JP5743817B2 - Processing equipment - Google Patents

Description

  The present invention relates to a processing apparatus for grinding or polishing a workpiece such as a semiconductor wafer.

  As a grinding device and a polishing device for grinding and polishing a workpiece such as a semiconductor wafer, those disclosed in Patent Documents 1 and 2 are well known and widely used.

  In these grinding devices and polishing devices, the peripheral speeds of the center part and the outer peripheral part of the work piece held and rotated by the holding table are different, so that the work amount per unit time is different and the progress of processing is different. . For this reason, there existed a problem that dispersion | variation will arise in the center part and outer peripheral part of the processed workpiece.

  Therefore, as a technique for solving this problem, Patent Document 3 proposes a grinding apparatus that can detect the flatness of a workpiece after grinding and can change the inclination of the holding table in accordance with the detected flatness. Yes. According to this technique, by adjusting the inclination of the holding table for the workpiece to be processed on the first sheet, a desired flatness can be easily realized for the second and subsequent workpieces.

JP 2002-200545 A JP 2006-216895 A JP 2008-264913 A

  However, when using a grinding apparatus as disclosed in Patent Document 3, after the workpiece is ground once, its flatness is detected, and the inclination of the holding table is adjusted based on the detected flatness. Therefore, the workpiece to be processed on the first sheet was not planned to be flattened by one grinding process.

  For this reason, the workpiece to be processed on the first sheet is premised on the detection of flatness and the subsequent tilt adjustment of the holding table. In some cases, the workpiece to be processed on the first sheet is processed. Therefore, it becomes necessary to repeat a series of steps such as grinding, detection of flatness, and inclination adjustment of the holding table.

  Therefore, the present invention proposes a processing apparatus for realizing that the workpiece to be processed on the first sheet is processed to a desired flatness by one processing.

  According to the first aspect of the present invention, the holding means having the holding surface for holding the workpiece, the processing means for grinding or polishing the workpiece held by the holding means, and the holding means for holding the holding means. A machining apparatus comprising a machining feed means for moving at a predetermined feed speed in a direction approaching and separating from a surface, and a control means for controlling the machining feed means, wherein the machining apparatus is a workpiece after machining. The desired flatness input means for inputting the desired flatness of the surface to be machined is further provided, and the processing means includes a processing wheel including a grinding wheel or a polishing pad, a mounter on which the processing wheel is mounted, and a spindle that supports the mounter. And a spindle unit including a motor for rotating the spindle, and the control means includes a maximum load current value of the motor that is being processed, and a workpiece that has been processed within the maximum load current value after processing. A storage unit that stores a maximum load current value table for each flatness of a processed surface indicating the flatness of the processed surface, a load current value monitor unit that monitors the load current value of the motor being processed, and a desired flatness and storage unit A selection unit for selecting the maximum load current value corresponding to the desired flatness from the stored maximum load current value table for each flatness of the surface to be processed, and the load current value of the motor being processed monitored by the load current value monitoring unit Is provided with a feed control section that controls the feed speed of the machining feed means so as to be equal to or less than the maximum load current value selected by the selection section.

  Preferably, the apparatus further includes flatness detecting means for detecting the flatness of the processed surface of the processed workpiece.

  In the processing apparatus of the present invention, the maximum load current value table for each surface flatness to be processed is stored in the control means, and the maximum load current value of the motor of the processing means is selected according to the desired flatness. The machining feed rate is controlled so that the load current value of the motor of the machining means being machined is within the selected maximum load current value. Can be processed to a desired flatness.

It is an external appearance perspective view of the grinding device which is an example of a processing device. It is a block diagram shown about a control means and a desired flatness input means. (A) is a figure shown about the example of the maximum load electric current value table for every to-be-processed surface flatness in the case of rough grinding. (B) is a figure shown about the example of the maximum load current value table | surface for every to-be-processed surface flatness in case finish grinding is made.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. As an example of the processing apparatus, an external perspective view of a semiconductor wafer grinding apparatus 2 is shown in FIG. 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.

  A rough grinding unit 10 as a processing means includes a grinding wheel 24 having a plurality of grinding wheels 26 for rough grinding, a mounter (not shown) that is rotatably housed in the housing 20 and on which the grinding wheel 24 is mounted. A spindle for supporting the mounter and a servo motor 22 for rotating the spindle are 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. The rough grinding unit moving mechanism 18 functions as a machining feed means. When the pulse motor 16 is driven by a pulse, 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 as processing means 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 grinding wheel 40 having a plurality of grinding wheels 42 for finish grinding, a mounter (not shown) that is rotatably accommodated in the housing 36 and is mounted with the grinding wheel 40, and supports the mounter. And a servo motor 38 for rotating the spindle.

  The finish grinding unit 28 includes a finish grinding unit moving mechanism 34 including a ball screw 30 that moves the finish grinding unit 28 in the vertical direction along the pair of guide rails 19 and a pulse motor 32. The finish grinding unit moving mechanism 34 functions as a work feeding means. 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 with a porous ceramic material, and serves as a holding means for sucking and holding a wafer placed on the holding surface of the suction chuck by operating a vacuum suction means. Function.

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

  Flatness detection means for detecting the flatness of the processed surface (back surface) of the processed wafer placed on each chuck table 46 at each position of the rough grinding region B and the finish grinding region C 47, 48 are provided. The specific structure of the flatness detecting means 47, 48 is not particularly limited. For example, probes 47a, 48a that swing to scan the processing surface (back surface) of the wafer are provided, and the probe 47a is provided. , 48a can be considered to detect the flatness.

  A front portion of the housing 4 includes 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 loading mechanism (loading arm) 60, and a wafer unloading. 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. ing.

  The spinner cleaning device 64 is equipped with a spinner table 68 having a diameter smaller than that of the semiconductor wafer 11 that rotates by sucking and holding the ground semiconductor wafer 11. Reference numeral 70 denotes a cover of the spinner cleaning device 64.

  As shown in FIG. 2, in this embodiment, in the rough grinding unit 10 and the finish grinding unit 28, pulse motors 16 and 32 that move each unit in the vertical direction and servos that rotationally drive the grinding wheels 24 and 40. Control means 80 for controlling the motors 22 and 38 is provided.

  The control means 80 is a processing surface flatness indicating the maximum load current value M of the servo motors 22 and 38 being processed and the flatness H of the processing surface of the wafer 11 processed within the maximum load current value M. A storage unit 81 for storing the maximum load current value tables T1 and T2 (see FIGS. 3A and 3B) and a load current value monitor unit 82 for monitoring the load current values of the servo motors 22 and 38 being processed. And a selection unit 83 for selecting the maximum load current value corresponding to the desired flatness from the desired flatness and the maximum load current value table for each flatness of the work surface stored in the storage unit, and monitoring by the load current value monitoring unit A feed control unit 84 that controls the feed speed of the machining feed means so that the load current value of the motor being machined is equal to or less than the maximum load current value selected by the selection unit 83.

  The storage unit 81 stores a data table conceptually shown in FIGS. 3 (A) and 3 (B). FIG. 3A shows the maximum load current value M when driving the servo motor 22 of the rough grinding unit 10 and the flatness H of the processed surface of the wafer 11 processed within the maximum load current value M. Is a conceptual diagram of the maximum load current value table T1 for each flatness of the work surface. Note that “flatness” in the present specification is a difference between the maximum thickness dimension and the minimum thickness dimension of a workpiece, and for example, a unit of micrometer (μm) is used.

  The maximum load current value table T1 for each flatness of the work surface shows the maximum load current value when the work piece is a silicon wafer and is processed by the grinding amount V1 using a # 320 (type) grinding wheel. For example, when the maximum load current value M is “5” A (ampere) or less, the flatness H is “3” μm. .

  Further, the maximum load current value table T1 for each flatness of the work surface associates the maximum load current value M with the shape of the work surface. In other words, for example, when the maximum load current value M is “5” A or less, it is associated with a middle concave shape (a shape in which the thickness of the center portion of the workpiece is thinner than the thickness of the outer peripheral portion). .

  FIG. 3B similarly shows the maximum load current value M when driving the servo motor 38 of the finish grinding unit 28 and the processed surface of the wafer 11 processed within the maximum load current value M. It is a conceptual diagram of the maximum load current value table T2 for each processed surface flatness in which the flatness H is associated.

  Similarly, the maximum load current value table T2 for each flatness of the work surface is the maximum when the work piece is a silicon wafer and is machined by a grinding amount V2 using a # 2000 count (type) grinding wheel. The load current value M is associated with the flatness H. For example, when the maximum load current value M is “6” A or less, the flatness H is “3” μm. .

  Further, similarly, the maximum load current value M and the shape of the surface to be processed are associated with each other in the maximum load current value table T2 for each flatness of the surface to be processed. That is, for example, when the maximum load current value M is “9” A or less, it is associated with a middle convex shape (a shape in which the thickness of the center portion of the workpiece is thicker than the thickness of the outer peripheral portion). .

  The maximum load current value tables T1 and T2 for each surface flatness to be processed are prepared by performing test processing in advance and collecting data, and are stored in the storage unit 81. The maximum load current value table for each flatness of the work surface is created, for example, for each material of the work piece, each kind of grinding wheel, and each grinding amount. When the maximum load current value tables T1 and T2 for each surface flatness to be processed are created, the measurement results by the flatness detecting means 47 and 48 can be used as data.

  Then, when the desired flatness (desired flatness) is designated by creating and storing the maximum load current value tables T1, T2 for each flatness of the work surface in advance, the designated flatness is designated. A maximum load current value M corresponding to the degree can be specified. In the present embodiment, as shown in FIG. 2, the selection unit 83 is provided in the control unit 80, so that the maximum load current value M corresponding to the desired flatness input by the desired flatness input unit 90 is stored in the storage unit. 81 is selected.

  The desired flatness input unit 90 is an input unit for inputting information to the selection unit 83 of the control unit 80, and includes, for example, a touch panel. The input information input by the desired flatness input means 90 includes the desired flatness of the workpiece after processing, the material of the workpiece, the type of grinding wheel, the grinding amount, and the like. The form of the desired flatness input means 90 is a form in which a specific numerical value is input. For example, the maximum load current value table T1 for each flatness of the work surface shown in FIG. It is also possible to select the numerical value displayed on the screen.

  Then, the selection unit 83 selects the maximum load current value table for each surface flatness to be processed corresponding to the input information, and the desired flatness in the selected maximum load current value table for each surface flatness to be processed. The maximum load current value M corresponding to the flatness H that coincides with is selected.

  As shown in FIG. 2, during machining, the load current value monitoring unit 82 of the control means 80 monitors the load current values of the servomotors 22 and 38, and the monitored load current values are sent to the feed control unit 84. Is input. The feed control unit 84 is for controlling the feed speed of the machining feed means (rough grinding unit moving mechanism 18 and finish grinding unit moving mechanism 34). Specifically, the feed control unit 84 controls the pulse motors 16 and 32. The moving speed of the grinding wheels 24 and 40 is controlled.

  In the feed control unit 84, the load current value of the servo motors 22 and 38 being processed monitored by the load current value monitor unit 82 is equal to or less than the maximum load current value M selected by the selection unit 83. The feed speed of the processing feed means, that is, the moving speed of the grinding wheels 24 and 40 is controlled.

  Next, the grinding process in the grinding apparatus 2 having the above configuration will be described. Each chuck table 46 in the grinding apparatus 2 is assumed to have an inclination, and it is assumed that the desired flatness cannot be obtained in the wafer after the back surface grinding. According to the above embodiment, the desired flatness is obtained. The degree can be realized.

  As shown in FIGS. 1 and 2, first, the wafer 11 in the wafer cassette 50 is taken out by the wafer transfer robot 54 and placed on the positioning table 56, and placed in the wafer carry-in / out area A by the wafer carry-in mechanism 60. Placed.

  When the turntable 44 rotates and the wafer 11 is moved to the rough grinding region B, the back surface of the wafer 11 is rough ground by the rough grinding unit 10. The rough grinding is performed by rotating the grinding wheel 24. By inputting the desired flatness obtained after the rough grinding in advance, the control means 80 causes the maximum load current value M (( The feed rate of the machining feed means (rough grinding unit moving mechanism 18) is controlled so as not to exceed the drive current value of the servo motor 22.

  For example, when the desired flatness is designated as “2” μm in FIG. 3A, the control unit 80 performs control so that the maximum load current value M is “6” A or less, and rough grinding is performed. At the stage of finishing, it is possible to make a state of rough grinding with a concave shape and a flatness of “2” μm.

  Next, when the turntable 44 rotates and the wafer 11 is moved to the finish grinding region C, the back surface of the wafer 11 is finish ground by the finish grinding unit 28. The finish grinding is performed by rotating the grinding wheel 40. By inputting the desired flatness required after the finish grinding in advance, the control means 80 causes the maximum load current value M (( The feed speed of the machining feed means (finish grinding unit moving mechanism 34) is controlled so as not to exceed the drive current value of the servo motor 38).

  For example, when the desired flatness is designated as “2” μm in FIG. 3B, the control means 80 performs control so that the maximum load current value M is “7” A or less, and rough grinding is performed. In the stage where the finishing is completed, it is possible to obtain a state in which a finish grinding process is performed with a concave shape and a flatness of “2” μm.

  As described above, in the processing apparatus of the present invention, the maximum load current values T1 and T2 for each surface flatness to be processed are stored in the control means 80, and the maximum load of the motor of the processing means is determined according to the desired flatness. A current value M is selected. Since the machining feed rate is controlled so that the motor of the machining means being machined is within the selected maximum load current value, even the workpiece to be machined on the first sheet can be obtained by one machining. Can be machined to flatness.

  Also, as shown in FIG. 1, the flatness after processing is confirmed by providing flatness detection means 47 and 48 for detecting the flatness of the processed surface (back surface) of the processed wafer. Is also possible.

  In the present embodiment, the grinding unit is provided in each of the two columns, and the processing apparatus in which rough grinding and finish grinding are continuously performed has been described. However, the processing apparatus in which one grinding unit is provided. The present invention is also applicable. Moreover, although it demonstrated using the example of the grinding process, naturally this invention is applicable also in the processing apparatus with which a polishing process is made.

DESCRIPTION OF SYMBOLS 2 Grinding apparatus 10 Coarse grinding unit 11 Semiconductor wafer 16 Pulse motor 18 Coarse grinding unit moving mechanism 22 Servo motor 24 Grinding wheel 32 Pulse motor 34 Grinding unit moving mechanism 38 Servo motor 40 Grinding wheel 46 Chuck table 80 Control means 81 Storage part 82 Load Current value monitor unit 83 selection unit 84 control unit 90 desired flatness input means

Claims (2)

Holding means having a holding surface for holding the workpiece;
Processing means for grinding or polishing the workpiece held by the holding means;
A machining feed means for moving the machining means at a predetermined feed speed in a direction approaching and separating from the holding surface of the holding means;
A control device for controlling the processing feed means,
The processing apparatus further includes desired flatness input means for inputting the desired flatness of the processed surface of the workpiece after processing,
The processing means includes
A processing wheel including a grinding wheel or polishing pad;
A mounter to which the processing wheel is mounted;
A spindle unit including a spindle for supporting the mounter and a motor for rotating the spindle;
Have
The control means includes
Stores the maximum load current value of each motor surface flatness indicating the maximum load current value of the motor being processed and the flatness of the processed surface of the workpiece processed within the maximum load current value. A storage unit to
A load current value monitor unit for monitoring the load current value of the motor during processing;
A selection unit that selects a maximum load current value corresponding to the desired flatness from the desired flatness and the maximum load current value table for each flatness of the work surface stored in the storage unit;
Feed control for controlling the feed speed of the machining feed means so that the load current value of the motor being processed monitored by the load current value monitoring unit is equal to or less than the maximum load current value selected by the selection unit And
A processing apparatus comprising: A flatness detecting means for detecting the flatness of the processed surface of the workpiece after processing;
The processing apparatus according to claim 1.

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