JP4032268B2 - Wafer planar processing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wafer flat surface processing apparatus, and more particularly to a wafer flat surface processing apparatus for grinding a back surface of a semiconductor wafer in a semiconductor wafer manufacturing process.
[0002]
[Prior art]
A surface grinding apparatus for grinding the back surface of a semiconductor wafer includes a chuck table and a grindstone. The chuck table holds the surface of the semiconductor wafer by suction, and presses the grindstone against the back surface of the semiconductor wafer. The back surface of the wafer is ground by rotating the grinding wheel.
[0003]
Such a surface grinding apparatus has feed means for feeding and moving a grindstone to a table by a screw feed device, and controls the grinding amount of the semiconductor wafer by controlling the feed amount of the grindstone by the feed means.
[0004]
[Problems to be solved by the invention]
By the way, recent semiconductor wafers are required to be thinned as ICs are highly integrated. Due to such demands, high grinding accuracy is required for the surface grinding apparatus.
However, since the conventional surface grinding apparatus controls the grinding amount of the semiconductor wafer by quantitative feeding by the screw feeding device, there is a limit to the fine feeding, and the semiconductor wafer cannot be ground to a desired thin thickness. There is a drawback that there are cases.
[0005]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a wafer processing apparatus capable of improving the processing accuracy of a wafer.
[0006]
[Means for solving the problems]
In order to achieve the above-mentioned object, the present invention provides a table holding a wafer and a grindstone by moving a grindstone for processing the wafer in a relatively approaching direction by rotating a screw rod of a screw feeding means. In the wafer surface processing machine that grinds the wafer by rotating the grindstone and the wafer relative to each other while pressing the wafer, the precise grinding of the wafer by the quantitative movement only by the rotation of the screw rod of the screw feeding means is completed. after then stopping the rotation of the screw rod of the screw feed means, under the state where the rotation of the threaded rod is stopped in the feed screw means, by relatively pressing and the said grindstone wafer at a constant pressure It is characterized in that a pressing means is provided that performs a slight movement in a relatively approaching direction to spark out the wafer.
[0007]
According to the first aspect of the present invention, the pressing means is provided in the planar processing apparatus, and the pressing means is driven to process the wafer while pressing the wafer and the grindstone with a controlled pressure. As a result, processing by micro feed that is difficult to achieve with the screw feed device becomes possible, so that wafer processing accuracy can be improved. According to the first aspect of the present invention, in the processing step by quantitative feed such as roughing and fine processing, only the feeding means is driven to process the wafer, and in the processing step by micro feed such as spark out, The wafer is processed by driving only the means and pressing the wafer and the grindstone with a constant pressure. Thus, in the wafer processing process, the wafer can be processed with high accuracy and efficiency by separately controlling the feeding means and the pressing means.
[0008]
According to the second aspect of the present invention, since a cylinder device, a piezoelectric element, or a magnetostrictive element is applied as the pressing means, processing by minute feed becomes possible.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a wafer flat surface processing apparatus according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a perspective view of a semiconductor wafer surface grinding apparatus to which the present invention is applied, and FIG. 2 is a plan view.
As shown in FIG. 1, the main body 12 of the surface grinding apparatus 10 is provided with a cassette storage stage 14, an alignment stage 16, a rough grinding stage 18, a finish grinding stage 20, and a cleaning stage 22.
[0010]
Two cassettes 24, 24 are detachably set on the cassette storage stage 14, and a large number of wafers 26 before back surface grinding are stored in these cassettes 24, 24. The wafers 26 are held one by one by a transfer robot 28 and are sequentially transferred to the alignment stage 16 which is the next process. The transfer robot 28 is suspended and supported by a beam 30 erected on the main body 12 via an elevating device 32. The elevating device 32 is connected to a feed screw device (not shown) built in the beam 30. When the elevating device 32 is fed and moved by the feed screw device, the transfer robot 28 moves the beam 30. It can reciprocate in the direction of arrows A and B in FIGS. 1 and 2 along the arrangement direction. By the movement of the transfer robot 28 and the operation of the transfer robot 28, the wafers 26 are sequentially transferred in accordance with a predetermined route in the surface grinding apparatus 10.
[0011]
If the transfer robot 28 is suspended and supported as in the present embodiment, the interval between the cassette storage stage 14 and the alignment stage 16 can be reduced, and the surface grinding apparatus 10 can be downsized. That is, when the transfer robot 28 is installed on the upper surface of the apparatus main body 12, the transfer robot 28 must be installed in the space between the cassette storage stage 14 and the alignment stage 16 for the purpose of transferring the wafer 26. For this reason, the surface grinding apparatus 10 is unnecessarily enlarged by the space. In contrast, the surface grinding apparatus 10 of the present embodiment effectively uses the space above the apparatus main body 12 as an installation space and an operation space for the transfer robot 28, so that the apparatus can be downsized.
[0012]
The robot 28 is a general-purpose industrial robot, and has a horseshoe-shaped arm 34 that holds the wafer 26 by suction, three links 36, 38, 40, and the like. At the tip of the arm 34, suction pads 35 and 35 for sucking the wafer 26 are provided. The arm 34 is supported by the link 36 so that its base end portion is rotatable about the axis, and can be rotated about the axis by a driving force from a motor (not shown). The link 36 is rotatably connected to the link 38 via a shaft 42, and can rotate about the shaft 42 by a driving force from a motor (not shown). The link 38 is rotatably connected to the link 40 via a shaft 44 and can be rotated around the shaft 44 by a driving force from a motor (not shown). Furthermore, since the link 40 is connected to the output shaft of the motor (not shown) via the shaft 46, the link 40 can be rotated around the shaft 46 by driving the motor. The motor is connected to a lifting rod (not shown) of the lifting device 32. Therefore, according to the robot 28, the operation of the arm 34 and the three links 36, 38, 40 is controlled by the respective motors, and the contraction operation of the lifting rod of the lifting device 32 is controlled, thereby the cassette 24. It is possible to take out the wafer 26 accommodated in the wafer and transfer it to the alignment stage 16.
[0013]
The alignment stage 16 is a stage for aligning the wafer 26 conveyed from the cassette 24 at a predetermined position. The wafer 26 aligned by the alignment stage 16 is again sucked and held by the suction pads 35 and 35 of the transfer robot 28 and then transferred toward the empty chuck table 48. Adsorbed and held in position.
[0014]
The chuck table 48 is installed on the turntable 50, and chuck tables 52 and 54 having the same function are installed on the turntable 50 at a predetermined interval. The chuck table 52 is positioned on the rough grinding stage 18, and the attracted wafer 26 is rough ground here. The chuck table 54 is positioned on the finish grinding stage 20, and the attracted wafer 26 is finish ground (fine grinding, spark out) here.
[0015]
The thickness of the wafer 26 sucked and held on the chuck table 48 is measured by a measurement gauge (not shown). The wafer 26 whose thickness has been measured is positioned on the rough grinding stage 18 by rotating the turntable 50 in the direction of arrow C in FIGS. 1 and 2 and is roughly ground by the cup-type grindstone 56 of the rough grinding stage 18. As shown in FIG. 1, the cup-type grindstone 56 is connected to an output shaft (not shown) of a motor 58 and is attached to a grindstone feeding device (screw feeding device) 62 via a support casing 60 of the motor 58. . The grindstone feeding device 62 moves the cup-shaped grindstone 56 up and down together with the motor 58, and the cup-shaped grindstone 56 is pressed against the back surface of the wafer 26 by this downward movement. Thereby, the back surface rough grinding of the wafer 26 is performed. The downward movement amount of the cup-type grindstone 56, that is, the amount of grinding by the cup-type grindstone 56 is set based on the reference position of the cup-type grindstone 56 registered in advance and the thickness of the wafer 26.
[0016]
The thickness of the wafer 26 coarsely ground by the rough grinding stage 18 is measured by a thickness measurement gauge (not shown) after the cup-type grindstone 58 is retracted from the wafer 26. The wafer 26 whose thickness has been measured is positioned on the finish grinding stage 20 by turning the turntable 50 in the same direction, and is finely ground and sparked out by the cup-type grindstone 64 of the finish grinding stage 20 shown in FIG. The finish grinding stage 20 will be described later.
[0017]
After the cup-type grindstone 64 is retracted from the wafer 26, the wafer 26, which has been finish-ground by the finish grinding stage 20, is transferred to the position of the empty chuck table 48 shown in FIG. Is done. The wafer is adsorbed by a suction pad 68 provided at the tip of the transfer arm 66 and having the same diameter as the wafer, and is then transferred to the cleaning stage 22 by the rotation of the transfer arm 66 in the direction of arrow D in FIG. , Where it is washed.
[0018]
The wafer 26 cleaned by the cleaning stage 22 is sucked and held by the transfer robot 28, transferred to the cassette storage stage 14, and stored in a predetermined shelf of a predetermined cassette 24. The above is the flow of the wafer processing process by the surface grinding apparatus 10 of the present embodiment.
Next, the finish grinding stage 20 will be described.
[0019]
As shown in FIG. 3, the cup-type grindstone 64 of the finish grinding stage 20 is connected to the output shaft 74 of the motor 72. Further, guide blocks 76, 76 constituting LM (linear motion) guides are provided on the side surface of the motor 72, and the guide blocks 76, 76 are provided on the inner side surface of the support casing 78. It is engaged with the rail 80 so as to be movable up and down. Accordingly, the cup-type grindstone 64 is attached to the support casing 78 together with the motor 72 so as to be movable up and down.
[0020]
Guide blocks 82 and 82 constituting an LM (linear motion) guide are provided on the outer surface of the support casing 78, and the guide blocks 82 and 82 are provided on the inner surface of the screw feeder housing 84. The guide rail 86 is engaged so as to be movable up and down. A nut member 86 projects from the outer surface of the support casing 78. The nut member 86 is disposed in the housing 84 through an opening 85 formed in the housing 84 and is screwed into a screw rod 88 of a screw feeding device. An output shaft 92 of a motor 90 is connected to the upper end of the screw rod 88. Therefore, when the screw 90 is rotated by driving the motor 90, the cup-type grindstone 64 is moved up and down together with the support casing 78 by the feeding action of the screw feeding device and the rectilinear action of the guide block 82 and the rail 86. Moving.
[0021]
By the way, a piston 96 of an air cylinder device 94 as a pressing means is connected to the upper surface of the motor 72 through a through hole 79 of the casing 78. A regulator 98 that controls the internal pressure P of the cylinder 95 is connected to the cylinder 95 of the air cylinder device 94. Therefore, when the internal pressure P is controlled by the regulator 98, the pressing force of the cup-type grindstone 64 against the wafer 26 can be controlled. Although not shown, a lock mechanism for mechanically locking and unlocking the expansion and contraction of the piston 96 is provided. The lock mechanism is driven and controlled by a CPU (not shown) when the grinding process is switched from precise grinding to spark-out. In FIG. 3, reference numeral 100 denotes a motor that rotates the chuck table 54, and an output shaft 102 of the motor 100 is connected to the lower surface of the chuck table 54.
[0022]
Next, the operation of the finish grinding stage 20 configured as described above will be described.
First, when the wafer 26 adsorbed on the chuck table 54 is positioned below the cup-type grindstone 64, the motor 90 of the screw feeding device is driven to move the casing 78 downward so that the cup-type grindstone 64 contacts the wafer 26. .
[0023]
Next, the cup-type grindstone 64 is rotated by the motor 72 and the wafer 26 is rotated by the motor 100.
Next, by driving the motor 90 of the screw feeder and moving the casing 78 downward, precise grinding by the quantitative feed of the screw feeder is started. At this time, the contraction of the piston 96 is locked in advance by a lock mechanism. As a result, the fixed feed amount of the screw feeder and the grinding amount of the wafer 26 become equal, so that the grinding amount can be easily detected.
[0024]
Next, when the precision grinding by the fixed amount feeding of the screw feeding device is completed, the motor 90 of the screw feeding device is rotated in the reverse direction by a little amount and stopped. As a result, the cup-type grindstone 64 is retracted slightly upward from the wafer 26. Next, the lock of the piston 96 by the lock mechanism is released, and the internal pressure P of the cylinder 95 is set to a desired pressure by the regulator 98. As a result, the piston 96 extends due to the internal pressure P, so that the cup-type grindstone 64 moves downward and comes into contact with the wafer 26 to press the wafer 26 with a constant pressure. By controlling the pressing force by the regulator 98 and continuing grinding, the wafer 26 is sparked out by constant pressure feeding.
[0025]
When the spark-out is completed after a predetermined time has elapsed, the cup-type grindstone 64 is retracted from the wafer 26 by a screw feeder. This completes the precise grinding and spark-out of the wafer 26 in the finish grinding stage 20.
As described above, in the present embodiment, since the air cylinder device 94 capable of grinding the wafer 26 with a constant pressure is provided, it is possible to perform grinding by fine feed which is difficult to achieve with the screw feed device. . Therefore, the grinding accuracy of the wafer 26 can be improved.
[0026]
Further, in the present embodiment, only the screw feeding device is driven to finely grind the wafer 26, and only the air cylinder device 94 is driven to perform spark out. As described above, when the screw feeding device and the air cylinder device 94 are separately driven and controlled, the wafer 26 can be accurately and efficiently ground.
In this embodiment, the air cylinder device 94 is applied as the pressing means. However, the present invention is not limited to this, and the same effect can be obtained by applying a hydraulic cylinder device, a piezoelectric device, or a magnetostrictive element. . That is, the form is not limited as long as it is a means for pressing the grindstone at a constant pressure. Further, instead of pressing the cup-type grindstone 64 against the wafer 26, a mechanism for pressing the wafer 26 against the cup-type grindstone 64 with a constant pressure may be employed.
[0027]
Further, in the present embodiment, the cup-type grindstone is moved up and down to grind the wafer, but the wafer side may be moved up and down to grind the wafer.
In the present embodiment, the pressing means is provided only for the finish grinding stage 20, but the rough grinding stage 18 may be provided with a pressing means. In this case, it is possible to perform rough grinding, fine grinding, and spark out at each of the stages 18 and 20 without distinguishing the grinding process as in the rough grinding stage and the finish grinding stage. That is, it is possible to perform rough grinding and fine grinding with a constant feed operation by a screw feed device, and to perform spark out with a constant pressure feed operation by a pressing means. As a result, a multi-type surface grinding apparatus having two grinding stages can be provided.
[0028]
In this embodiment, the surface grinding apparatus that grinds the back surface of the wafer has been described. However, a CMP apparatus that uses a polishing cloth instead of a cup-type grindstone and a blade instead of a cup-type grindstone are used. Then, the present invention may be applied to a dicing apparatus that cuts a wafer into dice.
[0029]
【The invention's effect】
As described above, according to the planar processing apparatus for wafers according to the present invention, pressing means is provided in the planar processing apparatus, and the pressing means is driven to process the wafer while pressing the wafer and the grindstone with a predetermined pressure. Since it did in this way, the processing precision of a wafer can be improved.
[Brief description of the drawings]
1 is an overall perspective view of a surface grinding apparatus for a semiconductor wafer according to an embodiment of the present invention. FIG. 2 is a plan view of the surface grinding apparatus shown in FIG. 1. FIG. Side view including partial cross section of finish grinding stage [Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Surface grinding apparatus 12 ... Main body 14 ... Cassette storage stage 16 ... Alignment stage 18 ... Rough grinding stage 20 ... Finish grinding stage 22 ... Cleaning stage 26 ... Wafer 48, 52, 54 ... Chuck table 56, 64 ... Cup type grindstone 94 ... Air cylinder device

Claims (2)

A table holding the wafer and a grindstone for processing the wafer are quantitatively moved in a relatively approaching direction by rotating the screw rod of the screw feeding means, and the grindstone and the wafer are pressed against each other. In a wafer planar processing apparatus that grinds a wafer by relatively rotating, the precise grinding of the wafer by the quantitative movement only by the rotation of the screw rod of the screw feeding means is completed, and the rotation of the screw rod of the screw feeding means is stopped. Then , under the state where the rotation of the screw rod of the screw feeding means is stopped , the grindstone and the wafer are relatively pressed with a constant pressure so as to move in a relatively approaching direction. A wafer processing apparatus comprising a pressing means for performing a spark-out. 2. The wafer planar processing apparatus according to claim 1, wherein the pressing means is a cylinder device, a piezoelectric element, or a magnetostrictive element.

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