DE102018130595A1 - Sensor station and method for measuring wafers - Google Patents

Abstract

A sensor station for measuring wafers comprises at least one sensor device for measuring at least one property of a wafer and at least a section of a conveyor device. The conveying device defines a conveying direction, the moving wafers along the conveying device determining a space to be kept free for the moving wafers. The sensor device generates at least one measuring point on an underside and / or on an upper side of the space to be kept free and is carried by a main support. The sensor station has a calibration device, the calibration device comprising at least one arm and a drive system for moving the arm. A reference piece is arranged on the arm, the arm being movably mounted so that the reference piece can assume a rest position and a measurement position. The reference piece is arranged in the rest position outside and in the measuring position within a range of the sensor device.

Description

The invention relates to a sensor station and a method for measuring wafers, comprising at least one sensor device for measuring at least one property of a wafer and at least a portion of a conveying device, the conveying device defining a conveying direction, the moving wafers along the conveying device being one for the moving wafers Determine the space to be kept free, the sensor device generating at least one measuring point on an underside and / or on an upper side of the space to be kept free.

Such a sensor station is off WO 2015/199930 A1 known. The known sensor station comprises three sensor devices, each containing a near infrared superluminescent diode for the purpose of three-track thickness measurement on wafers. The wafers are moved along a conveyor in the form of an endless belt with two individual belts and thus determine a space to be kept free. The sensor devices are arranged, for example, above the space to be kept free and each generate a measuring point on an upper side of the space to be kept free.

Another sensor station of this type is out KR 10 2016 0021979 A known. A conveyor in the form of an endless belt with two individual belts conveys wafers through this sensor station, the moving wafers determining a space to be kept free. The sensor station comprises three sensor devices, each of which has a few sensors. The sensors are designed as capacitive thickness sensors. A first sensor of each sensor device is arranged above and a second sensor below the space to be kept free. The first and second sensors of the sensor devices each produce three measuring points on the top and on the bottom of the space to be kept free.

It has been found that the thickness measurements of such sensor stations generally do not correspond to the specified measuring accuracies of the sensors, so that the measuring accuracy of the sensor stations is relatively poor in relation to the measuring accuracies of the sensor types used. The object of the present invention is therefore to further improve the measuring accuracy of the sensor stations, preferably without having to switch to more expensive or slower sensors, for example. It is preferably the object of the present invention to improve the measuring accuracy of the sensor stations in such a way that a simple standard deviation of at most 0.3 μm is achieved between two calibration processes or preferably with a throughput of at least 6000 wafers per hour.

To achieve the aforementioned object, the invention teaches a sensor station for measuring wafers, comprising at least one sensor device for measuring at least one property, in particular a thickness, of a wafer and at least a portion of a conveyor device, the conveyor device defining a conveying direction, the moving wafers along determine a space to be kept free for the moving wafers of the conveying device, the sensor device generating at least one measuring point on an underside and / or on an upper side of the space to be kept free, the sensor device being carried by a main support,
wherein the sensor station has a calibration device, the calibration device comprising at least one arm and a drive system for moving the arm, a reference piece - preferably with a known property, in particular a thickness - being arranged on the arm, the arm being movably mounted, so that the reference piece can assume a rest position and a measurement position, the reference piece being arranged in the rest position outside and in the measurement position within a range of the sensor device.

The invention is based on the knowledge that the sensors are subject to a hardly predictable drift during operation of the sensor station, as a result of which measurement results can be falsified in some cases. The calibration device can be used to carry out calibration measurements on the reference piece within the sensor station at regular intervals. The values measured on the wafers can be corrected accordingly again and again, so that the sensor drift no longer has any significant influence on the measurements. As a result, the above-mentioned task is solved.

The expression “arranged in a range of the sensor device” means in particular that the reference piece can be measured by the sensor device without the sensor device having to be removed or converted or further preferably readjusted or even further preferably mechanically manipulated / switched over. The expression “at least one property of a wafer” is understood to mean, for example, a sawing depth profile of a surface of the wafer and / or a deflection of the wafer and / or — particularly preferably — a thickness of the wafer.

The reference piece is preferably arranged at one end of the arm. The known thickness of the reference piece is preferably less than 1.0 mm, more preferably less than 0.5 mm and even more preferably less than 0.3 mm. The known thickness of the reference piece is expediently greater than 0.1 mm, further preferably greater than 0.12 mm and particularly preferably greater than 0.14 mm or 0.16 mm. The known thickness of the reference piece ideally corresponds to 0.2 mm. The reference piece may, for example, be made of metal, preferably steel, or comprise metal or steel. Typically, wafers have square or quasi-square (square with chamfered corners) dimensions with an edge length or length of 125 mm or 156 mm or 163 mm with a wafer thickness of typically 0.15 mm to 0.18 mm. These wafers define a space to be kept free, which corresponds, for example, to a tape the length of the sensor station with a thickness of 0.18 mm and a width of 156 mm.

According to a particularly preferred embodiment, the reference piece in the measuring position is at least partially located within the space to be kept free. The reference piece is expediently arranged completely outside the space to be kept free in the rest position. The expression “measuring position at least partially within the space to be kept clear” means in particular that the reference piece or other objects partially located within the space to be kept clear would collide with the conveyed wafers during operation of the sensor station. If, on the other hand, the reference piece lies completely outside the space to be kept free, a collision of the wafers with the reference piece is impossible. The rest position of the reference piece is expediently located in the top view downstream of the measuring point. It is preferred that the reference piece is arranged in the rest position above the space to be kept free, which is particularly advantageous in the case of a massive design of the main support, for example made of mineral material / rock / granite. According to another preferred embodiment, one / the main support comprises aluminum, wherein the rest position of the reference piece can be located above or below the space to be kept free.

It is particularly within the scope of the invention if the calibration device comprises at least one linear guide, the linear guide preferably determining a linear movement section of the arm between the measuring position and the rest position. This has the advantage that, due to the cramped conditions in the area of the sensor device, the reference piece can reach the measuring point more easily than, for example, a rotary movement. The linear movement section is preferably the only linear movement section or overall the only movement section between the rest position and the measurement position. The direction of movement of the linear movement section is advantageously aligned parallel to the conveying direction in the plan view. The linear guide advantageously comprises a linear rail and further advantageously a carriage corresponding to the linear rail. It is preferred that the linear rail is attached to the arm or to the top of the arm. The linear guide preferably comprises a stationary support element. It is preferred that a carriage or the carriage is attached to an underside of the stationary support element. The arm is preferably movable relative to the support element between the measuring position and the rest position of the reference piece.

The calibration device particularly preferably comprises a stop for defining the measurement position. A section of one or the stationary support element or the linear guide advantageously forms a stop bearing. The arm preferably comprises a stop element, which is further preferably designed as a stop screw. It is preferred that the stop bearing and the stop element touch each other in the measuring position of the reference piece and expediently not touch each other in the rest position of the reference piece. The stop element is advantageously arranged above the linear rail. It is expedient if a stop surface of the stop element points in the direction of the sensor device.

It is particularly within the scope of the invention that the calibration device has at least one spring. The spring may be designed as a helical spring, for example. It is preferred that the spring is connected between the drive source or the electric motor and the arm, so that the arm is mounted elastically in relation to the drive system or the drive source. It is preferred that the spring or the drive system or the drive train is designed such that the spring generates a contact pressure of the stop element on the stop bearing in the measuring position of the reference piece. The spring is preferably stretched in the measuring position of the reference piece, so that a contact pressure of the stop element acts on the stop bearing. According to a preferred embodiment, the drive system comprises a rest position sensor for detecting when the rest position has been reached. A first end of the spring is expediently connected to the drive train, for example to a lever part or a traverse. A second end of the spring is preferably attached to the arm. Two springs are preferably associated with the at least one arm, with the arm preferably being arranged between the two springs in plan view.

It is very preferred that the arm comprises at least one driver for transferring the reference piece into the rest position. The driver may for example be designed as a roller or roller. An axis of the roller or of the driver is expediently oriented perpendicular to the conveying direction in plan view. It is preferred that the driver is arranged in a rear third of the arm. It is advantageous if the driver protrudes on both sides of the arm, so that a / the lever part in a preferred embodiment can touch the driver on both sides with a lower, fork-shaped end. The driver is preferably arranged in a top view between one / the first and a / the second end of the spring. A / the spring is preferably designed such that the spring exerts a tensile force on the arm so that the driver of the arm - in particular in the rest position and / or in sections during the transfer from the measuring position to the rest position or vice versa - is pressed against the drive train is pressed or pressed in the direction of the drive train.

It is within the scope of the invention that the sensor device has two sensors. A first sensor of the sensor device is preferably arranged above the space to be kept clear, further preferably a second sensor is located below the space to be kept clear. One measurement point is expediently assigned to the first and the second sensor, the two measurement points preferably overlapping one another in the plan view. The sensor device or the first and / or the second sensor of the sensor device advantageously comprises a light source and a light detector. It is possible for the light source to emit light with a wavelength above 550 nm. The light source preferably emits visible light. It is particularly preferred that the light source is a diode and preferably a laser diode. It is advantageous that the light detector has at least one diode row with a plurality of pixels. It is very particularly preferred that the first and / or second sensor or the sensor device is a triangulation sensor or comprises a triangulation sensor. The first and the second sensor are advantageously identical in construction.

According to a preferred embodiment, the sensor station has a plurality of sensor devices. The top view of the sensor devices is expediently arranged, the measuring points assigned to the sensor devices expediently forming a connecting line, the connecting line preferably being oriented transversely — in particular perpendicularly — to the conveying direction. The sensor station preferably comprises at least three sensor devices for the purpose of generating three measurement lines on the top and / or bottom of the wafers. It is preferred that a first measurement line runs in a middle third of the wafer, whereas the second and third measurement lines run in a left and right third of the wafer. It is possible for the sensor stations to comprise four or more sensor devices for generating four or more measuring lines. For example, the sensor station has five sensor devices. For each wafer, a sensor is expediently assigned a measurement track for imaging a sawing depth profile, and each sensor device is assigned a measurement line for imaging a wafer thickness. It is possible to convert a measurement track on the surface of a wafer with a measurement track on the underside of the wafer into a measurement line by forming the difference. It is preferred that a plurality of measurement tracks are generated on the top and on the bottom of the wafers. It is expedient that each measurement line comprises at least 2000 measurement values, preferably at least 5000 measurement values and particularly preferably at least 10000 measurement values per wafer.

According to a preferred embodiment, the main support - preferably predominantly - has a metal and in particular aluminum. In the case of a special embodiment, the main support comprises a mineral material. The mineral material preferably comprises rock and particularly preferably granite. It is expedient if the main support has a lower support group, which is arranged below the space to be kept free. The main support expediently comprises an upper support group which is arranged above the space to be kept free. The main support expediently comprises one or more recesses between the upper and the lower support group for the purpose of guiding the conveyor device or the wafers 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 side walls which at least partially and preferably completely surround the at least one sensor device in plan view. The upper support group preferably has at least one partition, so that the upper support group forms at least two chambers for at least two sensor devices. The at least one sensor is expediently attached to an inside of a side wall or the intermediate wall. The wall thickness of the side walls or the intermediate wall is preferably at least 15 mm, more preferably at least 20 mm and particularly preferably at least 25 mm. Ideally, the wall thickness of the side walls or the intermediate wall is at least 30 mm. It is expedient if the wall thickness of the side walls or intermediate 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 walls or the intermediate wall is at most 60 mm.

According to a very advantageous embodiment, the sensor station has a base frame, it being preferred that at least one damper is arranged between the base frame and the main support. The damper can e.g. B. be pneumatic or hydraulic. The damper particularly preferably comprises an elastic element and in particular a rubber element. It is advantageous if at least three dampers are arranged on the base frame. According to a preferred embodiment, the main support sits on the at least one damper. It is particularly preferred if the sensor device (s) is / are attached to the main support and in particular is / are rigidly attached. The calibration device is preferably attached to the main support and in particular rigidly attached. According to a very particularly preferred embodiment, a / the front end element and / or a / the / rear end element of the conveying device is arranged on the base frame, further preferably the at least one damper not between the front end element and / or the rear end element on the one hand and the base frame on the other is interposed, so that preferably the front end element and / or the rear end element are not damped or are not carried by the main support.

The calibration device particularly preferably comprises a computing unit, the computing unit being designed to use measured values determined by the sensor device on the reference piece for a calibration of measured values determined on the wafers via the sensor device. It is preferred that the measured values determined depict a thickness of the reference piece or the wafers on the reference piece or on the wafers. The calibration device preferably comprises a control unit of the arm. The control unit is preferably designed to move the arm from the rest position into the measuring position or vice versa. The wafers to be measured are expediently removed individually from a first collection container by a removal station upstream of the sensor station. The separated wafers then preferably pass through the sensor station and are then preferably fed to a sorting station. A material flow of the wafers in the sensor station is advantageously stopped when the first collecting container is empty. The material flow of the wafers in the sensor station is conveniently started as soon as the first collecting container has been replaced by a second collecting container. The times of the stop and the start of the material flow of the wafers in the sensor station preferably define an interruption time for the purpose of exchanging the collecting container. The material flow of the wafers can be stopped, for example, by stopping the conveying device. The material flow of the wafers is preferably stopped by no further wafers being transferred to the conveying device, it being preferred that the conveying device is in operation at least temporarily and preferably continuously during the interruption time. In particular, it is preferred that the last wafer of the first collecting container and the first wafer of the second collecting container define the interruption time. The expression “in the sensor station” preferably means “in the range of the sensor device” and particularly preferably “at the at least one measuring point”. It is very particularly preferred that the computing unit and / or the control unit is / are designed such that the sensor device measures the reference piece during the interruption time. The measurement values determined on the reference piece are expediently used for the calibration of measurement values determined on wafers. The interruption time may be up to 10 or 7 or 5 seconds, for example. The interruption time advantageously amounts to at least 0.5 or 1.0 or 1.5 or 2 seconds.

The conveyor device particularly preferably comprises at least a section of an endless conveyor, further preferably the endless conveyor having at least two endless individual belts which are parallel to one another at least in sections. A complete endless conveyor is advantageously assigned to the sensor station. The expression “complete endless conveyor” means in particular that the rotation of the endless conveyor defines the extent of the endless conveyor in the conveying direction and preferably that the endless conveyor is not able to move wafers from previous stations to the sensor station or from the sensor station without the aid of further conveyor devices to promote subsequent stations. The endless belt or the individual belts expediently comprise an elastomer, the elastomer preferably being part of a layer contacting the wafer. Each of the two individual bands is preferably at least 5 mm, more preferably at least 10 mm, particularly preferably at least 12 mm and ideally at least 14 mm wide. Each of the two individual strips is expediently at most 40 mm, preferably at most 30 mm, particularly preferably at most 25 mm and ideally at most 18 mm wide. The distance between the two individual belts in the plan view is expediently at least 20 mm, preferably at least 30 mm, particularly preferably at least 35 mm and ideally at least 40 mm. It is advantageous if the distance in plan view between the two individual bands is at most 110 mm, preferably at most 90 mm, particularly preferably at most 80 mm and ideally at most 70 mm.

It is within the scope of the invention that a motor, in particular an electric motor, is assigned to the conveying device. It is advantageous if the motor has a motor shaft protruding on one side or, preferably, a motor shaft on both sides. The motor shaft is preferably rigidly connected at least on one side and more preferably on both sides of the motor housing to one or one drive wheel in each case. The drive wheel or the drive wheels expediently have a width which is suitable for receiving a single belt. It is expedient if the conveying device comprises at least one, preferably two pressure rollers per drive wheel. The one or two pressure rollers are preferably arranged such that the individual belt wraps around the drive wheel by at least 90 °, preferably by at least 120 ° and particularly preferably by at least 150 °. It is expedient if the conveyor device has / have at least two and preferably at least three deflecting rollers for the endless belt or for each individual belt. The at least one pressure roller and / or the deflection rollers are expediently designed to receive a single strip.

The conveyor device or the endless conveyor is particularly preferably guided through the main support. Advantageously, the conveyor comprises a front end element at a front end and a rear end element at a rear end. The front end element comprises at least one deflection roller and further preferably two deflection rollers for the endless belt or for each individual belt. The rear end element preferably has / the drive wheel or the drive wheels and preferably comprises at least one deflection roller for the endless belt or for each individual belt. Further advantageously, at least one pressure roller and preferably two pressure rollers are provided for the endless belt or for each individual belt on the rear end element. The front and / or rear end element may have steel, for example, and preferably a steel housing. It is very preferred that the front end element and / or the rear end element is / are attached to the underframe. The lower support group or a / the main block of the lower support group is expediently arranged between the front end element and the rear end element, a gap preferably remaining between the front or rear end element on the one hand and the lower support group or the main block on the other hand.

According to a very particularly preferred embodiment, the conveyor device or the endless conveyor or the individual belts rests at least in sections on the main support or the lower support group or the main block. A first section of the conveyor device / endless conveyor / individual belts preferably lies in the conveying direction before the at least one measuring point on the main support / the lower support group / the main block. Advantageously, a second section of the conveyor / endless conveyor / individual belts lies in the conveying direction behind the at least one measuring point on the main support / the lower support group / the main block. It is particularly preferred if the main support / the lower support group / the main block defines at least a section of a movement path - in particular in the vertical direction - of the conveying device / endless conveyor / the individual belts by lying thereon. This ensures that the conveyor in the area of the measuring point is decoupled from the drive of the conveyor, so that any vibrations emanating from the drive of the conveyor are reduced in the area of the measuring point. Another advantage is that in the area of the measuring point, the wafers are synchronized with the sensor device with respect to any height movements, so that any relative movements in the height direction between the wafers and the sensor device are reduced.

According to a preferred embodiment, the drive system has a drive source and a drive train. The drive source preferably comprises at least one electric motor. The drive train preferably has a connecting rod or at least one spindle. According to a first embodiment, the drive source is connected to the connecting rod. The connecting rod is expediently connected to a lever part which is rotatably mounted via a lever axis. Compared to the connecting rod, the lever part is preferably connected to the at least one arm or to several arms. The lever part is preferably connected to the at least one arm with the interposition of at least one / the spring.

According to a second embodiment, the drive source or the at least one electric motor is connected to a spindle of the drive train. The drive source advantageously comprises two electric motors, each of which is connected to a spindle. A traverse is preferably connected to one end of the at least one spindle, so that the drive source can press the at least one arm from the rest position into the measuring position via the spindle and the traverse. In the top view, the traverse is oriented transversely and preferably perpendicularly to the conveying direction. Advantageously, at least one spring is arranged between the crossmember and the at least one arm, so that the at least one arm is elastically mounted relative to the drive source or the crossmember. The crossmember expediently comprises at least one opening and the arm has at least one driver, the driver being passed through the The opening protrudes so that the traverse can pull the at least one arm from the measuring position into the rest position.

To achieve the aforementioned object, the invention teaches a method for measuring wafers, wherein wafers to be measured are removed from a first collecting container and fed to a sensor station - in particular a sensor station according to the invention - the wafers being conveyed through the sensor station by means of a conveying device, the sensor station comprises at least one sensor device, the sensor device measuring at least one property of the wafers, a material flow of the wafers in the sensor station being stopped when, for example, the first collection container is empty, the material flow of the wafers in the sensor station being started as soon as, for example, the first collection container was replaced by a second collecting container, the times of the stop and the start of the material flow of the wafers in the sensor station defining an interruption time, the sensor device being a reference piece with an egg within the interruption time a known value of the property is measured, the measurement of the reference piece being used to calibrate measured values of the wafers.

The reference piece is expediently in a measuring position during its measurement. The property of the wafers advantageously corresponds to the thickness of the wafers. It is expedient that after the measurement of the reference piece, the reference piece is brought into a rest position. The material flow of the wafers in the sensor station is advantageously restarted after the reference piece has left the measuring position or has reached the rest position. It is expedient that the material flow of the wafers in the sensor station is stopped again when the second collecting container is empty. The reference piece is then advantageously transferred again from the rest position into the measuring position.

• 1 einen Ausschnitt der erfindungsgemäßen Sensorstation in einer perspektivischen Seitenansicht,
• 2 eine Hauptstütze der Sensorstation aus 1 in einer Draufsicht,
• 3 die Sensorstation der 1 in einer vollständigen Seitenansicht,
• 4 die Sensorstation der 1 in einer vollständigen Hinteransicht,
• 5 eine Seitenansicht eines Arms der Sensorstation aus 1 in einer Messposition,
• 6 den Arm aus 5 während der beginnenden Überführung von der Messposition in eine Ruheposition,
• 7 den Arm aus 5 während der Überführung von der Messposition in die Ruheposition,
• 8 den Arm aus 5 in der Ruheposition,
• 9 eine erfindungsgemäße Sensorstation eines zweiten Ausführungsbeispieles in einer perspektivischen Draufsicht und
• 10 die Sensorstation aus 9 in einer perspektivischen Ansicht von unten.

The invention is explained in detail below using two exemplary embodiments. They show a schematic representation

• 1 a detail of the sensor station according to the invention in a perspective side view,
• 2nd a main support of the sensor station 1 in a top view,
• 3rd the sensor station of the 1 in a full side view,
• 4th the sensor station of the 1 in a full rear view,
• 5 a side view of an arm of the sensor station 1 in a measuring position,
• 6 arm out 5 during the beginning transfer from the measuring position to a rest position,
• 7 arm out 5 during the transfer from the measuring position to the rest position,
• 8th arm out 5 in the rest position,
• 9 an inventive sensor station of a second embodiment in a perspective top view and
• 10th the sensor station 9 in a perspective view from below.

In the 1 and 2nd A sensor station according to the invention is shown from two perspectives or a top view. For the sake of clarity, the side walls in 1 as well as parts in 2nd omitted. The sensor station from the 1 and 2nd For example, a wafer removal station, not shown here, may be connected downstream, in which a removal device individual wafers 1 removed from a collecting container and handed over to an endless conveyor. The endless conveyor of this embodiment reaches the wafers 1 then on to the sensor station. The sensor station can be arranged in front of a wafer sorter, also not shown here, so that the sensor station is part of a wafer line.

The wafers 1 from the previous station are from a conveyor 3rd (see 1 ) of the sensor station, transported in a conveying direction F and through recesses 43 (see 4th ) in a main pillar 13 , 36 , 37 through the main support 13 through to the end of the sensor station. There are the wafers 1 then handed over to the wafer sorter, for example. The wafers 1 define according to 1 through their movement a space to be kept free 4th ; would become an object in this space to be kept clear 4th the wafers collided 1 with the said object. In this exemplary embodiment, a total of six sensors are located approximately in the middle of the sensor station 12 for measuring the wafers 1 .

The conveyor 3rd includes according to the 1 to 8th an endless belt which, in this exemplary embodiment, has two individual belts which are parallel to one another 14 having. The single bands 14 are preferred over three pulleys 18th guided and by a drive wheel 20th driven. There are preferably two pressure rollers 19th the drive wheel 20th adjacent, so that the respective single volume 14 the drive wheel 20th wrapped around 180 °. In this embodiment, both drive wheels are driven by a common electric motor. The two front pulleys 18th on the one hand and the rear pulley 18th , the two pressure rollers 19th as well as the drive wheel 20th on the other hand (per single volume 14 ) are on a front end element 35a or rear end element 35b connected. The rear end element 35b likes the electric motor of the conveyor, not shown here 3rd have and - like the front end element 35a - Include a steel case.

The two end elements 35 a, b like, for example, using screws on a base 39 be attached, s. 3rd and 4th . The base 39 preferably comprises steel, with steel further preferably having a relatively or absolutely predominant part in the underframe 39 owns. The mainstay 13 This special exemplary embodiment comprises a large number of granite blocks which are fastened to one another by means of screw connections and together the main support 13 form. The mainstay 13 likes preferably on three dampers 40 be stored, which in turn on the base 39 are attached and serve the vibration damping. The mainstay 13 includes a lower, below the space to be kept free 4th arranged support group 36 and an upper one, above the space to be kept free 4th support group located 37 . The lower support group 36 likes a main block 42 made of granite, on which the individual bands 14 come to a length of, for example, 350 mm. This is how the wafers are 1 in the field of sensors 12 as well as the sensors 12 even from the drive of the individual belts 14 decoupled and at most have very small relative movements in the vertical direction.

The mainstay 13 This exemplary embodiment encloses a total of three sensor devices 2nd (see 1 and 2nd ), each sensor device 2nd one above and one below the space to be kept free 4th arranged sensor 12 having. The sensors are preferably 12 Laser triangulation sensors, so every sensor 12 has a laser diode as a transmitter and a diode array as a receiver. The light beam of every sensor 12 is on the top or bottom of the respective wafer 1 thrown, reflected there and detected by the respective diode row. For example, the distance of a wafer increases 1 to the sensor 2nd , the light beam is captured by a pixel on the diode row located a little further out. This pixel shift follows trigonometric relationships over which the distance of the wafer 1 to the sensor 2nd can be determined in the submicron range.

The points at which the light beam is the top or bottom of the space to be kept free 4th intersects, are preferably called measuring points. Because of the movement of the wafers 1 learns the measuring point of each sensor 12 a corresponding relative movement to the wafer 1 . This causes the stationary sensors to feel 12 the wafers 1 from a line and capture one measurement track per wafer 1 . Every sensor 12 likes, for example, 15,000 measurement values per measurement track or wafer 1 to capture.

By arranging a sensor 12 above and a sensor 12 below the space to be kept free 4th can be on either side of the wafer 1 one measuring track each are determined, which provide information about the respective saw depth profile. The wafers are expediently 1 placed on the wafer line in such a way that the sawing grooves are located in a top view transversely to the conveying direction F. In addition, the arrangement of the sensors 12 above and below the space to be kept free 4th also a thickness of the respective wafer 1 be determined. For this purpose, a measuring track on the upper side and a measuring track on the lower side are converted into a measuring line by forming the difference, which measuring line has a thickness as well as a deflection of the wafer 1 along the wafer 1 maps. By providing a total of three sensor devices 2nd with two sensors each 12 A total of six measurement tracks and three measurement lines can be created. For example, two measurement tracks or a measurement line run in the middle of the wafer 1 , two further measurement tracks or another measurement line in a left third of the wafer 1 and two further measurement tracks or a further measurement line in a right third of the wafer 1 . An overall deviation - for example with regard to the thickness - can also be determined across all measurement tracks.

The three lower sensors 12 of this embodiment are in the lower support group 36 arranged and attached to this. For the arrangement of the lower sensors 12 are corresponding recesses in the lower support group 36 intended. The upper support group 37 includes sidewalls 21st as well as a partition 22 . The top sensors 12 are located between the side walls 21st or the partition 22 and are each on the corresponding side or partition 21st , 22 attached. In particular a look at 2nd illustrates the arrangement of the top sensors 12 within the upper support group 37 . The sensors 12 are in this embodiment by means of screws on the main support 13 attached and each have a plug-in coupling 38 for sensor connection cable. Exterior walls 23 made of sheet metal limit the sensor station on their right or left side.

The sensor station includes overlooking 1 in addition, a calibration device according to the invention 5 which in turn prefers three arms 6 with a reference piece arranged at the end of each arm 8th having. The three reference pieces 8th each have a thickness, which for example an average thickness of the wafers 1 corresponds. The thickness variation of each reference piece determined by the top and bottom is preferred 8th the respective thickness or thickness variation of the reference piece is very small 8th exactly known. The calibration device 5 is in 2nd not shown.

A drive system 7 the calibration device 5 is preferably designed to the three arms 6 with their reference pieces 8th so that the reference pieces 8th move out of a rest position and finally are exactly at the 6 measuring points and thus the position of the wafers 1 take (measuring position). This preferably happens whenever the material flow of the wafers 1 is interrupted for a short time because an empty collecting container at the beginning of the wafer line has to be replaced by a full collecting container. The drive system runs within this interruption time 7 - With preferably running conveyor 3rd - the reference pieces 8th to the measuring position. Then reference measurements are made, based on which on the wafers 1 measured values can be calibrated. This will result in any drift of the sensors 12 largely compensated, so that the measurement accuracy is significantly increased. During the reference measurements, the empty collection container is replaced by a full collection container. Then the reference pieces 8th move back to the respective rest position and the wafers 1 of the full collection container one after the other from the conveyor 3rd fed.

The drive system 7 of the embodiment of the 1 to 8th includes an electric motor 15 on which a connecting rod is preferred 16 connected. The connecting rod 16 in turn is advantageously with a lever part 24th connected, which is about a lever axis 25th is pivotable. At each of the three lower ends of the tripartite lever part 24th are the three arms 6 connected so the arms 6 from the in 1 shown rest position can be transferred to the measuring position, making the reference pieces 8th are at the six measuring points. The process of movement between measuring and rest position is the following 5 to 8th refer to.

In 5 is an enlarged side view of two sensors 12 a sensor device 2nd , one arm 6 as well as the associated drive system 7 shown. In 3rd is the reference piece 8th in a measuring position and thus within the space to be kept clear 4th immediately above the single bands 14 . The connecting rod 16 was from the electric motor 15 moved so that it is in the rearmost position, causing the arm 6 in turn due to the leverage of the lever part 24th is in the foremost position.

At each of the three lower, fork-shaped ends of the lever part 24th are preferably two springs 27 attached to the first spring end, while the other spring end to a rear portion of the respective arm 6 attacks. The respective arm is in the top view 6 preferably between the two springs associated with it 27 , as well as between two prongs of the respective fork-shaped lower end of the lever part 24th . As a result, the movements of the lever part 24th and the poor 6 over six feathers 27 elastically supported to each other. The springs are in the measuring position 27 preferably in a more stretched condition so that it has a pulling force on the arm 6 exercise which towards the sensor device 2nd works.

This tensile force is advantageously absorbed by a stop 10th , 11 in the form of a stop element designed as a stop screw 11 On the arm 6 , the stop element 11 on a stop bearing 10th of a rigid support element 26 strikes. The support element 26 preferably has a carriage on its underside 30th on which with the support member 26 firmly connected and thus in relation to the support element 26 is immobile. At the top of the arm 6 is advantageously a linear rail 29 attached which to the carriage 30th is slidably mounted. The support element 26 is conveniently from a suspension 28 carried. The suspension 28 , the support element 26 as well as the carriage 30th are part of a linear guide 9 . The linear guide 9 determines the direction of movement of the arm 6 as well as the stop bearing 10th of the support element 26 also the exact location of the measurement position. This means that the arm is in the measuring position 6 from the electric motor 15 or the drive train 16 , 24th decouples so that any vibrations of the electric motor 15 or the lever part 24th not on the arm 6 be transmitted.

In the next, in 6 In the step shown, the measurements have meanwhile been ended and the connecting rod 16 set in motion so that the right end of the connecting rod 16 has rotated about 45 ° counterclockwise. This has the lever part 24th with its lower end slightly shifted to the right, although the reference piece 8th is still in the measuring position. This is due to the springs 27 , what a 5 were in a more stretched state and in 6 still pulling on the arm 6 towards the sensor device 2nd exercise so that the stop element 11 from the stop camp 10th has not yet solved. Indeed shows 6 the moment just before the stop element 11 from the stop camp 10th has solved.

In 7 has the electric motor 15 rotated about 35 ° further so that the lever part 24th has moved a little further to the right with its lower end. The lower end of the lever part struck 24th to a driver 41 of the arm 6 at what the arm 6 yourself with the lower end of the lever part 24th moved synchronously to the right. This has the stop element 11 from the stop camp 10th solved. The feathers 27 only exert a slight pull on the driver 41 or the lifting part 24th out. The driver 41 This exemplary embodiment is designed as a roller which projects on both sides in a top view transversely to the conveying direction. In particular is 7 that the reference piece 8th no longer located at its two measuring points; instead there is the reference piece 8th now above the room to be kept clear 4th . However, the arm protrudes 6 with its lower edge still in the space to be kept clear 4th inside.

This is then facing 8th no longer the case because of the lever part 24th the arm 6 about the carrier 41 has moved further to the right because of the electric motor 15 the connecting rod 16 has now rotated by almost 180 °. The lower edge of the arm is also located here 6 clearly above the space to be kept clear 4th so the wafer 1 - as shown - can be passed through the sensor station again and measured. The reference piece 8th is now in the rest position, which is determined by a rest position sensor 34 (see 8th ) is determined.

9 and 10th show a perspective side plan view and a perspective view from below of a second embodiment of the invention. The second exemplary embodiment differs with respect to the first exemplary embodiment according to FIG 1 to 8th especially with a view to the drive system 7 . So the drive system has 7 or the drive source of the second embodiment two electric motors 15 which in the top view left and right of the two single bands 14 are arranged. The electric motors 15 drive one spindle each 17th so that a traverse 31 can be moved back and forth. Between the traverse 31 and upper ends of the arms 6 are two feathers each 27 arranged (s. 9 ) so the arms 6 in relation to the traverse 31 are mounted elastically.

The linear guide 9 of the second embodiment is almost the same as that of the first embodiment, so the arms 6 of the second embodiment perform the same movement as those arms 6 of the first embodiment. So point the top ends of your arms 6 of the second embodiment also stop elements 11 in the form of stop screws, which with stop bearings 10th of the support elements 26 interact. A rest position sensor is also in the case of the second exemplary embodiment 34 provided which is the rest position of the traverse 31 and therefore the poor 6 or the reference pieces 8th detected. In the case of the two respective exemplary embodiments, there are also the conveying device 3rd who have favourited Main Support 13 and the sensor device 2nd identical to one another or essentially identical to one another.

With a view to 10th it can be seen that the traverse 31 openings at the bottom 32 having. Through these openings 32 protrude driver 33 through which on the undersides of the arms 6 are attached. The carriers 33 serve the arms 6 to be taken along from the measuring position to the rest position.

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• WO 2015/199930 A1 [0002]
• KR 1020160021979 A [0003]

Claims (10)

Sensor station for measuring wafers (1), comprising at least one sensor device (2) for measuring at least one property of a wafer (1) and at least a portion of a conveyor device (3), the conveyor device (3) defining a conveying direction, the moving wafers (1) determine a space (4) to be kept free for the moving wafers (1) along the conveyor device, the sensor device (2) generating at least one measuring point on an underside and / or on an upper side of the space (4) to be kept free, the sensor device (2) is carried by a main support (13), the sensor station having a calibration device (5), the calibration device (5) comprising at least one arm (6) and a drive system (7) for moving the arm (6), wherein a reference piece (8) is arranged on the arm (6), the arm (6) being movably mounted so that the reference piece (8) can assume a rest position and a measurement position, wherein the reference piece (8) is arranged in the rest position outside and in the measuring position within a range of the sensor device (2). Sensor station after Claim 1 , wherein the reference piece (8) in the measuring position is at least partially located within the space (4) to be kept free. Sensor station after Claim 1 or 2nd , wherein the calibration device (5) comprises at least one linear guide (9), the linear guide (9) determining a linear movement section of the arm (6) between the measuring position and the rest position. Sensor station according to one of the Claims 1 to 3rd The calibration device (5) has a stop (10, 11) for defining the measurement position. Sensor station according to one of the Claims 1 to 4th wherein the drive system has at least (7) a spring (27). Sensor station according to one of the Claims 1 to 5 The sensor device (2) has two sensors (12). Sensor station according to one of the Claims 1 to 6 The sensor station has a base frame (39), it being preferred that at least one damper (4) is arranged between the base frame (39) and the main support (13). Sensor station according to one of the Claims 1 to 7 The conveyor device (3) comprises at least a section of an endless conveyor, the endless conveyor preferably having two endless individual belts (14) that are parallel to one another at least in sections. Sensor station according to one of the Claims 1 to 8th The conveyor device (3) rests in sections on the main support (13). Method for measuring wafers (1), the wafers (1) to be measured being removed from a first collecting container and a sensor station - in particular a sensor station according to one of the Claims 1 to 9 - are supplied, the wafers (1) being guided through the sensor station by means of a conveyor device (3), the sensor station comprising at least one sensor device (2), the sensor device (2) measuring at least one property of the wafers (1), wherein a material flow of the wafers (1) in the sensor station is stopped when, for example, the first collecting container is empty, the material flow of the wafers (1) in the sensor station being started as soon as, for example, the first collecting container has been replaced by a second collecting container, the times of the stop and the start of the material flow of the wafers (1) in the sensor station define an interruption time, the sensor device (2) measuring a reference piece (8) with a known value of the property within the interruption time, the measurement of the reference piece (8) for Calibration of measured values of the wafer (1) is used.

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