JP4940242B2 - Measuring system for inspecting the surface of a substrate - Google Patents

Description

  The present invention relates to a measuring apparatus for inspecting the surface of a substrate. This measuring device has a sensor, and this sensor can be positioned by a surface positioning system at a predetermined interval with reference to the surface to be measured. The present invention further relates to a measuring system having a plurality of the above measuring devices.

  In the field of flat surface inspection, 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, a method is known in which possible defects in a printed circuit board structure of a substrate used in a liquid crystal display (LCD liquid Crystal Display) can be inspected before the LCD is manufactured. 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 with respect 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 that enables accurate measurement even on a non-planar substrate surface. It is a further object of the present invention to provide a measuring system that can measure an uneven substrate surface particularly speedily.

The first object of the present invention is solved by a measuring system for inspecting the surface of a substrate having the characteristic configuration described in the characterizing part of claim 1. This measuring system has at least two measuring devices for inspecting the surface of a substrate, and each of these measuring devices includes a sensor for detecting the surface and a pneumatic element arranged alongside the sensor. A measuring head is included. The pneumatic element has one inlet opening and at least one outlet opening facing downward. Each of these measuring devices further includes a surface positioning system that accurately positions the measuring head in the xy plane above the substrate and a compressed air generator that is pneumatically coupled to the inlet opening. Therefore, if compressed air is added to the pneumatic element, the measuring head can be positioned at a predetermined height with respect to the substrate. Each measuring device included in the measuring system additionally has a coupling device, which is arranged between the surface positioning system and the measuring head and constitutes this coupling device, The measuring head can be freely tilted at least within a predetermined angle range about the axis oriented in the xy plane. Accordingly, these measuring devices are arranged with each other so that the sensors are arranged along the measurement line.

  The present invention is based on the knowledge that accurate height adjustment of the sensor can be easily performed by supporting the sensor with air on the substrate surface. An air cushion is formed by the air flowing out through the outlet opening, and the measurement head can freely slide on the substrate surface on the air cushion. For this reason, only the xy position of the measuring head with respect to the substrate is determined by the surface positioning system described above. The height of the air cushion is determined by the strength of the air flow, and the vertical distance from the measurement head is determined based on the substrate surface.

  An important advantage of supporting the measuring head with an air cushion is that the sensor height is easily adjusted automatically even when the surface is wavy. This automatic height adjustment is based on the fact that the measuring head is always at a height determined by the thickness of the air cushion, relative to the area of the substrate to be measured.

According to claim 1 , the measuring device additionally comprises a coupling device, which is arranged between the surface positioning system and the measuring head. The advantage of this is that the coupling device described above is configured depending on the inspection task to be processed each time, and apart from the parallel movement of the measuring head parallel to the xy plane, It is possible to move. The coupling device also has a spring element, so that the soft positioning of the sensor can be ensured even if the positioning system moves suddenly.

According to the second aspect of the present invention, the above-described coupling device is configured so that the measurement head can freely move within at least a predetermined movement range along the z direction perpendicular to the xy plane. The advantage of this is that the sensor height relative to the substrate is determined solely by the air cushion. Therefore, the height of the sensor with reference to the substrate can be freely determined by appropriately controlling the drive of the compressed air generator.

According to the first aspect of the present invention, the above-described coupling device is configured so that the measuring head can be freely tilted at least within a predetermined angle range about the axis. Here, this axis is oriented parallel to the xy plane. Advantageously, the coupling device described above allows tilting about any axis parallel to the substrate surface, so that the sensor can be placed at a suitable tilt to prevent irregularities on the substrate surface with short undulations. This sensor can be adapted.

  It should be noted that such a coupling device usually has a plurality of coupling elements each exerting a holding force on the measuring head. Advantageously, the coupling elements are arranged one above the other so that the force lines corresponding to the individual holding forces intersect at the center of gravity of the measuring head. In this way, even if the measuring head suddenly moves in parallel, no rotational moment acts on the measuring head. The inclination of is avoided.

According to a third aspect of the present invention, the coupling device includes an upper coupling element fixedly connected to the pneumatic element, and a lower coupling connected to the upper side via a suspension portion having a joint. Elements. This upper coupling element is positioned along the x and y directions by a positioning system. Since the positioning of the upper coupling element along the z-axis is determined by the pneumatic support described above, the measuring head and thus also the sensor is always maintained at a predetermined distance from the substrate surface to be measured.

According to claim 4 , the suspension with the joint includes at least two rods, the upper ends of these rods being on the upper coupling element and the lower end of the rods. Are connected to the lower coupling element in one ball element. The advantage of the suspension part of this type is that if the rod length is appropriately selected and the ball joint is disposed spatially advantageously, tilting movement about the virtual rotation axis becomes possible. . Here, the rotation axis is located immediately below the sensor. This guarantees that the sensors described above are always placed at predetermined intervals on the substrate surface to be measured, even when tilted.

  When the hanging part having a joint is provided with three rods, it can be tilted about an arbitrary axis oriented parallel to the xy plane or parallel to the substrate surface to be measured. Please be careful. This advantageously allows the spacing between the sensor and the substrate surface to be optimized even when the substrate surface has uneven undulations.

According to claim 5 , the pneumatic element, preferably having an air channel with corresponding inlet openings and outlet openings, is arranged around the sensor. The advantage of doing this is that a uniform force acts on the measuring head along the z-axis direction, so that the air cushion cannot form a rotational moment that can cause the measuring head to tilt. .

According to claim 6 , the at least one outlet opening is a nozzle, wherein the nozzle is configured such that the velocity of the flowing air at least approximately reaches the speed of sound. Such a high flow rate can be obtained by the above-mentioned air nozzle having a hydrodynamically advantageous taper in the nozzle cross section. With such a taper, a high outflow velocity as described above is obtained first, and a good air fluid resistance is obtained second.

  The advantage of the high flow rate as described above is that the pressure ratio in the pneumatic element is small even when the height of the measuring head relative to the substrate surface to be measured changes undesirably. It only changes. For example, in any case, the air pressure does not drop sharply in the pneumatic element. This guarantees that the sensor head cannot undesirably float and land, which guarantees a particularly stable height positioning of the measuring head.

According to claim 7 , the sensor has an optical, capacitive and / or inductive sensor element. Therefore, as described above, the measuring apparatus that performs pneumatic positioning in the height direction can be realized with any sensor type without any particular change.

  The basis of the present invention is that a long line sensor can be obtained simply by arranging a plurality of measuring heads in contact with each other in a predetermined manner. Since this line sensor can be bent in accordance with the shape of a non-flat substrate surface or a corrugated substrate surface, each sensor is automatically positioned at a predetermined interval from the substrate surface to be measured.

  It should be noted that the present invention also includes a measurement system in which a plurality of measurement heads are arranged in a two-dimensional grid. As a result, an area sensor can be obtained in which each sensor is automatically adjusted to a predetermined height by bending in accordance with the shape of the substrate surface which is not flat as in the case of the line sensor described above.

  Additional advantages and features of the present invention will be apparent from the illustrative description of the presently preferred embodiments presented below.

In the drawing, FIG. 1 schematically shows a plan view of a pneumatically supported measuring head and two different sectional views,
FIG. 2 schematically shows a plan view of a measuring device supported by air pressure,
FIG. 3a schematically shows how the sensor is suspended from the upper coupling plate supported by air pressure,
FIG. 3b schematically shows the movement of the suspension shown in FIG. 3a, where the sensor is tilted about a virtual axis of rotation,
FIG. 4 schematically shows a measuring system having four measuring heads arranged in contact with each other on one measuring line.

  It should be noted here that the reference signs of corresponding components in the drawings differ only in the first number and / or are distinguished by the last letter.

  FIG. 1 shows a measuring head 110, supported by air pressure, according to an embodiment of the invention in three different planes. A plan view of the measuring head is shown in the lower left, where the observation direction extends along the z-axis. In the upper part, the measuring head is shown in a sectional view parallel to the xz plane. In the lower right, the measuring head is shown in a sectional view parallel to the yz plane. Here, the x, y and z axes form an orthogonal coordinate system, and each axis is perpendicular to a plane stretched by two other axes.

  The measuring head 110 has a sensor 111, which can be any sensor, for example an optical, capacitive or inductive sensor. The sensor 111 is surrounded by a pneumatic element 112, which constitutes an air channel 113. The pneumatic element 112 has two inlet openings 115 on its upper side, and these openings are pneumatically coupled via a compressed air line to a compressed air generator, for example a pump. The compressed air line and the compressed air generator are not shown in FIG. 1 for the sake of clarity.

  A number of nozzle-like outlet openings are formed under the pneumatic element 112, and these openings form an air flow 195 between the measuring head 110 and the substrate surface to be measured. The An air cushion is formed by the air flow 195 and rests on the air cushion, and the measuring head 110 slides on the substrate 190 at a predetermined interval. Accordingly, an air gap 196 is formed between the lower side of the measurement head 110 and the substrate 190. The thickness of the air gap 196 and thus the spacing between the measuring head 110 and the substrate 190 depends on the strength of the air flow 195.

The coupling between the measuring head 110 and the positioning system takes place via the spring element 130. The spring element 130 is configured as follows. That is,
(A) no relative movement can occur in the x and y directions between the positioning system and the measuring head 10;
(B) A loose connection is made in the z-axis direction between the positioning system and the measuring head 10. This loose connection allows free relative movement between the positioning system and the measuring head 10 at least within a predetermined movement range, starting from a zero position determined by the thickness of the air cushion. Thus, it is ensured by the spring element 130 that the measuring head is accurately positioned only in the xy plane by a positioning system not shown in FIG. It is possible to move to each measuring point on the substrate 190 by correspondingly driving the positioning system.

  Another advantage of coupling the measuring head 10 to the positioning system via the spring element 130 is that the measuring head 110 can be tilted with respect to the positioning system. This tilt can be centered on any axis in the x-axis, y-axis or xy plane. Examples of two tilts about the x-axis and y-axis are shown in FIG. 1 by double arrows, respectively.

  Therefore, it should be confirmed that out of all six degrees of freedom of movement of the measuring head 110 that can be considered in principle, that is, three degrees of freedom of translation along the axes x, y and z, Of the three degrees of freedom of rotational movement about the x, y and z axes, only the translation in the x and y directions and the rotational movement about the z axis fix the positioning system and the measuring head 110. To be excluded by combining them.

  As shown in the lower right cross-sectional view, the spring element 130 further has the property that only a holding force is applied to the measuring head 110 by the positioning system, where the force lines of these holding forces are: It extends along the longitudinal direction of each part of the spring element 130. The spring element 130 and the measurement head 110 are connected so that the lines of holding force acting from different sides intersect at the center of gravity of the measurement head 110. The center of gravity is determined by the starting point of the force vector G, and this force vector is indicated by the gravity of the measuring head 110 acting in the z-axis direction. The advantage of the plurality of lines of force intersecting at the center of gravity of the measuring head 110 is that no rotational moment acts on the measuring head even when the measuring head 110 moves with an impact. The undesired inclination is avoided with high reliability.

  FIG. 2 shows a plan view of a measuring device supported by air pressure, and this measuring device has the measuring head 110 shown in FIG. This measuring head 110 is denoted here by reference numeral 210. A measuring head 210, for example having a sensor 211 and a pneumatic element 212 with two inlet openings 215, is fixed to the positioning system 220 by a spring element 230. The manner of fixing and the degree of freedom of movement of the measuring head 210 left by the spring element 230 are as described in detail above with reference to FIG. Accordingly, the measurement head 210 can be freely positioned parallel to the xy plane by appropriately controlling the positioning system 220 within a predetermined operation region. For this purpose, the positioning system 220 has an x-direction guide part 221 on two opposite sides, and the spring element 230 slides along the x direction by a drive part (not shown) in this x-direction guide part. be able to. The measuring head 210 is slidable along the spring element 230 in the y direction by a driving unit (not shown).

  A compressed air generator 250 is provided to supply the compressed air necessary to form an air cushion between the measuring head 210 and the underlying substrate. The compressed air generator 250 is secured to the frame of the positioning system 220 in the embodiment described herein. In order to reduce the vibration transmitted to the measuring head 210, a material for damping the vibration is provided between the compressed air generator 250 and the positioning system 220 (not shown). Compressed air is supplied to the pneumatic element 212 via a flexible compressed air line 251.

  FIG. 3a shows an advantageous suspension of sensor 311 according to another embodiment of the present invention. By this suspending portion, the sensor 311 can be freely tilted about the virtual rotating pole VP. The suspension includes an upper coupling plate 331 which is positioned in an operating region parallel to the surface to be measured of the substrate 390 by a surface positioning system (not shown). The upper coupling plate 331 is freely movable along the z direction at least within a predetermined movement range. Accordingly, the height of the sensor 311 and the height of the upper coupling plate 331 are determined by the height of the air cushion. This air cushion is formed between the substrate 390 and a pneumatic element (not shown) arranged alongside the sensor 390.

  The suspension part further includes a lower coupling plate 333 that is connected to the sensor 311. The two coupling plates 331 and 333 are connected to each other via two fixed rods 332a and 332b, and the ends of these rods are supported by ball joints 334, respectively. Two ball joints 334 are provided below the upper coupling plate 331. Two ball joints 334 are provided on the upper side of the lower coupling plate 333.

  It should be noted that the above suspension can be realized without the lower coupling plate 333. In this case, the lower two ball joints 334 are provided directly on the sensor 311.

  In the situation shown in FIG. 3 a with the sensor in its initial position, the two fixed rods 332 a and 332 b are arranged symmetrically with respect to the axis of symmetry 338. The two lower ball joints 334 are spaced apart by a distance l. The sensor 311 has a height d along the z direction with the lower coupling plate 333 attached to the sensor 311.

  FIG. 3b schematically shows the case where the sensor 311 (not shown) is tilted from its initial position. Here, depending on the height d, the position of the upper ball joint 334, the length of the two fixed rods 332a and 332b, and the interval l are designed according to the height d. Is tilted around a virtual rotating pole. This guarantees that even if the substrate surface is wavy, the sensor 311 always bends in accordance with the shape of the substrate surface at a predetermined interval.

  Note that the two two-dimensional views of FIGS. 3a and 3b only illustrate the basic manner of operation of the suspension of sensor 311. FIG. A suspension with three fixed rods can also be used to ensure free tilting movement about any virtual axis of rotation. Here, the rotation axis is parallel to the surface of the substrate to be measured, and thus parallel to the xy plane. In this case, the three fixed rods are likewise preferably arranged symmetrically with respect to the axis of symmetry 338 of the sensor suspension in a three-dimensional space.

  FIG. 4 shows a measurement system having four measurement heads 410a, 410b, 410c and 410d arranged in contact with each other on one measurement line. One positioning system is assigned to each of the measuring heads 410a, 410b, 410c and 410d, and this positioning system can position the corresponding measuring head in the xy plane. Alternatively and particularly preferably, at least some of the measuring heads 410a, 410b, 410c and 410d are fixedly connected to each other along the x and y directions. The measurement heads 410a, 410b, 410c and 410d can move in the z-axis direction independently of each other, and can freely move around a virtual rotating pole below the measurement heads 410a, 410b, 410c and 410d. Can tilt to.

  Although not shown, the measurement heads 410a, 410b, 410c, and 410d are supported by air on the substrate 490 and tilted freely so that the individual measurement heads 410a, 410b, 410c or 410d can be bent optimally according to the shape. Here, the substrate has a corrugation exaggerated and exaggerated in FIG. In order to clarify this, the initial position of the central axis of the measuring head before being bent in accordance with the shape of the corrugated substrate surface is shown, and reference numerals 416a, 416b, 416c or 416d are given. Reference numerals 417a, 417b, 417c or 417d are attached to the final position of the central axis of the measuring head after being bent in accordance with the shape of the corrugated substrate surface.

  In the state shown in FIG. 4, the measuring heads 410a and 410b are inclined in the opposite direction to the clockwise direction compared to their initial positions. The measuring head 410c is not tilted, and the measuring head 410d is tilted clockwise compared to its initial position.

FIG. 2 is a plan view and two cross-sectional views of a measurement head supported by air pressure. It is a top view of the measuring apparatus supported by an air pressure. It is a figure which shows a mode that a sensor is suspended from the upper coupling plate supported by an air pressure. It is a figure which shows the motion of the suspension part shown to FIG. It is a figure showing a measuring system which has four measuring heads arranged in contact with each other on one measuring line.

Explanation of symbols

  100 measuring device, 110 measuring head, 111 sensor, 112 pneumatic element, 113 air channel, 114 outlet opening / nozzle, 115 inlet opening, 130 spring element, 190 substrate, 195 air flow, 196 air gap, 210 measuring head , 211 sensor, 212 pneumatic element, 215 inlet opening, 220 positioning system, 221 x direction guide, 230 spring element, 250 compressed air generator, 251 (flexible) compressed air line, 311 sensor, 331 upper coupling Plate, 332a fixed rod, 332b fixed rod, 333 lower coupling plate, 334 ball joint, 338 axis of symmetry, 390 substrate, VP Hypothetical rotating pole, l spacing between lower ball joints, d sensor and combined plate thickness, 410a, b, c, d measuring head, 416a, b, c, d first position of central axis, 417a, b, c, d center axis final position, 490 (extremely bent) substrate

Claims (7)

In a measurement system for inspecting the surface of a substrate,
The measuring system has at least two measuring devices (100) for inspecting the surface of the substrate (190),
Each of the measuring devices (100)
A measuring head (110) having a sensor (111) for detecting the surface and a pneumatic element (12) arranged alongside the sensor (111);
The pneumatic element includes an inlet opening (115) and at least one outlet opening (114) facing downward;
Each measurement device (100) further includes a surface positioning system (220) configured to accurately position the measurement head (110, 210) in the xy plane on the substrate (190);
A compressed air generator (250),
When the compressed air generator (250) is pneumatically coupled to the inlet openings (115, 215) and compressed air is applied to the pneumatic elements (112, 212), the substrate (190) is removed. The measuring head (110, 210) can be positioned at a predetermined height with respect to a reference,
Each measuring device (100) included in the measuring system additionally has a coupling device (130, 230),
The coupling device (130, 230) is arranged between the surface positioning system (220) and the measuring head (110, 210),
The coupling device (130, 230) is configured so that the measuring head (110) can be freely tilted at least within a predetermined angular range about the axis (VP) oriented in the xy plane,
The measurement system characterized in that the measurement devices (100) are arranged with each other so that the sensors are arranged along a measurement line . The coupling device (130) is configured such that the measuring head (110) is freely movable within a predetermined movement range along the z direction perpendicular to the xy plane. ,
The measurement system according to claim 1 . The coupling device is
An upper coupling element (331) fixedly connected to said pneumatic element;
A lower coupling element (333) connected to the upper coupling element (331) via a suspension with a joint,
The measurement system according to claim 1 . The hanging part having the joint includes at least two rods (332a, 332b),
The upper end of the rod is connected to the upper coupling element (331) by one ball element (334), and the lower end is connected to the lower coupling element (331). 333),
The measurement system according to claim 3 . Said pneumatic element (112) is arranged around the sensor (111),
The measurement system according to any one of claims 1 to 4 . Said at least one outlet opening (114) is an air nozzle;
The air nozzle was configured so that the velocity of the flowing air approximately reached the speed of sound.
The measurement system according to any one of claims 1 to 5 . Said sensor (111) comprises optical, capacitive and / or inductive sensor elements,
The measurement system according to any one of claims 1 to 6 .

Images