JP4977449B2 - Wafer grinding method and grinding apparatus - Google Patents

Description

  The present invention relates to a wafer grinding method and a grinding apparatus for grinding at least one surface of a wafer sliced from a semiconductor ingot such as a silicon ingot.

  In the manufacturing process of a semiconductor device, a semiconductor ingot such as a silicon ingot is sliced to form a wafer, and both surfaces of the wafer are ground to form a flat surface. The semiconductor ingot is sliced by a cutting machine such as an inner peripheral cutting machine or a multi-wire saw. However, undulation is generated on both sides of the wafer into which the semiconductor ingot is sliced by the cutting machine, and the undulation remains even if both sides of the wafer having the undulation are ground as they are. That is, when grinding one surface of a wafer having undulation, if the other surface of the wafer is sucked and held on the chuck table of the grinding device, the undulation generated on the other surface is elastically deformed. Is attracted to the suction surface of the chuck table. When one surface of the wafer thus sucked and held is ground, one surface of the wafer is ground to a flat surface when sucked and held by the chuck table. However, if the wafer is removed from the chuck table after grinding, Since it springs back and returns to the state before elastic deformation, undulation remains on one ground surface.

As a method for grinding a wafer to solve the above-described problems, when grinding one surface of a wafer formed by slicing a semiconductor ingot, a wax is applied to the other surface of the wafer and cured, and the cured wax side Has been proposed in which one surface of a wafer is ground by sucking and holding the wafer on a chuck table of a grinding apparatus. (For example, refer to Patent Document 1).
Japanese Patent Application No. 2000-5982

  Thus, the wafer grinding method disclosed in the above publication includes a step of applying a wax to the other surface of the wafer when grinding one surface of the wafer, and a wax applied to the other surface of the wafer. It is necessary to carry out a process for flattening the surface of the film, and the working efficiency is poor.

  The present invention has been made in view of the above-mentioned facts, and a main technical problem thereof is grinding of a wafer capable of efficiently grinding at least one surface of a wafer formed by slicing a semiconductor ingot into a flat surface. It is to provide a method and a grinding apparatus.

In order to solve the main technical problem, according to the present invention, a wafer grinding method for grinding one surface of a wafer formed by slicing a semiconductor ingot,
A chuck table having a holding surface formed in a conical shape with the rotation center as a vertex and holding only the central region of the wafer by suction and holding the central region of the other surface of the wafer by concentrating the wafer with the rotation center as a vertex. A wafer holding step for holding the shape ,
The chuck table that holds and holds only the center area of the wafer is rotated, and the grinding wheel is brought into contact with one surface of the wafer held in a conical shape with the rotation center as a vertex while rotating the grinding wheel provided with the grinding wheel. A grinding step of grinding one surface of the wafer,
A method for grinding a wafer is provided.

Further, according to the present invention, in a wafer grinding apparatus comprising: a chuck table mechanism for holding a wafer; and a grinding means having a grinding wheel for grinding the wafer held by the chuck table mechanism.
The chuck table mechanism includes a chuck table having a holding surface formed in a conical shape with the rotation center as an apex and having a suction holding chuck for sucking and holding only the central region of the wafer, and a drive for driving the chuck table to rotate. Source,
The grinding wheel has a support base, a grinding wheel disposed annularly on a lower surface of the supporting base, comprising a drive mechanism for rotating the said supporting Jimotodai, the lower surface of the support base The grinding wheel arranged in an annular shape is in contact with a region extending from the center of rotation to the outer periphery of one surface of the wafer in which only the center region is sucked and held in a conical shape with the rotation center as an apex at the chuck holding chuck of the chuck table. Is configured to
A wafer grinding apparatus is provided.

  The chuck holding chuck of the chuck table is made of resin. Moreover, it is desirable that the resin forming the suction holding chuck is hard urethane.

According to the present invention, since the wafer is sucked and held on the chuck table having the holding surface formed in a conical shape with the center of rotation as the apex, the influence of the elastic deformation of the sea urchin is very small. Therefore, even if one surface of the wafer is ground and then removed from the chuck table, undulation remains very little on the one surface ground by the spring back. As described above, according to the present invention, when grinding one surface of the wafer as in the conventional grinding method, it is necessary to carry out a step of applying wax to the other surface of the wafer, a step of removing wax, and the like. Therefore, one surface of the wafer formed by slicing the semiconductor ingot can be efficiently ground to a flat surface.

Preferred embodiments of a wafer processing method and a grinding apparatus according to the present invention will be described below in more detail with reference to the accompanying drawings.
FIG. 1 shows a perspective view of a grinding apparatus constructed in accordance with the present invention.
A grinding apparatus 1 shown in FIG. 1 includes an apparatus housing generally indicated by numeral 2. This device housing 2 has a rectangular parallelepiped main portion 21 that extends long and an upright wall 22 that is provided at the rear end portion (upper right end in FIG. 1) of the main portion 21 and extends substantially vertically upward. ing. A pair of guide rails 221 and 221 extending in the vertical direction are provided on the front surface of the upright wall 22. The grinding unit 3 is mounted on the pair of guide rails 221 and 221 so as to be movable in the vertical direction.

  The grinding unit 3 includes a moving base 31 and a spindle unit 32 attached to the moving base 31. The movable base 31 is provided with a pair of legs 311 and 311 extending in the vertical direction on both sides of the rear surface. The pair of legs 311 and 311 is slidably engaged with the pair of guide rails 221 and 221. Guided grooves 312 and 312 are formed. As described above, a support portion 313 protruding forward is provided on the front surface of the movable base 31 slidably mounted on the pair of guide rails 221 and 221 provided on the upright wall 22. The spindle unit 32 is attached to the support portion 313.

  The spindle unit 32 includes a unit housing 321 mounted on the support portion 313, a rotating spindle 322 rotatably disposed on the unit housing 321, and a servo motor as a drive source for rotationally driving the rotating spindle 322. 323. The lower end of the rotary spindle 322 protrudes downward beyond the lower end of the unit housing 321, and a disk-shaped mounter 324 is provided at the lower end. The mounter 324 is formed with a plurality of bolt insertion holes (not shown) at intervals in the circumferential direction. The grinding wheel 4 is detachably mounted on the lower surface of the mounter 324. The grinding wheel 4 includes an annular support base 41 and a plurality of grinding wheels 42 arranged annularly on the same circumference on the lower surface of the annular support member 41. Is mounted on the lower surface of the mounter 324 by fastening bolts 325. In the spindle unit 32 configured as described above, when the servo motor 323 is driven, the grinding wheel 4 is rotated via the rotary spindle 322 and the mounter 324. Accordingly, the servo motor 323, the rotary spindle 322, and the mounter 324 function as drive means for driving the grinding wheel 4 to rotate.

  The polishing apparatus shown in FIG. 1 includes grinding feed means 5 for moving the polishing unit 3 in the vertical direction (a direction perpendicular to a holding surface of a chuck table described later) along the pair of guide rails 221 and 221. ing. The grinding feed means 5 includes a male threaded rod 51 disposed on the front side of the upright wall 22 and extending substantially vertically. The male screw rod 51 is rotatably supported by bearing members 52 and 53 whose upper end and lower end are attached to the upright wall 22. The upper bearing member 52 is provided with a pulse motor 54 as a drive source for rotationally driving the male screw rod 51, and an output shaft of the pulse motor 54 is transmission-coupled to the male screw rod 51. A connecting portion (not shown) that protrudes rearward from the center portion in the width direction is also formed on the rear surface of the movable base 31, and a through female screw hole (not shown) that extends in the vertical direction is formed in this connecting portion. The male screw rod 51 is screwed into the female screw hole. Accordingly, when the pulse motor 54 rotates in the forward direction, the moving base 31, that is, the polishing unit 3 is lowered or moved forward, and when the pulse motor 54 rotates in the reverse direction, the moving base 31, that is, the polishing unit 3 is raised or moved backward.

  A chuck table mechanism 6 is disposed in the main portion 21 of the housing 2. As shown in FIG. 2, the chuck table mechanism 6 includes a support table 61 and a chuck table 62 disposed on the support table 61 so as to be rotatable about a rotation center axis extending substantially vertically. The support base 61 is slidable on a pair of guide rails 23 and 23 extending in a direction indicated by arrows 23a and 23b in the front-rear direction (a direction perpendicular to the front surface of the upright wall 22). The workpiece loading / unloading area 24 shown in FIG. 1 (position shown by a solid line in FIG. 2) and the cutting tool 33 constituting the spindle unit 32 are opposed to each other by a chuck table moving mechanism 66 described later. It is moved between the machining area 25 (the position indicated by the two-dot chain line in FIG. 2).

  The chuck table 62 is configured to suck and hold only the central region of a wafer as a workpiece. As shown in FIG. 3, the chuck table 62 is formed into a disk shape by a cylindrical base 621 and hard urethane having a plurality of ventilation holes. The suction holding chuck 622 is formed. The chuck table 62 configured as described above sucks and holds the wafer placed on the holding surface 622a which is the upper surface of the suction holding chuck 622 by operating a suction means (not shown). Note that the holding surface 622a of the suction holding chuck 622 in the illustrated embodiment is formed in a conical shape with the rotation center P1 as an apex, as shown exaggeratedly in FIG. The holding surface 622a formed in the conical shape has a gradient (H / R) of 0.00001 to 0.001 when the radius is R and the height of the apex is H. In the illustrated embodiment, the radius R of the holding surface 622a of the suction holding chuck 622 is set to 20 mm, and the height H of the apex is set to 20 μm.

  Returning to FIG. 2 and continuing the description, the chuck table 62 is configured to be rotated by a servo motor 63 as a drive source disposed on the support base 61. The chuck table mechanism 6 in the illustrated embodiment includes a cover member 64 that has a hole through which the chuck table 62 is inserted, covers the support base 61 and the like, and is movably disposed together with the support base 61.

  Continuing with reference to FIG. 2, the grinding apparatus in the illustrated embodiment includes a chuck table moving mechanism 66 that moves the chuck table 62 along the pair of guide rails 23 in the directions indicated by the arrows 23a and 23b. is doing. The chuck table moving mechanism 66 includes a male screw rod 661 disposed between the pair of guide rails 23 and 23 and extending in parallel with the guide rails 23 and 23, and a servo motor 662 that rotationally drives the male screw rod 661. The male screw rod 661 is screwed into a screw hole 611 provided in the support base 61, and the tip end portion thereof is rotatably supported by a bearing member 663 attached by connecting a pair of guide rails 23 and 23. Yes. The servo motor 662 has a drive shaft connected to the base end of the external thread rod 661 by transmission. Therefore, when the servo motor 662 rotates forward, the support base 61, that is, the chuck table mechanism 6 moves in the direction indicated by the arrow 23a. When the servo motor 662 reversely rotates, the support base 61, that is, the chuck table mechanism 6 moves in the direction indicated by the arrow 23b. It is done. The chuck table mechanism 6 that is moved in the directions indicated by the arrows 23a and 23b is selectively positioned in a workpiece loading / unloading area indicated by a solid line and a machining area indicated by a two-dot chain line in FIG.

  Returning to FIG. 1, the description will be continued. On both sides in the moving direction of the support base 61 constituting the chuck table mechanism 6, the cross-sectional shape is a reverse channel shape as shown in FIG. 23, bellows means 67 and 68 covering the male screw rod 661 and the servo motor 662 are provided. The bellows means 67 and 68 can be formed from any suitable material such as campus cloth. The front end of the bellows means 67 is fixed to the front wall of the processing unit 211, and the rear end is fixed to the front end surface of the cover member 64 of the chuck table mechanism 6. The front end of the bellows means 68 is fixed to the rear end surface of the cover member 64 of the chuck table mechanism 6, and the rear end is fixed to the front surface of the upright wall 22 of the apparatus housing 2. When the chuck table mechanism 6 is moved in the direction indicated by the arrow 23a, the bellows means 67 is expanded and the bellows means 68 is contracted, and when the chuck table mechanism 6 is moved in the direction indicated by the arrow 23b, the bellows means. 67 is contracted and the bellows means 68 is extended.

The grinding apparatus in the illustrated embodiment is configured as described above, and a wafer grinding method for grinding one surface of a wafer formed by slicing a semiconductor ingot by the grinding apparatus will be described below.
FIG. 4 shows a front view of a wafer formed by slicing a semiconductor ingot processed according to the present invention. A wafer 10 shown in FIG. 4 is formed in a disk shape having a diameter of, for example, 200 mm, and exaggerated bulges 101 are generated on the upper and lower surfaces thereof.

  In order to grind one surface of the wafer 10 shown in FIG. 4 using the grinding apparatus 1 shown in FIG. 2, it is shown on the chuck table 62 of the chuck table mechanism 6 positioned in the workpiece loading / unloading area 24. The wafer 10 is transported by a transport means that does not. That is, as shown in FIG. 5, the central region of the other surface (the lower surface in FIG. 5) of the wafer 10 is placed on the holding surface 622 a of the suction holding chuck 622 constituting the chuck table 62. Then, by operating a suction means (not shown), the central region of the wafer 10 is sucked and held on the chuck table 62 (wafer holding step). When the central region of the wafer 10 is sucked and held on the chuck table 62 in this way, the holding surface 622a of the suction holding chuck 622 constituting the chuck table 62 is formed in a conical shape with the rotation center P1 as the apex as described above. Therefore, the wafer 10 also has a conical shape with the rotation center P1 as a vertex. Since the wafer 10 is sucked and held only on the suction holding chuck 622 of the chuck table 62, the influence of the elastic deformation of the shell 101 is very small. In particular, in the illustrated embodiment, the suction holding chuck 622 of the chuck table 62 that sucks and holds the central region of the wafer 10 is formed of hard urethane having a plurality of air holes, and therefore the other surface of the wafer 10 (FIG. 5). The bottom surface 101 of the wafer 10 is elastically deformed slightly, so that the bottom surface 101 of the wafer 10 is not elastically deformed. Accordingly, the wafer 10 is sucked and held on the suction holding chuck 622 of the chuck table 62 in a natural state where the undulation 101 is generated.

  When the wafer holding step described above is performed, the chuck table moving mechanism 66 (see FIG. 2) is operated to move the chuck table mechanism 6 in the direction indicated by the arrow 23a, and the chuck table 62 holding the wafer 10 is moved into the machining area. 25. When the chuck table 62 holding the wafer 10 is positioned in the machining area 25 in this way, the chuck table 62 is rotated in the direction indicated by the arrow 62a in FIG. The servo motor 323 is driven to rotate the grinding wheel 4 in the direction indicated by the arrow 4a at a rotational speed of, for example, 6000 rpm. Then, the pulse motor 54 of the grinding feed means 5 is driven to rotate forward, and the grinding wheel 4 is lowered and fed by grinding as indicated by an arrow 4b. As a result, the plurality of grinding wheels 42 of the grinding wheel 4 press against one surface which is the upper surface of the wafer 10 with a predetermined pressure, and the one surface which is the upper surface of the wafer 10 is ground over the entire surface (grinding step). ). In this grinding process, the grinding water is supplied to the grinding portion by the grinding wheel 42 by a grinding water supply means (not shown). By carrying out the grinding step, the undelli 101 formed on one surface which is the upper surface of the wafer 10 is removed, and one surface which is the upper surface of the wafer 10 is formed into a flat surface. In the wafer 10 that has been subjected to the grinding process in this way, even if it is removed from the chuck table 62 to grind the other surface, the bulge 101 generated on the other surface is not elastically deformed as described above. Therefore, the undulation 101 does not remain on one surface ground by the spring back.

  When one surface of the wafer 10 is ground by performing the above-described grinding process, the other surface of the wafer 10 is ground. In grinding the other surface of the wafer 10, one surface of the wafer 10 is sucked and held on the chuck table 62 of the grinding device, and the other surface of the wafer 10 is ground as described above. In the grinding of the other surface of the wafer 10, since one surface of the wafer 10 is formed into a flat surface by performing the above-described grinding process, it is conventionally used to suck and hold the entire surface of the wafer 10. It can also be implemented by existing grinding equipment.

1 is a perspective view of a grinding apparatus constructed according to the present invention. The perspective view of the chuck table mechanism which comprises the grinding device shown in FIG. Sectional drawing which expands and shows the principal part of the chuck table which comprises the chuck table climate shown in FIG. The front view of the wafer formed by slicing the semiconductor ingot processed by the wafer grinding method by the present invention. Explanatory drawing of the wafer holding | maintenance process and grinding process in the grinding method of the wafer by this invention.

Explanation of symbols

1: Grinding device 2: Device housing 3: Grinding unit 31: Moving base 32: Spindle unit 321: Unit housing 322: Rotary spindle 323: Servo motor 324: Mounter 4: Grinding wheel 41: Support base 42: Grinding wheel 5 : Grinding feed means 54: pulse motor 6: chuck table mechanism 61: support table 62: chuck table 621: chuck table base 622: suction holding chuck 63: servo motor 64: cover member 10: semiconductor wafer

Claims (4)

A wafer grinding method for grinding one surface of a wafer formed by slicing a semiconductor ingot,
A chuck table having a holding surface formed in a conical shape with the rotation center as a vertex and holding only the central region of the wafer by suction and holding the central region of the other surface of the wafer by concentrating the wafer with the rotation center as a vertex. A wafer holding step for holding the shape ,
The chuck table that holds and holds only the center area of the wafer is rotated, and the grinding wheel is brought into contact with one surface of the wafer held in a conical shape with the rotation center as a vertex while rotating the grinding wheel provided with the grinding wheel. A grinding step of grinding one surface of the wafer,
A method for grinding a wafer. In a wafer grinding apparatus comprising: a chuck table mechanism for holding a wafer; and a grinding means having a grinding wheel for grinding the wafer held by the chuck table mechanism.
The chuck table mechanism includes a chuck table having a holding surface formed in a conical shape with the rotation center as an apex and having a suction holding chuck for sucking and holding only the central region of the wafer, and a drive for driving the chuck table to rotate. Source,
The grinding wheel has a support base, a grinding wheel disposed annularly on a lower surface of the supporting base, comprising a drive mechanism for rotating the said supporting Jimotodai, the lower surface of the support base The grinding wheel arranged in an annular shape is in contact with a region extending from the center of rotation to the outer periphery of one surface of the wafer in which only the center region is sucked and held in a conical shape with the rotation center as an apex at the chuck holding chuck of the chuck table. Is configured to
A wafer grinding apparatus characterized by that.   The wafer grinding apparatus according to claim 2, wherein the suction holding chuck of the chuck table is made of resin.   4. The wafer grinding apparatus according to claim 3, wherein the resin forming the suction holding chuck is hard urethane.

Images