the etchant 2 in the liquid tank 10 upon receiving the takeout signal, a washing nozzle 40 for spraying a washing liquid W for washing the etchant 2 away from the surface of the specimen 1, and an image processor 80 that determines the number of crystal defects in presence on the surface of the specimen 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an apparatus and an inspection method for inspecting a crystal defect of a sample, and more particularly to an inspection apparatus and an inspection method that can be performed consistently from etching of a sample to counting of crystal defects.

  Currently, there are ICs (Integrated Circuits) that are installed in many electronic devices such as digital cameras and control the operation of the electronic devices. Although this IC is small in size, it can perform complex signal processing at a high speed, so this IC is very effective when it is desired to reduce the size of the electronic device itself that is desired to be controlled. When manufacturing such an IC, a semiconductor substrate made of silicon single crystal is subjected to a semiconductor manufacturing process such as lithography, etching, impurity introduction, etc., so that circuit elements such as transistors and diodes are integrated and formed. They are manufactured by wiring and connecting them. Depending on the degree of integration, these ICs include small to large scale integration (LSI), very large scale integration (VLSI), and ultra large scale integration (ULSI), and are formed adjacent to each other as the degree of integration increases. The gap between the circuit elements to be processed is reduced. For this reason, the higher the integration degree of the IC, the more accurate the semiconductor manufacturing process is required. In order to increase the degree of IC integration, it is required not only to improve the accuracy of the semiconductor manufacturing process, but also to improve the quality of the semiconductor substrate to be subjected to the semiconductor manufacturing process.

  A semiconductor substrate is obtained by cutting a silicon single crystal layer grown by a crystal growth process into a wafer shape. Depending on the growth conditions and the growing apparatus, crystal defects may occur in the silicon single crystal layer. Are known. This crystal defect occurs when the etching solution is applied to the surface of the semiconductor substrate in a semiconductor manufacturing process or the like, so that the part with the crystal defect dissolves faster than the part without it. It becomes apparent as a hole (pit). If this etch pit appears in the etching process of the semiconductor manufacturing process, the etching with the etchant becomes deeper than desired, or the etchant flows into the generated etch pit and etches in an unexpected direction. May occur, for example, by eroding adjacent wiring or circuit elements and short-circuiting them. Accordingly, the number of etch pits present in the semiconductor substrate is one of the indexes for evaluating the quality of the semiconductor substrate. The smaller the number of etch pits, the higher the quality. The higher the number, the lower the quality. If the quality of the semiconductor substrate is evaluated in this way, for example, it is highly integrated on a high-quality semiconductor substrate and low integrated on a low-quality semiconductor substrate. Thus, the degree of integration can be changed, and the yield when manufacturing the IC can be improved.

  Conventionally, when the number of etch pits is counted, the surface of the semiconductor substrate is visually observed and counted. However, the size of each etch pit is very small, such as several μm to several hundred μm, and it is difficult to visually identify it. Therefore, the surface of the semiconductor substrate is observed with an optical microscope, or Then, after the surface was photographed by a camera or the like, the photographed image was enlarged and displayed by an image display device (for example, see Patent Document 1). For this reason, in order to observe the entire surface of the semiconductor substrate, a great amount of time and effort are imposed on the observer. Accordingly, there has been proposed a method in which the number of etch pits is automatically counted by an apparatus rather than visually (see, for example, Patent Document 2). Such counting devices include, for example, a device that discriminates and counts the presence or absence of etch pits by analyzing the brightness, shading, color, etc. of the image of the surface of the semiconductor substrate taken, or irradiates the surface of the semiconductor substrate with light. In addition, there is one that counts by determining the presence or absence of etch pits from the reflected light reflected on the surface of the semiconductor substrate among the irradiated light. According to such a counting device, since the number of etch pits can be automatically counted, it is possible to significantly reduce the burden on the observer and the counting time as compared with the case of counting visually. .

However, since such a counting device counts only the crystal defects exposed on the surface of the semiconductor substrate being observed and manifested as etch pits, it is not exposed on the surface, ie, the semiconductor substrate The crystal defects existing inside are not counted. However, when the semiconductor manufacturing process is performed, not only the surface of the semiconductor substrate but also the inside thereof is etched by the etching solution, so the number of crystal defects present in the inside is also an object for quality evaluation. It is possible to evaluate the quality with higher accuracy. The number of crystal defects in the silicon single crystal layer does not change so much in the plane direction, but the number of crystal defects may change greatly in the growth direction due to external factors during the growth. Therefore, for example, even if the observed surface is a semiconductor substrate having a small number of etch pits, there may be a large number of etch pits inside the semiconductor substrate. In the conventional counting device, it was not possible to count such crystal defects existing inside the semiconductor substrate. However, if it was intended to do so, it was necessary to perform the following manual operation. It was. That is, first, the observed semiconductor substrate is manually removed from the counting device by an observer, and immersed in an etching solution to be etched. When the observer determines that the desired depth has been etched, the semiconductor substrate is manually removed from the etching solution, washed with a cleaning solution to completely stop the etching, and then returned to the counting device. It was set and the number of etch pits was counted by a counting device. As described above, almost all processes other than counting have to be performed manually.
JP-A-8-111444 JP-A-8-21801

  However, since the size of the etch pit is usually very small, if the surface of the semiconductor substrate to be evaluated is damaged while it is being manually removed from the counting device or moved, the etch pit Will be crushed by the scratch, and the counting cannot be performed correctly. Therefore, it was necessary to pay close attention to the handling of the semiconductor substrate to be evaluated, and it was necessary to improve the environment and facilities for that purpose. In particular, when trying to evaluate a very small size semiconductor substrate having a chip type side of about 200 μm, the semiconductor substrate itself may be lost during removal or movement. Is very difficult to handle manually. Accordingly, the present invention has been invented in view of the above-described background art, and an object thereof is to provide an apparatus and an inspection method for inspecting a crystal defect of a semiconductor substrate more efficiently.

  In order to solve the above problems, a crystal defect inspection apparatus of the present invention is an apparatus for inspecting a crystal defect of a sample which is an object to be inspected, and is a liquid formed so as to contain an etching solution for etching the surface of the sample. The measurement means for measuring the amount of the tank and the sample immersed in the etching liquid in the liquid tank measured by the etching liquid, and the measurement result of the measurement means are input and compared with a predetermined value. When the measurement result is equal to or greater than the predetermined value, a control unit that outputs a take-out signal, and a sample that is movably supported in and out of the etching solution in the liquid tank and that can receive a signal from the control unit, When the take-out signal from the control unit is inputted, the sample transfer means for taking out the supported sample from the etching solution in the liquid tank and the surface of the sample taken out by the sample transfer means are washed. Pouring a cleaning means for washing out the etching solution adhering to its surface, it is made and a counting means for determining the number of crystal defects present in the washed surface of the sample.

  The crystal defect inspection method of the present invention is a method for inspecting a crystal defect of a sample which is an object to be inspected, and the sample is immersed in an etching solution capable of etching the surface of the sample to be inspected. Subsequently, the amount of the immersed sample etched by the etching solution is measured, and when the measurement result is a predetermined value or more, the sample is taken out from the etching solution, and the cleaning solution is applied to the surface of the taken-out sample. Then, the etching solution adhering to the surface is washed away, and the number of crystal defects existing on the surface of the cleaned sample is obtained.

  In the crystal defect inspection apparatus and crystal defect inspection method of the present invention, since the sample surface etching to the counting of crystal defects existing on the etched sample surface are performed consistently, the inspection can be performed efficiently. It becomes.

  An embodiment according to a crystal defect inspection apparatus and a crystal defect inspection method of the present invention will be described below with reference to FIGS. FIG. 1 shows a state where the sample 1 is immersed in the etching solution 2, and FIG. 2 shows a state where the sample 1 is pulled up from the etching solution 2.

  This crystal defect inspection apparatus includes a liquid tank 10, an elevator 20 and a sample stage 21 as a sample transfer means, a liquid receiver 22, a measuring instrument 30, a controller 32, a cleaning nozzle 40, and a dryer. A nozzle 50, a camera 70, an image processing unit 80, a density calculation unit 81, and a display 90 are provided.

  The liquid tank 10 is formed in a box shape with an upper surface opened so that the etching solution 2 can be accommodated, and the sample 1 can be taken in and out through the opened upper surface. The size of the opening is larger than the size of the sample stage 21 so that the sample stage 21 can pass through the opening while the sample 1 is placed thereon.

  The sample stage 21 has a box shape with an open upper surface. A lift shaft 202 is connected to the side surface of the sample stage 21 and is supported by the support shaft 201 of the lift 20 via the lift shaft 202. On the lower surface, there is a sample mounting portion 211 for mounting and supporting the sample 1. The sample placement part 211 is formed in a mesh shape, and the etching solution 2 can freely pass through the sample placement part 211 through the mesh. In addition, the fineness of the mesh is not particularly limited, and may be appropriately adjusted according to the size of the sample 1 to be placed. In short, the sample 1 should not be dropped from the mesh. What is necessary is just to form smaller than the size of the sample 1.

  The liquid receiving part 22 has a box shape with an open top surface, and the size of the opening and the bottom surface is larger than the size of the sample mounting part 211 to the extent that the sample stage 21 can be accommodated. In addition, a rotating shaft 203 is connected to the side surface, and is supported by the support shaft 201 of the elevator 20 via the rotating shaft 203. Also, a part of the bottom surface has the entire thickness direction. It has a drainage hole 221 that penetrates. Thereby, as shown in FIG. 2, when the liquid receiving unit 22 is positioned below the sample stage 21, the cleaning liquid W sprayed from the cleaning nozzle 40 toward the sample 1 is used as the mesh-shaped sample mounting unit 211. The received cleaning liquid W can be discharged from the drain hole 221. As shown in FIG. 2, the drain hole 221 is arranged so that the drain hole 221 is outside the liquid tank 10 when the liquid receiver 22 is positioned below the sample stage 21, that is, above the liquid tank 10. It is desirable to provide it at such a position, and by doing so, it is possible to prevent the cleaning liquid W discharged from the drain hole 221 from flowing into the liquid tank 10.

  The elevator 20 includes a support shaft 201 fixed to the liquid tank 10, a lift shaft 202 that moves up and down along the axial direction of the support shaft 201, a rotary shaft 203 that rotates about the support shaft 201, and a support shaft 201. And a drive motor 204 that moves the lifting shaft 202 up and down and rotates the rotating shaft 203. Further, the elevating shaft 202 is also connected to the sample stage 21, and the sample stage 21 also moves up and down as the elevating shaft 202 moves up and down. Similarly, the rotating shaft 203 is connected to the liquid receiving unit 22, and the liquid receiving unit 22 also rotates as the rotating shaft 203 rotates. The lowering range of the lifting shaft 202 is a lower limit position L where the sample mounting portion 211 of the sample stage 21 contacts the bottom surface of the liquid tank 10, and the upper limit is the proximity of the sample mounting portion 211 of the sample stage 21 to the camera 70. The upper limit position H to be set is set. The rotary shaft 203 is provided at a position M between the upper limit position H and the lower limit position L of the lift range of the lift shaft 202 and is configured to rotate in accordance with the lift of the lift shaft 202. That is, when the elevating shaft 202 is at a position lower than the position M of the rotating shaft 203, the rotating shaft 203 has an angle of about 180 degrees with respect to the elevating shaft 202 around the support shaft 201 as shown in FIG. 2 and when the lifting shaft 202 is at a position higher than the position M of the rotating shaft 203, as shown in FIG. That is, the elevator shaft 202 and the rotary shaft 203 rotate to a position where they overlap each other in the axial direction of the support shaft 201. Accordingly, the liquid receiving unit 22 connected to the rotating shaft 203 does not interfere with the lifting / lowering operation of the sample stage 21 connected to the lifting / lowering shaft 202, and the cleaning liquid W is applied to the sample 1 supported by the sample stage 21. In the case of spraying the liquid, since the liquid receiving part 22 receives the cleaning liquid W, it is possible to prevent the cleaning liquid W from flowing into the liquid tank 10.

  The measuring device 30 includes an irradiation unit 301 that irradiates laser light toward the surface of the sample 1, a light receiving unit 302 that receives the laser light reflected by the surface of the sample 1, and a distance between the measuring device 30 and the sample 1. An etching amount calculation unit 303 is provided that calculates the amount by which the sample 1 is etched from the obtained distance value. The etching amount calculation unit 303 measures the elapsed time from the time when the irradiation unit 301 irradiates the sample 1 with laser light to the time when the laser light is reflected by the surface of the sample 1 and received by the light receiving unit 302. At the same time, the distance between the sample 1 and the measuring instrument 30 is obtained by multiplying the elapsed time by the propagation speed of the laser beam. By performing cumulative addition on the obtained distance after the sample 1 is immersed in the etching solution 2, the amount of the sample 1 etched can be obtained. The irradiation unit 301 is set so as to irradiate the laser beam at a constant time interval. If this time interval is adjusted according to the speed at which the sample 1 is etched, the etching amount of the sample 1 is set. Can be obtained with higher accuracy, which is preferable.

The control unit 32 is connected to the etching amount calculation unit 303, the drive motor 204, the camera 70, the on-off valve 401, and the on-off valve 501. When taking out the sample 1 from the etching solution 2, the control unit 32 compares the value of the etching amount of the sample 1 obtained by the etching amount calculating unit 303 with a predetermined value set in advance. When the value of the etching amount is equal to or greater than a predetermined value, an extraction signal is output to the drive motor 204. When the drive motor 204 receives the take-out signal, the drive motor 204 drives the motor and raises the lifting shaft 202. As a result, the sample stage 21 connected to the lifting shaft 202 is taken out of the etching solution 2 as shown in FIG. 2 from the state in which the sample 1 is immersed in the etching solution 2 as shown in FIG. It becomes a state. When cleaning the sample 1 taken out from the etching solution 2, the control unit 32 outputs an opening control signal to the on-off valve 401 when the elevating shaft 202 reaches the upper limit position H, thereby opening / closing the on-off valve. 401 is opened and the cleaning liquid W is sprayed to the cleaning nozzle 40. Then, after opening the on-off valve 401, a closing control signal is output to the on-off valve 401 when a predetermined time elapses to close the on-off valve 401. At the same time, an open control signal is output to the open / close valve 501 of the drying nozzle 50 to open the open / close valve 501, and gas is injected toward the sample 1 to dry the sample 1. Then, after opening the on-off valve 501, when a predetermined time has elapsed, a closing control signal is output to the on-off valve 501 to close the on-off valve 501, and an imaging start signal is output to the camera 70. Start shooting the surface of the. When the camera 70 finishes photographing the surface of the sample 1, the camera 70 outputs the photographed data to the image processing unit 80, so that the photographed data is received by the control unit 32. When receiving image data from the camera 70, the control unit 32 determines that shooting has been completed and outputs a descent signal to the drive motor 204. The drive motor 204 drives the motor to lower the lifting shaft 202. As a result, the sample 1 can be immersed in the etching solution 2 and the sample 1 can be etched again. It should be noted that the predetermined time during which the on-off valve 401 and the on-off valve 501 are opened may be the same time length or may be different time lengths separately. Further, the predetermined value set in advance in the control unit 32 may be appropriately adjusted according to the material and growth method of the sample 1 to be inspected. For example, the crystal defect of the sample 1 to be inspected is long in the growth direction. If it extends, set the predetermined value large so that the same etch pit is not counted repeatedly before and after etching, and if it does not extend long in the growth direction, set the predetermined value small. Thus, it is only necessary to inspect finely along the growth direction so that changes in crystal defects in the growth direction can be determined in detail.

  The cleaning nozzle 40 includes an opening / closing valve 401 that opens and closes in response to a control signal input from the control unit 32. When an opening control signal is input from the control unit 32, the valve is opened to control closing. When a signal is input, the valve is closed. That is, the cleaning nozzle 40 is controlled to eject the cleaning liquid W according to the opening / closing operation of the opening / closing valve 401. In this way, by spraying the cleaning liquid W onto the surface of the sample 1, even after the sample 1 is taken out from the etching liquid 2, it is continuously etched by the etching liquid 2 adhering to the surface. Can be completely stopped. Further, since the cleaning liquid W is jetted only when the sample stage 21 is positioned below the liquid receiving part 22, it is possible to prevent the cleaning liquid W from flowing into the liquid tank 10. Note that the spray amount and spray time of the cleaning liquid W are not particularly limited, and may be set to an amount and time that can wash away the etching liquid 2 attached to the sample 1. Further, the type of the cleaning liquid W is not particularly limited as long as it can wash away the etching liquid 2 adhering to the sample 1. For example, pure water is used. That's fine.

  The drying nozzle 50 includes an on-off valve 501 that opens and closes in response to a control signal input from the control unit 32. When an opening control signal is input from the control unit 32, the valve is opened to control closing. When a signal is input, the valve is closed. That is, in the drying nozzle 50, as with the cleaning nozzle 40, the gas injection for drying the sample 1 is controlled according to the opening / closing operation of the opening / closing valve 501. Thus, the liquid adhering to the surface of the sample 1 is dried by injecting the gas toward the sample 1. The gas injection amount and the injection time are not particularly limited as long as the surface of the sample 1 is sufficiently dried. Furthermore, the kind of the gas is not particularly limited, and for example, air may be used. In this case, it is preferable that a cylinder for storing the gas does not need to be separately prepared. In addition, when air is used, it is preferable that the surface of the sample 1 be dried more efficiently if heated and warmed before the air is jetted.

  When the camera 70 receives the imaging start signal from the control unit 32, the camera 70 starts imaging the surface of the sample 1. The captured image is converted into data and output to the image processing unit 80. This image data includes information such as the color, brightness, and brightness of the captured image. If a zoom lens (not shown) is connected to the camera 70, an enlarged image of the surface of the sample 1 can be taken without changing the distance between the camera 70 and the surface of the sample 1. Can be preferable.

  The image processing unit 80 analyzes the image data input from the camera 70 and counts the number of etch pits present in the image. This count is based on the analysis of all the differences in color, brightness, and brightness between the etch pit and non-etch pits included in the image data. Count. Note that the number of etch pits is not limited to such an image processing method, and may be performed using a conventionally used image processing technique. Data to be analyzed includes color, brightness, brightness and darkness. Any one of these may be used, or a combination thereof.

  The density calculation unit 81 obtains the number of etch pits obtained in the current inspection obtained by the image processing unit 80, the inspection performed before the inspection, that is, the number of etch pits obtained in the previous inspection, Based on the etching amount of the sample 1 in the inspection, the density of etch pits existing within the etching amount is obtained. That is, the average value of the number of etch pits existing on one surface inspected in the current inspection and another surface inspected in the previous inspection is obtained, and the obtained average value is determined for the etching amount and the sample 1. By dividing by the area, the etching density per volume of the sample 1 is calculated. When the density is obtained in this way, the density of etch pits in the depth direction of the sample 1, that is, the growth direction of the silicon single crystal layer that is the source of the sample 1, can be grasped, and the quality of the sample 1 is set in the growth direction. Can be evaluated. Note that the etching amount used for calculating the density and the value of the area of the sample 1 are set in advance in the density calculating unit 81, which is formed so that data from the etching amount calculating unit 303 can be input. Thus, the input data may be used.

  The display 90 displays the image data input from the image processing unit 80 on the screen. If the user visually confirms this, the shape and size of the etch pit can be visually observed.

  The sample 1 which is an object to be inspected by this inspection apparatus is, for example, Si (silicon), GaN (gallium nitride), GaAs (gallium arsenide) or the like as a semiconductor material grown by CVD (Chemical Vapor Deposition). Although an epitaxial wafer cut out from an epitaxial layer grown by the method can be used, a sample grown by any other material and method can be inspected as an inspection object. The size of the sample 1 can be efficiently inspected from a very small size such as an IC chip having a side of about 200 μm to a large size of 200 mm (8 inches) or more. When inspecting a sample having a size of about 200 μm on a side, the mesh eye of the sample mounting unit 211 may be set to about 100 μm, for example. The etching solution 2 may be phosphoric acid when the sample 1 is an epitaxial wafer. However, when the material of the sample 1 is changed, the etching solution 2 may be changed as appropriate.

  Next, an operation for inspecting a crystal defect of the sample 1 will be described.

  First, the sample 1 is mounted and supported on the sample mounting portion 211 of the sample stage 21. When the sample 1 is placed on the sample placing portion 211, the drive motor 204 lowers the lifting shaft 202 and immerses the sample stage 21 into the etching solution 2 in the liquid tank 10. As a result, the sample 1 is immersed in the etching solution 2 as shown in FIG. The immersed sample 1 starts to be etched by the etching solution 2.

  While the sample 1 is immersed in the etching solution 2, the irradiation unit 301 irradiates the laser beam every predetermined time. When the light receiving unit 302 receives the irradiated laser light reflected by the surface of the sample 1, the etching amount calculation unit 303 is based on the elapsed time from irradiation by the irradiation unit 301 to light reception by the light receiving unit 302. Then, the distance between the surface of the sample 1 and the measuring instrument 30 is obtained. When the value of the distance is obtained, the etching amount of the sample 1 from the time when the sample 1 is immersed in the etching solution 2 is calculated by adding to the accumulated distance value calculated so far. When the calculated etching amount is output to the control unit 32, the control unit 32 compares the inputted etching amount with a predetermined value set in advance. When the etching amount is larger than the predetermined value, an extraction signal is output to the drive motor 204. The drive motor 204 raises the lifting shaft 202 when the take-out signal is input. Thereby, the sample stage 21 connected to the elevating shaft 202 is taken out from the etching solution 2.

  When the sample stage 21 is taken out from the etching solution 2 and rises to a position higher than the liquid receiving part 22, the liquid receiving part 22 rotates around the support shaft 201 as shown in FIG. 2 and below the sample stage 21. To position. Then, the cleaning liquid W is sprayed from the cleaning nozzle 40 toward the sample 1 to clean the etching liquid 2 adhering to the surface of the sample 1. When the predetermined time has elapsed, the spraying of the cleaning liquid W is stopped. Thereby, the etching of the sample 1 is completely stopped. Subsequently, warm air is jetted from the drying nozzle 50 toward the sample 1 to dry the sample 1. When the predetermined time has elapsed, the hot air injection stops.

  When the sample 1 is dried, the surface of the sample 1 is photographed by the camera 70. The captured image data is output to the image processing unit 80. In addition, when the surface of the sample 1 is large and the camera 70 cannot capture the entire surface of the sample 1 in one shooting, the shooting may be performed in multiple shots. May be stored in the camera 70 once, the entire surface of the sample 1 is imaged, and all the stored image data may be output to the image processing unit 80 in a lump.

  The image processing unit 80 analyzes the input image data and counts the number of etch pits. For this analysis, for example, the color, brightness, brightness and darkness of the etch pit portion and the non-etch pit portion in the image data are differentiated, etch pits are extracted from the difference values, and the number is counted. Thereafter, the obtained number of etch pits is displayed on the display 90. At the same time, if the photographed surface image of the sample 1 is displayed on the display 90, the user can check the size and shape of the etch pit. By inspecting the crystal defects of the sample 1 in this way, the number of etch pits at the desired depth of the sample 1 can be automatically obtained without manually handling the sample 1, and particularly manual operation. Therefore, it is possible to efficiently evaluate extremely small samples that are extremely difficult to handle.

  When the image data is output from the camera 70 to the image processing unit 80, the control unit 32 outputs a lowering signal to the drive motor 204, lowers the sample stage 21 again, and removes the sample 1 placed thereon. It is immersed in the etching solution 2. If the subsequent steps are the same as described above, the number of etch pits existing on the surface below the surface of the sample 1 just inspected can be obtained. It is possible to obtain the density of etch pits from the number of.

  The cleaning nozzle 40 operates the on-off valve 401 in accordance with a control signal from the control unit 32. However, other than this, for example, the on-off valve 401 is operated in accordance with the rotation angle of the rotary shaft 203. You may make it open and close. In this case, an angle meter for measuring the rotation angle of the rotation shaft 203 is required. For example, when the angle formed by the rotation shaft 203 and the lifting shaft 202 is about 0 degrees, that is, the liquid receiving unit 22 is the sample stage. When it is located directly below 21, the valve may be opened. Further, when the angle formed between the rotary shaft 203 and the lifting shaft 202 is equal to or larger than a predetermined size, if the valve is closed, only when the sample stage 21 is positioned below the liquid receiving unit 22, Since the cleaning liquid W is ejected, the cleaning liquid W can be prevented from flowing into the liquid tank 10.

  Further, the drive motor 204 is used as means for driving the lifting shaft 202 and the rotating shaft 203. However, this is not limited to the motor, and other components such as a hydraulic cylinder, a pneumatic cylinder, etc. Any device that can drive the rotary shaft 203 may be used. Further, if a gear or belt is interposed between the rotary shaft 203 and the lifting shaft 202 and mechanical interlocking is performed between them, the driving shaft 204 can be provided on the lifting shaft 202, for example. It can be rotated according to the raising / lowering of the raising / lowering shaft 202, and the drive motor for driving the rotating shaft 203 can be omitted.

  Moreover, although what measured the distance between the measuring device 30 and the sample 1 with the laser beam was used for the measuring device 30, in addition to this, while emitting an ultrasonic wave toward the sample 1, for example, Of the emitted ultrasonic waves, the one reflected by the surface of the sample 1 is received, and the distance between the measuring instrument 30 and the sample 1 is measured by the elapsed time from the injection to the received time. Also good. The method of calculating the etching amount on the surface of the sample 1 from the measured distance may be the same method as described above.

  In addition, when the size of the sample 1 is sufficiently larger than the size of the etch pit to be measured, that is, when the sample 1 having a large size is inspected, the etch pit is formed without enlarging the photographed image. Since it is difficult to discriminate, in that case, the camera 70 may zoom in on the surface of the sample 1 and then take an image thereof, or the entire surface of the sample 1 may be zoomed up. After the image is taken, the taken image data may be enlarged on the data by the image processing unit 80 so that the etch pit can be identified. Further, in the case of outputting the image data to the image processing unit 80, in the above description, all of the image data is once stored in the camera 70 and then output in a batch. However, each time the camera 70 captures the image data, You may make it output to the image process part 80 each time.

  In the above, the sample stage 21 is moved up and down with respect to the support shaft 201 to take out and immerse the sample 1 from the etching solution 2 in the liquid tank 10. The liquid tank 10 is movably connected to the support shaft 201, and the liquid tank 10 is moved up and down so that the sample 1 is taken out and immersed in the etching liquid 2 of the liquid tank 10. Also good.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to this embodiment and can be implemented in various forms.

In one embodiment of this invention, it is the schematic which shows the state which has immersed the sample in the etching liquid. In the same embodiment, it is the schematic which shows the state which took out the sample from etching liquid.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Liquid tank 20 Elevator 21 Sample stage 22 Receiving part 30 Measuring instrument 32 Control part 40 Cleaning nozzle 50 Drying nozzle 70 Camera 80 Image processing part 81 Density calculation part 201 Support axis 202 Elevating axis 203 Rotating axis 204 Drive motor 211 Sample mounting part 221 Drain hole 301 Irradiation part 302 Light receiving part 303 Etching amount calculation part 401 On-off valve 501 On-off valve W Cleaning liquid

Claims (7)

An apparatus for inspecting a crystal defect of a sample as an inspection object,
A liquid tank formed so as to accommodate an etching solution for etching the surface of the sample;
Measuring means for measuring the amount of the sample immersed in the etching liquid in the liquid tank being etched by the etching liquid;
A control unit that inputs a measurement result of the measuring means and compares it with a predetermined value, and outputs a take-out signal when the measurement result is equal to or greater than the predetermined value;
The sample is supported so as to be able to move in and out of the etchant in the liquid tank, and a signal from the control unit can be input, and when the take-out signal from the control unit is input, the supported sample is transferred to the liquid tank. A sample transfer means for removing from the etching solution;
A cleaning means for pouring a cleaning liquid onto the surface of the sample taken out of the sample transfer means, and washing away the etching liquid adhering to the surface;
A crystal defect inspection apparatus comprising: a counting means for determining the number of crystal defects present on the surface of the cleaned sample. The measurement means includes an irradiation unit that irradiates the sample surface with laser light, and
Among the irradiated laser light, a light receiving unit that receives the laser light reflected on the sample surface,
The crystal defect inspection apparatus according to claim 1, further comprising: an etching amount calculation unit that calculates an etching amount of the sample surface from the laser beam received by the light receiving unit.   2. The sample transfer means has a mesh-like sample placement portion for placing and supporting a sample, and is immersed in an etching solution in the liquid tank portion together with the placed sample. Or the crystal defect inspection apparatus of Claim 2.   The crystal defect inspection apparatus according to any one of claims 1 to 3, further comprising a liquid receiving portion that receives the cleaning liquid so that the cleaning liquid poured by the cleaning means does not flow into the liquid tank.   The apparatus further comprises a density calculating unit that calculates a crystal defect density per volume of the sample based on the etching amount measured by the measuring unit and the number of crystal defects obtained by the counting unit. The crystal defect inspection apparatus according to claim 1.   After the counting means obtains the number of crystal defects in the sample, the control unit outputs a descending signal to the sample transporting means, and the sample transporting means inputs the descending signal and then removes the supported sample from the liquid. 6. The crystal defect inspection apparatus according to claim 1, wherein the crystal defect inspection apparatus is immersed in an etching solution in a bath. A method for inspecting a crystal defect of a sample to be inspected,
Immerse the sample in an etchant that can etch the surface of the sample to be inspected.
Subsequently, the amount of the immersed sample was measured by the etching solution, and when the measurement result is a predetermined value or more, the sample was taken out from the etching solution,
Pour the cleaning solution onto the surface of the sample taken out, wash away the etching solution adhering to the surface,
A crystal defect inspection method characterized in that the number of crystal defects present on the surface of the cleaned sample is obtained.

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