JP2008100319A - Grind processing method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grind processing method capable of sensing a grind finishing point in grind processing at high accuracy, and obtaining a high-quality product at efficient grind processing, and a grind processing device using the method. <P>SOLUTION: A control object 42 whose surface is a light reflection face 43 is placed at a same level as a grinding face at the time of final finishing, and is provided in parallel to a grinding object 41 in a processing area of a grinding stone for grinding a grinding face of the grinding object. Lights are radiated on the light reflection face 43 of the control object 42 during grinding, and reflection lights 57 from the light reflection face 43 are monitored. The time when variation of the reflection lights 57 is sensed by a contact of the light reflection face 43 and a grinding stone 33 is regarded as a grind finishing point, and the grinding is completed. Therefore, the grind finishing point can be sensed at high accuracy in grinding, so as to realize high accurate and efficient grind processing. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a grinding method and a grinding apparatus for finishing processing by detecting a grinding end point by irradiated light in grinding processing of electronic devices such as semiconductor materials and liquid crystal panels.

  2. Description of the Related Art Currently, a CMP (Chemical Mechanical Polishing) apparatus used in planarization processing of electronic devices has become an important apparatus that determines the quality of products in grinding and polishing processes of semiconductor wafers and liquid crystal display panels. In particular, since electronic device products require a precision of micro-unit tolerances, this device can perform high-precision machining, and at the same time, has the performance to achieve constant high-precision machining. There must be.

  In addition, since the materials to be processed, such as silicon plates for wafers and quartz substrates for liquid crystal display panels, are hard and brittle materials, processing with constant and high accuracy in conventional etching, grinding, and polishing processes. Not only is it difficult to do, it can also damage the material.

  Such a defect occurs in one of the grinding and polishing steps of the production process, resulting in a large number of defective products. In addition, in the case of processing a large material, for example, by performing grinding and polishing by conventional chemical etching, even if the material is not directly damaged, processing time is required, so that the production efficiency is lowered.

  At present, when these electronic devices are indispensable for general household goods, the decrease in yield in the production process as described above adversely affects not only the performance of each company but also the market economy. For this reason, various developments have been made on planarization techniques including this CMP apparatus.

  Among them, JP-A-8-330260 (Patent Document 1) and JP-A-10-112449 (Patent Document 2) as a polishing method and polishing apparatus according to this CMP apparatus, and JP-A-10-10 as a polishing amount measuring apparatus. Japanese Patent No. 260015 (Patent Document 3) is known. Hereinafter, with reference to FIG. 13A, FIG. 13B, and FIG.

  The basic structure of the CMP apparatus shown in FIGS. 13A, 13B, and 14 includes a rotary table 111 having a polishing pad 112 attached to the upper surface, and a polishing object holding unit that holds a polishing object 141 such as a silicon wafer. 121 and a reference object holding unit 122 that holds a reference object 142 to be processed in the same manner as the polishing object 141. In addition, a nozzle 131 that supplies a polishing agent 132 of loose abrasive onto the polishing pad 112 is provided.

  When this apparatus is operated, the polishing agent 132 is supplied from the nozzle 131 to the upper surface of the polishing pad 112, and the upper surface of the polishing pad 112 is rotated while the polishing object 141 and the reference object 142 held by the holding portions 121 and 122 rotate. At the same time, it is polished.

  In this case, the reference object 142 is irradiated with light on the processing surface 143 while being processed simultaneously with the polishing object 141, and the reflected light 154 is received by the light receiving element 152, and the polishing amount is detected. That is, in this apparatus, the in-process measurement for continuously monitoring the processing state of the reference object 142 is performed, and the reflected light 154 that is continuously received is monitored, so that the polishing amount in the current processing is the same as the processing finish. It is determined whether or not the polishing amount has been reached, and the polishing process is terminated by transmitting a stop signal to the drive control unit of the apparatus with the point of time when it is determined that the polishing amount has been reached as the end point of the polishing process.

  The basic structure of the apparatus described above is the same in any of the techniques of Patent Document 1 to Patent Document 3, but the detection means for detecting the end of the polishing process is different, so that point will be described below.

  FIGS. 13A and 13B are schematic configuration diagrams of the polishing method and the polishing apparatus described in Patent Document 1 and Patent Document 2, respectively.

  As for the plate thickness dimension of the polishing object according to the prior art described in Patent Document 1 of FIG. 13A, the reference object 142 is irradiated with light, and the plate thickness Δd is detected from the reflected light.

  Then, the polishing amount is detected from the plate thickness Δd0 at the start of the polishing process and the plate thickness Δd measured at the present time, and this detected polishing amount is detected when the final finished dimensions are processed in advance under the same material and under the same conditions. Comparing the polishing amount, if both are the same, it is determined that the polishing process is completed.

  Here, the thickness Δd is measured by reflecting the light 153 emitted from the light source 151 above the reference object 142 by the reflected light 154 reflected by the upper surface 144 of the reference object 142 and further transmitting from the upper surface 144. This is done by detecting the phase difference from the reflected light 154 reflected on the processed surface 143.

  Next, the apparatus and method described in Patent Document 2 shown in FIG. 13B measure the thickness Δd by an optical interference type film thickness measurement method using the light source 151 as a laser beam. The detail of the D part of the figure is an enlarged view of the interference film thickness meter and shows the shape of the slit 161 used for the measurement. The detail of the E part of the figure is a reference object showing the principle of the interference film thickness meter. FIG.

  In the detailed view of part D in FIG. 6, the laser beam 153 emitted from the light source 151 passes through the slit 161 of the interference film thickness meter and then passes through the upper surface 144 of the reference object 142 to reach the processing surface 143. The reflected laser beam 154 passes through the slit 161 again and is received by the light receiving element 152. Here, the laser beam 153 is transmitted through the inside of the processing surface 143 of the reference object 142 as shown in FIG. E, which is a detailed view of the reference object 142, and measures the change in the amount of reflected light 154 caused by the light interference. Is used to detect the film thickness Δd.

  The reflected light 154 of the laser beam 153 incident on the reference object 142 includes light 154a reflected on the upper surface of the reference object 142, light 154b reflected on the processing surface 143, and grooves formed on the polishing pad 112. There are three types of light 154 c reflected by the surface 115. Among them, the light 154a reflected from the upper surface of the reference object 142 and the light 154d reflected from the processed surface 143 interfere with each other and cancel each time the optical path difference becomes a half wavelength. Further, the light 154d reflected by the groove surface 115 of the polishing pad 112 becomes a disturbance to detect the film thickness, and thus is reduced by the slit 161. Then, the polishing amount is detected from the change in the intensity of the reflected light 154 in the polishing process to detect the end of the process.

  FIG. 14 is a schematic configuration diagram of a polishing amount measuring apparatus described in Patent Document 3. In this apparatus, the reference object 142 is irradiated with the laser beam 151 via the beam splitter 162 and polished using the difference in phase between the reflected lights reflected on the processing surface 143 and the upper surface 144, respectively. The processing amount of the reference object 142 is measured. That is, the laser beam 151 emitted from the light source passes through the beam splitter 162, enters the reference object holding hole 158 directly below, and irradiates the reference object 144. A part of the irradiation light 153 passes through the inside of the reference object 142 and is reflected by the processing surface 143, and a part of the irradiation light 153 is reflected by the upper surface 144 of the reference object 142, and the beam splitter 162. Return to each. Then, these two reflected lights 156 and 157 returning to the beam splitter 162 are changed in optical path by the beam splitter 162 and introduced into the signal processing unit and the position detection unit 172 in the light detection unit 171, where the polishing amount is reduced. Detected.

In any of the above prior arts, the polishing process is monitored by in-process measurement, and the polishing amount is detected from the measurement by the optical interferometry to detect the end of the polishing process.
JP-A-8-330260 JP-A-10-112449 JP-A-10-260015

  In the prior arts of Patent Documents 1 to 3, the optical interferometry used in the detection means in any case can detect the film thickness of the thin film with high accuracy.

  However, unless the light applied to the processing surface 143 of the reference object 142 is efficiently reflected, the film thickness cannot be detected and polished with high accuracy. Further, since the irradiation light 153 for detecting the film thickness is transmitted through the reference object 142 and reflected by the processing surface 143, the reflected light 154 is received by the light receiving element 152. In addition, there is an inconvenience such as attenuation due to reflection or refraction.

  Further, since the reflected light 154 fluctuates due to the rotational movements of the rotary table 111 and the reference object holding unit 122, it is highly likely that a time lag will occur when detecting the end of the polishing process.

  In other words, unless the reflected light 154 from the reference object 142 is reliably detected and the end of the polishing process can be reliably detected, high-precision polishing and a process with a certain accuracy cannot be realized.

  In any case described in Patent Document 1 to Patent Document 3, the polishing pad 112 and the slurry-like free abrasive abrasive 132 are used for polishing, and this abrasive 132 is used as the polishing object 141. Since it uniformly reaches the processing surface 143, it can be uniformly polished, and a highly accurate finish is realized. Therefore, it is more suitable for the final finishing process such as polishing rather than grinding.

  However, in recent years, large-scale materials such as display panels are often processed, and if the abrasive 132 of free abrasive grains, which is advantageous for precise polishing, is used for processing such large materials, it only takes a long processing time. Production efficiency decreases. Moreover, heat is generated when the processing time is extended for a long time, and the heat generated by the polishing process lowers the quality of the product and leads to a decrease in yield. Therefore, in the case of processing a large material, in order to efficiently process to the finished size, it is desirable that the apparatus has a plurality of processing steps including not only polishing processing but also grinding processing.

  In addition, the abrasive 132 using the slurry-like loose abrasive particles is scattered widely by the rotation of the rotary table 111 and the reference object holding unit 122 or the polishing object holding unit 121 during the polishing process. As a result, the light source 151 or the light receiving device 152 for detection is always in a dirty state, hindering detection at the end of processing, and lowering the processing accuracy.

  Therefore, the present invention provides a grinding method and a grinding device capable of detecting a grinding end point in grinding with high accuracy and obtaining a high-quality product by efficient grinding and polishing.

  In order to solve the above problems, the grinding method according to the present invention is such that the reference object whose surface is a light reflecting surface has the same level as the ground surface at the time of final finishing of the object to be ground. And in parallel with the grinding object so as to be located in the processing region of the grinding wheel for grinding the grinding surface of the grinding object, and in this state, the light is reflected on the light reflecting surface of the reference object during the grinding process. And the reflected light from the light reflecting surface is monitored, and when it is detected that the reflected light fluctuates due to contact between the light reflecting surface and the grinding wheel, this is determined by the grinding wheel. It is characterized in that the grinding process is terminated as a grinding end point of the object to be ground.

  According to the present invention, as the grinding process proceeds and the grinding object reaches the final finish dimension, the reference object placed at the same level as the grinding surface of the grinding object comes into contact with the grinding wheel, thereby Since the state of the surface of the reference object changes and the reflected light fluctuates, the end point of grinding can be detected without causing a time lag by capturing the fluctuation of the reflected light.

  Further, as the reference object, a reference object having substantially the same thickness dimension as the final finished thickness dimension of the grinding object may be used.

  In this case, leveling of the reference object with respect to the grinding object becomes unnecessary by simply arranging the grinding object and the reference object before grinding on the same plane.

  Further, as the reference object, a reference thin film may be used in which a metal thin film that reflects light is formed on the surface, and the metal thin film is used as a light reflecting surface.

  In this case, since the light irradiated on the reference object is efficiently reflected by the light reflecting surface, it is easy to detect the fluctuation of the received reflected light, and the grinding end point is reliably detected.

  Further, as the reference object, a reference object in which a colored coating that reflects light is applied to the surface and the colored coating film is used as a light reflecting surface may be used.

  In this case, even if the grinding wheel is slightly in contact with the light reflecting surface of the reference object, the colored coating is peeled off, so that a so-called color sensor can be used for monitoring the reflected light. The increase in the accuracy of detecting the grinding end point can be expected.

  Moreover, you may use the reference target object by which the water repellent process was performed to the light reflection surface as said reference target object.

  In this case, even if foreign matter is scattered on the reflective surface of the reference object during grinding, the reflective surface is subjected to water repellent treatment. There is no possibility that the reflection of the light irradiated to the object on the reflecting surface is obstructed by the foreign matter.

  Moreover, it is good also as performing grinding while removing the light reception obstruction | occlusion factor of the said reflected light which arises during grinding by gas injection.

  In this case, since the scattering of the grinding scraps and the grinding fluid on the optical path of the light reflected by the reflection surface of the reference object is eliminated, the light from the reflection surface of the reference object is easily received.

  Further, every time the grinding process is finished, the grinding wheel is returned to the grinding start point returned from the position at the grinding end point by a distance corresponding to the initial idle feed movement amount and the machining movement amount of the grinding wheel. The next grinding process may be started from the grinding process starting point.

  In this case, regardless of the wear state of the grinding wheel, it is possible to automatically return the grinding wheel to the grinding start point when starting the next grinding process, and it is possible to automate the entire process.

  Further, the grinding apparatus according to the present invention is such that the grinding wheel for grinding the grinding surface of the object to be ground and the surface of the grinding object at the time of final finishing of the grinding object have the same level and the surface of the grinding wheel. A reference object that is arranged side by side with the grinding object so as to be located in the processing region and whose surface is a light reflecting surface, a light irradiation means for irradiating light to the reference object, and the light While monitoring the reflected light emitted from the irradiation means and reflected by the light reflecting surface of the reference object, when detecting the fluctuation of the reflected light, this is regarded as the grinding end point of the grinding object by the grinding wheel Grinding end means for ending grinding with the grinding wheel is provided.

  According to the present invention, high-precision grinding can be performed in the production process, so that the yield can be improved.

  The reference object may have a thickness dimension substantially the same as the final finished thickness dimension of the grinding object.

  In this case, since the reference object only needs to be installed on the same level as the installation surface of the grinding object, the time for installing the grinding object or reference object in the apparatus can be shortened.

  The reference object may be formed with a metal thin film that reflects light on a surface thereof, and the metal thin film may be used as a light reflecting surface.

  In this case, since the light irradiated on the reference object is efficiently reflected by the light reflecting surface, it is easy to detect the fluctuation of the received reflected light, and the grinding end point is reliably detected.

  The reference object may be provided with a colored coating that reflects light on a surface thereof, and the surface may be a light reflecting surface with the colored coating film.

  In this case, even if the grinding wheel is slightly in contact with the light reflecting surface of the reference object, the colored coating is peeled off, so that a so-called color sensor can be used for monitoring the reflected light. The increase in the accuracy of detecting the grinding end point can be expected.

  Further, the reference object may be subjected to a water repellent treatment on its light reflecting surface.

  In this case, even if foreign matter is scattered on the reflective surface of the reference object during grinding, the reflective surface is subjected to water repellent treatment. There is no possibility that the reflection of the light irradiated to the object on the reflecting surface is obstructed by the foreign matter.

  Also, the reference object is very good exchangeable with other reference objects.

  In this case, the reference object can be properly used according to the material of the grinding object for each production process.

  Moreover, you may further provide the gas injection means which removes the light reception obstruction | occlusion factor of the reflected light which arises during grinding.

  In this case, since the scattering of the grinding scraps and the grinding fluid on the optical path of the light reflected by the reflection surface of the reference object is eliminated, the light from the reflection surface of the reference object is easily received.

  In addition, every time the grinding process is finished, the grinding wheel is returned to the grinding process starting point which is returned from the position at the grinding end point by a distance corresponding to the initial idle feed movement amount and the machining movement amount of the grinding wheel. A return means may be further provided.

  In this case, the grinding wheel can be returned to the grinding start point without recognizing the wear amount of the grinding wheel which is different for each process every time the grinding process is completed by the apparatus of the present invention. A new grinding process can be started.

  According to the present invention, since a grinding end point can be detected with high accuracy in grinding, high-precision polishing can be performed efficiently. Therefore, when the present invention is applied to, for example, grinding of a large electronic device, high processing dimensional accuracy can be realized, and at the same time, high-quality products can be efficiently and mass-produced as compared with the conventional one. .

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 8.

  First, a liquid crystal display panel as an example of a grinding object processed by the grinding apparatus according to the present embodiment will be briefly described with reference to FIG. FIG. 1 is a cross-sectional view showing a structure of a liquid crystal display panel of a grinding apparatus.

  Grinding apparatus This liquid crystal panel has the surface (P surface) of the protective substrate 85 with this grinding apparatus after the liquid crystal substrate 81, the liquid crystal 82, the sealing substrate 83, the color filter 84, and the protective substrate 85 are bonded together in this order. Grinded. Since this protective substrate 85 has other members 86 such as a frame laminated on the surface (P surface), the protective substrate 85 is processed to have a flatness defined to a plate thickness of several tens of μm.

  Next, the configuration of the grinding apparatus will be described with reference to FIGS.

  FIG. 2 is a front view of the grinding apparatus, and FIG. 3 is a view taken along line AA in FIG.

  A plurality of liquid crystal panel fixing jigs 21 are radially arranged on the upper surface of the rotary table 11 and fixed by an electromagnetic chuck 13. Further, the reference object fixing jig 22 is fixed by the electromagnetic chuck 13 within the rotation trajectory of the liquid crystal panel fixing jig 21. A liquid crystal panel 41 shown in FIG. 1 as an object to be ground is fixed to the upper surface of the fixing jig 21, and a reference object 42 is fixed to the upper surface of the fixing jig 22 by a vacuum chuck 27. Above the periphery of the turntable 11, a grindstone substrate 32 having a plurality of grinding wheels 33 (12 in the illustrated example) radially arranged on the lower surface is disposed. A liquid crystal panel 41 and a reference object 42 are provided. Is rotated around the center axis 31 of the grindstone substrate. A grindstone arm 36 is mounted on the upper end of the grindstone substrate central axis 31, and the grindstone substrate 32 is configured to move up and down by the grindstone arm 36. The grinding wheel 33 is pressed toward the liquid crystal panel processing surface 44 while being rotated in the direction indicated by the arrow in FIG. 3, while the liquid crystal panel 41 and the reference object 42 on the rotary table 11 are below the grinding wheel 33. The liquid crystal panel 41 is uniformly ground by passing along with the rotation of the turntable 11.

  Above the passage path along which the reference object 42 moves by the rotation of the turntable 11, a light detection unit 51 that detects a grinding end point, a grinding end point detection unit 71, and a drive control unit 72 that stops the grinding process. Is provided.

  The light detection unit 51 includes a light source 58 that irradiates the reflection surface 43 of the reference object 42, and a light receiving element 55 that receives the reflected light 57 that is emitted from the light source 58 and reflected by the reflection surface 43. The light source 58 includes a light emitting diode, an irradiation optical fiber for leading the light from the light emitting diode to the reflecting surface 43 of the reference object 42, and the reflected light that is reflected by the reflecting surface 43 and returned to the ground. A combination of the return optical fiber 52 leading to the exit portion 71 is preferably used. In addition, an optical device such as a condenser lens for adjusting the size and the amount of light of the irradiation light 56 emitted from the light source 58 is provided at an appropriate position of the light detection unit 51. The reflected light 57 emitted from the light detection unit 51 and reflected by the reflection surface 43 of the reference object 42 is guided to the grinding end point detection unit 71 via the feedback optical fiber 52. For example, a photoelectric sensor is provided in the grinding end point detection unit 71, and the fluctuation in the amount of the reflected light 57 received through the feedback optical fiber 52 is constantly monitored during processing to detect the occurrence of the fluctuation. The end point of grinding is detected.

  Further, the light detection unit 51 is provided with an inlet 53 for drawing compressed gas therein and an injection port 54 for injecting the compressed gas toward the reference object 42, and the compressed gas is detected by the light detection unit. By passing through the inside and being jetted onto the reference object 42, it is possible to prevent light reception inhibition factors such as grinding scraps and grinding fluid from adhering to the light detection unit 51.

  Separately, in order to prevent foreign matters such as grinding scraps and grinding fluid from adhering to the light reflecting surface 43 of the reference object 42 or to remove these foreign matters adhering to the light reflecting surface 43, light A blow unit 61 capable of injecting compressed gas toward the reference object 42 is installed near the side of the detection unit 51.

  FIG. 4 is a schematic cross-sectional view showing a state when the fixing jig, the liquid crystal panel, and the reference object are fixed. As shown in FIG. 4, the vacuum chuck 27 includes a porous suction plate 23 fitted in a recess formed on the upper surface of the fixing jigs 21 and 22, and the recess and the fixing jigs 21 and 22. It is composed of one or a plurality of suction holes 24 communicating with the outside, and suction means such as a suction pump and a vacuum pump (not shown). Then, by operating this suction means, the liquid crystal panel 41 and the reference object 42 are fixed to the upper surfaces of the fixing jigs 21 and 22 via the suction plates 23 in the fixing jigs 21 and 22, respectively. Here, since the adsorption plate 23 is in direct contact with the liquid crystal panel 41, it is preferably a porous material having air permeability, no irregularities on the surface, and having rigidity, such as ceramic or resin. It is preferable to use a material that has a low surface roughness and does not adversely affect the surface when it comes into contact. Moreover, you may use what gave many through-holes to the board | plate material with low surface roughness instead of the porous adsorption | suction board 23. FIG.

  Next, the operation of the grinding apparatus according to this embodiment will be described. In addition, it replaces with description of the grinding method which concerns on this invention with this operation | movement description.

  First, the liquid crystal panel 41 is fixed on the fixing jig 21 fixed on the rotary table 11 by the electromagnetic chuck 13, and the reference object 42 is fixed on the fixing jig 22 fixed on the fixing table 11 by the electromagnetic chuck 13. These are fixed by the vacuum chuck 27 of the fixing jigs 21 and 22, respectively.

  After the fixing of the liquid crystal panel 41 and the reference object 42 is completed, the rotary table 11 and the grindstone substrate 32 are rotated, respectively, and then the grindstone substrate 32 is lowered by the grindstone substrate arm 36 to the liquid crystal panel 41 on the grindstone substrate 32. Press. As a result, the liquid crystal panel 41 and the reference object 42 on the rotary table 11 pass under the rotating grinding wheel 33 as the rotary table 11 rotates, and the liquid crystal panel 41 is made uniform by the grinding wheel 33. Grinded.

  During the grinding process, the light detection unit 51 irradiates light to the passage path of the reference object 42, so that the light reflection surface 43 of the reference object 42 detects light each time the turntable 11 rotates once. The light from the part 51 is reflected, and the grinding end point detecting part 71 continues to monitor the fluctuation of the light quantity of the reflected light 57.

  As the grinding process proceeds, the liquid crystal panel 41 is ground to a target thickness, and when the grinding progresses further, the grinding wheel 33 comes into contact with the reflecting surface 43 of the reference object 42. As a result, the surface roughness of the reflective surface 43 changes and the amount of reflected light 57 varies greatly. The fluctuation of the light amount is detected by the light detection unit 51, and this is regarded as a grinding end point, and a grinding stop signal is transmitted from the grinding end point detection unit 71 to the drive control unit 72. When the stop command is issued from 72 to the drive unit such as the rotary table 11 and the grindstone substrate 32, the grinding process is completed.

Next, the fluctuation detection of the reflected light 57 by the above-described light detection unit 51 will be described in detail below.
As shown in FIG. 4, the reference object 42 used here has a mirror surface finish of about 0.01 to Ra0.05 as the surface roughness of the reflecting surface 43, and the thickness dimension is the final finished dimension of the liquid crystal panel 41. Processed to be the same as h. Since the thickness dimension h1 of the liquid crystal panel 41 fixed to the same level as the reference object 42 is larger than the thickness dimension h of the reference object 42 at the start of grinding, the grinding wheel 33 is moved to the reference object 42. And the liquid crystal panel 41 alone is ground by the grinding wheel 33.

  Only when the thickness dimension of the liquid crystal panel 41 reaches the final finished dimension h, the liquid crystal panel 41 is ground on the light reflecting surface 43 of the reference object fixed at the same level as the ground surface at the time of final finishing of the liquid crystal panel 41. The grindstone 33 comes into contact, and the light reflecting surface 43 is cut by the grindstone 33. The reflective surface 43 of the reference object 42 that has been mirror-finished in advance is slightly ground to change the surface roughness. For example, when the surface is changed from Ra 0.01 to Ra 0.3, Compared with the amount of light, the amount of reflected light 57 is drastically reduced. When the amount of the reflected light 57 changes in this way, it is determined that the liquid crystal panel 41 has reached the final finished size, and the apparatus is stopped to finish the grinding process.

  The reference object 42 is not limited to the one described above, and may have a structure as shown in FIGS.

  5 to 7 are longitudinal sectional views when the reference object 42 is fixed to the reference object fixing jig 22. In this example, a thin film is further formed on the light reflecting surface 43 in order to reliably detect the fluctuation of the reflected light 57 from the light reflecting surface 43 of the reference object 42.

  FIG. 5 shows a case where a metal thin film 45 is applied to the processed surface 43 of the reference object 42. For example, a thin film such as Ni or Al that reflects light is formed on the light reflecting surface 43 by plating or coding. Yes.

FIG. 6 shows a specific example of the above-described water-repellent treatment. Here, a water-repellent coating 46 is formed on the reflective surface 42. The water-repellent coating 46 is formed by applying light-transmitting ZrO ₂ having water repellency or a fluorine-based resin to the processed surface 43 of the reference object 42 by vacuum deposition.

  Further, FIG. 7 shows a specific example in which the metal thin film 45 shown in FIG. 5 and the water repellent coating 46 shown in FIG. 6 are combined, and the reflective surface 43 of the reference object 42 is provided with the metal thin film 45, A translucent water-repellent coating 46 is superimposed thereon.

  Even if any of these reference objects 42 described above is used, detection by light becomes efficient, and dirt and foreign matter are less likely to adhere to the light reflecting surface 43 of the reference object 42, so that the reflected light 57 is generated. It becomes difficult to attenuate. Therefore, the detection accuracy of the grinding end point is increased, and a highly accurate grinding process is realized.

<Example>
Embodiments of the apparatus according to the present invention will be described below with reference to FIGS.

  FIG. 8 is an overall perspective view of a grinding apparatus that is an embodiment of the present invention.

  The basic structure of the grinding apparatus according to the present embodiment is the same as that of a conventionally known vertical rotary surface grinder, and in order to further increase the dimensional accuracy of the grinding process, positioning detection means for the grinding object and the grinding tool, A means for detecting a grinding end point is provided.

  A rotary table 11 driven by a motor installed inside the apparatus base 14 and a segment grindstone 35 in which a plurality of grindstones are integrated are installed facing the rotary table 11. The segment grindstone 35 is composed of a circular main body and a plurality of detachable grinding whetstones 33 arranged radially on the main body, and the rotary table 11 and the segment grindstone. The central shafts 12 and 31 are arranged eccentrically with respect to 35, and the segment grindstone 35 rotates around the central shaft 31 on the circumference of the rotating rotary table 11. The segment grindstone 35 can be moved up and down by a ball screw or a linear guide constituting the grindstone tool actuator 34, and is moved to a position to press a grinding object such as the liquid crystal panel 41 during grinding.

  A plurality of liquid crystal panel fixing jigs 21 are radially arranged on the rotary table 11 and fixed by the electromagnetic chuck 13 on the upper surface of the rotary table 11. A liquid crystal panel 41 is fixed to the upper surface of the liquid crystal panel fixing jig 21. Each of the plurality of liquid crystal panel fixing jigs 21 is provided with an air pipe 25 and is connected to a vacuum pump inside the apparatus base 14 via a manifold 26 provided on the central shaft 12 of the rotary table 11. Since the upper surface of the liquid crystal panel fixing jig 21 has suction holes 24 at a plurality of locations and is mirror-finished, the liquid crystal panel 41 is fixed by a uniform suction force by operating the vacuum pump. 21 is fixed.

  A reference object fixing jig 22 is installed on the upper surface of the turntable 11 so as to be positioned on the rotation locus of the liquid crystal panel fixing jig 21. Similarly to the liquid crystal panel fixing jig 21, the reference object fixing jig 22 is provided with an air pipe 25 on the manifold 26, and the reference object 42 is fixed by a suction force.

  FIG. 9 is an enlarged view of a portion B in FIG.

  This apparatus is provided with a rotational position detector 16 that detects the flatness of the rotary table 11 with an optical sensor. In addition, a grinding end point detecting device 74 that detects a grinding end point with light applied to the reference object 42 and a blow unit 61 that injects compressed gas onto the processed surface of the reference object 42 or the liquid crystal panel 41 are provided in the apparatus. It is installed on the wall 15. These can be adjusted in position by the variable arm 63 so that the rotating reference object 42 passes just below.

  Next, the processing order by the grinding apparatus according to the present embodiment will be described.

  First, the fixing jigs 21 and 22 are fixed on the rotary table 11 by the electromagnetic chuck 13, and the liquid crystal panel 41 and the reference object 42 are moved to the fixing jigs 21 and 22 by the vacuum chuck 27 by operating the vacuum pump. Fix it.

  Then, after the rotary table 11 is rotated, the segment grindstone 35 is moved to the position where the liquid crystal panel 41 is pressed by the grindstone tool actuator 34. This starts grinding.

  Here, if a diamond grindstone of # 3000 suitable for grinding hard and brittle materials is used as the segment grindstone 35, efficient grinding can be performed.

  When the grinding process is started, the rotational position detector 16 monitors in real time whether the tilt of the rotary table 11 and the flatness during rotation are appropriate using an optical sensor. Thereby, the liquid crystal panel 41 is ground with an appropriate flatness.

  FIG. 10 is a longitudinal sectional view showing the structure of the grinding end point detection device and the reference object of the grinding apparatus according to the present embodiment.

  The end of grinding is detected by a change in the amount of light irradiated and the amount of reflected light when the grinding end point detection device 74 passes the processed surface of the reference object 42.

  Since this grinding end point detection device 74 is periodically positioned directly above the reference object 42, the reference object through which the light 56 irradiated from the built-in optical fiber 52 passes below is provided. The light is reflected by the upper surface of 42 and received by the optical fiber 52 again.

  At the start of the grinding process, the light quantity of the reflected light 57 on the light reflecting surface 42 of the reference object 42 is constant, but the reference object is obtained when the liquid crystal panel 41 is ground to the same final finishing dimension. The reflective surface 43 of the object 42 is simultaneously scraped by the segment grindstone 35, the surface roughness of the reflective surface 43 changes, and the amount of reflected light 57 is drastically reduced. This change in the amount of light is detected as a grinding end point, and thereafter, a signal is transmitted from the control unit to stop driving of each part.

  Here, in order to surely detect this sudden change in the amount of light, outside air is sucked from the suction port 53 provided in the grinding end point detection device 74, and the reference target is supplied from the injection port 54 through the grinding end point detection device 74. By injecting the compressed gas toward the object 42, foreign matter is prevented from adhering to a detection device such as an optical fiber inside the grinding end point detection device 74. In addition, since a blow unit 61 that prevents foreign matter from adhering to the reflective surface 43 of the reference object 42 is also provided, by reflecting the compressed gas from the blow unit 61 toward the reference object 42, reflection is performed. Grinding waste and grinding fluid can be reliably removed from the surface 43.

  The grinding apparatus according to the above embodiment can be an automatic grinding apparatus by having a control unit that performs numerical control and sequencer control. An example of this automatic grinding apparatus will be described below with reference to FIGS.

  FIG. 11 is a process flowchart of the automatic grinding apparatus. Hereinafter, the process sequence of the automatic grinding method will be described according to the process flowchart.

  First, the liquid crystal panel 41 and the reference object 42 are respectively fixed on the turntable 11 via the fixing jigs 21 and 22.

  Next, the position of the segment grindstone 35 at the start of machining is set. This processing start point is driven by the grindstone tool actuator 34 to lower the segment grindstone 35. For example, the control unit obtains position information of the segment grindstone 35 contacting the liquid crystal panel 41 via a laser sensor, an electric microsensor, or the like. To do. Then, the segment grindstone 35 is once lifted from the liquid crystal panel processing surface 44 in order to set the position offset by a certain distance from the contacted position by the control unit as the processing origin. The control unit recognizes this position as the machining start point (step S1).

  Subsequently, the segment grindstone 35 spaced upward from the reflective surface 43 of the liquid crystal panel 41 is fed in accordance with parameters such as the cutting speed or the cutting feed amount of the segment grindstone 35 programmed in advance at the above-described processing start point. Is done. The segment grindstone 35 descends to a position where it comes into contact with the liquid crystal panel 41 while rotating according to these parameters, and starts machining (step S2).

  As the grinding process, first, rough grinding is performed (step S3), and it is determined whether or not the rough grinding amount set during this time is reached (step S4). If the rough grinding amount has not reached the set amount, the process returns to step S3 to continue the rough grinding. If the rough grinding amount has reached the set amount, medium grinding is performed (step S5).

  Again, it is always determined whether or not the intermediate grinding amount has reached the set intermediate grinding amount (step S6). If not, the process returns to step S5 to continue the intermediate grinding. If the intermediate grinding amount has reached the set amount, the air blowing device and the end point detection device are operated (step S7).

  Next, fine grinding is started with the air blow device and the end point detection device being operated (step S8). Here, when the grinding end point is detected by the light detection device (step S9), the cutting of the segment grindstone 35 is stopped, and the process proceeds to the spark-out process (step 10). If the grinding end point is not detected in step S9, it is determined that the grinding end point has not yet been reached, the process returns to step S8, and precise grinding is continued.

  If it is determined that the spark-out process for a certain time has been completed (step S11), the control unit stores the coordinate position of the segment grindstone 35 at this time, and then adds the segment grindstone to the cutting feed amount of all processes including idle feed. The machining start point is automatically set by increasing the distance corresponding to the amount obtained by adding the wear amount of 35 (step S12). If the spark-out time has not reached the set time, the process returns to step S10 to continue the spark-out.

  If the segment grindstone 35 automatically returns to the next processing start point, the air blow device and the end point detection device are stopped (step S13), and then the automatic operation is terminated (step S14). Then, the next liquid crystal panel is set (step S15), the process returns to step S2, and the next grinding process is started.

  FIG. 12 is a machining process diagram of the automatic grinding apparatus according to the present embodiment.

  The grinding process of the liquid crystal panel 41 in the present embodiment increases the amount of grinding because it must be thinned. Therefore, conventionally, as an efficient process, the type of grinding apparatus or grindstone was changed for each process. On the other hand, in the grinding apparatus according to the present embodiment, the control unit is programmed to reduce the parameters such as the grinding wheel cutting speed step by step, so that one kind of accuracy is not caused by the grinding stone replacement. Multiple grinding processes can be performed with a grindstone.

  In FIG. 12, “(1) Machining start point setting” of O is the origin setting position of the segment grindstone 35, and “(2) Machining start” of O to S indicates idle feeding. In this idle feed process, the segment grindstone 35 is lowered at the grindstone cutting speed f1, and thereafter, grinding is performed at the same grindstone cutting speed f1 from S where the grinding process is actually started to "(3) rough grinding" in the process of M1. By increasing the grindstone cutting speed in these idle feeding and “(3) rough grinding” steps, grinding can proceed without considering the final finished dimensional accuracy, so the processing time is shortened.

  Next, when “(4) medium grinding” starts after the cutting feed amount reaches M1, the grinding wheel substrate cutting speed is lowered to f2. Then, from M2 that has approached the finished machining size, the grinding end point detection device 74 described in the first embodiment is operated, and grinding is performed with the grindstone cutting speed as low as f3 as “(3) precision grinding”. For example, the cutting amount per rotation of the rotary table is set to about 0.1 μm. Thereby, the detection accuracy of the grinding end point detection device 74 is increased, and the grinding end point can be accurately detected.

  In the final “(7) spark-out” step, the cutting feed is stopped and the grinding wheel cutting speed becomes zero. During this time, the segment grindstone 35 automatically increases the distance obtained by adding the grindstone wear amount to the cutting feed amount including the idle feed from O to E from the coordinates at the time point F, and is set as the processing start point. Further, the grinding end point detecting device 74 is also stopped, and F becomes “(10) End of automatic operation”.

  If the grinding wheel cutting speed and the cutting feed amount of each grinding process are programmed in the control unit, highly accurate and efficient grinding is automatically performed, leading to an increase in production efficiency.

  The grinding method and the grinding apparatus of the present invention can be used as a polishing method and its apparatus. And by using fixed abrasives suitable for grinding and polishing objects, not only semiconductor devices but also display devices such as plasma displays or energy devices such as solar cells, glass members that need to be flattened Alternatively, the present invention can also be used in mechanical parts that require nanoscales or precision machine parts such as medical equipment.

It is sectional drawing which shows the structure of the liquid crystal panel made into a grinding target object in the grinding method which concerns on embodiment of this invention. It is a schematic diagram explaining the grinding method which concerns on embodiment of this invention. It is an AA arrow line view in FIG. It is a schematic sectional drawing which shows the state at the time of fixation of a fixing jig, a liquid crystal panel, and the reference object. It is a schematic sectional drawing which shows the other example of the target object for a reference. It is a schematic sectional drawing which shows the other example of the target object for a reference. It is a schematic sectional drawing which shows the other example of the target object for a reference. 1 is an overall perspective view of a grinding apparatus according to an embodiment of the present invention. It is a partial expansion perspective view of the B section shown in FIG. It is a longitudinal cross-sectional view of the grinding | polishing end point detection part of the grinding processing apparatus which concerns on the Example of this invention, and the reference target object. It is a flowchart which shows the process of the automatic grinding apparatus which concerns on the Example of this invention. It is a process diagram of the grinding process of the grinding apparatus concerning the example of the present invention. (A) is a schematic block diagram of the grinding | polishing method and its apparatus which concern on patent document 1, (b) is a schematic block diagram of the grinding | polishing method and polishing apparatus which concern on patent document 2. FIG. It is a schematic block diagram of the direction optical polishing amount measuring apparatus which concerns on patent document 3.

Explanation of symbols

33 Grinding wheel 41 Grinding object 42 Reference object 43 Light reflecting surface 45 Metal thin film 46 Water repellent coating 51 Light detection unit 52 Optical fiber 56 Irradiation light 57 Reflected light 61 Blow unit 71 Grinding end point detection unit 74 Grinding end point detection apparatus

Claims (15)

  The reference object whose surface is a light reflecting surface is a grinding wheel for grinding the grinding surface of the grinding object so that the light reflecting surface is at the same level as the grinding surface at the time of final finishing of the grinding object. In parallel with the grinding object so as to be located in the processing region, and in this state, the light reflecting surface of the reference object is irradiated during the grinding process and the reflected light from the light reflecting surface is monitored, When it is detected that the reflected light has changed due to contact between the light reflecting surface and the grinding wheel, this is regarded as a grinding end point of the object to be ground by the grinding wheel, and the grinding process is terminated. A characteristic grinding method.   2. The grinding method according to claim 1, wherein a reference object having a thickness dimension substantially the same as a final finished thickness dimension of the grinding object is used as the reference object.   3. The grinding method according to claim 1 or 2, wherein a metal thin film that reflects light is formed on the surface as the reference object, and the reference object having the metal thin film as a light reflecting surface is used. .   3. The grinding method according to claim 1, wherein the reference object is provided with a colored coating that reflects light on a surface thereof, and the reference object having a light reflecting surface with the colored coating film is used. .   The grinding method according to any one of claims 1 to 4, wherein a reference object having a light-reflecting surface subjected to a water repellent treatment is used as the reference object.   The grinding method according to any one of claims 1 to 5, wherein the grinding process is performed while removing the light reception inhibition factor of the reflected light generated during the grinding process by gas injection.   Each time the grinding process is finished, the grinding wheel is returned to the grinding start point returned from the position at the grinding end point by a distance corresponding to the initial idle feed movement amount and the machining movement amount of the grinding wheel. The grinding method according to any one of claims 1 to 6, wherein the next grinding process is started from a starting point. A grinding wheel for grinding a grinding surface of an object to be ground;
The ground surface of the grinding object at the time of final finishing is flush with the grinding object so that the surface is at the same level and located in the processing region of the grinding wheel, and the surface is a light reflecting surface. A reference object, and
A light irradiation means for irradiating the reference object with light;
The reflected light emitted from the light irradiation means and reflected by the light reflecting surface of the reference object is monitored, and when the fluctuation of the reflected light is detected, this is used as a grinding end point of the grinding object by the grinding wheel. A grinding end means for ending the grinding by the grinding wheel,
A grinding apparatus characterized by comprising:   The grinding apparatus according to claim 8, wherein the reference object has a thickness dimension substantially the same as a final finished thickness dimension of the grinding object.   The grinding apparatus according to claim 8 or 9, wherein a metal thin film that reflects light is formed on a surface of the reference object, and the metal thin film serves as a light reflecting surface.   10. The grinding apparatus according to claim 8, wherein the reference object is provided with a colored coating that reflects light on the surface thereof, and the colored coating film forms the surface as a light reflecting surface. .   12. The grinding apparatus according to claim 8, wherein the light reflection surface of the reference object is subjected to a water repellent treatment.   The grinding apparatus according to any one of claims 8 to 12, wherein the reference object is replaceable with another reference object.   The grinding apparatus according to any one of claims 8 to 13, further comprising a gas injection unit that removes a light reception inhibition factor of the reflected light generated during the grinding process.   Grinding wheel return means for returning the grinding wheel to the grinding processing start point that is returned by a distance corresponding to the initial idle feed movement amount and processing movement amount of the grinding wheel from the position at the grinding end point every time grinding processing is completed. The grinding apparatus according to claim 8, further comprising:

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