JP2011187519A - Chuck table of wafer cleaning apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chuck table of a cleaning apparatus where the adhesion of grinding shavings to the rear side of a wafer, and the generation of a flaw to be caused by the grinding shavings can be prevented. <P>SOLUTION: The chuck table of the wafer cleaning apparatus includes a rotatable chuck table base, and at least three vacuum suction pads which are composed of elastic members arranged on the upper surface of the chuck table base with equal spaces therebetween in a shape of a concentric circle with the center of rotation of the chuck table base as a center where the chuck table base has a suction path which communicates with each of the vacuum suction pads. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a chuck table for a wafer cleaning apparatus for cleaning an upper surface or an upper surface and side surfaces while rotating the wafer.

  In a semiconductor device manufacturing process, a process of cleaning a wafer having a plurality of semiconductor devices formed on the upper surface can be found in many scenes. For example, even in a wafer grinding process for precisely grinding a wafer to a predetermined thickness, a cleaning process is essential, and a wafer cleaning apparatus is incorporated in the grinding apparatus (see, for example, Japanese Patent No. 3377121).

  In the grinding apparatus, a large amount of grinding waste is generated to grind the wafer. Therefore, in order to remove grinding debris, it is necessary to clean the ground surface of the wafer with pure water or the like immediately after the completion of grinding. At the time of cleaning, the ground wafer is placed on the rotary chuck table for cleaning with the grinding surface facing up, and the chuck table rotates at a high speed while the wafer is sucked and held, and the wafer is cleaned from above the wafer. The deionized water or the like is ejected vigorously, so that grinding waste on the wafer is removed by the water pressure of the cleaning water and the centrifugal force of rotation.

Japanese Patent No. 3377121

  However, in the conventional cleaning device, since the wafer is directly sucked and held by the chuck table having the suction holes, the grinding dust blown off by the cleaning stays in the atmosphere around the cleaning device, and there is a chuck of the cleaning device. There is a possibility of adhering to the upper surface of the table.

  If grinding debris adheres to the upper surface of the chuck table, it will come into contact with the back side of the wafer placed on the chuck table, causing scratches on the back side of the wafer, or grinding debris adhering as dust, which causes problems in the next process. There is a possibility.

  In particular, when grinding a wafer cut from an ingot with a wire saw or the like to a predetermined thickness, the wafer is directly sucked and held by a chuck table without attaching a protective tape to the surface of the wafer, and then ground. Since the ground wafer is also directly sucked and held by the chuck table of the cleaning device, the back surface of the wafer is easily damaged by grinding debris.

  The present invention has been made in view of the above points, and the object of the present invention is to prevent grinding scraps from adhering to the wafer back side opposite to the grinding surface, and to prevent generation of scratches due to the grinding scraps. A chuck table for a cleaning apparatus is provided.

  According to the present invention, there is provided a chuck table for a wafer cleaning apparatus, wherein the chuck table base is rotatable, and the upper surface of the chuck table base is concentrically spaced from the upper surface of the chuck table base so as to be concentrically spaced from each other. And at least three vacuum suction pads made of elastic members, and the chuck table base has a suction path communicating with each of the vacuum suction pads. A chuck table for a cleaning apparatus is provided.

  According to the present invention, only a few vacuum suction pads are in contact with the wafer back surface opposite to the grinding surface, so that the wafer and the chuck table are in contact with each other only in a very small area. Therefore, the possibility of problems due to contact can be suppressed.

It is a schematic perspective view of the grinding device which employ | adopted the chuck table of the wafer cleaning apparatus of this invention. It is a perspective view of the chuck table of the cleaning device according to the embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, there is shown a schematic perspective view of a grinding apparatus 2 having a chuck table 68 of a wafer cleaning apparatus according to the present invention. The chuck table 68 of the wafer cleaning apparatus of the present invention is particularly suitable for cleaning a silicon wafer sliced from a silicon ingot with a wire saw or the like.

  Reference numeral 4 denotes a housing (base) of the grinding apparatus 2, and two columns 6 a and 6 b are provided upright on the rear side of the housing 4. A pair of guide rails (only one is shown) 8 extending in the vertical direction is fixed to the column 6a.

  A rough grinding unit 10 is mounted along the pair of guide rails 8 so as to be movable in the vertical direction. The rough grinding unit 10 is attached to a moving base 12 whose housing 20 moves up and down along a pair of guide rails 8.

  The rough grinding unit 10 includes a housing 20, a spindle (not shown) rotatably accommodated in the housing 20, a servo motor 22 that rotationally drives the spindle, and a plurality of rough grinding grinding wheels fixed to the tip of the spindle. A grinding wheel 24 having 26 is included.

  The rough grinding unit 10 includes a rough grinding unit moving mechanism 18 including a ball screw 14 and a pulse motor 16 that move the rough grinding unit 10 up and down along a pair of guide rails 8. When the pulse motor 16 is pulse-driven, the ball screw 14 rotates and the moving base 12 is moved in the vertical direction.

  A pair of guide rails 19 (only one is shown) 19 extending in the vertical direction are also fixed to the other column 6b. A finish grinding unit 28 is mounted along the pair of guide rails 19 so as to be movable in the vertical direction.

  The finish grinding unit 28 is attached to a moving base (not shown) in which the housing 36 moves in the vertical direction along the pair of guide rails 19. The finish grinding unit 28 includes a housing 36, a spindle (not shown) rotatably accommodated in the housing 36, a servo motor 38 that rotationally drives the spindle, and a grinding wheel 42 for finish grinding fixed to the tip of the spindle. A grinding wheel 40 is included.

  The finish grinding unit 28 includes a finish grinding unit moving mechanism 34 including a ball screw 30 and a pulse motor 32 that move the finish grinding unit 28 in the vertical direction along the pair of guide rails 19. When the pulse motor 32 is driven, the ball screw 30 rotates and the finish grinding unit 28 is moved in the vertical direction.

  The grinding device 2 includes a turntable 44 disposed so as to be substantially flush with the upper surface of the housing 4 on the front side of the columns 6a and 6b. The turntable 44 is formed in a relatively large-diameter disk shape, and is rotated in a direction indicated by an arrow 45 by a rotation drive mechanism (not shown).

  On the turntable 44, three chuck tables 46 are arranged so as to be rotatable in a horizontal plane, spaced from each other by 120 ° in the circumferential direction. The chuck table 46 has a suction chuck formed in a disk shape by a porous ceramic material, and sucks and holds the wafer placed on the holding surface of the suction chuck by operating a vacuum suction means.

  The three chuck tables 46 arranged on the turntable 44 are rotated in accordance with the turntable 44, so that the wafer loading / unloading area A, rough grinding area B, finish grinding area C, and wafer loading / unloading are performed. The region A is sequentially moved.

  In the front portion of the housing 4, a wafer cassette 50, a wafer transfer robot 54 having a link 51 and a hand 52, a positioning table 56 having a plurality of positioning pins 58, a wafer carry-in mechanism (loading arm) 60, and a wafer carry-out A mechanism (unloading arm) 62, a spinner cleaning device 64 that cleans and spin-drys the ground wafer, and a storage cassette 66 that stores the ground wafer that has been cleaned and spin-dried by the spinner cleaning device 64 are provided. ing.

  Mounted on the spinner cleaning device 64 is a chuck table 68 according to an embodiment of the present invention that rotates by sucking and holding a ground semiconductor wafer. Reference numeral 70 denotes a cover of the spinner cleaning device 64.

  Next, the detailed structure of the chuck table 68 according to the embodiment of the present invention will be described with reference to FIG. The chuck table 68 has a disk-shaped chuck table base 72, and the upper surface of the chuck table base 72 is spaced apart at equal intervals concentrically around the rotation center of the chuck table 68. Three vacuum suction pads 74 are arranged so as to protrude from the upper surface of the base 72. The vacuum suction pad 74 is made of an elastic member such as rubber.

  Each vacuum suction pad 74 is connected to a vacuum suction source 78 via a suction path 76. An electromagnetic valve 80 is inserted in the suction path 76, and the vacuum suction pad 74 is selectively connected to the suction source 78 by selective switching of the electromagnetic valve 80.

  The spinner cleaning device 64 includes a cleaning nozzle 82 that ejects a cleaning solution 83 such as pure water when cleaning a ground wafer. The ground wafer 11 is rotated while the back surface is sucked and held by a vacuum suction pad 74. The cleaning liquid 83 ejected from the cleaning nozzle 82 is cleaned.

  Hereinafter, the operation of the grinding apparatus 2 that grinds and cleans the wafer 11 sliced from the silicon ingot will be described. The wafer 11 sliced from the ingot has a thickness of about 1 mm.

  A plurality of wafers 11 sliced from the ingot are accommodated in the wafer cassette 50 without attaching a protective tape or the like to the surface, and the wafer cassette 50 is placed on the base 4. The wafer 11 accommodated in the wafer cassette 50 is transported by the wafer transport robot 54 in the up / down motion and the forward / backward motion, and is placed on the wafer positioning table 56.

  The wafer placed on the wafer positioning table 56 is centered by a plurality of positioning pins 58 and then turned on the chuck table 46 positioned in the wafer loading / unloading area A by the turning operation of the loading arm 60. And sucked and held by the chuck table 46.

  Next, the turntable 44 is rotated 120 degrees counterclockwise, and the chuck table 46 holding the wafer is positioned in the rough grinding region B. While rotating the chuck table 46 at, for example, 300 rpm with respect to the wafer thus positioned, the grinding wheel 24 is rotated in the same direction as the chuck table 46, for example, at 6000 rpm, and the rough grinding unit moving mechanism 18 is operated to perform roughing. A grinding wheel 26 for grinding is brought into contact with the back surface of the wafer.

  Then, the grinding wheel 24 is ground and fed by a predetermined amount at a predetermined grinding feed speed to perform rough grinding. The wafer is ground to a desired thickness while measuring the thickness of the wafer with a contact or non-contact thickness gauge.

  The chuck table 46 holding the wafer after the rough grinding is positioned in the finish grinding region C by rotating the turntable 44 counterclockwise by 120 degrees, and is finished by the finish grinding unit 28 having the finish grinding wheel 42. Grinding is performed.

  The chuck table 46 holding the wafer 11 that has finished finish grinding is positioned in the wafer carry-in / out area A by rotating the turntable 44 120 degrees counterclockwise.

  After the suction holding of the wafer held on the chuck table 46 is released, the wafer is adsorbed by the wafer unloading mechanism (unloading arm) 62, and is transported to the spinner cleaning device 64 by turning the unloading arm 62. The

  The wafer 11 conveyed to the spinner cleaning device 64 is suction-held by the vacuum suction pad 74 of the chuck table 68 so that the chuck table 68 rotates at a predetermined speed in the direction of arrow A at a predetermined speed. A cleaning liquid 83 such as pure water is ejected from the nozzle 82 to clean the ground surface.

  During the cleaning of the wafer 11, the grinding dust blown off by the cleaning may accumulate in the atmosphere around the spinner cleaning device 64, and may adhere to the upper surface of the chuck table 68 of the spinner cleaning device 64.

  In the chuck table 68 of the present embodiment, only three points of the vacuum suction pad 74 are in contact with the back surface of the wafer 11, so that the wafer 11 contacts the wafer 11 only in a very small area. Therefore, the problem of grinding scraps scratching the back surface of the wafer 11 can be suppressed.

  After the cleaning is completed, the wafer 11 is spin-dried by the spinner cleaning device 64. Next, the wafer 11 is stored at a predetermined position of the storage cassette 66 by the wafer transfer robot 54.

  Since the wafer 11 sliced from the silicon ingot needs to be ground on both surfaces thereof, the surface on the opposite side to the ground surface ground in each of the above steps is ground. Is repeated to finish the wafer 11 to a thickness of about 700 μm.

2 Grinding device 10 Rough grinding unit 11 Semiconductor wafer 28 Finish grinding unit 44 Turntable 46 Chuck table 64 Spinner cleaning device 68 Chuck table 72 Chuck table base 74 Vacuum suction pad 82 Cleaning nozzle

Claims (1)

A chuck table for a wafer cleaning device,
A rotatable chuck table base;
Comprising at least three vacuum suction pads made of elastic members arranged on the upper surface of the chuck table base in a concentric circle centered on the center of rotation of the chuck table base and spaced at equal intervals;
The chuck table of a wafer cleaning apparatus, wherein the chuck table base has a suction path communicating with each of the vacuum suction pads.

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