JP4922396B2 - Measuring apparatus and measuring method for inspection of substrate surface - Google Patents

Description

  The present invention relates to a measuring apparatus and a measuring method for inspecting the surface of a substrate. The measuring device has a sensor, which can position the surface to be measured at a predetermined interval.

  In the field of surface inspection of flat surfaces, sensors are usually positioned at predetermined intervals on the substrate surface to be measured. This positioning is usually performed by a positioning system, which can position the sensor in a plane parallel to the surface to be measured. For this reason, the entire surface to be measured can be scanned, for example by means of a meandering movement, by correspondingly driving and controlling the positioning system. In order to obtain a high measurement speed, a sensor having a large number of individual sensors is also used. Here, by measuring a plurality of measurement points simultaneously, the measurement time for a predetermined area is reduced according to the number of individual sensors. .

  Different sensors are used depending on the nature of the measurement task to be processed. Optical inspection typically uses a camera with, for example, a line or area sensor. In a capacitive measurement task, a large number of measurement pins to which a predetermined AC or DC voltage is applied are used. As the measurement signal, a small current flowing through each measurement pin is used, which depends on the capacitance between the measurement pins or on each measurement point on the surface to be measured.

  For example, methods are known that can be inspected before manufacturing the LCD for possible defects in the printed circuit board structure of the substrate used in a liquid crystal display (LCD liquid crystal display). Here, by performing a corresponding capacitive measurement between the measurement pin and the printed circuit board structure facing one of the plurality of measurement pins, it is possible to identify unwanted shorts, breaks and constrictions in the printed circuit board structure. it can. These defects can be repaired prior to subsequent processing of the LCD substrate, or the LCD substrate can be extracted from the manufacturing process. In any case, the manufacturing cost of the liquid crystal display can be greatly reduced.

  For highly accurate inspection, it is usually necessary to set and maintain the distance between the sensor and the substrate surface to be measured with high accuracy. However, if the substrate to be measured has a non-planar surface or a slightly corrugated surface, it is much more difficult to maintain a precise spacing. Therefore, in order to measure a non-planar surface, a positioning system is used which can not only position the sensor in a plane parallel to the surface to be measured, but also in a direction perpendicular to this plane. There must be. However, this vertical positioning relative to the surface to be measured usually slows down the measurement process and reduces the measurement accuracy.

  An object of the present invention is to provide a measuring apparatus and a measuring method that enable accurate measurement even on a non-flat substrate surface.

  This problem is solved by the requirements stated in the independent claims, and advantageous embodiments of the invention are described in the dependent claims.

  Independent claim 1 describes a measuring device for inspecting the surface of a substrate. The measuring device includes (a) a holding member (110) and (b) an air-mounted element. The air-mounted element is attached to the holding member, and the holding member With the surface to be inspected, an air support can be formed, and the holding member can adapt the air-mounted element to surface undulations. The measuring device further comprises (c) at least one sensor, the sensor being attached to an air-mounted element, the air-mounted element configured to inspect the surface of the substrate Has been.

  The basic recognition of the present invention is that the air-mounted element is constructed using a flexible sensor carrier. In this case, the flexible sensor carrier can be configured without using a completely fixed member or a fixed material. Thus, an air-mounted element resembles an easily bendable ruler that can conform to the surface to be inspected, possibly in the presence of irregularities. The flexible construction of the air-mounted element makes it possible in particular to adapt to long distance corrugations or corrugations of the substrate surface to be inspected.

  The air-mounted element can be constructed using, for example, thin glass having a required flexibility. The flexibly air-mounted element may be at least partially made of a plastic such as polyvinyl chloride (PVC), or a fiber reinforced material such as a carbon fiber composite.

  The holding member is, for example, a holder arm, and an element that is flexibly air-mounted is held in the holder arm from at least two sides. The air-mounted element can then be attached to the holder arm using a flexible solid flange.

  In this context, the concept of a solid flange is understood as the location of a component with reduced bending stiffness (verminderten Biegesteifigkeit), and a component with a clearly higher bending stiffness compared to a solid flange. It is a limited place from the area next to. In this way, the holding member and the air-mounted element can be produced integrally as a moving pair (kinematisches Paar), for example by a micromechanical structuring system. Reduced bending stiffness is generally formed by locally reducing the cross section. At that time, the cross section may be reduced along one spatial direction or a plurality of spatial directions. When changing the cross-section, different geometric shapes may be used. A leaf spring flange is obtained when the cross-section is reduced to a constant value that is relatively small along the flange and over a predetermined section. However, the cross-section may vary continuously so that the taper has, for example, an arc shape.

  The air support may be constituted by a blow nozzle composed of elements that are flexibly air-mounted. The predetermined measurement interval between the sensor and the substrate surface to be inspected can be defined by a force equilibrium between a pneumatic force and a force caused by, for example, a weight force (Gewichtskraft). In this case, the pneumatic force is generated by the air flow between the substrate surface to be measured and the flexibly air-mounted element. The force of weight depends on the mass of the measuring head with air-mounted elements and sensors and possibly holding members. In doing so, the force of weight and the force of the pneumatic are opposed to each other, where the force of the pneumatic is increased, for example, by increasing the air flow in order to increase the measuring distance. In addition, the dynamic stability of the air support can be improved by the opposing forces.

  A force equilibrium can also occur between a pneumatic force and another force, so that surfaces that are not oriented upwards with respect to gravity can also be measured. Further, another force as a force of weight can inspect a substrate surface that is not oriented downward with respect to gravity. For example, such a substrate surface can be inspected by pressing the measuring head from below using a vacuum suction device, in which case the measurement interval is, on the other hand, (a) a pneumatic Depending on the balance of force between the normal force and the gravity of the measuring head, and on the other hand, between (b) the pneumatic force and the upwardly oriented pressing force of the vacuum suction part Determined by force balance. Naturally, as long as the measuring head is pressed against the surface of the substrate at a suitable angle, the surface can be inspected, whether it is a vertical surface or an oblique surface. Of course, another means for generating a force may be used as the vacuum suction device.

  According to an embodiment of the invention as claimed in claim 2, it additionally comprises a positioning system coupled to the holding member and / or the substrate to be inspected so that the sensor is relative to the surface. Positioning is possible.

  The positioning system may be a so-called surface positioning system in which the sensor can move two-dimensionally relative to the substrate surface. At that time, the substrate may be positioned two-dimensionally, or a measurement head that is a holding member having air-mounted elements and sensors may be positioned two-dimensionally.

  The positioning system is advantageous in that the substrate is movable along a first direction and the measuring head is movable along a second direction, the second direction being angled with respect to the first direction. May be configured to be oriented in the vertical direction. In this way, the two linear motions can be combined to accurately scan the substrate surface in two dimensions.

  Of course, the measuring head may be simply positioned in one dimension relative to the substrate. Even in this case, a plurality of sensors are used in the measuring device or measuring head, and the sensors are arranged, for example, in a line so that the sensors are angled with respect to the linear movement direction, or preferably in the vertical direction. When oriented in the direction, the surface of the substrate can be scanned in a planar shape.

  According to another embodiment of the invention as claimed in claim 3, the measuring device additionally has a fail-safe coating (Notlaufbeschichtung) which is configured on the air-mounted element. This should be inspected, for example, if an air-mounted element and the substrate surface are inadvertently in mechanical contact due to failure of the blow-air forming device and thereby damage of the air support. The substrate surface has the advantage that it is not impaired. For example, a Teflon film is suitable as the fail-safe coating.

  The fail-safe coating further achieves the advantage that the sensor attached to the air-mounted element can be protected from being damaged by the substrate.

  According to claim 4, the measuring device additionally comprises a bias force generator configured to allow the air-mounted element to be accessible to the surface under a mechanical bias force.

  With such a bias force forming device, the advantage is obtained that the air-mounted element can be particularly well adapted to the three-dimensionally shaped surface of the substrate. In this way, the distance between the air-mounted element or measuring head and the substrate surface to be inspected can be made constant both in time and space. Therefore, if a measuring head having a large number of sensors is used, this sensor can be guided on the substrate surface at a fixed measurement interval relatively easily.

  A bias force forming device acting in the opposite direction relative to the air support can have, for example, a magnetic field forming unit so that the air-mounted element is pressed in the direction of the substrate surface to be inspected by magnetic force. The The magnetic field forming unit can have, for example, one or more electromagnets provided from the layer of the measuring head on the back side of the substrate. A magnetic attractive force is generated by the magnetic member attached to the flexibly air-mounted element during the corresponding current feeding of the electromagnet or magnets. In this way, the air-mounted element can generate an attractive force acting almost flat on the substrate surface, where the flat acting force is in force equilibrium with the aforementioned pneumatic force. Form. The measurement interval can be precisely adjusted by correspondingly fitting the relationship between the pneumatic force and the magnetic attractive force.

  According to the fifth aspect, the bias force generation device is a vacuum suction device. The vacuum suction device has an advantage that the pneumatic air mounting force and the pneumatic vacuum suction device can be easily adjusted to a stable equilibrium state to be advantageous for vacuum suction. As a result, the measuring head can be attached to the substrate surface to be inspected at an accurately determined measuring interval, for example, 10 μm. Thus, as a result of the inherent flexibility of air-mounted elements, the entire measuring head can be adapted almost exactly to the corrugation of the substrate surface to be inspected.

  Using a pneumatic bias force forming device, the bias force forming device can be considered to be a blow air forming device for air support of an air-mounted element, as compared to another means of creating a substantially uniform bias force, which can also be considered. It has the advantage of being able to bind pneumatically. This can be done, for example, by using a Venturi tube or other pneumatic member, so that using only one compressed air or vacuum forming device, the blow air required for the air mount can also be a pneumatic bias force. It is also possible to form a negative pressure necessary for the above.

  According to claim 6, it additionally has at least one distance sensor arranged on the air-mounted element. This has the advantage that the measuring interval can be controlled at least to a predetermined location of the measuring head during operation of the measuring device. Thus, for example, the interval information can be taken into account when evaluating the measurement signal detected by the sensor.

  Advantageously, a large number of distance sensors may be used, so that the respective measuring distances can be detected at a defined number of locations on the measuring head.

  According to claim 7, the distance sensor is an optical distance sensor and / or a capacitive distance sensor.

  A confocal distance sensor is particularly suitable as an optical distance sensor, which, unlike a distance sensor based on the triangulation measurement principle, guides the illumination and measurement beams coaxially. As a result, distance measurements can be performed in a volume region that extends very little in the lateral direction. Moreover, the advantage of the confocal distance sensor is that a very small measuring distance can be measured with high accuracy, ie with a very high depth resolution of the order of μm. Confocal distance sensors are described, for example, in WO 2005/078383 A1, EP 1398597 A1, or DE 19608468 A1. In addition to this confocal sensor, for example, an interference sensor that provides appropriate accuracy with high resolution may be used.

  According to claim 8, the measuring device additionally comprises an adjustment unit connected to the distance sensor and the bias force generator and / or the distance sensor and the blow air generator. This makes it possible to form a closed loop, ie an adjustment circuit with feedback coupling, for height adjustment, so that there is always a constant distance between the air-mounted element or measuring head and the substrate surface to be inspected. It is possible to achieve a predetermined measurement interval.

  Independent claim 9 describes a measuring method for inspecting the surface of a substrate. This measuring method comprises the following steps: a step of moving the measuring device described above relative to the surface of the substrate, wherein the step results in the elasticity of the air-mounted element. , At least one sensor moves at a predetermined measuring distance from the surface.

  The recognition of the invention is that as a result of the flexibility of the air-mounted element, the measuring head of the measuring device can be automatically adapted to the three-dimensional surface structure of the substrate surface. In this way, the distance of the at least one sensor from the surface to be inspected can be made constant both temporally and spatially.

In the following, the invention will be described in detail with the aid of the preferred embodiments shown in the drawings. In the schematic drawing,
FIG. 1 is a cross-sectional view showing that a flexible and pneumatic biased sensor carrier conforms to a wavy surface of a substrate,
FIG. 2 shows a plan view of the sensor carrier shown in FIG.

  It should be noted here that the reference numerals of corresponding components in the drawings differ only in the first number.

  FIG. 1 shows a measuring device 100 according to an embodiment of the invention, which has a flexible sensor carrier 120, which uses a surface positioning system 115, It is possible to move on the surface 141 to be inspected of the substrate 140. At that time, positioning can be performed within a positioning plane formed by the x-axis and the y-axis.

  The measuring device 100 has a holding member 110, which is the holding arm 110 according to the embodiment shown here. Two attachment members 111 are formed on the holding arm. The flexible sensor carrier 120 is coupled to the mounting member 111 via one solid joint (Festkoerpergelenk) 112. The advantage of attaching the flexible sensor carrier 120 using the solid joint 112 is that the sensor carrier 120 and both attachment members 111 can be manufactured integrally, for example, by a micromechanical structuring method. Of course, any other suspended or mechanical coupling member may be used in place of the solid joint 112.

  A plurality of sensors 130 are mounted on the flexible sensor carrier 120, and the plurality of sensors 130 are provided in a line along the x-axis. Each sensor 130 is any sensor, such as an optical, capacitive and / or inductive sensor. The sensors 130 may be provided flat, so that the surface 141 can be scanned particularly effectively by operating a number of sensors 130 simultaneously.

  The flexible sensor carrier 120 further has several blow air channels 131 that are pneumatically coupled using a blow air generator 132 in a manner not shown. By correspondingly applying compressed air to the blow air channel 131, an air flow is formed, and this air flow flows out from the lower opening of the blow air channel 131 in the direction of the substrate surface 141. In this way, an air cushion is formed between the lower surface of the flexible sensor carrier 120 and the surface 141, and this air cushion is formed on the surface 141 to be inspected on the air layer of the sensor carrier 120. Produce. The flexible sensor carrier 120 is also referred to as an air mounted element 120 in connection with the above description.

  The side surface of the air-mounted element 120 on the side of the surface 141 to be inspected has a so-called fail-safe coating 121. According to the embodiment described here, the fail-safe coating is a Teflon layer 121 that damages the sensor 130 and / or the surface 141 of the substrate if the blow-air generator 132 fails due to an error. To prevent it.

  As can be seen from FIG. 1, for the sake of easy understanding, the waveform of the surface 141 of the substrate is strongly exaggerated in FIG. Here, the air-mounted element 120 can be adapted to corrugation (irregularity) on the surface 141 based on the inherent flexibility or elasticity of the element. In this way, all sensors 130 can be positioned on the surface 141 at approximately the same measurement interval, regardless of the waveform of the substrate surface 141 as shown. This is also the case for the movement of the flexible sensor carrier 120, in which the air-mounted element 120 can dynamically adapt to the three-dimensional structure of the surface 141.

  Therefore, when using a corresponding elastic material for the air-mounted element 120, there is actually no problem and the largest height of 50 μm to 150 μm between the wave crest and wave trough along the z-axis direction. The corrugated surface can be compensated for by a corresponding adaptation of the flexibly air-mounted element 120. In so doing, the high flexibility of the air-mounted element 120 makes it possible to adapt to corrugations of relatively short distances in a plane parallel to the x-axis and the z-axis.

  In order to improve the ability of the flexibly air-mounted element 120 to fit, in particular, short distance corrugations, an inlet 133 is additionally formed in the flexibly air-mounted element 120. The inlet is pneumatically coupled to the vacuum forming device 134 in a manner not shown. In this way, apart from the force of the weight of the flexible sensor carrier 120 acting in the direction of the substrate 140, a suction force for pulling the sensor carrier 120 in the direction of the substrate 140 is additionally formed. In this case, at a predetermined measuring distance, it is formed on the one hand between the tensile weight force and the vacuum suction force, and on the other hand, the tensile weight force and the blow air generated from the blow air channel 231. The force balances with the repelling air mount force. By appropriately selecting the ratio of these forces, the measurement distance between the individual sensor 130 and the substrate surface 141 can be adjusted. For this reason, both the blow air generator 132 and the vacuum forming device 134 are coupled to the adjustment unit 137.

The air-mounted element 120 can be configured using, for example, thin glass having a required flexibility. The flexibly air-mounted element may be at least partially made of a plastic such as polyvinyl chloride (PVC), or a fiber reinforced material such as a carbon fiber composite. The advantage of using ceramic, glass or carbon fiber composites for the manufacture of air-mounted elements 120 is that each of these materials can be accurately processed, so that the blow air channel 131 and / or Alternatively, the air inlet 233 can be formed in the flexible sensor carrier 120 with high accuracy.
In particular, the blow air channel 131 can be formed using laser processing. In this way, for example, the blow air channel 131 may be formed to have a diameter of only 4 μm, so that the pneumatic waste volume can be reduced accordingly.

  The aforementioned measuring apparatus 100 can be used, for example, when inspecting a semi-finished liquid crystal display. In doing so, the structure of the conductor tracks mounted on the substrate surface is inspected, with the corresponding substrate having a lateral extent of 300 mm to 400 mm along the substrate surface 141. Naturally, it is also possible to inspect substrates of different dimensions using the air mount described above for the unique flexible sensor carrier 120, in which case all of the results of the adaptability of the flexible sensor carrier 120 are always In the case of the sensor 130, a substantially constant measurement distance can be obtained with respect to the surface to be inspected.

  The advantage of the measuring device 100 described above is that the sensor carrier 120 can be scaled to the size of the surface 141 to be examined each time, depending on the application. Therefore, according to different inspection tasks, it is possible to produce an appropriate measuring device 100 that can dynamically adapt to the waveform of the surface to be inspected as a result of the flexibility of the sensor carrier 120 being used. it can.

  FIG. 2 shows a plan view of the sensor carrier 120 shown in FIG. According to the illustrated embodiment, three sensors 230 are integrated in the sensor carrier 220. Of course, more sensors 230 may be used, so that parallel scanning allows the surface of the substrate to be inspected particularly efficiently, i.e. at a particularly high speed.

  As can be seen from FIG. 2, each sensor 230 is provided with a large number of fine blow air channels 231 provided on the two intake ports 233 and on the left and right sides of each sensor 230. According to the embodiment described here, two air inlets 233 are formed immediately beside the sensor 230. For example, the blow air channel 231 is provided on the outer side. At a given measurement interval, any force can be used to balance the force between tensile gravity and vacuum suction force on the one hand and tensile weight force on the other hand and the repulsive air mount force. Of course, other geometric arrangements may be used. In this way, the sensor carrier 220 can be arranged at a stable height even with corrugation (irregularities) on the surface of a relatively short distance.

    Further, as can be seen from FIG. 2, a distance sensor 235 is further provided in the sensor carrier 220. The distance sensor is connected to an adjustment unit (not shown in FIG. 2) (see reference numeral 137 in FIG. 1). As a result, the measurement distance between each sensor and the surface to be inspected is accurately adjusted, It can also be maintained during the measurement operation. As each distance sensor, an optical or capacitive sensor distance sensor may be used. A confocal distance sensor is particularly suitable as an optical distance sensor, which, unlike a distance sensor based on the triangulation measurement principle, guides the illumination and measurement beams coaxially. As a result, distance measurements can be performed in a volume region that extends very little in the lateral direction.

  The embodiment described here is merely an explanation of each possible variant embodiment of the present invention. The requirements of each individual embodiment can also be combined with each other in an appropriate manner, so that a person skilled in the art discloses a number of different embodiments according to each variant disclosed herein. Can be considered.

A cross-sectional view of a flexible and pneumatic biased sensor carrier that fits the wavy surface of the substrate Plan view of the sensor carrier shown in FIG.

Explanation of symbols

Reference Sign List 100 Measuring Device 110 Holding Member, Holding Arm 111 Mounting Member 112 Solid Joint 115 Surface Positioning System 120 Air Mount Element, Flexible Sensor Carrier 121 Fail Safe Coating, Teflon Layer 130 Sensor 131 Blow Air Channel 132 Blow Air Generator 133 Intake Port 134 Vacuum generator 137 Adjustment unit 140 Substrate 141 Surface 220 Air mount element, flexible sensor carrier 230 Sensor 231 Blow air channel 233 Air intake port 235 Distance sensor

Claims (9)

In the measuring device for inspecting the surface (141) of the substrate (140),
Measuring equipment
A holding member (110);
Air-mounted elements (120, 220),
The holding member (110) and the air-mounted element are flexibly coupled, and the air-mounted element is movable at a predetermined distance from the surface (141) of the substrate (140),
The air mounted element (120, 220), the inspection with a surface (141) to be pre-Symbol substrate (140) is capable of forming an air support,
Before SL air mounted element (120, 220) has a resilient, is adaptable to undulations of the surface (141),
Having at least one sensor (130, 230);
Characterized in that said sensor (130, 230) is configured such that the attached to the air-mounted element (120, 220), inspects the surface (141) of the previous SL substrate (140) A measuring device. In addition,
A positioning system (115) coupled to the holding member (110) and / or the substrate (140) to be inspected;
The measuring device according to claim 1, wherein the positioning system (115) allows the sensors (130, 230) to be positioned relative to the surface (141). In addition,
3. The measuring device according to claim 1 or 2, further comprising a fail-safe coating (121) configured on the air-mounted element (120). In addition,
The air-mounted element (120, 220) has a bias force forming device (133, 134, 233) configured to be accessible to the surface (141) under a mechanical bias force. The measuring device according to any one of 1 to 3.   The measuring device according to claim 4, wherein the bias force generating device is a vacuum suction device (133, 134, 233). In addition,
6. Measuring device according to claim 4 or 5, comprising at least one distance sensor (235) arranged on an air-mounted element (220).   7. The measuring device according to claim 6, wherein the distance sensor is an optical distance sensor (235) and / or a capacitive distance sensor. In addition,
A distance sensor (235) and a bias force generator (133, 134, 233) and / or an adjustment unit (137) connected to the distance sensor (235) and blow air generator (131, 132, 231). 6. The measuring device according to 6 or 7. In the measuring method for inspecting the surface (141) of the substrate (140), the measuring method is:
A step of moving the measuring device (100) according to any one of claims 1 to 8 relative to the surface (141) of the substrate (140), wherein said at least one sensor (130, 230), said thanks to air mounted element (120, 220) has a resilient, and characterized in that it is moved at a predetermined measurement distance between said surface (141) Measuring method to do.

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