Sensor station and method for measuring wafers

Abstract

The present invention relates to a sensor station for measuring wafers, comprising at least one sensor device for measuring at least one characteristic of the wafer and at least one section of a conveying device. The conveying device defines a conveying direction, and the moving wafer determines a space that remains unobstructed for the moving wafer along the conveying device. The sensor device generates at least one measuring point on the lower side and / or the upper side of the unobstructed space and the sensor device is carried by a main support. The sensor station has a calibration device, which comprises at least one arm and a drive system for moving the arm. A reference piece is arranged on the arm, and the arm is movably supported so that the reference piece can occupy a static position and a measuring position. The reference piece is arranged outside the range of action of the sensor device in the static position, and is arranged within the range of action of the sensor device in the measuring position.

Description

Technical Field

[0001] The present invention relates to a sensor station and a method for measuring wafers, comprising at least one sensor device for measuring at least one characteristic of a wafer and at least one section of a conveying device, wherein the conveying device defines a conveying direction, and a moving wafer determines a space that remains unobstructed along the conveying device for the moving wafer, and the sensor device generates at least one measuring point on the lower side and / or upper side of the unobstructed space. Background Art

[0002] Such a sensor station is known from WO 2015 / 199930 A1. The known sensor station comprises three sensor devices, each of which contains a near-infrared superluminescent diode for three thickness measurements on a wafer. The wafer moves along the conveying direction in the form of a continuous belt with two single belts and thus defines a space that remains unobstructed. The sensor devices are arranged, for example, above the space to be kept unobstructed and each produces a measuring point on the upper side of the space to be kept unobstructed.

[0003] Another such sensor station is known from KR 10 2016 0021979 A. A conveyor in the form of a continuous belt with two single belts conveys the wafers through the sensor station, and the moving wafers determine a space to be kept unobstructed. The sensor station comprises three sensor devices, each of which has a pair of sensors. The sensors are designed as capacitive thickness sensors. The first sensor of each sensor device is arranged above the space to be kept unobstructed, and the second sensor is arranged below the space to be kept unobstructed. The first and second sensors of the sensor devices respectively generate three measuring points on the upper side and the lower side of the space to be kept unobstructed.

[0004] It has been found that the thickness measurements of such sensor stations generally do not correspond to the proposed measurement accuracy of the sensor, so that the measurement accuracy of the sensor station is relatively poor compared to the measurement accuracy of the sensor type used. Summary of the invention

[0005] The object of the invention is therefore to further improve the measuring accuracy of the sensor station, more precisely preferably without having to use more expensive or slower sensors, for example. The object of the invention is preferably to improve the measuring accuracy of the sensor station such that a simple standard deviation of at most 0.3 μm is achieved between two calibration processes or preferably at a throughput of at least 6000 wafers per hour.

[0006] In order to achieve the aforementioned objectives, the present invention teaches a sensor station for measuring wafers, which includes at least one sensor device for measuring at least one characteristic of the wafer, especially the thickness, and at least one section of a conveying device, wherein the conveying device defines a conveying direction, and the moving wafer determines a space that remains unobstructed along the conveying device for the moving wafer, and the sensor device generates at least one measuring point on the lower side and / or upper side of the space to be kept unobstructed, and the sensor device is carried by a main support.

[0007] The sensor station has a calibration device, which includes at least one arm and a drive system for moving the arm, on which a reference part is arranged, preferably a reference part with known properties, in particular a thickness, and the arm is movably supported so that the reference part can occupy a rest position and a measuring position, wherein the reference part is arranged outside the range of action of the sensor device in the rest position and within the range of action of the sensor device in the measuring position.

[0008] The invention is based on the recognition that sensors undergo almost unpredictable drifts during operation of a sensor station, which can partially falsify measurement results. By means of a calibration device, calibration measurements can be carried out at regular intervals on a reference piece in the sensor station. The values ​​measured on the wafer can thus be corrected accordingly again and again, so that the sensor drift no longer has a significant influence on the measurement. The object mentioned at the beginning is thus achieved.

[0009] The term "arranged within the range of action of the sensor device" means, in particular, that the reference element can be measured by the sensor device without having to dismantle or reconstruct the sensor device, or further preferably without having to readjust it, or more preferably without having to mechanically manipulate / switch it. The term "at least one property of the wafer" is understood to mean, for example, the cut profile of the surface of the wafer and / or the deflection of the wafer and / or particularly preferably the thickness of the wafer.

[0010] Preferably, the reference piece is arranged on one end of the arm. Preferably, the known thickness of the reference piece is less than 1.0 mm, further preferably less than 0.5 mm, and more preferably less than 0.3 mm. Suitably, the known thickness of the reference piece is greater than 0.1 mm, further preferably greater than 0.12 mm, and particularly preferably greater than 0.14 or 0.16 mm. Ideally, the known thickness of the reference piece is 0.2 mm. The reference piece can be made of metal, preferably steel, or include metal or steel, for example. Typically, in the case where the wafer thickness is typically 0.15 mm to 0.18 mm, the wafer has a square or quasi-square (square with oblique angles) size with an edge length of 125 mm or 156 mm or 163 mm. The wafer defines a space to be kept unobstructed, the space corresponding to, for example, a strip of sensor station length with a thickness of 0.18 mm in the case of a width of 156 mm.

[0011] According to a particularly preferred embodiment, the reference part is at least partially located in the space to be kept unobstructed in the measuring position. It is suitable that the reference part is completely arranged outside the space to be kept unobstructed in the static position. The term "measuring position at least partially located in the space to be kept unobstructed" means in particular that during the operation of the sensor station, the reference part or other objects partially located in the space to be kept unobstructed will collide with the transported wafer. If the reference part is completely outside the area to be kept unobstructed, the collision of the wafer with the reference part is excluded. It is suitable that the static position of the reference part is located downstream of the conveying flow of the measuring point in the top view. It is preferred that the reference part is arranged above the space to be kept unobstructed in the static position, which is particularly advantageous in the case of a solid design of the main support, for example, when it is composed of mineral material / rock / granite. According to another preferred design, the main support includes aluminum, and the static position of the reference part can be located above or below the space to be kept unobstructed.

[0012] In particular, within the scope of the invention, the calibration device comprises at least one linear guide, which preferably determines the linear movement section of the arm between the measuring position and the rest position. This has the advantage that due to the narrow proportions in the area of ​​the sensor device, the reference piece can reach the measuring point more easily than, for example, with a rotational movement. Preferably, the linear movement section is a single linear movement section or a linear section as a whole between the rest position and the measuring position. Advantageously, the movement direction of the linear movement section is oriented parallel to the conveying direction in a top view. Advantageously, the linear guide comprises a linear rail and more advantageously comprises a carriage corresponding to the linear rail. Preferably, the linear rail is fixed to the arm or to the upper side of the arm. Preferably, the linear guide comprises a static support element. Preferably, a carriage is fixed to the lower side of the static support element. Preferably, the arm can be moved relative to the support element between the measuring position and the rest position of the reference piece.

[0013] Particularly preferably, the calibration device comprises a stop for defining the measuring position. Advantageously, a section of the static support element or the linear guide forms the stop bearing. Preferably, the arm comprises a stop element, which is further preferably designed as a stop screw. Preferably, the stop bearing and the stop element are in contact with each other in the measuring position of the reference part and expediently do not contact each other in the static position of the reference part. The stop element is advantageously arranged above the linear rail. Expediently, the stop face of the stop element points in the direction of the sensor device.

[0014] In particular, within the scope of the present invention, the calibration device has at least one spring. The spring can be configured as a helical spring, for example. Preferably, the spring is connected between the drive source or the electric motor and the arm, so that the arm is elastically supported relative to the drive system or relative to the drive source. Preferably, the spring or the drive system or the transmission system is configured so that the spring generates an extrusion pressure of the stop element on the stop support in the measuring position of the reference part. Preferably, the spring is stretched in the measuring position of the reference part so that the extrusion pressure of the stop element acts on the stop support. According to a preferred embodiment, the drive system includes a rest position sensor for detecting the arrival of the rest position. The first end of the spring is suitably connected to the transmission system, for example, to a lever part or a crossbeam. The second end of the spring is preferably fixed to the arm. Preferably, the at least one arm is equipped with two springs, and further preferably, the arm is arranged between the two springs in a top view.

[0015] Particularly preferably, the arm includes a carrying member for transferring the reference member into the static position. The carrying member can be configured as a roller or a pulley, for example. It is suitable that the axis of the roller or the carrying member is oriented perpendicular to the conveying direction in a top view. Preferably, the carrying member is arranged at the rear third of the arm. Advantageously, the carrying member protrudes on both sides of the arm so that the lever part can contact the lower, forked end on both sides of the carrying member in a preferred configuration. Preferably, the carrying member is arranged between the first end and the second end of the spring in a top view. The spring is preferably configured so that the spring applies a traction force to the arm so that the carrying member of the arm - especially in the static position and / or in sections during the transfer from the measuring position to the static position or vice versa - presses against the drive train or squeezes in the direction of the drive train.

[0016] In the context of the present invention, the sensor device has two sensors. Preferably, the first sensor of the sensor device is arranged above the space to be kept unobstructed, and further preferably, the second sensor is located below the space to be kept unobstructed. It is expedient that the first and second sensors are respectively provided with measuring points, and preferably the two measuring points overlap each other in a top view. Advantageously, the sensor device or the first and / or second sensor of the sensor device comprises a light source and a light detector. It is feasible that the light source emits light with a wavelength higher than 550nm. Preferably, the light source emits visible light. It is particularly preferred that the light source is a diode and preferably a laser diode. Advantageously, the light detector has a diode array with a large number of pixels. It is particularly advantageous that the first and / or second sensor or the sensor device is a triangulation sensor or comprises a triangulation sensor. Advantageously, the first and second sensors are structurally identical.

[0017] According to a preferred embodiment, the sensor station has a large number of sensor devices. It is suitable that the sensor devices are arranged side by side in a top view, and the measuring points assigned to the sensor devices form a connecting line, which is preferably oriented transversely to - in particular perpendicular to - the conveying direction. Preferably, the sensor station includes at least three sensor devices to generate three measuring lines on the upper side and / or lower side of the wafer. Preferably, the first measuring line extends in the middle third of the wafer, and the second and third measuring lines extend in the left or right third of the wafer. It is feasible that the sensor station includes four or more sensor devices to generate four or more measuring lines. For example, the sensor station has five sensor devices. It is suitable that for each wafer, a measuring track for reflecting the cut profile is assigned to each sensor, or a measuring line for reflecting the wafer thickness is assigned to each sensor device. It is feasible that the measuring track on the upper side of the wafer can be converted into a measuring line by subtracting the measuring track on the lower side of the wafer. Preferably, a large number of measuring tracks are generated on the upper side and lower side of the wafer, respectively. Each measurement line expediently comprises at least 2000 measured values, preferably at least 5000 measured values ​​and particularly preferably at least 10000 measured values ​​per wafer.

[0018] According to a preferred embodiment, the main support preferably mainly comprises metal and in particular aluminum. In the case of a specific embodiment, the main support comprises a mineral material. The mineral material preferably comprises rock and particularly preferably comprises granite. It is suitable that the main support has a lower support group, which is arranged below the space to be kept unobstructed. It is suitable that the main support comprises an upper support group, which is arranged above the space to be kept unobstructed. The main support preferably comprises one or more recesses between the upper and lower support groups to guide the conveyor or the wafer through the main support. According to a preferred embodiment, the lower support group comprises at least one main block. The upper support group preferably comprises a side wall, which surrounds the at least one sensor device at least in a section and preferably completely around in a top view. Preferably, the upper support group has at least one intermediate wall, so that the upper support group forms at least two chambers for at least two sensor devices. It is suitable that at least one sensor is fixed on the inner side of the side wall or the intermediate wall. The wall thickness of the side wall or the middle wall is preferably at least 15 mm, further preferably at least 20 mm, and particularly preferably at least 25 mm. Ideally, the wall thickness of the side wall or the middle wall is at least 30 mm. Suitably, the wall thickness of the side wall or the middle wall is at most 100 mm, preferably at most 80 mm, and particularly preferably at most 70 mm. Ideally, the wall thickness of the side wall or the middle wall is at most 60 mm.

[0019] According to a very advantageous embodiment, the sensor station has a chassis, preferably at least one buffer is arranged between the chassis and the main support. The buffer can be pneumatic or hydraulic, for example. The buffer particularly preferably comprises an elastic element, and in particular a rubber element. Advantageously, at least three buffers are arranged on the chassis. According to a preferred embodiment, the main support is placed on at least one buffer. It is particularly preferred that the sensor device is fixed and in particular rigidly fixed to the main support. It is preferred that the calibration device is fixed and in particular rigidly fixed to the main support. According to a particularly preferred embodiment, the front end element and / or the rear end element of the conveying device are arranged on the chassis, and it is further preferred that at least one buffer is not connected between the front end element and / or the rear end element on the one hand and the chassis on the other hand, so that preferably the front end element and / or the rear end element is not damped or supported by the main support.

[0020] Particularly preferably, the calibration device comprises a calculation unit, which is configured to use the measured values ​​determined by the sensor device on the reference part for calibrating the measured values ​​determined by the sensor device on the wafer. Preferably, the measured values ​​determined on the reference part or on the wafer reflect the thickness of the reference part or the wafer. Preferably, the calibration device comprises a control unit for the arm. The control unit is preferably configured to move the arm from a stationary position to a measuring position or vice versa. It is suitable that the wafer to be measured is taken out of the first collecting container individually from a withdrawal station located upstream of the sensor station. The divided wafers then preferably pass through the sensor station and are preferably conveyed to the sorting station thereafter. Advantageously, when the first collecting container is empty, the material flow of the wafer is stopped in the sensor station. In practice, the material flow of the wafer is started in the sensor station as soon as the first collecting container is replaced by the second collecting container. Preferably, the time points of stopping and starting the material flow of the wafer in the sensor station define an interruption time for replacing the collecting container. For example, the material flow of the wafer can be stopped in the manner of stopping the conveying device. Preferably, the material flow of the wafers is stopped in such a way that no further wafers are conveyed to the conveying device, preferably the conveying device is in operation at least temporarily and preferably continuously during the interruption time. Particularly preferably, the last wafer of the first collecting container and the first wafer of the second collecting container define the interruption time. The term "in the sensor station" preferably means "in the range of action of the sensor device" and particularly preferably "at the at least one measuring point". Very particularly preferably, the calculation unit and / or the control unit is designed so that the sensor device measures during the interruption time of the reference piece. Suitably, the measured values ​​determined on the reference piece are used to calibrate the measured values ​​determined on the wafer. The interruption time can be, for example, up to 10 seconds or 7 seconds or 5 seconds. The interruption time advantageously amounts to at least 0.5 seconds or 1.0 seconds or 1.5 seconds or 2 seconds.

[0021] Particularly preferably, the conveying device comprises at least one section of a continuous conveyor, more preferably, the continuous conveyor has at least two continuous single belts that are parallel to each other at least in part of the section. Advantageously, the sensor station is equipped with a complete continuous conveyor. The term "complete continuous conveyor" means in particular that the circulation of the continuous conveyor defines the extension of the continuous conveyor in the conveying direction, and preferably, the continuous conveyor cannot convey the wafer from the previous station to the sensor station or from the sensor station to the subsequent station without the help of other conveying devices. Suitably, the continuous belt or the single belt comprises an elastomer, which is preferably a component of the layer that contacts the wafer. Each of the two single belts is preferably at least 5 mm, further preferably at least 10 mm, particularly preferably at least 12 mm, and ideally at least 14 mm wide. Suitably, each of the two single belts is at most 40 mm, preferably at most 30 mm, particularly preferably at most 25 mm, and ideally at most 18 mm wide. The spacing between two single belts is suitably at least 20 mm, preferably at least 30 mm, particularly preferably at least 35 mm, and ideally at least 40 mm in a top view. Advantageously, the spacing between two single belts is at most 110 mm, preferably at most 90 mm, particularly preferably at most 80 mm, and ideally at most 70 mm in a top view.

[0022] In the scope of the present invention, the conveying device is equipped with a motor, in particular an electric motor. Advantageously, the motor has a motor shaft extending from the motor housing on one side or - preferably - on both sides. Preferably, the motor shaft is rigidly connected to one or respectively one drive wheel at least on one side of the motor housing and more preferably on both sides. The drive wheel expediently has a width suitable for receiving a single belt. It is expedient that the conveying device comprises at least one, preferably two pressure rollers for each drive wheel. The one or two pressure rollers are preferably arranged so that the single belt surrounds the drive wheel at least 90°, preferably at least 120° and particularly preferably at least 150°. It is expedient that the conveying device has at least two, preferably at least three deflection rollers for the continuous belt or each continuous belt. It is expedient that at least one pressure roller and / or deflection roller is designed to accommodate a single belt.

[0023] Particularly preferably, the conveying device or continuous conveyor is guided through the main support. Advantageously, the conveying device comprises a front end element at the front end and a rear end element at the rear end. The front end element comprises at least one steering roller and more preferably two steering rollers for the continuous belt or each single belt. The rear end element preferably has a drive wheel or multiple drive wheels and preferably comprises at least one steering roller for the continuous belt or each single belt. More advantageously, at least one pressure roller and preferably two pressure rollers for the continuous belt or each single belt are provided on the rear end element. The front end element and / or the rear end element can, for example, have steel and preferably have a steel shell. Very preferably, the front end element and / or the rear end element are fixed to the chassis. It is suitable that the lower support group or the main block of the lower support group is arranged between the front end element and the rear end element, preferably leaving a gap between the front end element or the rear end element on the one hand and the lower support group or the main block on the other hand.

[0024] According to a particularly preferred embodiment, the conveyor or continuous conveyor or single belt is placed on the main support or the lower support group or main block at least in sections. Preferably, the first section of the conveyor / continuous belt / single belt is placed on the main support / lower support group / main block before at least one measuring point in the conveying direction. Advantageously, the second section of the conveyor / continuous belt / single belt is placed on the main support / lower support group / main block after at least one measuring point in the conveying direction. It is particularly preferred that the main support / lower support group / main block defines at least one section of the movement track of the conveyor / continuous conveyor / single belt, especially in the height direction, by the placement. It is thus achieved that the conveyor is decoupled from the drive of the conveyor in the area of ​​the measuring point, so that possible vibrations emitted by the drive of the conveyor in the area of ​​the measuring point are reduced. Another advantage is that in the area of ​​the measuring point, the wafer behaves synchronously with the sensor device with respect to possible height movements, so that possible relative movements between the wafer and the sensor device in the height direction are reduced.

[0025] According to a preferred embodiment, the drive system has a drive source and a transmission system. The drive source preferably includes at least one electric motor. The transmission system preferably has a connecting rod and at least one spindle. According to a first embodiment, the drive source is connected to the connecting rod. It is suitable that the connecting rod is connected to a lever component, which can be rotatably supported on the lever shaft. The lever component is preferably connected to at least one arm or to a plurality of arms relative to the connecting rod. Preferably, the lever component is connected to at least one arm with at least one / the spring connected in the middle.

[0026] According to a second embodiment, the drive source or at least one electric motor is connected to the main shaft of the transmission system. Advantageously, the drive source includes two electric motors, which are respectively connected to the main shaft. A crossbeam is preferably connected to one end of at least one main shaft, so that the drive source can press at least one arm from the rest position into the measuring position via the main shaft and the crossbeam. The crossbeam is oriented transversely and preferably perpendicularly to the conveying device in a top view. Advantageously, at least one spring is arranged between the crossbeam and the at least one arm, so that the at least one arm is elastically supported relative to the drive source or the crossbeam. Suitably, the crossbeam includes at least one opening, and the arm includes at least one carrier, which protrudes through the opening, so that the crossbeam can pull the at least one arm from the measuring position into the rest position.

[0027] In order to achieve the above-mentioned purpose, the present invention teaches a method for measuring a wafer, wherein a wafer to be measured is taken out of a first collecting container and conveyed to a sensor station, in particular to a sensor station according to the present invention, wherein the wafer is guided through the sensor station by means of a conveying device, the sensor station comprising at least one sensor device, the sensor device measuring at least one characteristic of the wafer, when, for example, the first collecting container is empty, the material flow of the wafer in the sensor station is stopped, if, for example, the first collecting container is replaced by a second collecting container, then the material flow of the wafer in the sensor station is started, the time points of stopping and starting the material flow of the wafer in the sensor station define an interruption time, during the interruption time the sensor device measures a reference part having a known characteristic value, and the measurement of the reference part is used to calibrate the measurement value of the wafer.

[0028] The reference element is advantageously located in the measuring position during its measurement. Advantageously, the characteristic of the wafer corresponds to the thickness of the wafer. Advantageously, after measuring the reference element, the reference element is transferred into the rest position. Advantageously, after the reference element has left the measuring position or has reached the rest position, the material flow of the wafer in the sensor station is restarted. Advantageously, when the second collecting container is empty, the material flow of the wafer in the sensor station is stopped again. Advantageously, the reference element is then transferred from the rest position into the measuring position again. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention is described in detail below with the aid of two embodiments.

[0030] Figure 1 A perspective side view showing a portion of a sensor station according to the present invention;

[0031] Figure 2 Show Figure 1 A top view of a main support member of a sensor station;

[0032] Figure 3 Show Figure 1A complete side view of the sensor station;

[0033] Figure 4 Show Figure 1 A complete rear view of the sensor station;

[0034] Figure 5 Show Figure 1 A side view of the arm of the sensor station in a measuring position;

[0035] Figure 6 Shows the transition from the measuring position to the rest position Figure 5 middle arm;

[0036] Figure 7 Shows the transition from the measuring position to the rest position Figure 5 the middle arm;

[0037] Figure 8 Shown in rest position Figure 5 middle arm;

[0038] Fig. 9 A perspective top view showing a sensor station according to the invention of a second embodiment; and

[0039] Fig.10 Show Fig. 9 A bottom-up stereoscopic view of the sensor station in Figure 1. DETAILED DESCRIPTION

[0040] exist Figure 1 and 2 The sensor station according to the present invention is shown in a perspective view and a top view, respectively. Figure 1 The side wall facing the observer and Figure 2 part of. Figure 1 and 2 The sensor station in the embodiment can be connected, for example, downstream of a wafer extraction station (not shown here), in which an extraction device takes out individual wafers 1 from a collection container and transfers them to a continuous conveyor. The continuous conveyor of this embodiment then transfers the wafers 1 to the sensor station. The sensor station can be arranged upstream of a wafer sorting station (also not shown here), so that the sensor station is an integral part of the wafer production line.

[0041] The wafer 1 from the preceding station is transported by the transport device 3 of the sensor station (see Figure 1 ) is removed, transported in the conveying direction F and passed through the recess 43 in the main support 13, 36, 37 (see Figure 4 ) is guided through the main support 13 to the end of the sensor station. There the wafer 1 is conveyed, for example, to a wafer sorter. The wafer 1 is Figure 1Its movement defines a space 4 to be kept clear; if an object is located in this space 4 to be kept clear, the wafer 1 collides with the object. In this embodiment, a total of six sensors 12 for measuring the wafer 1 are present, for example, in the middle of the sensor station.

[0042] The conveying device 3 is based on Figures 1 to 8 The continuous belt comprises two single belts 14 which are parallel to each other in this embodiment. Each single belt 14 is preferably guided via three deflection rollers 18 and driven by a drive wheel 20. Preferably, two pressure rollers 19 are adjacent to the drive wheel 20 so that the corresponding single belt 14 surrounds the drive wheel 20 by, for example, 180°. In this embodiment, the two drive wheels are driven by a common electric motor. The two front deflection rollers 18 on the one hand and the rear deflection roller 18, two pressure rollers 19 and the drive wheel 20 on the other hand (each single belt 14) are connected to the front end element 35a or the rear end element 35b. The rear end element 35b can have an electric motor of the conveying device 3 which is not shown here and - also the front end element 35a - comprises a steel housing.

[0043] The two end elements 35a, 35b can be fixed to the base frame 39 by means of screws, for example, see Figure 3 and 4 . The chassis 39 preferably comprises steel, wherein the steel further preferably occupies a relatively or absolutely dominant part of the chassis 39. The main support 13 of this particular embodiment comprises a plurality of granite blocks, which are fixed to each other by means of screw connections and together form the main support 13. The main support 13 can preferably be supported on three buffers 40, which are themselves fixed to the chassis 39 and serve to damp vibrations. The main support 13 comprises a lower support group 36, which is arranged below the space 4 to be kept free, and an upper support group 37, which is located above the space 4 to be kept free. The lower support group 36 can have a main block 42 consisting of granite, on which the single belt 14 is placed with a length of, for example, 350 mm. In this way, the wafer 1 in the area of ​​the sensor 12 and the sensor 12 itself are decoupled from the drive of the single belt 14 and have at most very small relative movements with respect to each other in the height direction.

[0044] The main support 13 of the embodiment described encloses a total of three sensor devices 2 (see Figure 1 and 2), each sensor device 2 has a sensor 12 arranged above and below the space 4 to be kept clear. Preferably, the sensors 12 are laser triangulation sensors, so that each sensor 12 has a laser diode as a transmitter and a diode array as a receiver. The light beam of each sensor 12 is projected onto the upper side or lower side of the corresponding wafer 1, reflected there and detected by the corresponding diode array. If, for example, the distance of the wafer 1 relative to the sensor 2 is increased, the light beam is detected by slightly more outer pixels of the diode array. The pixel shift follows a trigonometric relationship, via which the distance of the wafer 1 relative to the sensor in the submicron range can be determined.

[0045] The point at which the light beam intersects the upper or lower side of the space 4 to be kept clear is preferably referred to as the measuring point. Due to the movement of the wafer 1, the measuring point of each sensor 12 experiences a corresponding relative movement to the wafer 1. Thus, the stationary sensor 12 scans the wafer 1 linearly and detects one measuring track per wafer 1. Each sensor 12 can detect, for example, 15,000 measured values ​​per measuring track or wafer 1.

[0046] By arranging the sensor 12 above the space 4 to be kept free and the sensor 12 below the space to be kept free, a measuring track can be determined on each side of the wafer 1, which provides information about the corresponding cut profile. It is expedient to place the wafer 1 on the wafer production line in such a way that the cut In the top view, transverse to the conveying direction F. In addition, the thickness of the corresponding wafer 1 can also be determined by arranging the sensors 12 above and below the space 4 to be kept clear. For this purpose, the measuring tracks on the upper side and the measuring tracks on the lower side are converted into measuring lines by difference calculation, which reflect the thickness of the wafer 1 and the deflection along the wafer 1. By providing a total of three sensor devices 2 with two sensors 12 each, a total of six measuring tracks and three measuring lines can be created. For example, two measuring tracks or one measuring line extend in the middle of the wafer 1, two other measuring tracks or one other measuring line extend in the left third of the wafer 1, and two other measuring tracks or one other measuring line extend in the right third of the wafer 1. It is also possible to determine the total deviation on all measuring tracks, for example, regarding the thickness.

[0047] The three lower sensors 12 of the embodiment are arranged in the lower support group 36 and fixed thereon. In order to arrange the lower sensors 12, corresponding recesses are provided in the lower support group 36. The upper support group 37 includes side walls 21 and middle walls 22. The upper sensors 12 are located between the side walls 21 or the middle walls 22 and are fixed to the corresponding side walls or middle walls 21, 22, respectively. In particular Figure 2The arrangement of the upper sensor 12 in the upper support group 37 is schematically shown. In this exemplary embodiment, the sensors 12 are fixed to the main support 13 by means of screws and each have a plug coupling 38 for a sensor connecting cable. The outer wall 23 composed of sheet metal delimits the sensor station on its right or left side.

[0048] Sensor station Figure 1 The view of FIG. 5 also includes a calibration device 5 according to the invention, which itself preferably has three arms 6, each of which has a reference piece 8 arranged at the end of the respective arm. The three reference pieces 8 each have a thickness which corresponds, for example, to the average thickness of the wafer 1. Preferably, the thickness variation of each reference piece 8 determined by the upper side and the lower side is very small and in particular the respective thickness or thickness variation of the reference piece is precisely known. The calibration device 5 is Figure 2 Not shown.

[0049] The drive system 7 of the calibration device 5 is preferably configured to drive the three arms with their reference parts 8 so that the reference parts 8 move from a stationary position and finally precisely locate at a total of 6 measuring points and thus occupy the position of the wafer 1 (measuring position). This preferably occurs when the material flow of the wafer 1 is interrupted for a short time, because at the beginning of the wafer production line, an empty collection container must be replaced by a full collection container. During the interruption time, the drive system 7 - preferably in the case of a moving conveying device 3 - moves the reference part 8 to the measuring position. A reference measurement is then performed, with the aid of which the measured values ​​recorded on the wafer 1 can be calibrated. Thus, possible drifts of the sensor 12 are compensated as much as possible, so that the measurement accuracy is decisively improved. During the reference measurement, the empty collection container is replaced by a full collection container. Then, the reference part 8 is moved again to the corresponding stationary position, and the wafers 1 of the full collection container are conveyed to the conveying device 3 in sequence.

[0050] Figures 1 to 8 The drive system 7 of the embodiment of the present invention comprises an electric motor 15, to which a connecting rod 16 is preferably connected. The connecting rod 16 itself is advantageously connected to a lever part 24, which can be pivoted about a lever axis 25. Three arms 6 are connected to each of the three lower ends of the three-section lever part 24, so that the arms 6 can be moved from one end to the other. Figure 1 The rest position shown in FIG. 1 is transferred into the measuring position, whereby the reference element 8 is located at six measuring points. The movement process between the measuring position and the rest position is described in detail in the following Figures 5 to 8 Learned from.

[0051] exist Figure 5 2 shows an enlarged side view of the two sensors 12 of the sensor device 2, the arm 6 and the associated drive system 7. Figure 3In the measuring position, the reference element 8 is located in the space 4 to be kept clear, just above the single belt 14. The connecting rod 16 is moved by the electric motor 15 so that it is in the rearmost position, whereby the arm 6 itself is in the frontmost position due to the lever action of the lever part 24.

[0052] Preferably, two springs 27 are fastened to each of the three lower, fork-shaped ends of the lever part 24, each of which has a first spring end, while the other spring ends engage the rear section of the respective arm 6. In a top view, the respective arm 6 is preferably located between the two springs 27 associated with the arm and between the two shanks of the respective, fork-shaped lower end of the lever part 24. The movements of the lever part 24 and the arm 6 are thus elastically supported against each other via the six springs 27. In the measuring position, the springs 27 are preferably in a strongly stretched state, so that they exert a traction force on the arm 6 that acts in the direction of the sensor device 2.

[0053] The traction force is advantageously absorbed by stops 10, 11 in the form of stop elements 11 designed as stop screws on the arm 6, wherein the stop element 11 stops on the stop bearing 10 of the rigid support element 26. The support element 26 preferably has a carriage 30 on its underside, which is fixedly connected to the support element 26 and cannot move relative to the support element 26. A linear rail 29 is advantageously fixed on the upper side of the arm 6, which is slidably supported on the carriage 30. The support element 26 is expediently carried by a suspension 28. The suspension 28, the support element 26 and the carriage 30 are components of the linear guide 9. The linear guide 9 determines the direction of movement of the arm 6 and also the exact location of the measuring position via the stop bearing 10 of the support element 26. As a result, in the measuring position, the arm 6 is decoupled from the electric motor 15 or the drive train 16, 24, so that possible vibrations of the electric motor 15 or the lever part 24 are not transmitted to the arm 6.

[0054] In the next one, Figure 6 In the step shown in , the measurement is ended during this period and the connecting rod 16 is set in motion so that the right end of the connecting rod 16 is rotated, for example, 45° counterclockwise. As a result, the lever part 24 moves slightly to the right with its lower end, but the reference part 8 is always in the measuring position. The reason for this is the spring 27, which is Figure 5 In a state of strong tension, and Figure 6 In the process, a traction force is always applied to the arm 6 in the direction of the sensor device 2, so that the stop element 11 has not yet been disengaged from the stop support 10. However, Figure 6 The moment is shown shortly before the stop element 11 is detached from the stop carrier 10 .

[0055] exist Figure 7 In the embodiment, the electric motor 15 is further rotated by, for example, 35°, so that the lever part 24 has moved slightly further to the right with its lower end. Here, the lower end of the lever part 24 stops on the carrier 41 of the arm 6, whereby the arm 6 has moved to the right synchronously with the lower end of the lever part 24. As a result, the stop element 11 is disengaged from the stop bearing 10. The spring 27 only exerts a slight traction force on the carrier 41 or the lever part 24. The carrier 41 of this embodiment is designed as a pulley, which protrudes on both sides transversely to the conveying direction in a top view. In particular, Figure 7 It can be seen that the reference part 8 is no longer located at its two measuring points, but instead, the reference part 8 is now located above the space 4 to be kept unobstructed. However, the arm 6 still extends into the space 4 to be kept unobstructed with its lower edge.

[0056] exist Figure 8 This is no longer the case in the illustration of FIG, because the lever element 24 moves the arm 6 further to the right via the carrier 41, since the electric motor 15 has now turned the connecting rod 16 by approximately 180°. Here, too, the lower edge of the arm 6 is clearly above the space 4 to be kept free, so that the wafer 1—as shown—is guided back through the sensor station and can be measured. The reference element 8 is now in a rest position, which is indicated by the rest position sensor 34 (see FIG. Figure 8 )Sure.

[0057] Fig. 9 and 10 A stereoscopic side view-top view or a stereoscopic bottom view of a second embodiment of the present invention is shown. Figures 1 to 8 The difference from the first embodiment lies in the drive system 7. The drive system 7 or drive source of the second embodiment thus has two electric motors 15, which are arranged on the left and right sides of the two single belts 14 in a top view. The electric motors 15 each drive a spindle 17, so that the crossbeam 31 can move forward and backward. Two springs 27 are arranged between the crossbeam 31 and the upper end of the arm 6 (see Fig. 9 ), so that the arm 6 is elastically supported relative to the crossbeam 31.

[0058] The linear guide 9 of the second embodiment is almost identical to the linear guide of the first embodiment, so that the arm 6 of the second embodiment performs the same movements as the arm 6 of the first embodiment. Therefore, the upper end of the arm 6 of the second embodiment also has a stop element 11 in the form of a stop screw, which interacts with the stop bearing 10 of the support element 26. In the case of the second embodiment, a rest position sensor 34 is also provided, which detects the rest position of the crossbeam 31 and thus of the arm 6 or the reference element 8. In the case of the two corresponding embodiments, the conveying device 3, the main support 13 and the sensor device 2 are identical to one another or substantially identical to one another.

[0059] exist Fig.10 As can be seen in the view of FIG. 3 , the crossbeam 31 has an opening 32 on its underside. A carrying member 33 fixed to the underside of the arm 6 passes through the opening 32. The carrying member 33 is used to carry the arm 6 during the path from the measuring position to the rest position.

Claims

1. A sensor station for measuring a wafer (1), the sensor station comprising at least one sensor device (2) for measuring at least one property of the wafer (1) and at least one section of a transport device (3), the transport device (3) defining a transport direction, the moving wafer (1) defining a space (4) along the transport device that is to remain unobstructed for the moving wafer (1), the sensor device (2) generating at least one measuring point on the lower side and / or on the upper side of the unobstructed space (4), the sensor device (2) being carried by a main support (13), The sensor station has a calibration device (5), which comprises at least one arm (6) and a drive system (7) for moving the arm (6), on which a reference part (8) is arranged, the arm (6) being movably supported so that the reference part (8) can assume a rest position and a measuring position, wherein the reference part (8) is arranged outside the range of action of the sensor device (2) in the rest position and within the range of action of the sensor device in the measuring position.

2. The sensor station according to claim 1, wherein: In the measuring position, the reference element (8) is located at least partially within the space (4) to be kept free.

3. The sensor station according to claim 1, wherein: The calibration device (5) comprises at least one linear guide (9) which determines the linear movement section of the arm (6) between a measuring position and a rest position.

4. The sensor station according to any one of claims 1 to 3, wherein: The calibration device (5) has stops (10, 11) for defining the measuring position.

5. The sensor station according to any one of claims 1 to 3, wherein: The drive system (7) has at least one spring (27).

6. The sensor station according to any one of claims 1 to 3, wherein: The sensor device (2) has two sensors (12).

7. The sensor station according to any one of claims 1 to 3, wherein: The sensor station has a chassis (39).

8. The sensor station according to claim 7, wherein: At least one buffer (4) is provided between the base frame (39) and the main support member (13).

9. The sensor station according to any one of claims 1 to 3, wherein: The conveying device (3) comprises at least one section of a continuous conveyor.

10. The sensor station according to claim 9, wherein: The endless conveyor has two continuous single belts (14) which are parallel to one another at least in sections.

11. The sensor station according to any one of claims 1 to 3, wherein: The conveying device (3) is mounted in sections on the main support (13).

12. A method for measuring a wafer (1), wherein: The wafer (1) to be measured is removed from a first collecting container and conveyed to a sensor station, the wafer (1) being guided through the sensor station by means of a conveying device (3), the sensor station comprising at least one sensor device (2), the sensor device (2) measuring at least one property of the wafer (1), the material flow of the wafer (1) in the sensor station being stopped when the first collecting container is empty, the material flow of the wafer (1) in the sensor station being started if the first collecting container is replaced by a second collecting container, the interruption time being defined at the time points of the stopping and starting of the material flow of the wafer (1) in the sensor station, During the interruption time, the sensor device (2) measures a reference piece (8) having known characteristic values, and the measurement of the reference piece (8) is used to calibrate the measurement values ​​of the wafer (1).

13. The method according to claim 12, wherein: The sensor station is a sensor station according to one of claims 1 to 11.

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