Method for setting the height position of polishing equipment and dry polishing tools

Abstract

To reduce an amount of powder dust remaining in a support table of a dress unit.SOLUTION: A polishing device performs dry type polishing to a workpiece and includes: a holding table for holding the workpiece; a polishing unit which has a spindle and a mount and in which a dry type polishing tool is attached to the spindle through the mount; a moving mechanism which moves the polishing unit along a vertical direction; a processing chamber cover which covers the upper side and the side of the holding table disposed in a predetermined position and the workpiece when dry type polishing is performed to the workpiece held by the holding table and defines a processing chamber; a duct fixed to the processing chamber cover to suction powder dust; a support table disposed within the processing chamber; a dress part which is provided on an upper surface of the support table to dress the dry type polishing tool; and a gas jet part which may jet a gas for blowing off powder dust accumulated on the upper surface of the support table to the upper surface of the support table.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a polishing apparatus for performing dry polishing on a workpiece, and a method for setting the height position of a dry polishing tool with respect to the upper surface of a support table that supports a dressing portion disposed in a processing chamber cover of the polishing apparatus.

Background Art

[0002] For polishing a workpiece such as a semiconductor wafer, there are wet polishing such as CMP (Chemical Mechanical Polishing) using a polishing liquid and dry polishing without using a polishing liquid (see, for example, Patent Document 1).

[0003] In a polishing apparatus that performs dry polishing, dust such as polishing debris scatters in a predetermined space where polishing is performed (that is, a processing chamber defined by a processing chamber cover). Therefore, the dust in the processing chamber is sucked and removed through a duct connected to the processing chamber cover.

[0004] In this processing chamber, a dressing unit for roughening the polishing surface of the polishing pad is provided. The dressing unit includes a dressing portion (also referred to as a dresser portion or a dressing portion) that contacts the polishing pad and a support table that supports the dressing portion.

[0005] While the dressing portion is used for roughening the polishing surface, the upper surface of the support table is used for setting up the height position of the polishing pad. Specifically, while measuring the load applied to the support table, the polishing pad is lowered toward the support table, and the position of the polishing surface when the polishing surface (bottom surface) of the polishing pad contacts the upper surface of the support table (that is, when the load suddenly increases) is set as the reference position of the polishing pad (that is, origin positioning).

[0006] However, the dust deposited on the upper surface of the support table may not be sufficiently removed by the suction removal through the above-described duct. If dust remains on the upper surface of the support table, there is a risk that the reference position of the polishing pad may not be correctly measured. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2003-53662 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] This invention has been made in view of the aforementioned problems, and aims to reduce the amount of dust remaining on the support table of the dressing unit. [Means for solving the problem]

[0009] According to one aspect of the present invention, a polishing apparatus for performing dry polishing on a workpiece is provided, comprising: a holding table for holding the workpiece; a cylindrical spindle; a disc-shaped mount fixed to the lower end of the spindle, the polishing unit having a dry polishing tool mounted on the spindle via the mount; a moving mechanism for moving the polishing unit along the vertical direction; a processing chamber cover that covers the top and sides of the holding table and the workpiece, which are positioned at a predetermined location when performing dry polishing on the workpiece held by the holding table, and defines a processing chamber; a duct fixed to the processing chamber cover for sucking up dust; a support table located in the processing chamber; a dressing section provided on the upper surface of the support table for dressing the dry polishing tool; and a gas injection section capable of injecting gas onto the upper surface of the support table to blow away dust accumulated on the upper surface.

[0010] Preferably, the duct is fixed to the side of the processing chamber cover, and the gas injection unit is positioned in a location that allows it to inject gas toward the suction port of the duct when viewed from above the processing chamber cover.

[0011] According to another aspect of the present invention, a method for setting the height position of a dry polishing tool is provided for setting the height position of a dry polishing tool with respect to the upper surface of a support table that supports a dressing portion located in the processing chamber cover of a polishing apparatus for performing dry polishing on a workpiece, comprising: a gas injection step of reducing the amount of dust on the upper surface of the support table by injecting gas from a gas injection unit onto the upper surface of the support table to blow away dust accumulated on the upper surface and sucking the dust from a duct fixed to the processing chamber cover; a lowering step of lowering the dry polishing tool with respect to the support table located below the dry polishing tool so that the dressing portion is inserted into the through hole of the dry polishing tool, and bringing the lower surface of the dry polishing tool into contact with the upper surface of the support table; and a calculation step of calculating the height position of the upper end of the dressing portion based on the height position at which the lower surface of the dry polishing tool and the upper surface of the support table come into contact. [Effects of the Invention]

[0012] In a polishing apparatus according to one aspect of the present invention, dust accumulated on the upper surface of the support table is blown away by injecting gas from a gas injection unit. The blown-away dust is sucked out of the processing chamber through a duct, thereby reducing the amount of dust remaining on the support table.

[0013] In another aspect of the present invention, a method for calculating the height position involves injecting gas from a gas injection unit onto the upper surface of the support table to blow away dust accumulated on the upper surface, and simultaneously sucking up dust from a duct fixed to the processing chamber cover, thereby reducing the amount of dust on the upper surface (gas injection step). Therefore, compared to a method in which the dust accumulated on the support table is not reduced, the height position of the dry polishing tool relative to the upper surface of the support table can be set more accurately. [Brief explanation of the drawing]

[0014] [Figure 1] This is a perspective view of the polishing apparatus. [Figure 2] Figure 2(A) is a perspective view of the top side of the dry grinding tool, and Figure 2(B) is a perspective view of the bottom side of the dry grinding tool. [Figure 3] It is a side view of a partial cross-section of a dry grinding tool, a chuck table, etc. [Figure 4] It is a side view of a partial cross-section of a dry grinding tool, a dress unit, etc. [Figure 5] It is a flow chart of a dry grinding process, a dress process, etc. [Figure 6] It is a top view of a processing chamber showing a dry grinding process. [Figure 7] It is a top view of a processing chamber showing a dress process. [Figure 8] It is a side view of a partial cross-section of a grinding unit, etc. showing the setting of a conventional height position. [Figure 9] It is a flow chart of a method for setting the height position of the lower surface of a dry grinding pad. [Figure 10] It is a top view of a processing chamber showing a gas injection process. [Figure 11] It is a side view of a partial cross-section of a grinding unit, etc. showing a lowering process. [Figure 12] It is a side view of a partial cross-section of a support table, etc. in a calculation process.

Embodiments for Carrying Out the Invention

[0015] An embodiment according to an aspect of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view of a grinding apparatus 2 that performs dry grinding on a workpiece 11. The X-axis direction (front-rear direction), Y-axis direction (left-right direction), and Z-axis direction (up-down direction) shown in FIG. 1 are orthogonal to each other.

[0016] The X-axis direction includes a +X direction (rear direction) and a -X direction (front direction) that are opposite to each other, and the Y-axis direction includes a +Y direction and a -Y direction that are opposite to each other. Similarly, the Z-axis direction includes a +Z direction (upward direction) and a -Z direction (downward direction) that are opposite to each other.

[0017] The polishing apparatus 2 of this embodiment is a manual type apparatus. The polishing apparatus 2 has a base 4 that supports a plurality of components. The base 4 has a rectangular parallelepiped shape including a long portion along the X-axis direction. On the upper surface of the base 4, a rectangular opening 4a is formed in which the long portion is arranged along the X-axis direction.

[0018] A substantially square plate-like table cover 6 is provided in the opening 4a. On both sides of the table cover 6 in the X-axis direction, bellows-like cover members 8 that can expand and contract along the X-axis direction are provided. Below the table cover 6 and the cover members 8, an X-axis direction movement mechanism 10 is provided.

[0019] In FIG. 1, the approximate position of the X-axis direction movement mechanism 10 is indicated by an arrow, and its specific structure is omitted. The X-axis direction movement mechanism 10 has a pair of guide rails (not shown) arranged along the X-axis direction respectively.

[0020] On the pair of guide rails, a rectangular plate-like moving table (not shown) is slidably attached along the X-axis direction. On the lower surface side of the moving table, a nut portion (not shown) is provided.

[0021] A screw shaft (not shown) arranged along the X-axis direction is rotatably connected to the nut portion via a plurality of balls (not shown). A drive source (not shown) such as a stepping motor is connected to one end of the screw shaft. When the drive source is operated, the moving table moves along the X-axis direction.

[0022] A disc-shaped chuck table (holding table) 12 is provided on the table cover 6. The chuck table 12 is rotatably supported by the moving table of the X-axis direction movement mechanism 10.

[0023] As shown in FIG. 3, the chuck table 12 has a disc-shaped frame body 14 formed of non-porous ceramics. The outer diameter of the frame body 14 corresponds to the outer diameter 12b of the chuck table 12 and is, for example, 300 mm.

[0024] A disc-shaped recess is formed on the upper surface of the frame 14. A disc-shaped porous plate 16 made of porous ceramics is fixed in this recess. Multiple first channels are formed radially at the bottom of the recess in the frame 14.

[0025] Furthermore, a second channel is formed in the radial center of the recess, penetrating the frame 14 in the thickness direction of the frame 14. A suction source (not shown), such as a vacuum pump, is connected to the second channel via a solenoid valve (not shown).

[0026] When the solenoid valve is opened while the suction source is operating, negative pressure is transmitted to the upper surface of the porous plate 16 via the first flow path, the second flow path, etc. The upper surfaces of the frame 14 and the porous plate 16 are substantially flush and substantially flat, and function as holding surfaces 12a that suction and hold the workpiece 11.

[0027] A cylindrical rotating shaft 18 is fixed to the underside of the chuck table 12. In Figure 3, the rotating shaft 18 is shown by a dashed line. Power is transmitted to the rotating shaft 18 from a rotational drive source (not shown), such as a servo motor, fixed on the moving plate of the X-axis movement mechanism 10, and the rotating shaft 18 can rotate without restriction on the rotation angle.

[0028] Returning to Figure 1, a rectangular prism-shaped support column 20 is provided on the rear side of the base 4 in the +Y direction, with its longitudinal portion aligned along the Z-axis. A Z-axis movement mechanism (movement mechanism) 22 is provided on one side of the support column 20.

[0029] The Z-axis movement mechanism 22 has a pair of guide rails 24 that are arranged substantially parallel to each other in the Z-axis direction. A movable plate 26 is slidably fixed to the pair of guide rails 24. A nut portion (not shown) is provided on the back side of the movable plate 26.

[0030] A screw shaft 28, positioned along the Z-axis, is rotatably connected to this nut portion via a plurality of balls (not shown). A drive source 30, such as a stepping motor, is connected to the upper end of the screw shaft 28.

[0031] By rotating the screw shaft 28 with the drive source 30, the movable plate 26 moves along the Z-axis direction. A polishing unit 32 is provided on the surface side of the movable plate 26, and the polishing unit 32 is moved along the Z-axis direction by the Z-axis direction movement mechanism 22 described above.

[0032] The polishing unit 32 has a cylindrical support 34 fixed to the surface side of the movable plate 26. Inside the support 34 is a cylindrical spindle housing 36 whose longitudinal portion is arranged along the Z-axis direction.

[0033] A portion of a cylindrical spindle 38 (see Figure 3), whose longitudinal portion is aligned along the Z-axis, is rotatably housed in the spindle housing 36. A rotational drive source (not shown), such as a servo motor, is provided near the upper end of the spindle 38.

[0034] The lower end of the spindle 38 protrudes below the lower ends of the support 34 and the spindle housing 36. The upper side of a disc-shaped mount 40 made of metal is fixed to the lower end of the spindle 38.

[0035] A disc-shaped dry polishing tool 42 is fixed to the underside of the mount 40 using bolts (not shown). In this way, the dry polishing tool 42 is mounted on the spindle 38 via the mount 40.

[0036] Figure 2(A) is a perspective view of the top side of the dry polishing tool 42, and Figure 2(B) is a perspective view of the bottom side of the dry polishing tool 42. The dry polishing tool 42 has a disc-shaped base 44 made of a metal such as an aluminum alloy. The outer diameter of the base 44 is, for example, 450 mm.

[0037] A through-hole 44a of a predetermined diameter is formed in the center of the base 44 so as to penetrate the base 44. The diameter of the through-hole 44a is, for example, 140 mm. In addition, a plurality of screw holes 44b are formed at approximately equal intervals along the outer circumference of the upper side of the base 44.

[0038] When attaching the dry polishing tool 42 to the spindle 38, the aforementioned bolts are secured to each screw hole 44b via through holes (not shown) formed on the outer circumference of the mount 40. A disc-shaped dry polishing pad 46, approximately the same diameter as the base 44, is fixed to the lower surface of the base 44 with adhesive.

[0039] The dry polishing pad 46 is positioned concentrically with the base 44. A through hole 46a of a predetermined diameter is formed in the center of the dry polishing pad 46 so as to penetrate the dry polishing pad 46. The diameter of the through hole 46a is, for example, 150 mm.

[0040] The dry polishing pad 46 comprises abrasive grains and a bonding agent. The abrasive grains are formed from, for example, metal oxides such as cerium oxide, or silicon oxides such as quartz or fused silica. As the bonding agent, for example, epoxy resin, phenolic resin, or powder made from rubber such as natural rubber or synthetic rubber is used.

[0041] After mixing abrasive grains and bonding agent powder, the mixture is compressed and molded, and then fired to form a dry polishing pad 46. In the dry polishing pad 46, the abrasive grains are fixed to the bonding agent in such a manner that they are dispersed within the bonding agent, which has fused together after firing.

[0042] As shown in Figure 1, a polishing pad nozzle 50 is provided below the polishing unit 32 and in the +Y direction of the opening 4a. The polishing pad nozzle 50 sprays a room temperature gas 13 (see Figure 3), such as compressed air, upward.

[0043] Figure 3 is a partial cross-sectional side view of the dry grinding tool 42, chuck table 12, etc. As shown in Figure 3, the outer diameter 12b of the chuck table 12 is smaller than the outer diameter 46b of the dry grinding tool 42, and the grinding pad nozzle 50 is positioned away from the chuck table 12 in the Y-axis direction. Therefore, the grinding pad nozzle 50 does not interfere with the chuck table 12 when grinding the workpiece 11.

[0044] During polishing, the workpiece 11, which is held by suction on the holding surface 12a, is polished with a dry polishing pad 46, and gas 13 is sprayed from the opening 50a of the polishing pad nozzle 50 onto the lower surface (polishing surface) 46c of the dry polishing pad 46 that is not in contact with the workpiece 11.

[0045] During polishing, the polishing area on the lower surface 46c is heated to a range of 70°C to 80°C by the frictional heat generated between the workpiece 11 and the polishing pad. By injecting gas 13 from the opening 50a, the heated dry polishing pad 46 can be cooled, and the removal of polishing debris adhering to the dry polishing pad 46 can be promoted.

[0046] Now, let's return to Figure 1. The chuck table 12 can move between the loading / unloading position A1 located on the front side of the base 4 and the polishing position (predetermined position) A2 located on the rear side by the X-axis movement mechanism 10.

[0047] When the chuck table 12 is positioned at loading / unloading position A1, the workpiece 11 before dry grinding is loaded into the chuck table 12, or the workpiece 11 after dry grinding is unloaded from the chuck table 12.

[0048] The workpiece 11 has a disc-shaped silicon single crystal substrate, and this silicon single crystal substrate is subjected to dry polishing. However, the workpiece 11 is not limited to silicon, and may also have a single crystal substrate formed of other semiconductor materials such as silicon carbide (SiC) or gallium nitride (GaN).

[0049] In this embodiment, the surface 11a side of the workpiece 11 is held in place by suction on the holding surface 12a, and dry polishing is performed on the back surface 11b side of the workpiece 11. In this embodiment, no protective tape made of resin and having approximately the same diameter as the workpiece 11 is attached to the surface 11a side of the workpiece 11.

[0050] However, if a device such as an IC (Integrated Circuit) (not shown) is formed on the surface 11a side of the workpiece 11, protective tape (not shown) is attached to the surface 11a side to reduce damage to the surface 11a side.

[0051] When dry grinding is performed on the workpiece 11, the workpiece 11 is held in place by suction using the chuck table 12, and then the chuck table 12 is placed at the grinding position A2. The chuck table 12 and the workpiece 11 placed at the grinding position A2 are covered above and to the sides by a rectangular parallelepiped processing chamber cover 52.

[0052] In Figure 1, for ease of explanation, the machining chamber cover 52 is shown by a dashed line. The machining chamber cover 52 has a rectangular top wall 52a with its longer side in the X-axis direction. A through hole 52a1 is formed in the top wall 52a to allow the dry polishing tool 42 to move back and forth in the Z-axis direction (see Figure 4).

[0053] First side walls 52b1 and second side walls 52b2 are provided at both ends of the top wall 52a in the Y-axis direction, hanging down from the top wall 52a. A rear wall 52c is provided at the end of the top wall 52a in the +X direction, hanging down from the top wall 52a.

[0054] A front wall 52d is provided at the front end of the top wall 52a, hanging down from the top wall 52a, and a rectangular notch 52d1 is formed in the front wall 52d to allow the chuck table 12 to move into the machining chamber cover 52.

[0055] The space within the machining chamber cover 52, defined by the top wall 52a, the first side wall 52b1, the second side wall 52b2, the rear wall 52c, and the front wall 52d, becomes the machining chamber 52A (see Figure 4). The range of dust scattering, such as polishing debris generated during dry polishing, is largely limited to this machining chamber 52A.

[0056] One end of a duct 64 is fixed to the first side wall 52b1. A suction source 66, such as a vacuum pump, is connected to the other end of the duct 64. When the suction source 66 is operated, dust in the processing chamber 52A is sucked in.

[0057] A dressing unit 54 is located inside the processing chamber 52A. The dressing unit 54 has a rectangular plate-shaped support table 56 whose longitudinal direction is aligned with the Y-axis. The support table 56 is movable along the X-axis by an X-axis movement mechanism 10.

[0058] Similar to the table cover 6, bellows-shaped cover members 8 that can expand and contract along the X-axis are provided on both sides of the support table 56 in the X-axis direction. The support table 56 is slidably fixed to a pair of guide rails, similar to the chuck table 12.

[0059] However, the support table 56 moves along the X-axis direction by a screw axis and drive source (not shown) that are different from the screw axis and drive source that move the chuck table 12 along the X-axis direction.

[0060] The upper surface 56a (see Figure 4) of the support table 56 is provided with a cylindrical dressing portion 58 for dressing the dry polishing pad 46. The diameter of the dressing portion 58 is, for example, 8.0 mm, and the amount of protrusion from the upper surface 56a is, for example, 8.5 mm.

[0061] As shown in Figure 4, the dressing portion 58 has a cylindrical base 58a fixed to the upper surface 56a. A cylindrical grinding wheel portion 58b is fixed to the upper surface of the base 58a. The grinding wheel portion 58b has abrasive grains and a bonding material for fixing the abrasive grains.

[0062] The abrasive grains constituting the grinding wheel portion 58b are formed from, for example, SiC, cBN (cubic boron nitride), diamond, or metal oxides. The bonding material that fixes the abrasive grains is, for example, a thermosetting resin, in which the abrasive grains are dispersed. However, the bonding material is not limited to resin and may be a metal plating layer using a metal such as nickel.

[0063] Note that the dressing unit 54 shown in Figure 1 is located at standby position B1, which is intended for use with the chuck table 12 and polishing unit 32, while the chuck table 12 is located at loading / unloading position A1.

[0064] A dressing nozzle 60 is provided behind the opening 4a. The dressing nozzle 60 is fixed to the upper surface of the base 4 within the processing chamber 52A.

[0065] As shown in Figure 4, the opening 60a of the dressing nozzle 60 is adjusted in orientation and height so that when the dressing unit 54 is in standby position B1, a room temperature gas 13 such as compressed air hits the top of the dressing section 58.

[0066] In addition, within the processing chamber 52A, a support table nozzle (gas injection unit) 62 is provided in the +Y direction of the opening 4a. The support table nozzle 62 is fixed to the upper surface of the base 4 within the processing chamber 52A.

[0067] The opening 62a of the support table nozzle 62 is positioned higher than the upper surface 56a of the support table 56. From the opening 62a, a room temperature gas 13, such as compressed air, is injected toward the upper surface 56a of the support table 56.

[0068] Figure 4 is a partial cross-sectional side view of the dry polishing tool 42, dressing unit 54, etc. The orientation of the opening 62a is adjusted so that the gas 13 is injected diagonally downward toward the upper surface 56a of the support table 56. In addition, in a top view of the polishing apparatus 2, the orientation of the opening 62a in the XY plane is toward the suction port 64a of the duct 64 (see Figure 10).

[0069] As described above, the support table nozzle 62 is positioned to spray gas 13 toward the suction port 64a. Therefore, dust such as grinding debris accumulated on the upper surface 56a of the support table 56 is blown away by the gas 13 sprayed from the support table nozzle 62 toward the upper surface 56a and sucked in through the suction port 64a.

[0070] In the polishing apparatus 2 of this embodiment, dust accumulated on the upper surface 56a of the support table is blown away by injecting gas 13 from the support table nozzle 62. The blown-away dust is sucked out of the processing chamber 52A through the duct 64, thereby reducing the amount of dust remaining on the support table 56. For example, the amount of dust on the upper surface 56a can be almost eliminated.

[0071] As shown in Figure 1, gas 13 is supplied to the polishing pad nozzle 50, the dressing nozzle 60, and the support table nozzle 62 via a pipe (not shown) branching from the gas supply source 68. The gas supply source 68 in this embodiment is a compressed air supply source having a compressor, dryer, air tank, etc.

[0072] The gas supply source 68 supplies dry air at room temperature (for example, about 23°C) at a predetermined pressure (for example, 0.5 MPa) to the polishing pad nozzle 50, the dressing nozzle 60, and the support table nozzle 62, respectively.

[0073] The polishing apparatus 2 includes a controller (control unit) 70 that controls the operation of the X-axis movement mechanism 10, the rotation drive source and suction source of the chuck table 12, the Z-axis movement mechanism 22, the polishing unit 32, the nozzle 50 for the polishing pad, the nozzle 60 for the dressing section, the nozzle 62 for the support table, and so on.

[0074] The controller 70 has a computer that includes a processor (processing unit) such as a CPU (Central Processing Unit) and memory (storage device). The memory includes main memory such as DRAM (Dynamic Random Access Memory), SRAM (Static Random Access Memory), and ROM (Read Only Memory), and auxiliary storage such as flash memory, hard disk drive, and solid state drive.

[0075] The auxiliary storage device stores software containing a predetermined program. The controller 70's functions are realized by operating the processor and other components according to this software. Next, the method of using the polishing device 2 will be explained with reference to Figures 5 to 7.

[0076] Figure 5 is a flowchart of the dry polishing process S20, the dressing process S50, etc. First, the workpiece 11 is held by suction using the chuck table 12 located at the loading / unloading position A1, and then the chuck table 12 is moved to the polishing position A2 (workpiece loading process S10).

[0077] At this time, the chuck table 12 and the workpiece 11 are positioned directly below the polishing unit 32 in the machining chamber 52A. Next, while the chuck table 12 and the spindle 38 are rotated at predetermined rotational speeds, the dry polishing tool 42 is pressed against the back surface 11b of the workpiece 11 with predetermined pressure.

[0078] This performs dry polishing on the workpiece 11 (dry polishing process S20). Figure 6 is a top view of the processing chamber 52A showing the dry polishing process S20. In the dry polishing process S20, dry polishing is performed on the workpiece 11 while spraying gas 13 from the polishing pad nozzle 50 at, for example, a pressure of 0.5 MPa and a flow rate of 250 L / min.

[0079] After the dry grinding is complete, the chuck table 12 is returned to the loading / unloading position A1 and the workpiece 11 is collected (workpiece unloading process S30). If the predetermined number of dry grinding operations have not been completed (NO in S40), the process returns to the workpiece loading process S10 and dry grinding is performed on the remaining workpieces 11.

[0080] In contrast, when a predetermined number of dry polishing operations are completed (YES in S40), the dressing unit 54 is moved from the standby position B1 to the dressing position B2 to perform the dressing process S50. Figure 7 is a top view of the processing chamber 52A showing the dressing process S50.

[0081] In the dressing process S50, a gas 13 is sprayed from the polishing pad nozzle 50 at a pressure of 0.5 MPa and a flow rate of 200 L / min, while the dry polishing tool 42 is pressed against the dressing section 58 at a predetermined pressure and the spindle 38 is rotated at a predetermined rotational speed. In this way, the lower surface 46c of the dry polishing pad 46 is dressed.

[0082] Although suction from the duct 64 is continuously performed from the workpiece loading process S10 until the end of the dressing process S50, dust such as polishing debris accumulates in the dressing unit 54 located inside the processing chamber 52A.

[0083] By the way, if the dry polishing tool 42 is used for a predetermined period of time, polishing will become difficult due to the shedding of abrasive grains, etc., so it is necessary to replace the dry polishing tool 42 with a new one. After replacing the dry polishing tool 42 with a new one, it is necessary to set the height position of the dry polishing tool 42 (i.e., the lower surface 46c of the dry polishing pad 46).

[0084] However, as shown in Figure 8, if the height position is set with dust 15 accumulated on the dressing unit 54, the height position of the dry polishing tool 42 will be calculated inaccurately by the thickness of the dust 15. Figure 8 is a partial cross-sectional side view of the polishing unit 32, etc., showing a conventional method for setting the height position.

[0085] Figure 8 shows the case where the lower surface 46c of the dry polishing pad 46 is at a height position Z1, which is above the height position Z0 of the upper surface 56a of the support table 56, due to the dust 15 accumulated on the upper surface 56a.

[0086] Therefore, in this embodiment, the dressing unit 54 is cleaned according to the flowchart shown in Figure 9 to reduce the amount of dust 15 remaining on the dressing unit 54, and then the height position of the dry polishing tool 42 is set. Figure 9 is a flowchart of the method for setting the height position of the lower surface 46c of the dry polishing pad 46 in the polishing apparatus 2.

[0087] In setting the height position of the dry polishing tool 42, for example, first the dressing unit 54 is placed in standby position B1. Then, gas 13 is injected from the support table nozzle 62 onto the upper surface 56a of the support table 56, and gas 13 is also injected from the dressing nozzle 60 onto the dressing section 58.

[0088] For example, gas 13 is injected from the support table nozzle 62 at a pressure of 0.5 MPa and a flow rate of 300 L / min, while gas 13 is also injected from the dressing nozzle 60 at a pressure of 0.5 MPa and a flow rate of 200 L / min.

[0089] This process blows away the dust 15, such as polishing debris, that has accumulated on the upper surface 56a of the support table 56 and the dressing section 58, and also sucks up the scattered dust 15 from the duct 64, thereby reducing the amount of dust 15 on the upper surface 56a and the dressing section 58 (gas injection process S60).

[0090] Figure 10 is a top view of the processing chamber 52A showing the gas injection process S60. In the gas injection process S60, the dressing unit 54 may be fixed at the standby position B1, or it may be moved from the standby position B1 through the dressing position B2 to the front end position B3 in the processing chamber 52A. Alternatively, it may be moved back and forth between the standby position B1 and the front end position B3 one or more times.

[0091] In this way, the amount of dust 15 accumulated on the dressing unit 54 can be automatically reduced by the polishing device 2 using the support table nozzle 62, etc., thus eliminating the need for the operator to clean the dressing unit 54. This eliminates the need for the operator to clean, providing high convenience to the operator of the polishing device 2.

[0092] After the gas injection process S60, a support table 56 is positioned directly below the polishing unit 32 so that the dressing portion 58 is inserted into the through holes 44a and 46a of the dry polishing tool 42. The non-rotating dry polishing tool 42 is lowered relative to this support table 56 so that the lower surface 46c of the dry polishing pad 46 comes into contact with the upper surface 56a of the support table 56 (lowering process S70).

[0093] Figure 11 is a partial cross-sectional side view of the polishing unit 32, etc., showing the lowering process S70. Since dust 15 is largely removed from the upper surface 56a of the support table 56, when the lower surface 46c of the dry polishing pad 46 contacts the upper surface 56a of the support table 56, the height positions of the lower surface 46c and the upper surface 56a are approximately the same.

[0094] Figure 11 shows an example where the height position of the lower surface 46c and the upper surface 56a is the height position Z0. The height position Z0 is measured, for example, by measuring the change in load on the support table 56 using a load sensor (not shown) provided on the lower surface of the support table 56.

[0095] More specifically, the dry polishing pad 46 is lowered at a predetermined speed, and the height position of the lower surface 46c corresponding to the timing when the load change is measured by the load sensor is defined as the height position Z0 where the lower surface 46c and the upper surface 56a make contact.

[0096] This height position Z0 becomes the reference height position (i.e., the origin position) for the lower surface 46c. The controller 70 stores the height position Z0 in the auxiliary storage device and calculates the height position of the upper end of the dressing section 58 (i.e., the height position Z2 of the upper end of the grinding wheel section 58b) (calculation step S80).

[0097] Figure 12 is a partial cross-sectional side view of the support table 56, etc., showing the height position of the upper end of the dressing section 58, which is calculated in calculation step S80. The height position Z2 of the upper end of the grinding wheel section 58b is predetermined to be, for example, 8.5 mm from the upper surface 56a, so it is calculated as (height position Z0 + 8.5 mm).

[0098] As a result of reducing the amount of dust 15 on the upper surface 56a in this way, the height position Z0 can be accurately measured, so that in the next dressing process S50, the lower surface 46c of the dry polishing pad 46 can be accurately positioned at the height of the upper end of the dressing section 58. Therefore, it is possible to prevent the situation in the dressing process S50 where the lower surface 46c of the dry polishing pad 46 does not come into contact with the dressing section 58 and misses.

[0099] Furthermore, the structures, methods, etc., according to the above embodiments can be modified as appropriate without departing from the scope of the object of the present invention.

[0100] The polishing device 2 described above is manual, but it may also be a fully automatic type that performs rough grinding, finish grinding, and dry polishing in sequence. In the case of a fully automatic type, the polishing unit 32 moves along the X-axis instead of the chuck table 12 moving along the X-axis. [Explanation of Symbols]

[0101] 2: Polishing device, 4: Base, 4a: Opening, 6: Table cover, 8: Cover member 10:X-axis direction movement mechanism 11: Workpiece, 11a: Surface, 11b: Back surface, 13: Gas, 15: Dust 12: Chuck table (holding table), 12a: Holding surface, 12b: Outer diameter 14: Frame, 16: Porous plate, 18: Rotating shaft 20: Support column, 22: Z-axis direction movement mechanism (movement mechanism) 24: Guide rail, 26: Moving plate, 28: Screw shaft, 30: Drive source 32: Polishing unit, 34: Support, 36: Spindle housing, 38: Spindle 40: Mount, 42: Dry grinding tool, 44: Base, 44a: Through hole, 44b: Screw hole 46: Dry polishing pad, 46a: Through hole, 46b: Outer diameter, 46c: Bottom surface 50: Nozzle for polishing pad, 50a: Opening 52: Processing room cover, 52A: Processing room 52a: Top wall, 52a1: Through hole, 52b1: First side wall, 52b2: Second side wall 52c: Back wall, 52d: Front wall, 52d1: Notch 54: Dress unit, 56: Support table, 56a: Top surface 58: Dressing part, 58a: Base, 58b: Grinding wheel part 60: Nozzle for dressing part, 60a: Opening 62: Nozzle for support table (gas injection part), 62a: Opening 64: Duct, 64a: Suction port 66: Suction source, 68: Gas supply source, 70: Controller A1: Loading / unloading position, A2: Polishing position (predetermined position) B1: Standby position, B2: Dress position, B3: Front end position S10: Workpiece loading process, S20: Dry polishing process, S30: Workpiece unloading process S50: Dressing process, S60: Gas injection process, S70: Lowering process, S80: Calculation process Z0, Z1, Z2: Height position

Claims

1. A polishing apparatus for performing dry polishing on a workpiece, A holding table for holding the workpiece, A polishing unit comprising a cylindrical spindle and a disc-shaped mount fixed to the lower end of the spindle, wherein a dry polishing tool is attached to the spindle via the mount, A moving mechanism for moving the polishing unit along the vertical direction, When dry polishing is performed on the workpiece held by the holding table, a processing chamber cover is placed in a predetermined position to cover the top and sides of the holding table and the workpiece, defining the processing chamber, A duct fixed to the processing chamber cover for sucking up dust, A support table located inside the processing chamber, A dressing section is provided on the upper surface of the support table for dressing the dry polishing tool, A gas injection unit capable of injecting gas onto the upper surface of the support table to blow away the dust accumulated on the upper surface, A polishing apparatus characterized by being equipped with the following features.

2. The duct is fixed to the side of the processing chamber cover. The polishing apparatus according to claim 1, characterized in that the gas injection unit is positioned in a location that allows it to inject gas toward the suction port of the duct when viewed from above the processing chamber cover.

3. A method for setting the height position of a dry polishing tool, which involves setting the height position of the dry polishing tool relative to the upper surface of a support table that supports a dressing section located inside the processing chamber cover of a polishing apparatus for performing dry polishing on a workpiece, A gas injection process is performed to reduce the amount of dust on the upper surface of the support table by injecting gas from a gas injection unit onto the upper surface to blow away dust accumulated on the upper surface, and simultaneously sucking up the dust from a duct fixed to the processing chamber cover. Following the gas injection step, the dry polishing tool is lowered relative to the support table positioned below it so that the dressing portion is inserted into the through-hole of the dry polishing tool, and the lower surface of the dry polishing tool is brought into contact with the upper surface of the support table. A calculation step to calculate the height position of the upper end of the dressing portion based on the height position at which the lower surface of the dry polishing tool and the upper surface of the support table come into contact, A method for setting the height position of a dry polishing tool, characterized by comprising the following features.

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