JP2009125915A - Grinding wheel mounting mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grinding wheel mounting mechanism for a grinding device allowing the simultaneous or separate mounting of two kinds of grinding wheels if necessary. <P>SOLUTION: A grinding wheel includes a first grinding wheel 30 composed of a plurality of first grinding wheels 34 and mounted to a first annular wheel base 32 having an inner diameter of a first dimension, and a second grinding wheel 38 composed of a plurality of second grinding wheels 42 and mounted to a second wheel base 40 having outer diameters of second dimensions smaller than the first dimension. A wheel mount 28 has a first annular mounting surface 28a to mount the first wheel base, and a second mounting surface 28b formed at an inner peripheral part of the first mounting surface to mount the second wheel base. When mounting the first grinding wheel and the second grinding wheel to the first mounting surface and the second mounting surface, respectively, end faces of the second grinding wheels of the second grinding wheel project by a predetermined distance from end faces of the first grinding wheels of the first grinding wheel. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a grinding wheel mounting mechanism in a grinding apparatus.

  In the semiconductor device manufacturing process, a plurality of regions are partitioned by dividing lines called streets arranged in a lattice pattern on the surface of a semiconductor wafer having a substantially disk shape, and devices such as ICs and LSIs are placed in the partitioned regions. Form. Then, the semiconductor wafer is cut into individual semiconductor chips by cutting the semiconductor wafer along the streets with a cutting device.

  The wafer to be divided is formed to a predetermined thickness by grinding or etching the back surface before cutting along the street. In recent years, in order to achieve weight reduction and miniaturization of electrical equipment, the thickness of the wafer is required to be thinner, for example, about 50 μm.

  Grinding equipment that thinly grinds the backside of the wafer has been devised in various ways to finish it into a thin and high bending strength wafer in order to meet its requirements. However, as the wafer becomes thinner, it is handled in the post-grinding process. Has become a very difficult problem.

Therefore, in order to realize a thin wafer and easy handling, a grinding method for grinding only a portion where a device such as an IC or an LSI is formed on the wafer and leaving a convex portion in an excess area of the outer peripheral portion is disclosed in, for example, Japanese Patent Laid-Open No. 2007-2007. -19461.
JP 2007-19461 A

  However, the grinding wheel used in the above-described processing method differs greatly from the grinding wheel for grinding the entire surface of the wafer in terms of the outer diameter of the wheel and the arrangement diameter of the grinding wheels arranged in an annular shape (small compared). It cannot be used as a normal grinding wheel, and it is necessary to replace the grinding wheel.

  In addition, a grinding method having a reinforcing portion forming step that grinds only the central portion of a wafer on which a device such as an IC or LSI is formed on the wafer and leaves a convex portion in an excess region of the outer peripheral portion. Immediately before the division, it is necessary to grind only the convex portions and make the wafer flat to some extent.

  In this way, even in the grinding where only the outer peripheral convex part is ground and the wafer is flattened to some extent, a grinding apparatus is used, and it is necessary to grind with a grindstone of coarse abrasive grains and a grindstone of fine abrasive grains. Therefore, it is necessary to replace the grinding wheel one by one to achieve the desired grinding.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a grinding wheel mounting mechanism of a grinding apparatus capable of mounting two types of grinding wheels simultaneously or separately as necessary. That is.

  According to the present invention, there is provided a grinding wheel mounting mechanism for detachably mounting a grinding wheel on a wheel mount fixed to a spindle of a grinding apparatus, wherein the grinding wheel has an annular first wheel having an inner diameter of a first dimension. A first grinding wheel comprising a base and a plurality of first grinding wheels attached to the first wheel base; a second wheel base having an outer diameter of a second dimension smaller than the first dimension; A second grinding wheel composed of a plurality of second grinding wheels attached to the second wheel base, and the wheel mount is an annular shape on which the first wheel base of the first grinding wheel is mounted. A first mounting surface; and a second mounting surface that is provided on an inner peripheral portion of the first mounting surface and on which a second wheel base of the second grinding wheel is mounted. When the wheel and the second grinding wheel are mounted on the first mounting surface and the second mounting surface, respectively, the end surface of the second grinding wheel of the second grinding wheel is the first grinding wheel of the first grinding wheel. A grinding wheel mounting mechanism is provided that protrudes a predetermined distance from the end face of the grinding wheel.

  Preferably, the grinding wheel mounting mechanism includes a grinding water nozzle that ejects grinding water mounted on a central portion of the wheel mount, and the protruding height of the grinding water nozzle is the protruding height of the first and second grinding wheels. It is lower than this.

  More preferably, in a state where the first and second grinding wheels are mounted on the wheel mount, both the first and second grinding wheels can be attached and detached without interfering with the other.

  According to the present invention, since the wheel mount has the first mounting surface and the second mounting surface, the first grinding wheel having a normal outer diameter and the second grinding wheel having a small outer diameter are simultaneously used as the wheel mount. Since it is possible to mount, or if necessary, only one grinding wheel can be mounted, it is possible to grind the entire surface of the work piece with one spindle, and to the extra area of the outer periphery of the work piece It is possible to perform all of the grinding of the reinforcing part forming step that leaves the convex part and the grinding of only the convex part.

  In addition, the first and second grinding wheels can be freely selected and mounted on the wheel mount. If the grinding wheel of one of the grinding wheels is damaged or worn, only the grinding wheel is replaced. Can be economical. Furthermore, it is possible to provide a grinding device that is significantly less expensive and has a smaller space than a grinding device having two or more spindles, which is advantageous both in terms of economy and space.

  Hereinafter, a grinding wheel mounting mechanism according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view of a semiconductor wafer before being processed to a predetermined thickness. A semiconductor wafer 11 shown in FIG. 1 is made of, for example, a silicon wafer having a thickness of 700 μm, and a plurality of streets 13 are formed in a lattice shape on the surface 11a, and a plurality of streets partitioned by the plurality of streets 13 are formed. A device 15 such as an IC or LSI is formed in the region.

  The semiconductor wafer 11 configured as described above includes a device region 17 in which the device 15 is formed, and an outer peripheral surplus region 19 that surrounds the device region 17. A notch 21 is formed on the outer periphery of the semiconductor wafer 11 as a mark indicating the crystal orientation of the silicon wafer.

  A protective tape 23 is attached to the surface 11a of the semiconductor wafer 11 by a protective tape attaching process. Therefore, the front surface 11a of the semiconductor wafer 11 is protected by the protective tape 23, and the back surface 11b is exposed as shown in FIG.

  Hereinafter, a grinding apparatus 2 for grinding the back surface 11b of the semiconductor wafer 11 thus configured to a predetermined thickness will be described with reference to FIG. The housing 4 of the grinding device 2 is composed of a horizontal housing part 6 and a vertical housing part 8.

  A pair of guide rails 12 and 14 extending in the vertical direction are fixed to the vertical housing portion 8. A grinding means (grinding unit) 16 is mounted along the pair of guide rails 12 and 14 so as to be movable in the vertical direction. The grinding unit 16 is attached to a moving base 18 that moves up and down along a pair of guide rails 12 and 14 via a support portion 20.

  The grinding unit 16 includes a spindle housing 22 attached to the support portion 20, a spindle 24 rotatably accommodated in the spindle housing 22, and a servo motor 26 that rotationally drives the spindle 24. Grinding water is supplied to the grinding means (grinding unit) 16 via a hose 36. Preferably, pure water is used as the grinding water.

  The grinding apparatus 2 includes a grinding unit feed mechanism 44 that moves the grinding unit 16 in the vertical direction along the pair of guide rails 12 and 14. The grinding unit feed mechanism 44 includes a ball screw 46 and a pulse motor 48 fixed to one end of the ball screw 46. When the pulse motor 48 is pulse-driven, the ball screw 46 rotates and the moving base 18 is moved in the vertical direction via the nut of the ball screw 46 fixed inside the moving base 18.

  A chuck table unit 50 is disposed in the recess 10 of the horizontal housing portion 6. As shown in FIG. 4, the chuck table unit 50 includes a support base 52 and a chuck table 54 that is rotatably disposed on the support base 52. The chuck table unit 50 further includes a cover 56 having a hole through which the chuck table 54 is inserted.

  The chuck table unit 50 is moved in the front-rear direction of the grinding apparatus 2 by the chuck table moving mechanism 58. The chuck table moving mechanism 58 includes a ball screw 60 and a pulse motor 64 connected to one end of a screw shaft 62 of the ball screw 60.

  When the pulse motor 64 is pulse-driven, the screw shaft 62 of the ball screw 60 rotates, and the support base 52 having a nut screwed to the screw shaft 62 moves in the front-rear direction of the grinding device 2. Therefore, the chuck table 54 also moves in the front-rear direction according to the rotation direction of the pulse motor 64.

  As shown in FIG. 3, the pair of guide rails 66 and 68 and the chuck table moving mechanism 58 shown in FIG. 4 are covered with bellows 70 and 72. That is, the front end portion of the bellows 70 is fixed to the front wall that defines the recess 10, and the rear end portion is fixed to the front end surface of the cover 56. The rear end of the bellows 72 is fixed to the vertical housing portion 8, and the front end thereof is fixed to the rear end surface of the cover 56.

  In the horizontal housing portion 6 of the housing 4, a first wafer cassette 74, a second wafer cassette 76, a wafer transfer means 78, a wafer temporary mounting means 80, a wafer carry-in means 82, and a wafer carry-out means 84 are provided. A cleaning means 86 is provided. Further, an operation means 88 is provided in front of the housing 4 for an operator to input grinding conditions and the like.

  Further, a cleaning water spray nozzle 90 for cleaning the chuck table 54 is provided at the approximate center of the horizontal housing portion 6. The cleaning water jet nozzle 90 ejects cleaning water toward the wafer after grinding held by the chuck table 54 in a state where the chuck table unit 54 is positioned in the wafer carry-in / carry-out region.

  The chuck table unit 50 pulse-drives the pulse motor 64 of the chuck table moving mechanism 58 to receive the wafer from the grinding area on the back side of the apparatus and the wafer carry-in means 82 shown in FIG. It is moved to and from the wafer loading / unloading area on the near side.

  Next, the grinding wheel mounting mechanism of the embodiment of the present invention will be described in detail with reference to FIGS. As shown in FIGS. 5A and 6A, a wheel mount 28 is screwed to the tip of the spindle 24 with a plurality of screws 25.

  An annular first mounting surface 28a is formed on the outermost peripheral portion of the wheel mount 28, and a second mounting surface 28b retracted from the first mounting surface 28a is formed on the inner peripheral portion thereof. A plurality of holes 27 are formed in the first mounting surface 28a, and a plurality of screw holes 29 are formed in the second mounting surface 28b.

  Reference numeral 30 denotes a first grinding wheel having a first inner diameter dimension, and a plurality of grinding wheels 34 in which diamond abrasive grains are hardened by vitrified bond or the like are fixed to the lower surface of an annular wheel base 32.

  As shown in FIG. 6A, the first grinding wheel 30 is screwed into the screw holes of the first grinding wheel 30 through the holes 27 with the plurality of screws 33, whereby the first mounting surface 28a of the wheel mount 28 is obtained. Attached to.

  The second grinding wheel 38 shown in FIG. 5 (B) has an outer diameter of a second dimension smaller than the first dimension, and a plurality of grindings in which diamond abrasive grains are hardened by vitrified bond or the like on the outer periphery of the wheel base 40. A grindstone 42 is fixedly configured.

  The wheel base 40 of the second grinding wheel 38 has a center hole 41 and a plurality of holes 31 for inserting fixing screws. As shown in FIG. 5B and FIG. 6B, the second grinding wheel 38 is screwed into the screw hole 29 of the wheel mount 28 through the hole 31, so 2 is attached to the mounting surface 28b.

  A grinding water nozzle 92 is fixed to the second mounting surface 28 b of the wheel mount 28 by a plurality of screws 37. The outer diameter of the grinding water nozzle 92 is set smaller than the diameter of the center hole 41 of the second grinding wheel 38, and the second grinding wheel 38 is attached to and detached from the wheel mount 28 while the grinding water nozzle 92 is attached to the wheel mount 28. Is now possible.

  As shown in FIGS. 7 and 8, the second grinding wheel 38 can be mounted on the second mounting surface 28 b of the wheel mount 28 while the first grinding wheel 30 is mounted on the first mounting surface 28 a of the wheel mount 28. is there.

  Conversely, the first grinding wheel 30 can be mounted on the first mounting surface 28 a of the wheel mount 28 while the second grinding wheel 38 is mounted on the second mounting surface 28 b of the wheel mount 28. That is, both the first grinding wheel 30 and the second grinding wheel 38 can be attached to and detached from the wheel mount 28 without being obstructed by the other grinding wheel.

  As best shown in FIG. 8, the grinding water nozzle 92 is located in the center of the wheel mount 28 so that it protrudes lower than the grinding wheel 34 of the first grinding wheel 30 and the grinding wheel 42 of the second grinding wheel 38. It is fixed. The grinding water nozzle 92 ejects grinding water from at least four directions toward the grinding wheels 34 and 42 positioned in the outer peripheral direction.

  The grinding operation of the grinding device 2 configured as described above will be described below. The wafer housed in the first wafer cassette 74 is a semiconductor wafer having a protective tape mounted on the front surface side (surface on which the circuit is formed), and therefore the wafer is positioned with the back surface positioned on the upper side. Housed in the first cassette 74. As described above, the first wafer cassette 74 that accommodates a plurality of semiconductor wafers is mounted with a predetermined cassette of the housing 4 in the carry-in area.

  When all of the unprocessed semiconductor wafers contained in the first wafer cassette 74 placed in the cassette carry-in area are carried out, a plurality of semiconductor wafers are accommodated in place of the empty wafer cassette 74. A new first wafer cassette 74 is manually placed in the cassette loading area.

  On the other hand, when a predetermined number of ground semiconductor wafers are loaded into the second wafer cassette 76 placed in the predetermined cassette unloading area of the housing 4, the second wafer cassette 76 is manually unloaded. A new empty second wafer cassette 76 is placed in the cassette unloading area.

  The semiconductor wafer accommodated in the first wafer cassette 74 is conveyed by the vertical movement and forward / backward movement of the wafer conveyance means 78 and is placed on the wafer temporary placement means 80. The wafer placed on the temporary wafer placement means 80 is centered here, and then the chuck table of the chuck table unit 50 positioned in the wafer carry-in / out area by the turning operation of the wafer carry-in means 82. 54 and is sucked and held by the chuck table 54.

  When the chuck table 54 sucks and holds the wafer in this way, the chuck table moving mechanism 58 is operated to move the chuck table unit 54 and position it in the grinding area behind the apparatus.

  When the chuck table unit 50 is positioned in the grinding region, the center of the wafer held by the chuck table 54 is positioned at a position slightly beyond the outer circumference circle of the grinding wheel 30 as shown in FIG.

  Next, the chuck table 54 is rotated at, for example, about 100 to 300 rpm, the servo motor 26 is driven to rotate the grinding wheel 30 at 4000 to 7000 rpm, and the pulse motor 48 of the grinding unit feed mechanism 44 is driven to rotate forward. The grinding unit 16 is lowered.

  Then, the back surface of the wafer 11 is ground by pressing the grinding wheel 34 of the grinding wheel 30 against the back surface (surface to be ground) of the wafer 11 on the chuck table 54 with a predetermined load. By grinding in this way for a predetermined time, the wafer 11 is ground to a predetermined thickness.

  When grinding is completed, the chuck table moving mechanism 58 is driven to position the chuck table 54 in the wafer loading / unloading area on the front side of the apparatus. If the chuck table 54 is positioned in the wafer loading / unloading area, the cleaning water is sprayed from the cleaning water spray nozzle 90 and the ground surface (back surface) of the ground wafer 11 held by the chuck table 54 is held. Wash.

  Next, in the case of a grinding method in which only the back surface of the device region 17 of the wafer 11 is ground and the convex portion is left in the outer peripheral surplus region 19, the second grinding wheel 38 is mounted on the wheel mount 28 as shown in FIG. The wafer 11 is grounded by being mounted on.

  That is, in the case of this grinding method, as shown in FIG. 11, the rotation center P 1 of the chuck table 54 and the rotation center P 2 of the grinding wheel 42 are eccentric, and the outer diameter of the grinding wheel 42 is the device region 17 of the wafer 11. And an outer diameter of the boundary line 94 that is smaller than the diameter of the boundary line 94 and larger than the radius of the boundary line 94, and the annular grinding wheel 42 passes through the rotation center P 1 of the chuck table 54.

  While rotating the chuck table 54 in the direction indicated by the arrow 55 at 300 rpm and rotating the grinding wheel 42 in the direction indicated by the arrow 96 at 6000 rpm, the servo motor 26 is operated to move the grinding wheel 42 of the second grinding wheel 38 to the wafer. 11 is brought into contact with the back surface. Then, the second grinding wheel 38 is ground and fed downward by a predetermined amount at a predetermined grinding feed speed.

  As a result, on the back surface of the semiconductor wafer 11, as shown in FIG. 12, a region corresponding to the device region 17 is ground and removed to form a circular recess 98 having a predetermined thickness (for example, 50 μm). A region corresponding to the surplus region 19 remains to form an annular convex portion (annular reinforcing portion) 100.

  Next, referring to FIGS. 10A to 10C, the first and second grinding wheels 30 and 38 are attached to the wheel mount 28, and only the back surface of the wafer 11 corresponding to the device region 17 is attached. A grinding method will be described in which an annular convex portion is left in the outer peripheral surplus region 19 and then only the annular convex portion is ground to flatten the wafer to some extent.

  In this case, for example, the grinding wheel 42 for rough grinding is mounted on the second grinding wheel 38, and the grinding wheel 34 for finish grinding is mounted on the first grinding wheel 30. First, as shown in FIG. 10A, an annular reinforcing portion forming step is performed in which the second grinding wheel 38 leaves the outer peripheral surplus region 19 of the wafer 11 and grinds the back surface of the wafer 11 corresponding to the device region 17.

  Next, as shown in FIG. 10B, a rough grinding step of the annular reinforcing portion 39 is performed by the second grinding wheel 38, and then, as shown in FIG. 39 finish grinding steps are performed.

  As described above, according to the grinding wheel mounting mechanism of the present embodiment, the annular protrusion is formed in the outer peripheral surplus region 19 of the wafer 11, and then the annular protrusion is ground to flatten the entire wafer 11 to some extent. Can be implemented by mounting the first and second grinding wheels 30, 38 on one spindle 24.

It is a front side perspective view of a semiconductor wafer. It is a back surface side perspective view of the semiconductor wafer where the protective tape was stuck. 1 is an external perspective view of a grinding apparatus suitable for applying a grinding wheel mounting mechanism of the present invention. It is a perspective view of a chuck table unit and a chuck table feed mechanism. FIG. 5A is a perspective view showing a state where the first grinding wheel is mounted on the wheel mount, and FIG. 5B is a perspective view showing a state where the second grinding wheel is mounted on the wheel mount. FIG. 6A is a cross-sectional view of a state where the first grinding wheel is mounted on the wheel mount, and FIG. 6B is a cross-sectional view of a state where the second grinding wheel is mounted on the wheel mount. It is a perspective view which shows a mode that the 1st and 2nd grinding wheel is mounted | worn with a wheel mount. It is sectional drawing of the state in which the 1st and 2nd grinding wheel was mounted | worn with the wheel mount. FIG. 9 (A) is an explanatory view showing the state of grinding the entire back surface of the wafer with the first grinding wheel, and FIG. 9 (B) is the outer peripheral surplus by grinding only the back surface corresponding to the device region of the wafer with the second grinding wheel. It is explanatory drawing of the grinding method which leaves an annular convex part in an area | region. FIG. 10A is an explanatory diagram of a grinding process in which only the back surface corresponding to the device region of the wafer is ground by the second grinding wheel and an annular convex portion is left in the outer peripheral surplus region, and FIG. 10B is the second grinding wheel. FIG. 10C is an explanatory diagram showing a step of finish grinding the annular convex portion with a first grinding wheel. It is explanatory drawing of the recessed part grinding process implemented by the 2nd grinding wheel. It is an expanded sectional view of the semiconductor wafer in which the recessed part grinding process was implemented.

Explanation of symbols

2 Grinding machine 11 Semiconductor wafer 16 Grinding means (grinding unit)
24 Spindle 28 Wheel mount 28a First mounting surface 28b Second mounting surface 30 First grinding wheel 34 First grinding wheel 38 Second grinding wheel 42 Second grinding wheel 92 Grinding water nozzle

Claims (3)

A grinding wheel mounting mechanism for detachably mounting a grinding wheel on a wheel mount fixed to a spindle of a grinding device,
The grinding wheel comprises a first grinding wheel comprising an annular first wheel base having an inner diameter of a first dimension, and a plurality of first grinding wheels attached to the first wheel base;
A second grinding wheel comprising a second wheel base having an outer diameter of a second dimension smaller than the first dimension, and a plurality of second grinding wheels attached to the second wheel base;
The wheel mount is provided on an annular first mounting surface on which the first wheel base of the first grinding wheel is mounted, and an inner peripheral portion of the first mounting surface, and the second wheel base of the second grinding wheel And a second mounting surface on which is mounted,
When the first grinding wheel and the second grinding wheel are mounted on the first mounting surface and the second mounting surface, respectively, the end surface of the second grinding wheel of the second grinding wheel is the one of the first grinding wheel. A grinding wheel mounting mechanism that protrudes a predetermined distance from the end face of the first grinding wheel. Including a grinding water nozzle that ejects grinding water mounted on a central portion of the wheel mount;
2. The grinding wheel mounting mechanism according to claim 1, wherein the protruding height of the grinding water nozzle is lower than the protruding height of the first and second grinding wheels.   3. The grinding wheel mounting mechanism according to claim 1, wherein both the first and second grinding wheels are detachable in a state where the first and second grinding wheels are mounted on the wheel mount. .

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