JP2005158809A - Prober device, wafer-detecting method, wafer position measuring method and cassette position correcting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for surer detection of a wafer in a cassette at high speed, and to provide a prober device. <P>SOLUTION: The provider device 10 is provided with sensors 61 and 62 for detecting the existence of the wafer in the cassette, a driving means 54 which relatively moves the cassette 22 and the sensors in one direction, a pulse signal output part 55 for outputting a pulse signal synchronized with a moving distance by the driving means 54, a read timing generator 72 for outputting a reading timing signal when the pulse signal from the pulse signal output 55 is inputted for the prescribed number of times, a read part 71 for reading the output of the sensor, when the reading timing signal from the read timing generator 72 is inputted, and a wafer existence deciding part 83 for deciding the presence or the absence of the wafer in the cassette, based on the detection result of the sensor. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a prober apparatus, and more particularly to a prober apparatus for measuring characteristics of chips formed on a semiconductor wafer and a wafer detection method in a cassette capable of storing a large number of wafers.

  Many identical electric element circuits are formed on the surface of the semiconductor wafer, but the inspection of the formation quality of each electric element circuit is performed before the electric element circuits are cut into chips. The inspection of the electric element circuit formed on the surface of the semiconductor wafer is performed by, for example, an apparatus called a wafer prober disclosed in Patent Document 1 below.

  FIG. 1 is an external perspective view of a conventional prober device disclosed in Patent Document 1. In FIG. The prober apparatus 10 mainly includes a cassette stock 12, a wafer transport belt 14, an inspection table 16, an inspection unit 18, and the like.

The cassette stock 12 has an elevator mechanism (not shown), and a cassette 22 is placed on a plate 20 that moves up and down by the operation of the elevator mechanism. A plurality of wafers 24 are stored in the cassette 22.
The wafer 24 stored in the cassette 22 is pushed toward the transport belt 14 by the load pusher 26 and is carried forward by the transport belt 14. The wafer 24 is sucked and held by a suction collet 29 provided at the tip of the transfer arm 28 and moved onto the inspection table 16 by the transfer arm 28.

The inspection table 16 is provided on an XYZ moving mechanism. The inspection table 16 is moved in parallel in the XY direction by this XYZ moving mechanism and is moved up and down in the Z direction.
The wafer inspection unit 18 has a microscope 30, and a probe stage 32 is formed below the microscope 30. A probe card (not shown) corresponding to the wafer 24 to be inspected can be selected and attached to the probe stage 32.

  The wafer 24 that has been inspected is moved from the inspection table 16 onto the conveyor belt 1 by the unload arm 36, and stored in the original shelf of the cassette 22 by the unload pusher 38.

  The operation of the wafer prober apparatus 10 configured as described above will be described. First, the wafer 24 is taken out from the cassette 22, and the wafer 24 is transferred onto the inspection table 16 by the transfer belt 14 and the transfer arm 28, and the wafer is sucked by the suction chuck. Thereafter, the inspection table 16 is moved in the direction of the probe card based on image data captured by a CCD camera (not shown), and fine alignment adjustment is performed. Then, the probe needles of the probe card can be brought into contact with the electrode pads of the wafer 24 to sequentially inspect each element circuit. The above-described loading / unloading of the wafer 24 into / from the conveyor belt 14 is performed by an arm mechanism or the like in addition to the load pusher 26 and the unload pusher 38.

  In FIG. 2, the block diagram of the cassette stock 12 of the prober apparatus 10 is shown. The cassette stock 12 includes a housing 50 in which a cassette 22 that can store a plurality of wafers 24 is placed, a lifting / lowering means 53 that moves the cassette 22 and the plate 20 on which the cassette 22 is placed, and a motor 54 that drives the lifting / lowering means 53.

  As the motor 54, a stepping motor (pulse motor) is usually used. The motor control unit 55 generates a driving pulse signal for controlling the motor 54, and the motor driving circuit 56 outputs an excitation current for exciting each coil of the stepping motor based on the driving pulse signal.

  The motor control unit 55 is connected to a data bus of a calculator 80 constituted by a computer or the like which is a control unit that controls the prober device 10 and can exchange data with the calculator 80. Cassette height control data by the calculator 80 Based on the above, the driving pulse signal is generated.

  FIG. 3 is a cross-sectional view of the cassette stock 12 of FIG. The cassette 22 is open at the front and back, and the wafer 24 can be taken in and out by a load pusher 26 and an unload pusher 38. A plurality of slots (shelves) 52 for mounting and storing the wafers 24 are provided inside the side walls.

As shown in FIG. 1, the cassette stock 12 is provided with optical sensors 61 (transmission side) and 62 (reception side) for detecting whether or not the wafer 24 is stored in each slot 52.
In the optical sensors 61 and 62, when the wafer 24 is at the same height as the optical axis, the wafer 24 is interposed between the transmission side sensor 61 and the reception side 62, and the light transmitted from the transmission side sensor 61 is received. The presence of the wafer 24 is detected by detecting that it has not reached the side sensor 62.
The optical axes of the optical sensors 61 and 62 are provided substantially horizontally along the side surface of the cassette 22 in which the slot 52 is provided as shown in FIG.

  Further, the optical axes of the optical sensors 61 and 62 are provided at the same height as the contact portion of the load pusher 26 and the unload pusher 38 with the wafer 24. This is because the optical sensors 61 and 62 detect whether or not the wafer 24 controlled to be positioned at the load position is surely at the load position and can be loaded and unloaded by the load pusher 26 and the unload pusher 38. It is to do.

  The detection signal that is the output of the receiving side optical sensor 62 is converted into a digital signal by an analog-to-digital converter (ADC) 64 and connected to the data bus of the calculator 80 via an input / output means (I / O) 82. Available to the calculator 80.

  When the cassette 22 is put in the cassette stock 12 as described above and the wafer 24 stored in the cassette 22 is inspected, it is preliminarily confirmed that the wafer 24 is actually stored in the slot 52 to be stored. It is preferable to confirm.

Conventional detection of the wafer 24 in the cassette 22 is performed as follows.
1. The calculator 80 controls the motor control unit 55 so that the cassette 22 moves at a constant speed.
2. Each time from when the cassette 22 starts moving to the cassette 22 position when each slot 52 passes the optical axis height of the optical sensors 61 and 62 is calculated in advance. Measurement timing is generated at this time.
3. The calculator 80 reads the output signal of the optical sensor 62 at the generated timing by software processing.

This will be described with reference to FIGS. 4 (A) and 4 (B).
FIG. 4A shows the displacement of the cassette 22 with respect to time. Now, one of the plurality of wafers 24 housed in the cassette 22 is in a position where the optical axis of the optical sensors 61 and 62 is blocked when the position of the cassette 22 is between x1 and x2, and the other one. Is in a position to block the optical axes of the optical sensors 61 and 62 when the position of the cassette 22 is between x3 and x4.

  FIG. 4B is a time chart of the detection signal R <b> 1 of the sensor 61. As shown in the drawing, the signal R2 is not output at the time t1 to t2 when the position of the cassette 22 is between x1 and x2, and at the time t3 to t4 between x3 and x4.

  Therefore, if the measurement timing is generated and the output signal of the optical sensor is detected at t5 which is a time at one point between times t1 and t2 and t6 which is a time at one point between t3 and t4, each slot is detected. The presence or absence of the wafer 24 accommodated in 52 can be detected.

  Here, since each slot 52 is arrange | positioned at equal intervals and the cassette 22 is moving at equal speed, each slot 52 passes the optical-axis height of the optical sensors 61 and 62 by a fixed time interval. . Therefore, the calculator 80 can generate the measurement timing by measuring a certain time interval by the timer 81.

  As described above, in the conventional wafer detection method, while the cassette 22 is controlled at a constant speed, a measurement timing is generated once for each slot 52 by the timer, and the wafer 24 in each slot 52 is detected at this measurement timing. This is done by reading the output of an optical sensor that detects the presence or absence.

JP-A-8-250558

  The conventional wafer detection method in the cassette is based on the assumption that the cassette moves at a constant speed and that the optical sensor measures at equal time intervals. The positioning of the cassette is performed indirectly, and is not directly synchronized with the actual position of the cassette.

  Therefore, if other processing with high priority occurs in the calculator 80 that performs this software processing, a reading delay may occur. For this reason, as shown in FIGS. 4A and 4B, when the actual measurement timing is t5 'and t6', there is a problem that the wafer may be missed.

  Also, as shown in FIGS. 4C and 4D, when fluctuations occur in the constant speed control of the cassette 22, the wafer is positioned on the optical sensor optical axis at the original measurement timings t5 and t6. (I.e., the cassette position is not between x1 and x2 and between x3 and x4), and there is a problem that the wafer may be missed.

Further, in order to prevent such an error, there has been a problem that the moving speed of the cassette has to be lowered to have a margin, and the detection time is longer than necessary.
Furthermore, software that performs measurement processing using a timer usually uses the same processing device as the control unit of the prober device, but in order to increase the priority of measurement processing, the processing capability of this processing device is increased. There was a problem of occupying many.

  Furthermore, the wafer may be deformed in the semiconductor manufacturing process. In such a case, even if it is detected by the above-described optical sensor that the wafer is housed in the slot, it may not be pushed out by the load pusher 26. This is shown in FIG.

The wafer 24 accommodated in the slot 52 in the cassette 22 is deformed by the semiconductor manufacturing process of the previous process and the periphery is warped as shown in the figure. For this reason, when the load pusher 26 is to be brought into contact with the slot 52, the side surface portion of the side pusher 26 is greatly lowered, and the load pusher 26 does not have a contact area required for pushing out. I can't.
However, since the optical sensor detects the side surface of the wafer 24 only at one height of the slot 52 having a certain vertical width, the deformation of the wafer 24 as described above cannot be detected.

  In view of the above problems, an object of the present invention is to provide a method and a prober apparatus that can more reliably and rapidly detect a wafer in a cassette.

  In order to achieve the above object, the prober apparatus of the present invention keeps the position for detecting the wafer in the cassette at a constant interval while relatively moving the cassette position and the sensor for detecting the wafer.

  That is, according to the first embodiment of the present invention, a prober device for accommodating a cassette for storing wafers includes a sensor for detecting presence / absence of a wafer in the cassette, and a driving means for relatively moving the cassette and the sensor in one direction. A pulse signal output unit that outputs a pulse signal synchronized with a moving distance by the driving means, a read timing generation unit that outputs a read timing signal when the pulse signal from the pulse signal output unit is input a predetermined number of times, and a read timing generation A reading unit that reads the output of the sensor when a reading timing signal is input from the unit, and a wafer presence / absence determination unit that determines the presence / absence of a wafer in the cassette based on the detection result of the sensor.

The wafer presence / absence determining unit may determine the presence / absence of a wafer in the cassette based on the number of times the sensor detects the wafer. The driving means may move either the sensor or the cassette to move the sensor and the cassette relative to each other.
Further, the prober device may include a wafer position measuring unit that measures the position of the wafer based on the detection result of the sensor. A cassette position correcting unit that corrects the cassette position using the measurement result of the wafer position measuring unit may be provided.

  According to the second embodiment of the present invention, the wafer detection method in the cassette in the prober apparatus for storing the cassette for storing the wafer moves the detection position of the wafer in the cassette in one direction, and the movement distance of the detection position When the pulse signal is generated a predetermined number of times, the presence / absence of the wafer at the detection position is detected and the presence / absence of the wafer in the cassette is determined.

At this time, the presence / absence of a wafer in the cassette may be determined based on the number of wafer detections.
Further, the position of the wafer may be measured based on the detection result of the object, and the cassette position may be corrected using the measurement result of the wafer position.

  According to the prober apparatus and the wafer detection method of the present invention, the wafer is detected when the cassette and the sensor are actually relatively moved at regular intervals regardless of the delay of the reading time and the fluctuation of the relative movement speed between the cassette and the sensor. Therefore, there is no possibility of causing a wafer reading error.

  In particular, it is possible to improve the wafer detection accuracy by performing detection at a plurality of detection points for one slot and determining whether the wafer exists based on the number of detections. At this time, the plurality of detection points are at regular intervals regardless of the reading delay and the relative movement speed fluctuation, thereby further reducing the possibility of a wafer reading error.

  Further, in the software processing using the timer included in the control unit, it is not necessary to provide a margin for the reading speed necessary for the above-described reading delay, and the reading speed can be increased.

  Furthermore, since the timer of the control unit of the prober device is not used, the above-described optical sensor output reading function can be performed by hardware provided separately from the control unit of the prober device. Reduce the processing time occupation.

  In addition, according to the wafer position measuring method of the present invention, the wafer position is measured by detecting the wafer when the sensor and the cassette are actually relatively moved at regular intervals regardless of the reading delay and the relative movement speed fluctuation. Thus, the wafer position in the cassette can be accurately read. As a result, it is possible to determine whether or not the stored wafer has a deformation that occurs in the semiconductor manufacturing process as described above.

  Furthermore, according to the cassette position correcting method according to the present invention, since the cassette position is corrected based on the actual wafer position measurement result in the cassette, the wafer deformed in the semiconductor manufacturing process as described above is contained. At this time, it is possible to correct the cassette position in accordance with the wafer position and reliably perform the extrusion by the load pusher and the removal by the arm mechanism.

Hereinafter, preferred embodiments of a prober apparatus and a height measuring method according to the present invention will be described with reference to the accompanying drawings. FIG. 6 is a basic configuration diagram of a cassette stock according to the present invention.
The cassette stock 12 according to the present invention shown in FIG. 6 is mounted on a prober device similar to the prober device shown in FIG. 1, and among the components constituting the prober device of the present invention, the cassette stock 12 other than the cassette stock 12 of FIG. The constituent elements are the same as those of the prober apparatus shown in FIG. Therefore, description of these elements is omitted.

  Further, the cassette stock 12 according to the present invention shown in FIG. 6 has a configuration similar to that of the cassette stock shown in FIG. 2, and the same components are denoted by the same reference numerals and description thereof is omitted.

  The cassette stock 12 includes a housing 50 in which a cassette 22 that can store a plurality of wafers 24 is placed, an elevating means 53 that elevates and moves the cassette 22 and the plate 20 on which the cassette 22 is placed, and a motor 54 that drives the elevating means 53.

  As the motor 54, a stepping motor (pulse motor) is normally used and controlled by the motor control unit 55. The motor control unit 55 generates a driving pulse signal for controlling the motor 54, and the motor driving circuit 56 outputs an excitation current for exciting each coil of the stepping motor based on the driving pulse signal.

  The computer 80, which is a control unit that manages the prober device 10, is configured by a computer or the like, and the motor control unit 55 is connected to the data bus of the computer 80 and can exchange data with the computer 80. The motor controller 55 generates the driving pulse signal based on the cassette height control data from the calculator 80.

  As with the cassette stock shown in FIG. 2, the front and back surfaces of the cassette 22 are open, and the wafer 24 is taken in and out by a load pusher 26, an unload pusher 38, or other arm mechanism (not shown). I can do it. A plurality of slots (shelves) 52 for mounting and storing the wafers 24 are provided inside the side walls.

  Further, the cassette stock 12 is provided with optical sensors 61 (transmission side) and 62 (reception side) for detecting whether or not the wafer 24 is stored in each slot 52. Here, since the optical sensors 61 and 62 are fixed to the cassette stock 12, the optical sensors 61 and 62 and the cassette 22 move relative to each other when the cassette 22 is moved up and down by the motor 54.

  In the optical sensors 61 and 62, when the wafer 24 is at the same height as the optical axis, the wafer 24 is interposed between the transmission side sensor 61 and the reception side 62, and the light transmitted from the transmission side sensor 61 is received. The presence of the wafer 24 is detected by detecting that it has not reached the side sensor 62.

  The optical sensors 61 and 62 are provided so that the optical axis thereof is substantially horizontal along the side surface of the cassette 22. Similarly to the cassette stock of FIG. 2 described above, the optical axes of the optical sensors 61 and 62 are provided at the same height as the contact portions of the load pusher 26 and the unload pusher 38 with the wafer 24.

  A detection signal that is an output of the reception side optical sensor 62 is converted into a digital signal by an analog-digital converter (ADC) 64 and input to the reading unit 71. The reading unit 71 is connected to the data bus of the calculator 80 and can exchange data with the calculator 80.

  As described above, the motor 54 is driven by the driving pulse signal output from the motor control unit 55. The pulse of the driving pulse signal is output according to the rotation angle or the rotation speed for driving the motor 54. Therefore, the motor control unit 55 forms a pulse signal output unit that outputs a pulse signal in accordance with the rotation angle or the number of rotations of the motor in the prober apparatus according to the present invention.

  When a DC motor is used as the motor 54, an encoder 57 and a speed generator provided on the motor rotation shaft are provided as the pulse signal output unit, and the output signal is converted into a digital signal by the analog-digital converter 58. It is good also as using it. Of course, even when a stepping motor is used, the encoder 57 and the speed generator may be provided.

  Alternatively, the pulse signal output unit 32 may actually measure the position of the cassette 22 by an ultrasonic sensor or other means and output a pulse signal according to the amount of movement.

The output pulse signal S1 of the motor control unit 55 or the output pulse signal S1 ′ of the encoder (hereinafter simply referred to as “output signal S1 etc.”) has one pulse for each predetermined rotation angle or number of rotations of the motor 54. Is output.
Further, since the rotation angle or number of rotations of the motor 54 and the moving distance of the cassette 22 are in a proportional relationship, the number of pulses of the output signal S1 and the like and the moving distance of the cassette 22 are in a proportional relationship.

  The output signal S1 and the like are sent to the reading timing generator 72. The read timing generator 72 counts the number of pulses such as the output signal S1. When a pulse corresponding to a predetermined number of counts determined by a desired wafer 24 detection interval and the amount of movement of the cassette 22 with respect to one pulse of the output signal S1 or the like is input, a reading timing signal S2 is generated, and the reading unit To 71.

When the reading unit 36 receives the reading timing signal S <b> 2, the reading unit 36 reads the output signal of the receiving side optical sensor 62 via the analog-digital converter 64.
7A to 7D are time charts of the displacement and speed of the cassette 22 in the above-described series of operations, the corresponding output signal S1 and the like, and the read timing signal S2 by the read timing generator 71, respectively. ).

  As shown in the figure, the cassette 22 moves from time x1 to time t4 to x1 to x4 arranged at equal intervals in the cassette movement direction (vertical direction in the example in the figure). At this time, the speed of the cassette 22 is relatively fast v1 between x1 and x2, becomes relatively slow v2 between x2 and x3, and becomes v1 again between x3 and x4.

  As shown in FIGS. 7A to 7C, the output signal S1 and the like generate the same number of pulse signals in each of the sections x1 to x2, x2 to x3, and x3 to x4 regardless of changes in the moving speed. . Therefore, as shown in FIGS. 7A and 7D, it is assumed that the first reading timing signal has been generated, and the predetermined number of counts of the reading timing generating unit 72 is the distance of each section such as x1 to x2. If it is determined correspondingly, the read timing signal S1 is generated at each of the points x1, x2, x3, and x4 arranged at equal intervals. As described above, the detection points of the output of the optical sensor 62 are kept at regular intervals regardless of fluctuations in the moving speed of the cassette 22.

  The reading unit 71 sequentially stores the output signal (the presence / absence data of the wafer 24) of the optical sensor 62 read at the equally-spaced cassette 22 positions in this manner in a built-in buffer (not shown). When a predetermined number of data is accumulated or when a read request signal from the calculator 80 is input, a plurality of measured values accumulated in the buffer so far are transmitted to the calculator 80.

Thereafter, the presence / absence data of the wafer 24 received by the calculator 80 is processed by the wafer presence / absence determination unit 83.
The wafer presence / absence determination unit 83 determines whether a wafer existing in each slot 52 is detected by the optical sensors 61 and 62 based on the initial position of the cassette 22 and the position of each slot 52 set in advance by an instruction from the operator. The range of the position of the cassette 22 when the optical axis is blocked is obtained.

  Thereafter, the wafer presence / absence determination unit 83 extracts the presence / absence data of the wafer 24 corresponding to the obtained position range of the cassette 22. The number of data depends on the frequency of occurrence of the read timing signal, but for example, about 10 pieces of data are extracted per wafer 24.

  The wafer presence / absence determination unit 83 determines that a wafer is present in the slot 52 when data larger than the predetermined threshold number in the extracted data string indicates “wafer exists”, and if not, a wafer exists. Judge not to.

  The wafer presence / absence determining unit 83 is preferably realized by software processing by the calculator 80, but may be processed by separate hardware.

  As described above, according to the prober apparatus and the wafer detection method according to the present invention, wafer detection is performed when the cassette is actually moved at a constant interval regardless of the delay of the reading time and the fluctuation of the moving speed of the cassette. Therefore, there is no possibility of causing a wafer reading error.

  Further, the wafer side cross section is detected at a plurality of points having a predetermined constant interval in the moving direction of the cassette 22 per one wafer 24. Therefore, if the wafers have the same thickness, even if they are deformed as described above, the wafer side cross section is always detected more than a certain number, so that the wafer detection accuracy can be improved.

  Further, in the prober apparatus according to the present invention, the software executed by the calculator 16 does not perform software processing using a conventional timer and the output reading of the optical sensors 61 and 62, so that the occupied time is released.

  Further, as described above, each data string of the presence / absence data of the wafer 24 received by the calculator 80 is detected at a cassette position at a fixed interval. Therefore, if the position of the detection start point is known, the detection start point Based on the cassette position, the number of data up to the detected data of the target wafer (that is, the number of pulses at the reading timing), and the amount of movement of the cassette per reading timing, the upper and lower surfaces of the wafer 24 accommodated in each slot 52 The position can be measured.

  Thereby, it is possible to determine whether or not the wafer 24 accommodated in each slot 52 has the deformation generated in the semiconductor manufacturing process as described above and cannot be pushed out by the load pusher 26.

  This process is performed by the wafer position measurement unit 84. The wafer position measurement unit 84 is preferably realized by software processing by the calculator 80, but may be processed by separate hardware.

  Further, the position correction of the cassette 22 can be performed based on the position measurement value of each wafer 24 in each slot 52 measured by the wafer position measurement unit 84. The cassette 22 can be corrected in the following two types.

  In the first position correction, when the wafer 24 deformed in the semiconductor manufacturing process is placed in a certain slot 52, the load pusher 26 is brought into contact with the wafer in accordance with the position of the wafer 24 measured by the wafer position measuring unit 84. Position correction is performed to correct the cassette position so that the member can push the wafer 24 while being in contact with the upper surface and the lower surface of the wafer 24 (preferably in the middle). As a result, even when the wafer 24 deformed in the semiconductor manufacturing process is contained, the extrusion by the load pusher 26 and the removal by another arm mechanism can be surely performed.

The second position correction is correction of the reference position of the cassette 22. As described above, the alignment of the detection point of the detection data string and the actual position of the cassette 22 includes the initial position of the cassette 22, the number of data up to the detection point (that is, the number of pulses at the reading timing), and one reading timing. This is based on the amount of cassette movement per unit.
For this reason, if there is an error between the expected position of the cassette 22 and the actual position at the initial position of the cassette 22 serving as the alignment reference, the following inconvenience occurs in the wafer presence / absence determination unit 83 described above.

  As described above, the wafer presence / absence determination unit 83 extracts the presence / absence data of the wafer 24 corresponding to the position range of the cassette 22 when the wafer existing in each slot 52 blocks the optical axis of the optical sensors 61 and 62. If there is an error in the initial position of the cassette 22 serving as a reference for alignment, data detected in a predetermined range cannot be extracted, and an error occurs in the determination result.

In the second position correction, a reference wafer (for example, a wafer that has not undergone a semiconductor manufacturing process and has little deformation) is accommodated in a predetermined slot 52 of the cassette 22, and this position is measured by the wafer position measurement unit 84.
Since the slot position is known, the difference between the measurement position of the reference wafer and the planned measurement position is obtained and added to the reference position (initial position) of the cassette 22, thereby correcting the reference position of the cassette 22. It can be carried out.

  Further, the amount of movement of the slot 22 with respect to one pulse signal for driving the motor 54 may fluctuate due to wear of a member of the motor 54 or a member transmitting power of the motor 54. Then, since the generation frequency of the read timing signal with respect to the movement amount of the slot 22 varies, the detection interval between each data of the presence / absence data of the wafer 24 received by the calculator 80 varies.

In order to correct the variation in the detection interval between the data, a reference wafer is accommodated in a predetermined plurality of (for example, two) slots 52 of the cassette 22, and the position is measured by the wafer position measuring unit 84.
The actual movement amount of the cassette 22 from the measurement position of one reference wafer to the measurement position of the other reference wafer, the number of pulses of the driving pulse signal between them, the number of read timings, or the presence / absence data of the wafer 24 Find the ratio to the number. Then, the interval between detection positions corresponding to two consecutive presence / absence data of the wafer 24 is calculated and stored, and this is used for subsequent measurements.

  The cassette position correcting unit 85 is preferably realized by software processing by the calculator 80, but may be processed by separate hardware.

Note that the configuration of the prober apparatus according to the present invention shown in FIGS. 1 and 6 is shown only for the purpose of illustration, and does not limit the scope of the present invention.
Therefore, various configurations can be used for the prober according to the present invention, in particular, the pulse signal output method, the read timing generation unit, and the read unit used in the prober, and these are also within the scope of the present invention. included.

It is an external appearance perspective view of the conventional prober apparatus. It is a block diagram of the conventional cassette stock. It is A-A 'sectional drawing of the cassette stock of FIG. It is explanatory drawing of the conventional wafer detection method. It is a figure explaining the cassette which accommodated the deformed wafer. It is a block diagram of the cassette stock used for the prober apparatus which concerns on this invention. It is a time chart of each signal with respect to movement of a cassette.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Prober 12 ... Cassette stock 22 ... Cassette 24 ... Wafer 26 ... Load pusher 52 ... Slot 54 ... Motor 55 ... Motor control part 61, 62 ... Optical sensor 71 ... Reading part 72 ... Reading timing generation part 80 ... Calculator 83 ... Wafer presence / absence determining unit 84 ... wafer position measuring unit 85 ... cassette position correcting unit

Claims (12)

In a prober device that accommodates a cassette for storing wafers,
A sensor for detecting the presence or absence of the wafer in the cassette;
Drive means for relatively moving the cassette and the sensor in one direction;
A pulse signal output unit for outputting a pulse signal synchronized with a moving distance by the driving means;
A read timing generator that outputs a read timing signal when the pulse signal from the pulse signal output unit is input a predetermined number of times;
A reading unit that reads an output of the sensor when a reading timing signal is input from the reading timing generation unit;
A prober apparatus comprising: a wafer presence / absence determination unit that determines presence / absence of the wafer in the cassette based on a detection result of the sensor.   The prober apparatus according to claim 1, wherein the wafer presence / absence determination unit determines the presence / absence of the wafer in the cassette based on the number of times the sensor detects the wafer.   The prober apparatus according to claim 1, wherein the sensor detects presence or absence of the wafer at each position in the relative movement direction in the cassette along with the relative movement.   The prober apparatus according to claim 1, wherein the driving unit moves the cassette. In a prober device that accommodates a cassette for storing wafers,
A sensor for detecting the presence or absence of the wafer in the cassette;
Drive means for relatively moving the cassette and the sensor in one direction;
A pulse signal output unit for outputting a pulse signal synchronized with a moving distance by the driving means;
A read timing generator that outputs a read timing signal when the pulse signal from the pulse signal output unit is input a predetermined number of times;
A reading unit that reads an output of the sensor when a reading timing signal is input from the reading timing generation unit;
A prober apparatus comprising: a wafer position measuring unit that measures the position of the wafer based on a detection result of the sensor.   6. The prober apparatus according to claim 5, wherein the sensor detects presence / absence of the wafer at each position in the relative movement direction in the cassette along with the relative movement.   The prober apparatus according to claim 5 or 6, wherein the driving means moves the cassette.   8. The prober apparatus according to claim 5, further comprising a cassette position correcting unit that corrects the position of the cassette based on a measurement result obtained by the wafer position measuring unit. In a prober apparatus for accommodating a cassette for storing wafers, in the wafer detection method in the cassette,
Moving the detection position of the wafer in the cassette in one direction;
Generating a pulse signal synchronized with the moving distance of the detection position;
When the pulse signal is generated a predetermined number of times, the presence or absence of the wafer at the detection position is detected,
A wafer detection method comprising determining whether or not the wafer is in the cassette.   The wafer detection method according to claim 9, wherein the presence / absence of the wafer in the cassette is determined based on the number of detections of the presence of the wafer. A wafer position measuring method for measuring a position of the wafer in a prober apparatus that accommodates a cassette for storing a wafer,
Moving the detection position of the wafer in the cassette in one direction;
Generating a pulse signal synchronized with the moving distance of the detection position;
When the pulse signal is generated a predetermined number of times, the presence or absence of the wafer at the detection position is detected,
A wafer position measuring method, comprising measuring the position of the wafer.   12. The cassette position correcting method according to claim 11, wherein the position of the cassette is corrected based on the measurement position of the wafer by the wafer position measuring method according to claim 11.

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