JP5917994B2 - Measuring window structure for polishing equipment - Google Patents

Description

  The present invention relates to a polishing apparatus that polishes the surface of a thin plate-like workpiece such as a silicon wafer, glass, ceramics, or quartz, and in particular, a measurement window structure formed on a surface plate to measure the plate thickness of the workpiece during polishing. About.

  As a general example of a polishing apparatus for polishing the surface of a thin plate-like workpiece such as a silicon wafer, FIG. 5 shows a double-side polishing apparatus 70 described in Patent Document 1 and Patent Document 3. FIG. 5A is a schematic vertical cross-sectional view of the entire apparatus, and FIG. 5B is a schematic cross-sectional view showing the arrangement of the work 71. The double-side polishing apparatus 70 holds a thin plate-like work 71 on a carrier 72 and polishes the upper and lower surfaces of the work 71 with a rotating upper surface plate 73 and a lower surface plate 74. A polishing pad 75 is attached to the lower surface of the upper surface plate 73, and a polishing pad 76 is attached to the upper surface of the lower surface plate 74. A hook 89 attached to the upper surface plate 73 engages with a driver 86 at the upper end of the drive shaft 83, and the lower surface plate 74 is fixed to the drive shaft 84. Normally, the polishing is performed by rotating the drive shaft 83 and the drive shaft 84 in the opposite directions.

  The plurality of carriers 72 holding the plurality of workpieces 71 are arranged in mesh with the rotating internal gear 77 and sun gear 78, and each operates as a planetary gear. For this reason, each work 71 is polished from above and below in a state of complicated movement due to the revolution and rotation of each carrier 72. The internal gear 77 is driven by the drive shaft 87, and the sun gear 78 is driven by the drive shaft 88. The upper surface plate 73 can be moved up and down by a rod 79, and the work 71 is mounted and collected while the upper surface plate 73 is lifted upward.

  In such an apparatus, since the carrier 72 moves in a complicated manner, the polishing process is uniformly performed on the total number of the plurality of mounted works 71. And the total number of the some workpiece | work 71 with which it mounted | worn can be made into substantially constant board thickness. However, when batch processing is repeated to produce a large number of identical products, the processing conditions slightly change over time, so the same processing operation (predetermined number of revolutions, time, etc.) is the same. Thus, the plate thickness of the work 71 changes depending on the batch.

  Patent Document 2 describes a polishing apparatus that can determine the end point of a polishing operation by measuring the thickness of a workpiece 71 during polishing (during rotation of a surface plate). In this way, even if many batch processes are repeated, as long as the measurement is accurate, a constant plate thickness can be obtained for all the workpieces 71 to be collected.

  FIG. 6 shows a plate thickness measuring apparatus 190 described in Patent Document 2. In the plate thickness measuring device 190, infrared light emitted from the light source 191 is guided to the work 71 through the half mirror 192, the collimating lens 193, and the objective lens 194. Then, infrared rays reflected by the front and back surfaces of the work 71 are received by the light receiver 196 through the objective lens 194, the collimating lens 193, the half mirror 192, and the pinhole 195.

  This measurement system is called a confocal method, and is a method for obtaining a position showing the peak of reflected light by moving the objective lens 194 up and down. Since a strong peak of reflected light is obtained when the focal point is located on the front surface or the back surface of the work 71, the position of the objective lens 194 at the two peaks is measured, and the distance between the two points is set as the plate thickness of the work 71. Can do. Although this method has a drawback that the plate thickness measuring device 190 must be fixed to the upper surface plate 73, the plate thickness can be measured in real time during the polishing process, and the measured value is a predetermined plate. The polishing operation can be finished when the thickness is reached.

  In order to irradiate the work 71 being polished with infrared rays, a measurement hole 81 is provided in the upper surface plate 73, and a window plate 113 is attached thereto. The portion of the window is taken out and shown in FIG. The measurement window structure 110 is a structure that transmits measurement infrared rays through the window plate 113 and isolates the upper and lower surfaces of the upper surface plate 73. In other words, the structure prevents the foreign matter from entering the polishing surface with the workpiece 71 from the measurement hole 81 and prevents the abrasive on the polishing surface side from entering the measurement hole 81.

  The window plate 113 is firmly fixed to the rotating upper surface plate 73 and the lower surface thereof is positioned at substantially the same level as the lower surface of the upper surface plate 73. For this reason, the window plate 113 is formed with a large diameter at the top and a small diameter at the bottom. The measurement hole 81 is formed such that the lower end portion has a small diameter, and the small diameter portion of the window plate 113 is positioned at the small diameter portion of the measurement hole 81. And the seal | sticker is formed by the O-ring 114 in the step part, and is fixed with the screw | thread 115. FIG.

  The window plate 113 needs to be replaced from time to time because the lower surface is worn by the polishing process. In this case, since the window plate 113 is fixed with the screw 115, it can be replaced. However, since the screw 115 is in the hole of the measurement hole 81, there is some difficulty.

  Patent Document 3 describes another polishing apparatus that can determine the end point of a polishing operation by measuring the thickness of a work 71 during polishing (during rotation of a surface plate). This measurement system is one of the so-called light reflection interferometry methods, and measures by changing the wavelength of the light source. In this system, since the measuring device can be placed at a stationary position away from the upper surface plate 73, a practical device can be obtained.

  The measurement window structure 120 described here is shown in FIG. In the measurement window structure 120, a measurement hole 81 is provided in the upper surface plate 73, and the window plate 123 is bonded to the polished surface of the upper surface plate 73 with an adhesive layer 124. For this reason, it is considered very difficult to replace the window plate 123. For example, when the worn window plate 123 is peeled off, there is a high possibility that the nearby polishing pad 75 will be damaged. Further, when bonding again, it is necessary to finish the lower surface of the upper surface plate 73 serving as the bonding surface to a flat surface, and it is difficult to bond the window plate 123 horizontally.

  Patent Document 4 describes another polishing apparatus that can determine the end point of a polishing operation during polishing (during rotation of a surface plate). The system described here is one of the light reflection interferometry methods, and the end point is a point where a specific interference pattern is obtained. The measurement window structure 130 is shown in FIG. In the measurement window structure 130, a measurement hole 81 is provided in an upper surface plate 73, and a plug member 133 made of a transparent material is slidably attached vertically. And the bracket 135 is fixed to the upper part of the upper surface plate 73 with the fixing bolt 136, and the plug member 133 is urged | biased downward using the compression spring 137. FIG.

  The plug member 133 can be easily replaced on the upper surface plate 73 by removing the bracket 135 from the upper surface plate 73. However, since the plug member 133 requires a length that penetrates the upper surface plate 73, the transmission loss of the measurement light increases, and it is considered inappropriate for high-accuracy measurement. The purpose of biasing the plug member 133 by the compression spring 137 is to minimize the transmission loss of the measurement light due to the abrasive slurry by bringing the lower surface of the plug member 133 into contact with the surface of the work 71. However, when the workpiece 71 is held by the carrier 72 as in the double-side polishing apparatus 70, a step is generated due to the difference in the plate thickness between the workpiece 71 and the carrier 72 or the presence or absence of the workpiece 71 or the carrier 72. The biased plug member 133 may collide with the step, and the work 71, the carrier 72, or the plug member 133 may be damaged. Further, since the stopper member 133 is urged downward and brought into contact with the surface of the work 71 to perform measurement, the surface of the work 71 may be damaged by the contact, and desired high-precision processing is performed. I can't.

  As a result, the measurement window structure 110 is superior in that the measurement window structure can be used in the double-side polishing apparatus 70 and the window plate 113 can be replaced. As for the measurement system, the light reflection interferometry is excellent in that the measurement device can be placed at a stationary position away from the upper surface plate 73. However, as a result of the distance between the measurement device and the measurement object being increased, accuracy is increased. High measurement is required. And in order to keep the measurement accuracy high, it is required to position the window plate accurately, and it is also required to always be in the same state even when the window plate is replaced. That is, the distance between the window plate and the workpiece and the level of the window plate are required to be always constant with high accuracy.

JP 2001-191249 A JP 2002-59364 A JP 2010-30019 A JP 2002-170800 A

  Accordingly, an object of the present invention is to install on a surface plate (upper surface plate or lower surface plate) in order to measure the thickness of a workpiece during polishing (during surface plate rotation) in a polishing apparatus for polishing the surface of a silicon wafer or the like. An object of the present invention is to provide a measurement window structure capable of easily replacing a window plate. Another object of the present invention is to provide a measurement window structure capable of always positioning a window plate in an optimum state for measurement. It is another object of the present invention to provide a measurement window structure that can accurately measure a change in the plate thickness of a workpiece in the polishing process and can keep the plate thickness of the workpiece constant even when batch processing is repeated.

In order to solve the above problems, a measurement window structure according to claim 1 of the present invention is a polishing apparatus for polishing a thin plate-like workpiece, and penetrates the front and back of a surface plate to measure the thickness of the workpiece. A measurement window structure formed by attaching a window member to a measurement hole, wherein the window member is a cylindrical portion that can be inserted into the measurement hole, and a window plate provided at one end of the cylindrical portion; A fixing portion provided at the other end of the cylindrical portion, and the fixing portion is fixed to the surface side of the surface plate, and on the surface side of the surface plate, the fixing portion with respect to the surface of the surface plate It is characterized by having an angle adjusting mechanism for reducing the transmission loss of the measuring light by adjusting the mounting angle and relatively changing the angle formed between the surface of the workpiece and the facing surface of the window plate.

  A measurement window structure according to claim 2 of the present invention is characterized in that, in the measurement window structure according to claim 1, the angle adjusting mechanism includes a fixing means provided in the fixing portion. . A measuring window structure according to claim 3 of the present invention is characterized in that in the measuring window structure according to claim 2, the fixing means is a fixing bolt. A measurement window structure according to claim 4 of the present invention is the measurement window structure according to claim 1, wherein the angle adjustment mechanism includes a fixing means and an adjustment means provided in the fixing portion. It is a feature. The measurement window structure according to claim 5 of the present invention is the measurement window structure according to claim 4, wherein the fixing means is a fixing bolt and the adjusting means is an adjustment bolt. . Further, the measurement window structure according to claim 6 of the present invention is the measurement window structure according to any one of claims 1 to 5, wherein the mounting position of the window member is set on the surface side of the surface plate. It further has an axial direction position adjustment mechanism that moves in the axial direction of the measurement hole and changes the distance between the surface of the workpiece and the opposing surface of the window plate. In the measurement window structure according to claim 7 of the present invention, the angle adjustment mechanism also serves as the axial direction position adjustment mechanism.

  In the window structure for measurement according to the present invention, since the entire window member including the window plate is attached or detached on the surface side of the surface plate, the window plate can be easily replaced. At the same time, since the relative angle (parallelism) between the surface of the workpiece and the facing surface of the window plate can be adjusted on the surface side of the surface plate, the accuracy of measurement can be improved. Moreover, since the distance between the surface of the workpiece and the facing surface of the window plate can be adjusted on the surface side of the surface plate, the measurement accuracy can be further improved.

The 1st Example of the window structure for measurement of this invention is shown, (a) is a schematic sectional drawing of the window structure for measurement, (b) is a schematic partial cross-sectional front view of a window member, (c) is this window member. (D) is explanatory drawing which shows angle adjustment of a measurement hole and a window member, (e) is explanatory drawing which shows position adjustment (axial direction of a measurement hole) of a window member. The 2nd Example of the measurement window structure of this invention is shown, (a) is a schematic sectional drawing of a window structure for measurement, (b) is a schematic partial cross-sectional front view of a window member, (c) is this window member. (D) is explanatory drawing which shows angle adjustment of a measurement hole and a window member, (e) is explanatory drawing which shows position adjustment (axial direction of a measurement hole) of a window member. The deformation | transformation of the window member shown in 1st Example is shown, (a)-(c) is a 1st modification, (a) is a general | schematic partial cross section front view, (b) is the outline one of a cylindrical part. Partial cross-sectional front view, (c) is a schematic partial cross-sectional front view and a schematic plan view of a fixed portion. (D)-(f) is a 2nd modification, (d) is a general | schematic partial cross section front view, (e) is a general | schematic partial cross section front view of a cylindrical part, (f) is a schematic one of a fixing | fixed part. It is a partial sectional front view and a schematic plan view. The outline of the thickness measurement in the verification test of the present invention is shown, (a) is an explanatory view showing the outline of the double-side polishing apparatus and the thickness measurement apparatus, (b) is a schematic sectional view of the measurement window structure (first embodiment) ), (C) Schematic sectional view of the measurement window structure (second embodiment), (d) is a graph showing an example of changes in the plate thickness. A double-side polishing apparatus is shown, (a) is a schematic longitudinal sectional view of the whole, and (b) is a schematic transverse sectional view showing the arrangement of carriers and workpieces. It is the schematic which shows an example of the plate | board thickness measuring apparatus containing the conventional window structure for a measurement. It is explanatory drawing of the conventional window structure for a measurement, (a) is the window structure for a measurement described in FIG. 6, (b) (c) is another example of the window structure for a measurement.

  A measurement window structure 10 according to a first embodiment of the present invention is shown in FIG. 1A is a schematic sectional view of the measurement window structure 10, FIG. 1B is a schematic partial sectional front view of the window member 11, FIG. 1C is a schematic plan view of the window member 11, and FIG. FIG. 8E is an explanatory view showing angle adjustment between the window 81 and the window member 11, and FIG. 9E is an explanatory view showing position adjustment between the measurement hole 81 and the window member 11.

  The measurement window structure 10 is formed by providing a measurement hole 81 penetrating the front and back of the surface plate 80 of the polishing apparatus and attaching the window member 11 to the measurement hole 81. As shown in (b) and (c), the window member 11 includes a cylindrical portion 12 that can be inserted into the measurement hole 81, a window plate 13 provided at one end of the cylindrical portion 12, and the cylindrical portion 12. It consists of a flange-like fixing portion 14 provided at the end. As the material of the window plate 13, it is necessary to use a substance that transmits infrared rays, but polyvinyl chloride resin, polyethylene terephthalate, or the like can be used. As the material of the cylindrical portion 12 and the fixing portion 14, a lightweight material having a certain degree of strength, good workability, and chemical resistance is preferable.

The window member 11 is attached with the fixing portion 14 fixed to the surface side of the surface plate 80. For this reason, a plurality of screw holes 85 (female screws) are formed on the surface side of the surface plate 80, and a plurality of bolt holes 15 (burst holes) are formed in the fixing portion 14. And the fixing | fixed part 14 can be fixed to the surface plate 80 with the some fixing bolt 55 which is a fixing means. Here, in order to seal between the cylindrical part 12 and the measurement hole 81, a well-known sealing means can be used, and the O-ring 51 can be used in the vicinity of the window plate 13 of the cylindrical part 12. It is also preferable to use a gasket 52 such as a V-ring (registered trademark) between the surface of the surface plate 80 and the fixed portion 14.
In the present embodiment, slurry or washing water enters the inside of the cylindrical portion 12 and accumulates on the upper surface of the window plate 13 (surface attached to the cylindrical portion 12), which hinders measurement. A lid member may be provided at the other end of the cylindrical portion 12 so as not to become a problem. In this case, the lid member is preferably made of a material that transmits infrared rays, similarly to the window member 13.

In the measurement window structure 10 of the present invention, the fixing portion 14 of the window member 11 is fixed to the surface side of the surface plate 80 with fixing bolts 55. Therefore, when the window plate 13 needs to be replaced, the entire window member 11 can be replaced easily.
Moreover, the measurement window structure 10 of the present invention makes it possible to adjust the mounting angle of the fixing portion 14 with respect to the surface of the surface plate 80, thereby changing the angle formed by the facing surface of the window plate 13 with respect to the surface of the workpiece. be able to. That is, as shown in FIG. 1D, the angle θ formed between the axis a of the measurement hole 81 and the axis b of the cylindrical portion 12 can be freely adjusted.
Furthermore, the measurement window structure 10 of the present invention can move the attachment position of the window member 11 in the axial direction of the measurement hole 81, thereby changing the distance between the surface of the workpiece and the facing surface of the window plate 13. Can do. That is, as shown in FIG. 1 (e), the window member 11 can be moved in the direction of the axis a of the measurement hole 81.

  In order to adjust the angle and position, the gasket 52 uses an elastic material (for example, synthetic rubber, natural rubber, etc.), and the fastening force between the plurality of fixing bolts 55, that is, the screwing amount of each fixing bolt 55. Adjust by adjusting individually. For this reason, it is preferable that the number of fixing bolts 55 be at least three in consideration of stability. The fixing bolts 55 are not necessarily arranged on the concentric circles, and are not necessarily arranged at equal intervals. The adjustment angle θ compensates for the manufacturing error of the window member 11 and the installation accuracy between the window member and the peripheral member such as the surface plate, and is usually about 1 °. Further, the amount of movement in the axial direction can be determined as appropriate depending on the screwing amount of the fixing bolt 55 or the screwing amount of the fixing bolt 55 and the thickness and elasticity of the gasket 52.

  A measurement window structure 20 according to a second embodiment of the present invention is shown in FIG. 2A is a schematic sectional view of the measurement window structure 20, FIG. 2B is a schematic partial sectional front view of the window member 21, FIG. 2C is a schematic plan view of the window member 21, and FIG. FIG. 8E is an explanatory view showing the angle adjustment between 81 and the window member 21, and FIG. 9E is an explanatory view showing the position adjustment between the measurement hole 81 and the window member 21.

  The measurement window structure 20 is formed by providing a measurement hole 81 penetrating the front and back of the surface plate 80 of the polishing apparatus and attaching the window member 21 to the measurement hole 81. As shown in (b) and (c), the window member 21 includes a cylindrical portion 22 that can be inserted into the measurement hole 81, a window plate 23 provided at one end of the cylindrical portion 22, and the cylindrical portion 22. It consists of a flange-like fixing portion 24 provided at the end. As the material of the window plate 23, it is necessary to use a substance that transmits infrared rays to be used, but polyvinyl chloride resin, polyethylene terephthalate, or the like can be used. The material of the cylindrical portion 22 and the fixing portion 24 is preferably a lightweight material having a certain degree of strength, good workability, and chemical resistance.

The window member 21 is attached with the fixing portion 24 fixed to the surface side of the surface plate 80. For this reason, a plurality of screw holes 85 (female screws) are formed on the surface side of the surface plate 80, and a plurality of bolt holes 25 (burst holes) are formed in the fixing portion 24. And the fixing | fixed part 24 can be fixed to the surface plate 80 with the some fixing bolt 56 which is a fixing means. Further, a plurality of screw holes 26 (female screws) are formed in the fixing portion 24, and a plurality of adjustment bolts 57 are screwed into the plurality of screw holes 26 so that the tips of the adjustment bolts 57 are positioned on the surface of the surface plate 80. (The tip of the adjustment bolt 57 is in contact with the surface plate). Here, in order to seal between the cylindrical part 22 and the measurement hole 81, a well-known sealing means can be used, and the O-ring 51 can be used in the vicinity of the window plate 23 of the cylindrical part 22. Further, it is preferable to use a gasket 53 such as a V-ring (registered trademark) between the surface of the surface plate 80 and the fixing portion 24.
In this embodiment, slurry or washing water enters the cylindrical portion 22 and accumulates on the upper surface of the window plate 23 (surface attached to the cylindrical portion 22), which hinders measurement. A lid member may be provided at the other end of the cylindrical portion 22 so as not to become a problem. In this case, the lid member is preferably made of a material that transmits infrared rays, similarly to the window member 23.

In the measurement window structure 20 of the present invention, the fixing portion 24 of the window member 21 is fixed to the surface side of the surface plate 80 with fixing bolts 56, as in the measurement window structure 10. Therefore, when the window plate 23 needs to be replaced, the entire window member 21 can be replaced easily.
Further, the measurement window structure 20 can adjust the mounting angle of the fixing portion 24 with respect to the surface of the surface plate 80, as in the case of the measurement window structure 10. The angle formed by can be changed. That is, as shown in FIG. 2D, the angle θ formed by the axis a of the measurement hole 81 and the axis b of the cylindrical portion 22 can be freely adjusted.
Further, the measurement window structure 20 of the present invention can move the attachment position of the window member 21 in the axial direction of the measurement hole 81 on the surface side of the surface plate 80 more than the measurement window structure 10. Thus, the distance between the surface of the workpiece and the facing surface of the window plate 23 can be greatly changed. That is, as shown in FIG. 2 (e), the window member 21 can be moved in the direction of the axis a of the measurement hole 81.

In order to adjust the angle and the position, the fixing portion 24 includes a plurality of screw holes 26 (female screws) in addition to the plurality of bolt holes 25 (bucker holes). Then, an adjustment bolt 57 is screwed into each screw hole 26, and the tip of the adjustment bolt 57 is positioned on the surface of the surface plate 80. As a result, the angle and position of the window member 21 can be adjusted by individually adjusting and adjusting the screwing amount of each adjustment bolt 57. This adjustment can be finely adjusted more accurately only by the screwing amount of the adjusting bolt 57.
After the adjustment is completed, the fixing bolts 56 are screwed into the screw holes 85 provided in the surface plate 80 to fix the fixing portion 24 of the window member 21 to the surface plate 80. In this case, even if the fixing bolt 56 is loosened, the adjustment bolt 57 maintains the angle and position of the window member 21, and thus the posture can be maintained more stably.

  In the measurement window structures 10 and 20, the window members 11 and 21 can be made detachable from the cylindrical portions 12 and 22 and the fixing portions 14 and 24, respectively. Although two modifications of the window member 11 are shown in FIG. 3, the window member 21 can be similarly modified.

  FIGS. 3A to 3C show a window member 31 which is a first modified example, FIG. 3A is a schematic partial cross-sectional front view of the assembled window member 31, and FIGS. With the cylindrical portion 32 and the fixed portion 34 removed, (b) is a schematic partial sectional front view of the cylindrical portion 32, and (c) is a schematic partial sectional front view and schematic plan view of the fixed portion 34. is there. The cylindrical portion 32 is provided with a window plate 33 at one end and a male screw 36 at the other end.

A screw hole 37 (female screw) is provided at the center of the fixing portion 34. That is, the cylindrical part 32 and the fixed part 34 are formed in the form of a screw-in type flange joint. Therefore, the cylindrical portion 32 and the fixing portion 34 can be attached to or detached from each other by screwing the male screw 36 and the screw hole 37 together. As a result, when the window plate 33 needs to be replaced, or when the tubular portion 32 or the fixed portion 34 is damaged or deteriorated, only the member can be easily and economically replaced.
The fixing portion 34 is provided with a plurality of bolt holes 35. In addition, when this deformation is applied to the window member 21, a plurality of screw holes are provided in the fixing portion 34.

  FIGS. 3D to 3F show a window member 41 which is a second modified example, FIG. 3D is a schematic partial cross-sectional front view of the assembled window member 41, and FIGS. In a state where the cylindrical portion 42 and the fixing portion 44 are removed, (e) is a schematic partial sectional front view of the cylindrical portion 42, and (f) is a schematic partial sectional front view and a schematic plan view of the fixing portion 44. is there. The cylindrical portion 42 is provided with a window plate 43 at one end and a flange portion 46 at the other end.

Further, a part of the flange-shaped fixing portion 44 provided with the cylindrical hole 47 (buck hole) in the center is cut out in the radial direction from the cylindrical hole 47 toward the outer periphery, and a gap α is formed. The gap α can be narrowed by tightening the fixing bolt 48. Accordingly, the fixing portion 44 can be attached to the cylindrical portion 42 by being positioned at the other end through the cylindrical portion 42 in the cylindrical hole 47 of the fixing portion 44 and tightening the fixing bolt 48. Further, it can be removed by loosening the fixing bolt 48. Therefore, when it is necessary to replace the window plate 43, or when the tubular portion 42 or the fixed portion 44 is damaged or deteriorated, only the member can be easily and economically replaced.
The fixing portion 44 is provided with a plurality of bolt holes 45. In addition, when this deformation is applied to the window member 21, a plurality of screw holes are provided in the fixing portion 44.

The measurement window structure of the present invention was provided in a polishing apparatus, and a verification test was performed to determine the end point of the polishing process by measuring the plate thickness during polishing of the workpiece.
(Test equipment)
FIG. 4 (a) shows an outline of the test facility. The polishing apparatus is a double-side polishing apparatus 70, and the window member 11 or the window member 21 is attached to the upper surface plate 73 to configure the measurement window structure 10 or the measurement window structure 20. For this reason, the upper surface plate 73 is provided with a measurement hole 81 penetrating the front and back, and a plurality of screw holes 85 for attaching the fixing bolts 55 and 56. A plurality of workpieces 71 having a diameter of 300 mm can be mounted on the double-side polishing apparatus 70.

(Thickness measurement)
The plate thickness measuring device 90 employs a kind of light reflection interferometry. That is, infrared light having a wavelength of 1300 nm oscillated by the laser oscillator 91 is irradiated from the laser head 92 to the work 71 through the window member 21, and the reflected light is received, and the interference intensity with other reflected light is measured. The obtained data is sent to the data analysis unit 93, and the plate thickness is calculated in real time. The measured plate thickness is sent to the control unit 94 of the double-side polishing apparatus 70, where the end point is determined and the polishing process is terminated. While the window member 11 rotates once with the upper surface plate 73 in a few seconds, the laser head 92 can be installed at a stationary position about 1 m away from the window member 11.

(Attachment and Adjustment of Window Member) [First Example / FIG. 4B]
The attachment and adjustment of the window member 11 were performed according to the following procedure.
1) The calibration work 71 is positioned directly below the laser head 92.
2) Temporarily attach the window member 11 to the upper surface plate 73 (insert the window member 11 into the measurement hole 81).
3) Using the fixing bolt 55, the height of the window member 11 is adjusted by adjusting the screwing amount of the fixing bolt 55 as shown in FIG. This adjustment is performed in a state where the upper surface plate 73 is lifted upward by the rod 79, and the relative position between the lower surface of the window plate 13 and the lower surface of the upper surface plate 73 is finely adjusted.
4) The upper surface plate 73 is lowered to the position at the time of processing, and the upper surface plate 73 is rotated so that the measurement hole 81 is positioned below the laser irradiation point.
5) Irradiate the work 71 with infrared rays from the laser head 92 through the window plate 13.
6) Using the fixing bolt 55, the angle of the window member 11 is adjusted by finely adjusting the screwing amount of the fixing bolt 55 as shown in FIG. In this adjustment, the laser reflection intensity is monitored and adjusted so as to be equal to or higher than a predetermined intensity.
7) When the adjustment is completed, final fixing with the fixing bolt 55 is performed. (The fact that the fixing bolt 55 is screwed into the screw hole 85 also serves as fixing.)

(Attachment and Adjustment of Window Member) [Second Example / FIG. 4C]
The window member 21 was attached and adjusted in the following procedure.
1) The calibration work 71 is positioned directly below the laser head 92.
2) Temporarily attach the window member 21 to the upper surface plate 73 (insert the window member 21 into the measurement hole 81).
3) The height of the window member 21 is adjusted by adjusting the screwing amount of the adjustment bolt 57 using the adjustment bolt 57 as shown in FIG. This adjustment is performed in a state where the upper surface plate 73 is lifted upward by the rod 79, and the relative position between the lower surface of the window plate 23 and the lower surface of the upper surface plate 73 is finely adjusted.
4) The upper surface plate 73 is lowered to the position at the time of processing, and the upper surface plate 73 is rotated so that the measurement hole 81 is positioned below the laser irradiation point.
5) Irradiate the work 71 with infrared rays from the laser head 92 through the window plate 23.
6) Using the adjustment bolt 57, the angle of the window member 21 is adjusted by finely adjusting the screwing amount of the adjustment bolt 57 as shown in FIG. In this adjustment, the laser reflection intensity is monitored and adjusted so as to be equal to or higher than a predetermined intensity.
7) After the adjustment is completed, the window member 21 is finally fixed by screwing the fixing bolt 56 into the screw hole 85.

(Test results)
FIG. 4D is an example of the plate thickness measurement obtained by measuring the workpiece 71 in real time during polishing, and shows that the plate thickness is about 760 μm to about 740 μm in about 50 minutes. Yes. This result means that the plate thickness of the work 71 can be reliably polished with an accuracy of 1 μm, and even when batch processing is repeated to produce a large amount of the same product, high quality can be guaranteed. .

  As described above, the measurement window structure of the present invention can easily replace the window plate on the surface side of the surface plate. In addition, the relative angle between the workpiece and the window plate (parallelism between the workpiece and the window plate) and the position (distance between the workpiece and the window plate) are set as the relative angle between the surface of the surface plate and the fixing member (the surface plate). By adjusting the parallelism between the surface and the fixed member) and the position (distance between the surface of the surface plate and the fixed member), it is always possible to obtain the optimum state for measurement, and the transmission loss of the measurement light irradiated or reflected on the workpiece Can be measured in a very small state. For this reason, the measurement window structure of the present invention can also be applied to a measurement system in which the measurement device is installed at a position away from the measurement target. Regardless of the type of polishing equipment and measurement equipment, the workpiece thickness can be accurately measured in real time during polishing, and the workpiece thickness can always be finished with high accuracy. it can.

In the above embodiment, the case where the present invention is applied to a double-side polishing apparatus has been described. However, the present invention can be applied to other apparatuses (for example, a single-side polishing apparatus) without departing from the principle of the present application.
Moreover, although the said Example demonstrated by the content which comprised the window members 11 and 21 with the several member, the window members 11 and 21 (The cylindrical part 12 (22), the window board 13 (23), the fixing | fixed part 14 ( 24)) may be integrally formed of a material that allows measurement light (infrared rays) to pass therethrough.

  In the above embodiment, the fixing bolt is used as the means for adjusting the mounting angle of the fixing portion with respect to the surface of the surface plate. However, as another means for adjusting the mounting angle of the fixing portion with respect to the surface of the surface plate, Alternatively, it can be a combination of a headless bolt (planted bolt or hexagon socket head bolt) and two nuts. And the objective of this application can also be achieved by adjusting and fixing by pinching | interposing a flange-shaped fixing | fixed part with two nuts.

  In the above embodiment, the fixing bolt is used as a means for adjusting the mounting angle of the fixed portion with respect to the surface of the surface plate. However, as another means for adjusting the mounting angle of the fixing portion with respect to the surface of the surface plate, direct fixing is possible. A linear guide bearing is provided on the fixed part using a dynamic guide mechanism, a guide rail that engages the linear guide bearing is provided on the surface of the surface plate, and the linear guide bearing and the guide rail are relative to each other. The object of the present application can also be achieved by adjusting the angle and / or axial position by movement and locking the movement of the linear guide mechanism by the locking means that can lock the movement of the linear guide mechanism.

  In addition, although the adjustment bolt is used as the means for adjusting the mounting angle of the fixed portion with respect to the surface of the surface plate, the spacer is used as another means for adjusting the mounting angle of the fixing portion with respect to the surface of the surface plate. It is possible to adjust the mounting angle of the fixed part with respect to the surface of the surface plate by inserting spacers at several places between the surface of the platen and the fixed part and adjusting the distance between the surface of the surface plate and the fixed part as appropriate. is there. In this case, it is preferable to adjust the insertion amount (thickness) of the spacer for each insertion location.

  Furthermore, on the surface side of the surface plate, from the viewpoint of adjusting the relative angle (parallelism) between the workpiece surface and the facing surface of the window plate and / or the distance between the workpiece surface and the facing surface of the window plate, Using a leveling mechanism, a plurality of guide rails having a moving direction in the plane direction on the surface of the surface plate are provided radially around the measurement hole, and the upper side of the bearing engaged with the guide rail is directed downward toward the measurement hole. An inclined tapered block is connected, a screw shaft is provided in parallel to the guide rail at the rear end of the block, a bracket that supports the screw shaft is provided at the end of the guide rail opposite to the measurement hole, and the bottom surface of the fixed portion The mounting angle of the fixed part relative to the surface of the surface plate is adjusted by making the taper shape relative to the inclined shape on the upper side of the block, adjusting the screwing amount of the screw shaft individually and adjusting the distance between the surface of the surface plate and the fixed part as appropriate. Rukoto is possible.

10, 20 Measurement window structure 11, 21, 31, 41 Window member 12, 22, 32, 42 Cylindrical portion 13, 23, 33, 43 Window plate 14, 24, 34, 44 Fixed portion 71 Work 80 Surface plate 81 Measuring hole

Claims (7)

In a polishing apparatus for polishing a thin plate-like workpiece, a measurement window structure formed by attaching a window member to a measurement hole penetrating the front and back of a surface plate in order to measure the plate thickness of the workpiece ,
The window member includes a cylindrical portion that can be inserted into the measurement hole, a window plate provided at one end of the cylindrical portion, and a fixing portion provided at the other end of the cylindrical portion. The fixing part is fixed to the surface side,
On the surface side of the surface plate, the mounting angle of the fixed portion with respect to the surface of the surface plate is adjusted, and the angle between the surface of the workpiece and the facing surface of the window plate is relatively changed to change the measurement light beam. A measuring window structure having an angle adjusting mechanism for reducing transmission loss .   The measurement window structure according to claim 1, wherein the angle adjustment mechanism includes a fixing means provided in the fixing portion.   The measurement window structure according to claim 2, wherein the fixing means is a fixing bolt.   The measurement window structure according to claim 1, wherein the angle adjusting mechanism includes a fixing unit and an adjusting unit provided in the fixing unit.   The measurement window structure according to claim 4, wherein the fixing means is a fixing bolt, and the adjusting means is an adjusting bolt.   On the surface side of the surface plate, it further includes an axial position adjustment mechanism that moves the mounting position of the window member in the axial direction of the measurement hole and changes the distance between the surface of the workpiece and the facing surface of the window plate. The measurement window structure according to any one of claims 1 to 5, wherein:   The measurement window structure according to claim 6, wherein the angle adjustment mechanism also serves as the axial direction position adjustment mechanism.