Linear gauge

Abstract

To prevent grinding effluent from entering a probe inlet / outlet of a linear gauge casing.SOLUTION: A linear gauge 1 comprises: a probe 2 used for measuring the height of the top surface of an object to be measured by contacting the tip with the top surface of the object to be measured held on a holding surface 930 of a table 93 and extending perpendicularly to the holding surface 930; a casing 3 having a support surface 30 for supporting the probe 2 vertically movably on the holding surface 930 and having an inlet / outlet 36 for entering / exiting the probe 2; a blowout part 32 blowing air between the probe 2 side and the support surface 30; an exhaust channel 33 formed in the upper part of the casing 3 to exhaust air between the support surface 30 and the side of the probe 2; and an annular water seal part 5 which is located in the lower part of the casing 3 and surrounds the side of probe 2. The water seal part 5 comprises an annular water reservoir 50 surrounding the side of the probe 2 and collects water, and a drain 52 draining water from the lower end of the water reservoir 50. The water seal part 5 prevents fluid from entering the inlet / outlet 36 from the outside.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a linear gauge for measuring the height of the top surface of an object to be measured. [Background technology]

[0002] As disclosed in Patent Document 1, a grinding machine grinds a wafer held by a holding surface with a grinding wheel while measuring the thickness until the wafer reaches a predetermined thickness. The thickness is calculated as the difference between the height of the holding surface and the height of the upper surface of the wafer held by the holding surface. The holding surface height is measured by the height of a probe whose tip is in contact with the holding surface, and the wafer upper surface height is measured by the height of the probe whose tip is in contact with the upper surface of the wafer held by the holding surface.

[0003] Such height measuring instruments move a probe, which extends perpendicular to the holding surface, in a linear motion in the extension direction, and as disclosed in Patent Document 2, are equipped with a casing that forms a gap that supports the probe in a non-contact manner so that it can move linearly, and a water film forming section that forms a water film to cover the side of the probe protruding from the casing, preventing grinding chips from adhering to the probe. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-073785 [Patent Document 2] Japanese Patent Publication No. 2020-118503 Summary of the Invention [Problem to be solved by the invention]

[0005] However, depending on the processing conditions, the centrifugal force of the rotating grinding wheel is applied, and the grinding waste liquid containing grinding chips breaks the water film and enters the gap from the entrance and exit where the probe enters and exits the casing, preventing the linear movement of the probe and making it impossible to measure the normal height. Also, if the device is stopped with the grinding waste liquid remaining in the gap, the grinding chips dry and the probe becomes fixed, making the probe inoperable. Therefore, in a linear gauge, there is a problem of preventing the grinding waste liquid from entering the gap with the entrance and exit where the probe enters and exits the casing and measuring the accurate height of the object to be measured.

Means for Solving the Problems

[0006] The present invention for solving the above problems is a linear gauge that contacts the tip with the upper surface of an object to be measured held on the holding surface of a chuck table and measures the upper surface height of the object to be measured, comprising: a probe extending in a direction perpendicular to the holding surface; a casing having a support surface that supports the probe movably in a direction perpendicular to the holding surface and has an entrance and exit for the probe to enter and exit; an ejection part that ejects air between the side surface of the probe and the support surface; an exhaust passage formed in the upper part of the casing and communicating between the support surface and the side surface of the probe to exhaust the air ejected from the ejection part; and an annular water seal part disposed below the casing and surrounding the side surface of the probe. The water seal part includes an annular water reservoir that surrounds the side surface of the probe and stores water, and a drain port that drains the water from the lower end of the water reservoir. The water seal part prevents the entry of fluid from the outside into the entrance and exit. In the linear gauge according to the present invention, it is preferable that the drain port is formed in an annular shape, and the water drained from the drain port is caused to flow down to the tip of the probe so as to cover the entire side surface of the portion protruding downward from the drain port of the probe.

Effects of the Invention

[0007] The linear gauge according to the present invention is provided with a water seal portion including an annular water reservoir portion that surrounds the side surface of the probe and stores water, and a ring-shaped drain port that drains water from the lower end of the water reservoir portion. This can prevent grinding waste liquid containing grinding chips to which the centrifugal force of a rotating grinding wheel is applied from entering the casing from the inlet / outlet of the probe, and prevent dried grinding chips from adhering to the probe in the gap between the inlet / outlet and the probe. Further, the drain port is formed so as not to cause resistance to the linear movement of the probe in the vertical direction, and by adjusting the water pressure in the water reservoir portion, an air film along the probe as in the prior art becomes unnecessary, and a situation where grinding chips are dried by the air film and adhered to the probe is not caused.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0009] FIG. 1 is an overall perspective view showing an example of a linear gauge 1 according to the present invention, and FIG. 2 is a cross-sectional view of the linear gauge 1. The processing apparatus in which the linear gauge 1 is disposed includes a grinding unit having a grinding wheel provided by a linearly moving chuck table, and a grinding unit capable of positioning a measurement object 90 (see FIG. 2) with respect to the grinding unit. The grinding unit includes a one-axis grinding apparatus, a rough grinding unit and a finish grinding unit, and a two-axis grinding apparatus capable of positioning the measurement object 90 below the rough grinding unit or the finish grinding unit by a rotating turntable, a polishing apparatus that performs polishing on the measurement object 90 with a polishing pad, or a tool cutting apparatus that flattens the measurement object 90 with a swiveling cutting tool, etc.

[0010] The object 90 to be measured shown in FIG. 2 is, for example, a circular semiconductor wafer made of a silicon base material or the like. Note that the object 90 to be measured may be made of gallium arsenide, sapphire, gallium nitride, ceramics, resin, silicon carbide, etc. in addition to silicon, or may be a rectangular package substrate or the like. The upper surface 900 of the object 90 to be measured is a surface to be processed by a grinding wheel (not shown) or the like, and also serves as a surface to be measured whose height is measured by the linear gauge 1.

[0011] As shown in FIG. 2, the object 90 to be measured is in a state of being sucked and held by the chuck table 93. The chuck table 93, which is circular in plan view for example, has a part shown in the figure, and is made of, for example, a porous member or the like and has a substantially flat holding surface 930 for sucking and holding the object 90 to be measured. The holding surface 930 communicates with a suction source such as a vacuum generating device (not shown).

[0012] The linear gauge 1 of the direct-acting type shown in FIGS. 1 and 2 brings the tip 20 (lower end) of the probe 2 into contact with the upper surface 900 of the object 90 to be measured held on the holding surface 930 of the chuck table 93, and measures the upper surface height of the object 90 to be measured. Note that the surface to be measured for height measurement by the linear gauge 1 may be the holding surface 930. The linear gauge 1 shown in FIG. 2 has a probe 2 extending in a direction perpendicular to the holding surface 930 (Z-axis direction), a casing 3 having a support surface 30 that supports the probe 2 so as to be movable in a direction perpendicular to the holding surface 930 and having an entrance / exit 36 for inserting and removing the probe 2, an ejection portion 32 for ejecting air between the side surface of the probe 2 and the support surface 30, an exhaust passage 33 formed in the upper part of the casing 3 and communicating between the support surface 30 and the side surface of the probe 2 for exhausting the air ejected from the ejection portion 32, and an annular water seal portion 5 disposed on the lower side of the casing 3 for surrounding the side surface of the probe 2.

[0013] The probe 2 shown in FIGS. 1 and 2 has, for example, a cylindrical outer shape in this embodiment, and its tip 20 is rounded into a hemispherical shape. The upper end side of the probe 2 is connected, for example, by a fixing nut to the lower surface side of a flat connecting plate 62. And the middle upper side surface of the probe 2 is surrounded by and supported in a non-contact manner by the air ejected from the ejection part 32 formed in the casing 3 shown in FIG. 2.

[0014] The probe 2 can be lifted via the connecting plate 62 by a piston cylinder 64, for example, and can be lowered by its own weight. The piston cylinder 64 includes a piston 640 inside, a cylinder case 641 with a bottom on the proximal end side (-Z direction side), a rod 642 inserted into the cylinder case 641 and having its lower end attached to the piston 640, and at least a first air inlet 643 and a second air inlet 644 for allowing air to flow into the inside of the cylinder case 641. The upper end side of the rod 642 can contact the lower surface of the connecting plate 62, and the proximal end side of the cylinder case 641 is fixed to the upper surface of the bottom plate 121 of the housing 12 that houses the casing 3 and the like inside. In FIG. 1, only the bottom plate 121 of the housing 12 is shown.

[0015] As shown in FIG. 2, an air supply pipe 645 and an air supply pipe 646 communicate with the first air inlet 643 and the second air inlet 644 respectively, and the air supply pipe 645 and the air supply pipe 646 communicate with an air supply source 648 composed of a compressor or the like via a solenoid valve 647.

[0016] When the probe 2 is lifted and separated from the upper surface 900 of the object to be measured 90 by the piston cylinder 64 shown in FIG. 2, with the solenoid valve 647 in a state of communicating the air supply source 648 and the air supply pipe 646, the air supply source 648 supplies air into the cylinder case 641 from the second air inlet 644, thereby lifting the piston 640. Then, by bringing the rod 642 into contact with the lower surface of the connecting plate 62 and further lifting the connecting plate 62, the probe 2 connected to the connecting plate 62 is lifted.

[0017] On the one hand, when lowering the probe 2 to approach the upper surface 900 of the object to be measured 90 by the piston cylinder 64 shown in FIG. 2, the solenoid valve 647 communicates the air supply source 648 with the air supply pipe 645, and the air supply source 648 supplies air into the cylinder case 641 from the first air inlet 643 and discharges air from the second air inlet 644, thereby lowering the rod 642 at a regulated speed, limiting the speed at which the probe 2 descends due to its own weight, and preventing the probe 2 that has descended forcefully onto the object to be measured 90 from contacting and damaging the upper surface 900.

[0018] The casing 3 is fixed to the upper surface of the bottom plate 121 of the housing 12, and a cylindrical vertical hole for accommodating the probe 2 so as to be vertically movable corresponding to the shape of the probe 2 is formed penetrating in the Z-axis direction. The diameter of the vertical hole is set slightly larger than the diameter of the probe 2. And the upper end of the vertical hole in the state where the probe 2 is inserted communicates between the support surface 30 formed on the upper part of the casing 3 and the side surface of the probe 2 and serves as an exhaust passage 33 for exhausting the air jetted from the jetting portion 32 toward the side surface of the probe 2.

[0019] From the entrance / exit 36 formed at the bottom of the casing 3 shown in FIG. 2 and the entrance / exit 123 of the bottom plate 121 communicating with the entrance / exit 36, mainly the lower part of the probe 2 protrudes downward. The casing 3 is provided with a support surface 30 that surrounds the side surface of the probe 2 with a small gap provided and separated from the middle-upper side surface of the probe 2, and a jetting portion 32 composed of a plurality of jet outlets is formed on the support surface 30. Further, an air supply port 35 communicating with the air supply source 648 via a pipe 356 is formed on the outer surface of the casing 3, and the air supply port 35 and each jet outlet of the jetting portion 32 are communicated by an internal flow path 323 formed inside the casing 3.

[0020] For example, as shown in FIGS. 1 and 2, the linear gauge 1 includes a rotation restricting portion 17 that restricts the rotation of the cylindrical probe 2 about the Z axis. The rotation restricting portion 17 includes, for example, a vertically moving magnet 170 that is connected to the lower surface of the connecting plate 62 to which the probe 2 is connected and extends in the extending direction (Z-axis direction) of the probe 2, and, for example, two fixed magnets 173 and 174 that are attached to the side surface of the casing 3 and extend in the axial direction (+Z direction) of the probe 2 and are arranged so as to sandwich the vertically moving magnet 170 with a gap therebetween. A repulsive force acts between the two fixed magnets 173 and 174 and the vertically moving magnet 170 in a direction orthogonal to the elevating direction (Z-axis direction) of the probe 2. That is, the magnetic field of the vertically moving magnet 170 is directed in a direction repulsive to the magnetic field of the fixed magnets 173 and 174.

[0021] Due to this repulsive force, the horizontal distance between the fixed magnets 173 and 174 and the vertically moving magnet 170 is kept constant, and the direction of the vertically moving magnet 170 does not change. Therefore, since the vertically moving magnet 170 with an unchanged direction is connected to the probe 2 via the connecting plate 62, even if the probe 2 is formed in a cylindrical shape, the movement of the probe 2 in the rotational direction can be restricted. In FIG. 2, for the sake of easy understanding, the two fixed magnets 173 and 174 are shown separated from the casing 3. Note that the fixed magnets 173 and 174 may be erected in the Z-axis direction from the bottom plate 121 of the housing 12.

[0022] Note that the linear gauge 1 may not include the rotation restricting portion 17. In this case, for example, the shape of the upper middle portion inserted into the casing 3 of the probe 2 is not limited to a cylindrical shape, and may be a non-rotating shape, that is, a shape that is not a cylinder. Therefore, it may be a polygonal prism or an elliptical cylinder. Also, it may be a columnar shape in which only one surface is formed as a flat surface and the other surfaces are formed as curved surfaces. Correspondingly, the vertical hole of the casing 3 may be formed in the same shape as the probe 2.

[0023] As shown in FIGS. 1 and 2, a scale 63 is disposed at a corner of the lower surface of the connecting plate 62. The scale 63 has its upper end fixed to the lower surface of the connecting plate 62 and extends in the -Z direction parallel to the extending direction (Z-axis direction) of the probe 2. And a reading unit 635 for reading the scale of the scale 63 is disposed in the housing 12 so as to face the scale of the scale 63. For example, the reading unit 635 is an optical type that reads the reflected light of the scale of the scale 63, and the height of the probe 2 can be recognized by the reading value of the reading unit 635.

[0024] In the present embodiment, the housing 12 shown in FIG. 2 includes a bottom plate 121 parallel to the horizontal plane (X-axis Y-axis plane) and a cover 122 (not shown in FIG. 1) covering the upper part of the bottom plate 121. The casing 3, the piston cylinder 64, the scale 63, etc. are accommodated in the cover 122 so that the grinding water spray containing the grinding debris generated during grinding does not adhere to these components.

[0025] As shown in FIG. 2, a water seal portion 5 is disposed on the lower surface of the bottom plate 121 of the cover 122 below the casing 3. The water seal portion 5 includes an annular water reservoir portion 50 in a plan view that surrounds the side surface of the probe 2 and stores water, and a drain port 52 for draining water from the lower end of the water reservoir portion 50.

[0026] The water reservoir portion 50 is a substantially cylindrical cylindrical member, and its upper surface is fixed to the lower surface of the bottom plate 121 by bolts or the like (not shown). The upper end side of the circular through hole penetrating the center of the water reservoir portion 50 in the thickness direction is aligned with the entrance / exit 36 of the casing 3 and the entrance / exit 123 of the bottom plate 121. For example, it has substantially the same diameter as the entrance / exit 36 of the casing 3 and the entrance / exit 123 of the bottom plate 121.

[0027] The intermediate portion in the Z-axis direction of the through-hole that penetrates the center of the water storage portion 50 in the thickness direction is enlarged in diameter, and the enlarged portion forms a water storage chamber 500 where water is stored. And a water supply port 501 that penetrates the outer surface of the water storage portion 50 communicates with the water storage chamber 500. A water supply source 509 composed of a pump or the like (for example, pure water) that can send out water communicates with the water supply port 501 via a resin tube, a joint, etc. (not shown).

[0028] In the present embodiment, the drain port 52, which is the lower end of the through-hole formed in the water storage portion 50, is formed in an annular shape in a plan view in a state where the probe 2 is inserted, communicates with the water storage chamber 500, and has a smaller diameter than the water storage chamber 500. And the water drained from the drain port 52 flows downward toward the tip 20 of the probe 2 so as to cover the entire side surface of the portion protruding downward from the drain port 52 of the probe 2.

[0029] Hereinafter, using the linear gauge 1 described with reference to FIGS. 1 and 2, the height of the upper surface 900 of the object to be measured 90 that is sucked and held by the chuck table 93 shown in FIG. 2, rotates about the Z-axis together with the chuck table 93 for example, and is being ground while grinding water is supplied by a grinding wheel (not shown) will be described.

[0030] The piston cylinder 64 shown in FIG. 2 lowers the probe 2 in the -Z direction approaching the upper surface 900 of the object to be measured 90. Specifically, with the supply port of the solenoid valve 647 communicating with the air supply pipe 645, the air supply source 648 supplies air into the cylinder case 641 from the first air inlet 643, so that the air exhausted from the second air inlet 644 is exhausted to the atmosphere at a predetermined flow rate, and the piston 640 is lowered inside the cylinder case 641 at a regulated speed. Thereby, the descending speed of the probe 2 that tries to descend due to the self-weight of the probe 2 is limited to a regulated speed, and the impact when the tip 20 of the probe 2 contacts the object to be measured 90 is reduced.

[0031] At this time, air is supplied from the air supply source 648 into the casing 3, and the air is jetted from the jetting portion 32 toward the side surface of the probe 2, and the probe 2 is supported in a non-contact manner by the casing 3. Further, the rotation of the probe 2 is restricted by the rotation restricting portion 17. During the measurement of the height of the upper surface 900 of the object to be measured 90, since water is stored in the water storage chamber 500 of the water seal portion 5 described later, the air supplied between the side surface of the probe 2 and the support surface 30 of the casing 3 from the jetting portion 32 rises in the casing 3 and is exhausted from the exhaust passage 33 into the cover 122 outside the casing 3. Then, the air exhausted into the cover 122 is exhausted to the atmosphere from the exhaust port 124 formed in the upper plate of the cover 122. Note that a throttle valve 125 may be disposed at the exhaust port 124 to adjust the exhaust amount of the air in the cover 122 sealed by the throttle valve 125 from the exhaust port 124. By adjusting the throttle valve 125, the magnitude of the force pressing the probe 2 against the object to be measured 90 may be adjusted.

[0032] When the tip 20 contacts the upper surface 900 of the object to be measured 90 due to the lowering of the probe 2, the reading unit 635 reads the scale of the scale 63. Since the probe 2 descends by its own weight according to the change in the thickness reduced by the grinding of the object to be measured 90, in other words, the displacement of the upper surface 900 of the object to be measured 90, the reading unit 635 sequentially reads the changing scale, and thus the linear gauge 1 can sequentially measure the height at which the upper surface 900 of the object to be measured 90 descends.

[0033] Also, water L1 is sent out from the water supply source 509 shown in FIG. 2, and the water L1 passes through the water supply port 501 and is temporarily stored in the water storage chamber 500 within the water storage section 50. When a predetermined amount of water L1 is stored in the water storage chamber 500, the accumulated water L1 forms a water seal. Grinding water is supplied to the contact portion between the grinding wheel (not shown) and the object to be measured 90 through a nozzle (not shown) and inside the grinding unit, generating grinding waste liquid L2 that contains grinding chips and splashes on the upper surface 900. Also, a mist-like grinding water spray is generated by the rotating grinding wheel and the object to be measured 90 that is attracted and held by the chuck table 93 and rotates. This mist-like liquid may contain very fine grinding chips. Then, the water seal formed in the water storage chamber 500 can prevent these grinding waste liquid L2 and grinding water spray from entering the entrance / exit 123 of the bottom plate 121 and the entrance / exit 36 of the casing 3 from the drain port 52.

[0034] The water pressure in the water storage chamber 500 rises, and water L1 is drained downward from the drain port 52. Since water L1 continues to be supplied in a predetermined amount per unit time from the water supply source 509, water L1 is always stored in the water storage chamber 500, and the formation of the water seal continues.

[0035] The water L1 drained from the annular drain port 52 surrounding the probe 2 flows downward toward the tip 20 while forming a water film that covers the entire side surface of the portion protruding downward from the drain port 52 of the probe 2. The probe 2 is protected by this water film so that grinding chips do not adhere to it. That is, even if the grinding spray containing grinding chips flutters around the probe 2 protruding downward from the drain port 52, it is prevented from adhering to the side surface of the probe 2, drying, and the grinding chips sticking. The thickness, etc. of this water film can be adjusted by adjusting the amount of water supplied from the water supply source 509 to the water storage section 50.

[0036] As described above, the linear gauge 1 according to the present invention has a water seal portion 5 including an annular water reservoir portion 50 that surrounds the side surface of the probe 2 and stores water L1, and a drain port 52 that drains the water L1 from the lower end of the water reservoir portion 50. This configuration prevents grinding waste liquid containing grinding chips to which centrifugal force of a rotating grinding wheel (not shown) is applied from entering the casing 3 through the entrance / exit 36 of the probe 2, and prevents dried grinding chips from adhering to the probe 2 in the gap between the entrance / exit 36 and the probe 2. Further, the drain port 52 is formed so as not to impede the linear movement of the probe 2 in the vertical direction (Z-axis direction). By adjusting the water pressure in the water reservoir portion 50, a water film is formed that covers the entire side surface of the portion protruding downward from the drain port 52 of the probe 2, eliminating the need for an air film that follows the probe 2 as in the conventional art, and preventing a situation where grinding chips are dried by the air film and adhered to the probe 2.

[0037] It goes without saying that the linear gauge 1 according to the present invention is not limited to the above-described embodiment and may be implemented in various different forms within the scope of its technical idea. Also, the process of measuring the height of the upper surface 900 of the object to be measured 90 using the linear gauge 1 can be appropriately changed within the range where the effects of the present invention can be exhibited.

Explanation of Reference Numerals

[0038] 1: Linear gauge 12: Housing 121: Bottom plate 122: Cover 123: Entrance / exit of bottom plate 124: Exhaust port 125: Throttle valve 17: Rotation restricting portion 170: Up-and-down moving magnet 173, 174: Fixed magnet 2: Probe 20: Tip of probe 3: Casing 30: Support surface 32: Jetting portion 33: Exhaust passage 35: Air supply port 356: Pipe 36: Entrance / exit of casing 5: Water seal portion 50: Water reservoir portion 500: Water reservoir chamber 501: Water supply port 509: Water supply source 52: Drain port 62: Connecting plate 63: Scale 635: Reading portion 64: Piston cylinder 640: Piston 641: Cylinder case 642: Rod 643: First air inlet 644: Second air inlet 645, 646: Air supply pipe 647: Solenoid valve 648: Air supply source 90: Object to be measured 900: Upper surface of the object to be measured 93: Chuck table 930: Holding surface

Claims

1. A linear gauge that measures the top surface height of a measurement object by bringing the tip into contact with the top surface of the measurement object held on the holding surface of a chuck table, comprising a probe extending in a direction perpendicular to the holding surface, a casing having a support surface that supports the probe so as to be movable in a direction perpendicular to the holding surface and having an entrance / exit for inserting and removing the probe, a jetting portion that jets air between a side surface of the probe and the support surface, an exhaust passage formed in an upper portion of the casing that communicates between the support surface and the side surface of the probe and exhausts the air jetted from the jetting portion, and an annular water seal portion disposed below the casing that surrounds the side surface of the probe. The water seal portion includes an annular water reservoir portion that surrounds the side surface of the probe and stores water, and a drain port that drains the water from a lower end of the water reservoir portion. A linear gauge that prevents the entry of fluid from the outside into the entrance / exit by the water seal portion.

2. The linear gauge according to claim 1, wherein the drain port is formed in an annular shape, and the water drained from the drain port is caused to flow down to the tip of the probe so as to cover the entire side surface of a portion of the probe that protrudes downward from the drain port.

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