JP6537382B2 - Grinding machine idling method - Google Patents

Description

  The present invention relates to an idling method of a grinding device for warming up the grinding device.

  In order to thin a wafer such as a semiconductor wafer or an optical device wafer to a predetermined thickness, a grinding apparatus for grinding the wafer with a grinding wheel on which a plurality of grinding wheels are mounted is generally used.

  The grinding device performs idling operation (warm-up operation) at startup, checks whether or not there is a defect in the device, arranges the processing chamber and the chuck table to the same temperature as during processing, and with a predetermined accuracy It is prepared for processing. In practice, an idle operation is performed in which the spindle and the chuck table are rotated at the same rotational speed as at the time of grinding while spouting grinding water whose temperature is adjusted to a predetermined temperature.

  However, even if such idling operation is performed for a predetermined time, when grinding processing of a wafer is started, it is less likely to be within the desired in-plane thickness variation from the first wafer, and some precut is necessary. .

JP 2003-326458 A

  In order to cope with this problem, as a result of the inventor's earnest research, the temperature of the chuck table is higher during wafer grinding than during idling due to the processing heat generated during wafer grinding, so the shape change of the chuck table It has been found that it is necessary to grind a predetermined number of wafers or more before the shape change is stabilized.

  The present invention has been made in view of these points, and the object of the present invention is to provide a grinding apparatus capable of preparing a grinding apparatus in a state similar to the apparatus state at the time of grinding processing of a workpiece within a predetermined time. To provide an idling method.

According to the present invention, a chuck table for holding a workpiece, a grinding means for performing grinding while supplying grinding water to the workpiece held by the chuck table, the chuck table and the grinding means are covered. the chuck table processing chamber and the cover, a idling method of grinding apparatus provided with, while the predetermined temperature high temperature grinding water from grinding water to be supplied to the grinding process is supplied to the chuck table defining a working chamber Te An idling operation is carried out by rotating a grinding wheel attached to the grinding means and the grinding means to bring about an apparatus state affected by processing heat generated during grinding of a workpiece. An idling method is provided.

  According to the idling method of the grinding apparatus of the present invention, the grinding heat is simulated by carrying out the idling operation while supplying the grinding water which is higher in temperature by a predetermined temperature than the grinding time of the workpiece. Since the shape change of the chuck table can be completed during the idling operation, it is possible to grind the first workpiece from a desired thickness accuracy.

1 is a perspective view of a grinding device suitable for carrying out the idling method of the present invention. It is a partial cross section front view of the chuck table and grinding unit in idling. 3A is a cross-sectional view of the chuck table before deformation, and FIG. 3B is a cross-sectional view of the chuck table after deformation by heat. It is a partial cross section front view in grinding processing of the wafer hold | maintained at the chuck table.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, a perspective view of a grinding apparatus to which the idling method of the present invention is applied is shown. Reference numeral 4 denotes a housing of the grinding apparatus, and a column 8 is erected at the rear of the horizontal housing 6.

  A pair of guide rails 12 extending in the vertical direction is fixed to the column 8. The grinding unit 14 is mounted movably in the vertical direction along the pair of guide rails 12. The grinding unit 14 is attached to a moving base 16 that moves up and down along the pair of guide rails 12 via the support portion 18.

  The grinding unit 14 includes a housing 20 attached to a support 18, a spindle 22 (see FIG. 2) rotatably housed in the housing 20, and a servomotor 23 for rotationally driving the spindle 22.

  As shown in FIGS. 2 and 4, a wheel mount 24 is fixed to the tip of the spindle 22, and a grinding wheel 26 is detachably mounted to the wheel mount 24 by a screw (not shown). The grinding wheel 26 is composed of a base 28 and a plurality of grinding wheels 30 fixed to the outer periphery of the lower surface of the base 28.

  Referring back to FIG. 1, the grinding unit 14 includes a grinding unit feed mechanism 36 which moves the grinding unit 14 up and down along the pair of guide rails 12. The grinding unit feed mechanism 36 comprises a ball screw 32, a pulse motor 34 fixed to one end of the ball screw 32, and a nut screwed to the ball screw 32 disposed on the movable base 16. When the pulse motor 34 is driven, the ball screw 32 is rotated and the grinding unit 14 is moved in the vertical direction.

  A chuck table unit 42 is disposed in the recess 10 of the horizontal housing 6. The chuck table unit 42 includes a chuck table 44. The chuck table 44 is rotationally driven by a motor (not shown), and a workpiece moving position A and a grinding position B by a horizontal movement mechanism (chuck table movement mechanism) (not shown). And in the longitudinal direction of the apparatus, that is, in the Y-axis direction.

  As shown in FIG. 2, the chuck table 44 includes a table base 46 formed of metal such as SUS (stainless steel) and a suction holding portion 48 formed of porous ceramic mounted on the table base 46. There is. The outer periphery of the suction holding portion 48 is surrounded by the non-porous ceramic 50.

  The chuck table 44 is mounted on the rotation support portion 56. The suction holding unit 48 is selectively connected to a suction source (not shown) via suction paths 52 and 54 formed on the table base 46 and an electromagnetic switching valve.

  Referring again to FIG. 1, the chuck table unit 42 includes a chuck table cover 58 disposed to surround the chuck table 44 and a bellows 60 disposed at both ends of the chuck table cover 58 and covering the chuck table moving mechanism. It contains.

  The chuck table 44 positioned at the grinding position and the tip portion of the grinding unit 14 are covered by the processing chamber cover 38, and as shown in FIG. 2, the processing chamber 39 is defined inside the processing chamber cover 38. .

  The processing chamber cover 38 includes an upper plate 38a, a side plate 38b, and a front plate 38c, and the front plate 38c is formed with an opening 40 which allows the chuck table 44 to pass therethrough. A cylinder 38d is provided upright on the upper plate 38a, and the housing 20 of the grinding unit 14 is inserted into the cylinder 38d.

  A grinding water supply nozzle 64 for supplying grinding water toward the chuck table 44 and the grinding wheel 30 is disposed in the processing chamber 39, and the grinding water supply nozzle 64 is a constant hot water supply device 70 shown in FIG. It is connected to a water supply 68.

  An exhaust duct 66 is connected to the processing chamber 39, and the atmosphere in the processing chamber 39 is exhausted to the outside through the exhaust duct 66. An operation panel 62 for inputting a command to the grinding device 2 is disposed on the front portion of the horizontal housing 6.

  Referring to FIG. 3A, a cross-sectional view of the chuck table 44 before deformation is shown. FIG. 3B shows a cross-sectional view of the chuck table 44 after deformation by heating. Since the coefficient of thermal expansion of the table base 46 formed of SUS is larger than the coefficient of thermal expansion of the suction holding portion 48 formed of porous ceramic, the chuck table 44 is deformed into a concave shape.

  The shape of the chuck table 44 at the time of grinding a workpiece such as a wafer is as shown in FIG. 3B, and in the state where the shape change of the chuck table 44 is completed as described above, the workpiece after grinding is The inclinations and the like of the chuck table 44 and the grinding unit 14 are adjusted so that the thickness of the workpiece has a desired thickness variation.

  Next, with reference to FIG. 2, an idling method of the grinding apparatus according to the embodiment of the present invention will be described. The idling method of the grinding apparatus rotates the chuck table 44 at, for example, 300 rpm in the direction of arrow a and rotates the grinding wheel 22 at, for example, 6000 rpm in the direction of arrow b, as in grinding the workpiece. It is carried out for a predetermined time, for example, about 30 minutes, while supplying the grinding water adjusted to the predetermined temperature by the constant hot water supply device 70 from the nozzle 64.

  The idling method of the present embodiment is characterized in that the grinding water is supplied while the temperature of the grinding water in the idling operation is higher by a predetermined temperature than the temperature of the grinding water supplied at the time of the grinding process of the workpiece.

  When the temperature of the grinding water supplied during grinding of the workpiece is 23 ° C., the grinding water consisting of pure water supplied from the grinding water supply source 68 is passed through the constant hot water supply device 70 to 23 ° C. The idling operation was performed by setting the temperature range higher than the predetermined temperature.

  The range of the water temperature higher by a predetermined temperature than the grinding water supplied at the time of grinding is preferably in the range of 28 ° C. to 35 ° C., and more preferably 29 ° C. to 32 ° C. Accordingly, the predetermined temperature is in the range of 5 ° C. to 12 ° C., more preferably in the range of 6 ° C. to 9 ° C.

  When the idling operation is carried out for 25 minutes to 30 minutes while supplying the grinding water in this range, the fact that the shape change of the chuck table as shown in FIG. I was able to confirm.

  After completion of the idling operation of the grinding apparatus, grinding of the wafer 11 which is a workpiece is performed. At the time of grinding of the wafer 11, as shown in FIG. 4, the back surface of the wafer 11 is suctioned and held through the surface protection tape 13 attached to the surface of the wafer 11 by the suction holding unit 48 of the chuck table 44. Grinding was conducted.

  Here, the back surface of the wafer 11 corresponding to the device area on the front surface of the wafer 11 is ground to form the circular recess 15, and the peripheral excess area surrounding the device area is left to perform grinding as the annular projection 17. (Herein, this grinding method is defined as TAIKO grinding).

  In order to carry out TAIKO grinding of the wafer 11, the chuck table 44 is rotated at, for example, 300 rpm in the direction of arrow a and the grinding wheel 30 of the grinding wheel 26 rotating at, for example, 6000 rpm in the direction of arrow b Then, the grinding unit feeding mechanism 36 grinds and feeds the grinding unit 14 downward at a predetermined grinding feed rate, thereby performing TAIKO grinding for forming the circular recess 15 on the back surface of the wafer 11.

  At the time of the TAIKO grinding, TAIKO grinding was performed while supplying the grinding water set at 23 ° C. from the grinding water supply nozzle 64 by the constant hot water supply device 70 to the chuck table 44 and the grinding wheel 30.

  When TAIKO grinding of the wafer 11 was performed after the idling method of the grinding apparatus according to the present embodiment was performed, the in-plane thickness variation of the wafer 11 corresponding to the circular recess 15 could be suppressed to a small value.

  Here, since TAIKO grinding achieves parallelism between the surface of the suction holding portion 48 of the chuck table 44 and the grinding surface of the grinding wheel 30, a grinding wheel having a diameter larger than that of the TAIKO grinding wheel 26 is used for self grinding of the chuck table 44. Therefore, when TAIKO grinding of the wafer 11 is performed with the small-diameter TAIKO grinding wheel 26, the thickness variation of the circular recess 15 becomes large, and when the thickness of the circular recess 15 is plotted, the cross-sectional shape becomes a so-called hakama shape In general, the thickness variation is larger than the thickness variation of a fully ground wafer in which the entire back surface of the wafer is ground with a grinding wheel.

  Therefore, due to the occurrence of thickness variation in advance, a situation occurs in which the tolerance is easily exceeded with respect to the thickness variation tolerance in the wafer surface, and after idling, a certain number or more of wafers are processed. If TAIKO grinding is performed and processing heat is not generated, the thickness variation of the ground wafer does not fall within the allowable value.

  Therefore, the idling method of the grinding apparatus of the present invention can complete the shape change of the chuck table 44 within a short time by idling, and therefore, it is more effective to carry out the TAIKO grinding of the wafer 11. It goes without saying that the application of the idling method of the present invention to an overall grinding wheel for grinding the entire surface of the wafer 11 is effective.

11 wafer 14 grinding unit 15 circular recess 26 grinding wheel 30 grinding wheel 36 grinding unit feed mechanism 38 processing chamber cover 44 chuck table 48 suction holding portion 64 grinding water supply nozzle 66 exhaust duct 68 grinding water supply source 70 constant temperature hot water supply device

Claims (1)

A chuck table for holding a workpiece, grinding means for performing grinding while supplying grinding water to the workpiece held by the chuck table, the chuck table and the grinding means are covered to define a processing chamber An idler method of a grinding apparatus comprising: a processing chamber cover;
The idling operation is carried out by rotating the chuck table and the grinding wheel mounted on the grinding means while supplying the grinding water of a water temperature higher by a predetermined temperature than the grinding water supplied at the time of grinding processing to the chuck table. An idling method of a grinding apparatus characterized in that the apparatus is affected by the processing heat generated during grinding of a workpiece.

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