CN116197820A

CN116197820A - Linear scale

Info

Publication number: CN116197820A
Application number: CN202211444049.7A
Authority: CN
Inventors: 斋藤大
Original assignee: Disco Corp
Current assignee: Disco Corp
Priority date: 2021-11-30
Filing date: 2022-11-18
Publication date: 2023-06-02
Also published as: KR20230081640A; JP2023080735A; TW202323758A

Abstract

A linear scale is provided to prevent grinding waste liquid from entering an inlet and an outlet of a probe of a housing of the linear scale. A linear scale (1) for measuring the height of the upper surface of a measurement object held by a holding surface (930) of a table (93) by bringing the tip into contact with the upper surface of the measurement object has: a probe (2) extending perpendicularly to the holding surface; a housing (3) having a support surface (30) for supporting the probe so as to be movable in a direction perpendicular to the holding surface, and having an inlet/outlet (36) for allowing the probe to come in and out; an ejection unit (32) that ejects air between the probe side surface and the support surface; an exhaust path (33) formed at the upper part of the housing and exhausting air between the supporting surface and the side surface of the probe; an annular water seal part (5) which is arranged at the lower side of the shell and surrounds the side surface of the probe, wherein the water seal part is provided with: an annular water storage part (50) surrounding the side surface of the probe for water supply accumulation; and a water outlet (52) for discharging water from the lower end of the water storage part, and the water sealing part prevents fluid from entering the inlet and outlet from the outside.

Description

Linear scale

Technical Field

The present invention relates to a linear scale for measuring the height of the upper surface of an object to be measured.

Background

As disclosed in patent document 1, the grinding device grinds the wafer held by the holding surface to a predetermined thickness by a grinding tool while measuring the thickness of the wafer held by the holding surface. 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 height of the holding surface is measured by the height of the probe whose tip is in contact with the holding surface, and the height of the upper surface of the wafer 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.

Such a height measuring instrument moves a probe extending in a direction perpendicular to a holding surface in a linear motion in an extending direction, and as disclosed in patent document 2, the height measuring instrument includes: a housing forming a gap for supporting the probe in a freely direct-acting manner in a noncontact manner; and a water film forming part which forms a water film so as to cover the side surface of the probe protruding from the housing, thereby preventing the adhesion of the grinding dust to the probe.

Patent document 1: japanese patent laid-open No. 2008-073785

Patent document 2: japanese patent laid-open No. 2020-118503

However, there are the following problems: depending on the processing conditions, the grinding waste liquid containing the grinding dust, which is given a centrifugal force of the rotating grinding tool, breaks the water film, enters the gap from the probe and the inlet/outlet port through which the probe is moved in and out of the housing, and prevents the probe from moving straight, and thus the normal height cannot be measured. In addition, when the apparatus is stopped in a state where the grinding waste liquid enters the gap, there is a problem as follows: the chip dries and the probe is immobilized, resulting in the probe not being activated.

Accordingly, the following problems exist in the linear scale: preventing grinding waste liquid from entering a gap between the probe and an inlet and outlet for the probe to enter and exit from the housing, and measuring the accurate height of the measured object.

Disclosure of Invention

The present invention for solving the above-described problems is a linear scale for measuring an upper surface height of an object to be measured by bringing a tip into contact with the upper surface of the object to be measured held by a holding surface of a chuck table, the linear scale comprising: a probe extending in a direction perpendicular to the holding surface; a housing having a support surface for supporting the probe to be movable in a direction perpendicular to the holding surface, and having an inlet and an outlet for allowing the probe to come in and go out; an ejection unit that ejects air between the side surface of the probe and the support surface; a discharge path formed at an upper portion of the housing and communicating between the support surface and a side surface of the probe, for discharging the air discharged from the discharge portion; and an annular water seal portion disposed at the lower side of the housing and surrounding the side surface of the probe, the water seal portion having: an annular water storage part surrounding the side surface of the probe for water supply accumulation; and a drain port for draining the water from the lower end of the water storage part, and preventing the fluid from entering the inlet and outlet from the outside through the water seal part.

In the linear scale according to the present invention, it is preferable that the drain port is formed in a ring shape, and water discharged from the drain port flows down toward the tip of the probe so as to cover the entire side surface of the portion of the probe protruding downward from the drain port.

The water seal part of the linear scale of the invention has: an annular water storage part surrounding the side surface of the probe for water supply accumulation; and an annular water discharge port for discharging water from the lower end of the water storage portion, whereby grinding waste liquid containing grinding dust, which is given a centrifugal force of the rotating grinding tool, can be prevented from entering the housing from the inlet and outlet of the probe, and grinding dust dried in the gap between the inlet and outlet and the probe is not stuck to the probe. Further, by forming the water discharge port so as not to provide resistance to the vertical movement of the probe and adjusting the water pressure of the water reservoir, the conventional air film along the probe is not required, and the condition that the air film dries the chip and adheres the chip to the probe is not generated.

Drawings

Fig. 1 is a perspective view showing an example of a linear scale.

Fig. 2 is a cross-sectional view showing an example of a linear scale.

Description of the reference numerals

1: a linear scale; 12: a housing; 121: a bottom plate; 122: a cover; 123: an access opening of the bottom plate; 124: an exhaust port; 125: a throttle valve; 17: a rotation restriction portion; 170: moving the magnet up and down; 173. 174: a fixed magnet; 2: a probe; 20: the front end of the probe; 3: a housing; 30: a bearing surface; 32: a discharge section; 33: an exhaust path; 35: an air supply port; 356: piping; 36: an inlet and an outlet of the shell; 5: a water seal part; 50: a water storage part; 500: a water storage chamber; 501: a water supply port; 509: a water supply source; 52: a water outlet; 62: a connecting plate; 63: a graduated scale; 635: a reading section; 64: a piston cylinder; 640: a piston; 641: a cylinder barrel; 642: a rod; 643: a first air flow inlet; 644: a second air flow inlet; 645. 646: an air supply tube; 647: an electromagnetic valve; 648: an air supply source; 90: an object to be measured; 900: the upper surface of the measured object; 93: a chuck table; 930: a retention surface.

Detailed Description

Fig. 1 is an overall perspective view showing an example of the linear scale 1 of the present invention, and fig. 2 is a cross-sectional view of the linear scale 1. The processing device provided with the linear scale 1 is provided with the following devices: a grinding device capable of positioning a measurement object 90 (see fig. 2) with respect to a grinding unit having a grinding tool by a chuck table that moves directly; a biaxial grinding device having a rough grinding unit and a finish grinding unit, and capable of positioning the object to be measured 90 below the rough grinding unit or the finish grinding unit by using a rotating turntable; a polishing device for polishing the object 90 with a polishing pad; or a tool cutting device for flattening the object 90 to be measured by a rotating cutting tool.

The object to be measured 90 shown in fig. 2 is, for example, a circular semiconductor wafer formed of a silicon base material or the like. In addition to silicon, the object to be measured 90 may be formed of gallium arsenide, sapphire, gallium nitride, ceramics, resin, silicon carbide, or the like, or may be a rectangular package substrate or the like. The upper surface 900 of the object to be measured 90 is a surface to be processed by a grinding tool or the like, not shown, and is a surface to be measured whose height is measured by the linear scale 1.

As shown in fig. 2, the object 90 is attracted to and held by the chuck table 93. For example, the chuck table 93 is formed of a porous member, and the chuck table 93 has a substantially flat holding surface 930 configured to suction and hold the object 90, and the holding surface 930 communicates with a suction source such as a vacuum generator, not shown.

The linear scale 1 shown in fig. 1 and 2 is configured to measure the height of the upper surface of the object 90 by bringing the tip 20 (lower end) of the probe 2 into contact with the upper surface 900 of the object 90 held by the holding surface 930 of the chuck table 93. The surface to be measured, which is the object of height measurement of the linear scale 1, may be the holding surface 930.

The linear scale 1 shown in fig. 2 has: a probe 2 extending in a direction (Z-axis direction) perpendicular to the holding surface 930; a housing 3 having a support surface 30 for supporting the probe 2 so as to be movable in a direction perpendicular to the holding surface 930, and having an inlet/outlet 36 for allowing the probe 2 to come in and out; a discharge unit 32 for discharging air between the side surface of the probe 2 and the support surface 30; a discharge path 33 formed at the upper part of the housing 3 and communicating between the support surface 30 and the side surface of the probe 2, for discharging the air discharged from the discharge portion 32; and an annular water seal portion 5 disposed on the lower side of the housing 3 and surrounding the side surface of the probe 2.

In the present embodiment, the probe 2 shown in fig. 1 and 2 is formed in a cylindrical shape, for example, and the tip 20 of the probe 2 is rounded into a hemispherical shape. The upper end side of the probe 2 is coupled to the lower surface side of the flat plate-shaped coupling plate 62 by, for example, a fixing nut. The side surface of the upper middle portion of the probe 2 is supported in a noncontact manner by being surrounded by air discharged from the discharge portion 32 formed in the housing 3 shown in fig. 2.

The probe 2 can be raised by the connecting plate 62 by the piston cylinder 64, for example, and can be lowered by its own weight. The piston cylinder 64 has at least: a cylinder tube 641 having a piston 640 inside and having a bottom on a base end side (-Z direction side); a rod 642 inserted into the cylinder 641 and having a lower end mounted to the piston 640; and a first air inflow port 643 and a second air inflow port 644 for flowing air into the interior of the cylinder bore 641. The upper end side of the rod 642 can be brought into contact with the lower surface of the connecting plate 62, and the base end side of the cylinder tube 641 is fixed to the upper surface of the bottom plate 121 of the housing 12 of the internal storage case 3 or the like. In fig. 1, only the bottom plate 121 of the housing 12 is shown.

As shown in fig. 2, an air supply pipe 645 and an air supply pipe 646 are connected to each of the first air inflow port 643 and the second air inflow port 644, and the air supply pipe 645 and the air supply pipe 646 are connected to an air supply source 648 constituted by a compressor or the like via an electromagnetic valve 647.

When the probe 2 is lifted up and separated from the upper surface 900 of the object 90 by the piston cylinder 64 shown in fig. 2, the air supply source 648 is supplied from the second air inflow port 644 into the cylinder tube 641 in a state where the electromagnetic valve 647 communicates the air supply source 648 and the air supply tube 646, whereby the piston 640 is lifted up. Then, the lever 642 is brought into contact with the lower surface of the connecting plate 62 to further raise the connecting plate 62, thereby raising the probe 2 connected to the connecting plate 62.

On the other hand, when the probe 2 is lowered by the piston cylinder 64 shown in fig. 2 to approach the upper surface 900 of the object 90 to be measured, in a state in which the electromagnetic valve 647 communicates the air supply source 648 with the air supply tube 645, the air supply source 648 supplies air from the first air inflow port 643 into the cylinder tube 641 and flows out of the second air inflow port 644, whereby the rod 642 is lowered at a restricted speed, whereby the speed at which the probe 2 is lowered by the self weight of the probe 2 is restricted, and the probe 2 which is lowered strongly is prevented from contacting the object 90 to be measured to damage the upper surface 900.

The case 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 movable up and down is formed to penetrate in the Z-axis direction in accordance with the shape of the probe 2. The diameter of the longitudinal hole is set to be at least larger than the diameter of the probe 2. The upper end of the vertical hole through which the probe 2 is inserted serves as an exhaust passage 33, and the exhaust passage 33 is formed in the upper portion of the housing 3 and communicates between the support surface 30 and the side surface of the probe 2, and discharges air discharged from the discharge portion 32 toward the side surface of the probe 2.

The probe 2 mainly has a lower portion protruding downward from an inlet/outlet 36 formed in the bottom of the housing 3 and an inlet/outlet 123 of a bottom plate 121 communicating with the inlet/outlet 36 as shown in fig. 2. The housing 3 has a support surface 30 spaced apart from and surrounding the side surface of the upper middle portion of the probe 2 with a small gap therebetween, and a discharge portion 32 including a plurality of discharge ports is formed in the support surface 30. An air supply port 35 is formed in the outer surface of the housing 3 and communicates with an air supply source 648 via a pipe 356, and the air supply port 35 and the discharge ports of the discharge portion 32 communicate with each other through an internal flow path 323 formed in the housing 3.

For example, as shown in fig. 1 and 2, the linear scale 1 includes a rotation restricting portion 17 that restricts rotation of the cylindrical probe 2 about the Z axis. The rotation restricting portion 17 includes, for example: a vertically moving magnet 170 connected to the lower surface of the connecting plate 62 to which the probe 2 is connected, and extending in the extending direction (Z-axis direction) of the probe 2; and two

fixed magnets

173 and 174 that are attached to, for example, the side surface of the housing 3, extend in the axial direction (+z direction) of the probe 2, are disposed so as to sandwich the up-and-down moving magnet 170 with a gap therebetween, and apply a repulsive force between the two fixed magnets 173, the fixed magnet 174, and the up-and-down moving magnet 170 in a direction perpendicular to the up-and-down direction (Z-axis direction) of the probe 2. That is, the magnetic field of the up-and-down moving magnet 170 is directed to a direction that repels the magnetic fields of the fixed magnet 173 and the fixed magnet 174.

By this repulsive force, the distances of the fixed magnet 173 and the fixed magnet 174 from the horizontal direction of the up-and-down moving magnet 170 are kept constant, and the orientation of the up-and-down moving magnet 170 is not changed. Accordingly, the upward and downward moving magnet 170, which is constantly oriented, is connected to the probe 2 via the connecting plate 62, and therefore, even if the probe 2 is formed in a cylindrical shape, movement of the probe 2 in the rotational direction can be restricted. In fig. 2, for ease of explanation, two

fixed magnets

173 and 174 are shown separated from the housing 3.

The fixed magnet 173 and the fixed magnet 174 may be erected in the Z-axis direction from the bottom plate 121 of the housing 12.

In addition, the linear scale 1 may not have the rotation restricting portion 17. In this case, for example, the shape of the probe 2 inserted through the upper middle portion of the housing 3 is not limited to a cylindrical shape, and may be a non-rotating shape, that is, a non-cylindrical shape. Therefore, the prism may be a polygonal column or an elliptic column. In addition, only one surface may be formed into a flat surface and the other surface may be formed into a columnar shape having a curved surface. In response, the vertical hole of the housing 3 may be formed in the same shape as the probe 2.

As shown in fig. 1 and 2, a scale 63 is disposed at a corner of the lower surface of the connecting plate 62. The upper end of the scale 63 is 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. 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 reading unit that reads the reflected light of the scale 63, and the height of the probe 2 can be recognized by the reading value of the reading unit 635.

In the present embodiment, the housing 12 shown in fig. 2 includes a bottom plate 121 parallel to a horizontal plane (X-axis Y-axis plane) and a cover 122 (not shown in fig. 1) covering an upper portion of the bottom plate 121, and the housing 3, the piston cylinder 64, the scale 63, and the like are housed in the cover 122, so that grinding water mist including grinding dust generated during grinding does not adhere to these components.

As shown in fig. 2, a water seal portion 5 is disposed on the lower surface of the bottom plate 121 of the housing 12 below the case 3. The water seal portion 5 has: an annular water reservoir 50 surrounding the side surface of the probe 2 in plan view, for storing water; and a drain port 52 that discharges water from the lower end of the water storage portion 50.

The water reservoir 50 is a substantially cylindrical member, and its upper surface is fixed to the lower surface of the bottom plate 121 by a bolt or the like, not shown. The center of the upper end side of the circular through hole penetrating the center of the water storage portion 50 in the thickness direction coincides with the inlet/outlet 36 of the housing 3 and the inlet/outlet 123 of the bottom plate 121, and is, for example, substantially the same diameter as the inlet/outlet 36 of the housing 3 and the inlet/outlet 123 of the bottom plate 121.

The central portion of the through hole penetrating the center of the water storage portion 50 in the thickness direction is expanded in the Z-axis direction, and the expanded portion serves as a water storage chamber 500 for water supply accumulation. A water supply port 501 penetrating the outer surface of the water reservoir 50 is connected to the water reservoir 500. A water supply source 509, which is constituted by a pump or the like and is capable of delivering water (for example, pure water), is connected to the water supply port 501 via a resin pipe, a joint or the like, not shown.

In the present embodiment, the drain port 52 is formed in a ring shape in a plan view as a lower end of a through hole formed in the water reservoir 50 in a state where the probe 2 is inserted therethrough, communicates with the water reservoir 500, and has a smaller diameter than the water reservoir 500. The water discharged from the drain port 52 flows down toward the distal end 20 of the probe 2 so as to cover the entire side surface of the portion of the probe 2 protruding downward from the drain port 52.

The following will be described below: the height of the upper surface 900 of the object to be measured 90, which is sucked and held on the chuck table 93 shown in fig. 2 and rotates together with the chuck table 93 about the Z axis, for example, is measured using the linear scale 1 described with reference to fig. 1 and 2, and is ground while grinding water is supplied by a grinding tool not shown.

The piston cylinder 64 shown in fig. 2 lowers the probe 2 in the-Z direction near the upper surface 900 of the object 90 to be measured. Specifically, in a state in which the supply port of the electromagnetic valve 647 communicates with the air supply tube 645, the air supply source 648 supplies air from the first air inflow port 643 into the cylinder tube 641, and the air discharged from the second air inflow port 644 is discharged to the atmosphere at a predetermined flow rate, so that the piston 640 is lowered at a restricted speed in the cylinder tube 641. Accordingly, the lowering speed of the probe 2 to be lowered by the self weight of the probe 2 is limited to a limited speed, and the impact when the tip 20 of the probe 2 contacts the object to be measured 90 is reduced.

At this time, air is supplied from the air supply source 648 into the case 3, and air is ejected from the ejection unit 32 toward the side of the probe 2, so that the probe 2 is supported by the case 3 in a noncontact manner. Further, the rotation of the probe 2 is regulated by the rotation regulating portion 17. In the height measurement of the upper surface 900 of the object 90, since water is accumulated in the water storage chamber 500 of the water seal portion 5 described later, air supplied from the ejection portion 32 between the side surface of the probe 2 and the support surface 30 of the housing 3 rises in the housing 3, and is discharged from the exhaust passage 33 into the cover 122 outside the housing 3. The air discharged into the hood 122 is discharged to the atmosphere from the exhaust port 124 formed in the upper plate of the hood 122. Further, a throttle valve 125 may be disposed in the exhaust port 124, and the amount of exhaust gas discharged from the exhaust port 124 by the air in the sealed cover 122 may be adjusted by the throttle valve 125. The amount of force pressing the probe 2 against the object to be measured 90 can also be adjusted by adjusting the throttle valve 125.

When the tip 20 is brought into contact with the upper surface 900 of the object 90 by the lowering of the probe 2, the reading unit 635 reads the scale of the scale 63. The probe 2 descends by its own weight according to a change in the thickness of the object 90 reduced by grinding (in other words, according to a displacement of the upper surface 900 of the object 90), and thus the reading unit 635 sequentially reads the changed scale, whereby the descending height of the upper surface 900 of the object 90 can be sequentially measured by the linear scale 1.

Further, water L1 is sent from the water supply source 509 shown in fig. 2, and the water L1 is temporarily stored in the water storage chamber 500 in the water storage unit 50 through the water supply port 501. A predetermined amount of water L1 is stored in the water storage chamber 500, and the stored water L1 forms a water seal. Grinding water is supplied to a contact portion between a grinding tool, not shown, and the object 90 to be measured through a nozzle, not shown, and inside the grinding unit, and grinding waste liquid L2 containing grinding dust and splashed on the upper surface 900 is generated. Further, the object to be measured 90 is sucked, held and rotated by the rotating grinding tool and chuck table 93, and mist-like grinding water spray is generated. Sometimes the atomized liquid also contains very fine grinding dust. Further, by the water seal formed in the water storage chamber 500, the grinding waste liquid L2 and the grinding water mist can be prevented from entering the inlet and outlet 123 of the bottom plate 121 and the inlet and outlet 36 of the housing 3 from the water discharge port 52.

The water pressure in the water storage chamber 500 rises, and the water L1 is discharged downward from the water discharge port 52. Further, since the water L1 is continuously supplied from the water supply source 509 in a predetermined amount per unit time, the water L1 is always stored in the water storage chamber 500, and the water seal is continuously formed.

The water L1 discharged from the annular drain port 52 surrounding the probe 2 flows down toward the tip 20 while forming a water film covering the entire side surface of the portion of the probe 2 protruding downward from the drain port 52. The probe 2 is protected by the water film so that the grinding dust does not adhere to the probe 2. That is, even if the grinding spray including the grinding dust flies around the probe 2 protruding downward from the drain port 52, the grinding dust can be prevented from adhering to the side surface of the probe 2 and drying, and the grinding dust is prevented from sticking. The thickness of the water film or the like can be adjusted by adjusting the amount of water supplied from the water supply source 509 to the water reservoir 50.

As described above, the water seal portion 5 of the linear scale 1 of the present invention has: an annular water reservoir 50 surrounding the side surface of the probe 2, for storing the water supply L1; and a drain port 52 that discharges water L1 from the lower end of the water storage portion 50, whereby grinding waste liquid including grinding dust, to which centrifugal force of a not-shown rotary grinding tool is applied, can be prevented from entering the housing 3 from the inlet/outlet 36 of the probe 2, and grinding dust dried in a gap between the inlet/outlet 36 and the probe 2 is not stuck to the probe 2. Further, the drain port 52 is formed so as not to be a resistance to the vertical movement (Z-axis direction) of the probe 2, and the water film covering the entire side surface of the portion of the probe 2 protruding downward from the drain port 52 is formed by adjusting the water pressure of the water reservoir 50, so that the conventional air film along the probe 2 is not required, and the case where the air film dries the chips and adheres the chips to the probe 2 is avoided.

The linear scale 1 of the present invention is not limited to the above-described embodiment, and can be implemented in various ways within the scope of the technical idea. The step of measuring the height of the upper surface 900 of the object 90 using the linear scale 1 may be appropriately modified within a range that can exhibit the effects of the present invention.

Claims

1. A linear scale for measuring the height of the upper surface of an object to be measured by bringing the tip into contact with the upper surface of the object to be measured held by a holding surface of a chuck table,

the linear scale has:

a probe extending in a direction perpendicular to the holding surface;

a housing having a support surface for supporting the probe to be movable in a direction perpendicular to the holding surface, and having an inlet and an outlet for allowing the probe to come in and go out;

an ejection unit that ejects air between the side surface of the probe and the support surface;

a discharge path formed at an upper portion of the housing and communicating between the support surface and a side surface of the probe, for discharging the air discharged from the discharge portion; and

an annular water seal part which is arranged at the lower side of the shell and surrounds the side surface of the probe,

the water seal part has:

an annular water storage part surrounding the side surface of the probe for water supply accumulation; and

a water discharge port for discharging the water from the lower end of the water storage part,

fluid is prevented from entering the inlet and outlet from the outside by the water seal portion.

2. A linear scale according to claim 1, wherein,

the drain port is formed in a ring shape, and the water discharged from the drain port flows down toward the tip of the probe so as to cover the entire side surface of the portion of the probe protruding downward from the drain port.