TW201916976A - Grinding method of workpiece and grinding device that prevents the front surface protection member adhered to a front side of a workpiece from being erroneously ground by a grinding stone - Google Patents

Abstract

An object of the present invention is to prevent a front surface protection member adhered to a front side of a workpiece from being erroneously ground by a grinding stone in a grinding device. A solution is a grinding method that comprises: a step of covering a front surface of a workpiece with a protective member; a step of holding the workpiece with a holding surface of a chuck stage 30; a thickness measurement step of having a thickness measuring device 382 contacting a surface of the workpiece opposite to the held surface to measure a thickness and calculating an amount of variation according to first thickness data of the measurement and second thickness data measured at a time point after any time lapse from the measurement of the first thickness data; and a step of grinding a back surface of the workpiece. In the thickness measurement step, if the calculated amount of variation is less than a threshold value registered in advance, it is determined that the surface of the workpiece contacted by the thickness measuring device 382 is the back surface of the workpiece, and grinding is started; if the calculated amount of variation exceeds the pre-registered threshold value, it is determined that the surface of the workpiece which the thickness measuring device 382 contacts is the front surface protection member, and grinding is not started.

Description

Grinding method of workpiece and grinding device

The present invention relates to a grinding method for grinding a plate-shaped workpiece such as a semiconductor wafer and a grinding device for grinding the workpiece.

A workpiece in which a plurality of IC or LSI components are formed on the front surface is ground to be thinned to a predetermined thickness, and further divided into individual component wafers by a dividing device such as a dicing device and used for various electronic devices.

A grinding device for grinding a back surface of a workpiece (for example, see Patent Document 1), comprising: a chuck table that holds a front side of a workpiece to which the front surface protective member is attached; and a grinding means that rotatably supports the pair of chucks held by the chuck table The grinding stone is ground on the back side of the workpiece and the workpiece can be ground more efficiently. [Practical Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 5025200

[Problem to be Solved by the Invention] In the above-described grinding device, when the workpiece is held by the chuck table, the back side of the workpiece that does not cover the front surface protective member is erroneously adsorbed by the holding surface of the chuck table. When the back side of the workpiece is adsorbed by the holding surface of the chuck table, the front side protective member that grinds the workpiece on the front side of the grinding stone is used, and the current value of the motor that grinds the grinding stone exceeds the allowable value due to the machining failure. A situation in which the automatic operation of the grinding device is stopped may occur. In this case, it is necessary to trim (grind) the grinding stone to return to the normal state, resulting in an increase in the downtime of the grinding device.

Therefore, in the grinding device, there is a problem of preventing the front side protection member which is affixed to the front side of the workpiece by grinding the grinding stone.

[Means for Solving the Problem] In order to solve the above problems, the present invention is a grinding method for a workpiece, which is a grinding stone for grinding a back surface of a workpiece having a component formed in a region defined by a plurality of predetermined dividing lines formed in a lattice shape. The front surface of the workpiece has a front protection step of covering the front surface of the workpiece with a front protection member; a holding step of holding the workpiece with the holding surface of the chuck table after the front protection step is performed, the chuck table can be Rotating around a rotating shaft in the vertical direction in the axial direction; thickness measuring step, after performing the holding step, contacting the thickness measuring device with the surface of the workpiece and the surface held by the chuck table on the opposite side, and measuring the thickness of the workpiece Calculating the amount of change from the measured first thickness data, the time from the measurement of the first thickness data to the second thickness data measured after an arbitrary time; and the grinding step, the thickness measurement is performed After the step, the grinding stone rotated by the rotating shaft orthogonal to the holding surface is used to grind the back surface of the workpiece while supplying the grinding water; In the degree measuring step, if the calculated amount of change is less than a threshold value registered in advance, it is determined that the surface of the workpiece contacted by the thickness measuring device is a back surface of the workpiece where the sinking of the thickness measuring device is hard to occur, and the grinding step is started. And calculating the amount of change to exceed the threshold value of the pre-registration, determining that the surface of the workpiece contacted by the thickness measuring device is the front surface protection member that is prone to sinking of the thickness measuring device, and does not start the grinding. step.

The foregoing front protective member may be, for example, an adhesive film.

Further, in order to solve the above problems, the present invention provides a grinding apparatus including a chuck table for holding a workpiece, a thickness measuring means for measuring a thickness of a workpiece held by the chuck table, and a workpiece for grinding and holding the workpiece held by the chuck table. The grinding device is characterized in that the chuck table is rotatable about a rotation axis that is axially oriented in the axial direction, and the workpiece is adhered to the workpiece of the front protection member by the holding surface, and the thickness measuring means starts at the grinding of the workpiece The thickness measuring device is brought into contact with the surface of the workpiece and the surface held by the chuck table on the opposite side, and thickness measurement is performed. The grinding method uses a grinding grindstone that rotates with a rotating shaft orthogonal to the holding surface of the chuck table. Grinding the back surface of the workpiece while supplying the grinding water; the grinding device includes: a calculation means, the first thickness data measured by the thickness measuring means, and the time point from the measurement of the first thickness data to an arbitrary time Calculating the amount of change in the measured second thickness data; and controlling means, the amount of change calculated by the calculating means is pre-registered Threshold, then the grinding started, the threshold of the amount of change is beyond the pre-registered, an error without the grinding start.

The thickness measuring means is preferably used for thickness measurement of the workpiece before the start of grinding, and also for thickness control of the workpiece after the start of grinding.

[Effect of the Invention] When the thickness of the workpiece is measured by the thickness measuring means, when the measuring surface is a flexible front protecting member, the thickness measuring device provided by the thickness measuring means sinks the front protective member. The amount of change in the thickness of the workpiece becomes large. On the other hand, in the case where the measuring surface is the hard back surface of the ground surface of the workpiece, there is almost no sinking of the back surface of the thickness measuring device provided in the thickness measuring means, and the amount of change in the thickness of the workpiece becomes small. Therefore, the grinding method of the present invention includes: a front protection step of covering the front surface of the workpiece with the front protection member; and a holding step of holding the workpiece with the holding surface of the chuck table after the front protection step is performed, the chuck table can be wound around The rotation axis is rotated in the vertical direction in the axial direction; the thickness measurement step is performed after the holding step is performed, the thickness measuring device is brought into contact with the surface of the workpiece and the surface held by the chuck table is opposite, and the thickness of the workpiece is measured, from measurement to The first thickness data and the second thickness data measured after the measurement of the first thickness data to the second thickness data, and the change amount is calculated; and the grinding step, after the thickness measurement step is performed, the use and retention surface are used. The grinding stone that is rotated by the orthogonal rotating shaft grinds the back surface of the workpiece while supplying the grinding water. In the thickness measuring step, if the calculated amount of change is less than or equal to the threshold value registered in advance, the workpiece touched by the thickness measuring device is judged. The surface is the back surface of the workpiece where the sinking of the thickness measuring device is hard to occur, and the grinding step is started, and the calculated amount of change is exceeded. When the threshold value is recorded, it is judged that the surface of the workpiece to which the thickness measuring device is in contact is a front surface protective member which is liable to cause sinking of the thickness measuring device, and the grinding step is not started, whereby the workpiece is attracted to the chuck table in an erroneous state. In the case of holding, that is, when the back surface of the ground surface of the workpiece is accidentally sucked by the chuck table, the front protective member is not ground and the grinding failure is prevented.

The grinding device of the present invention includes: a calculation means for measuring the first thickness data measured by the thickness measuring means and the second thickness data measured from the time point from the measurement of the first thickness data to the lapse of an arbitrary time. The amount of change is calculated, and the control means starts the grinding when the amount of change calculated by the calculating means is equal to or less than the threshold value registered in advance, and indicates that the error is not the case where the amount of change exceeds the threshold value registered in advance. The grinding is started; thereby, when the workpiece is attracted and held in the wrong state by the chuck table, that is, when the back surface of the ground surface of the workpiece is accidentally sucked by the chuck table, it is not maintained. At present, the grinding of the front protective members by grinding means causes poor grinding.

The thickness measuring means of the grinding device is used for thickness measurement of the workpiece before the start of grinding, and also for thickness control of the workpiece after the start of grinding, thereby attempting to achieve miniaturization of the grinding device and preventing the manufacture of the grinding device The increase in cost.

The grinding device 3 of the present invention shown in Fig. 1 is a device for performing a grinding process on a workpiece W sucked and held by the chuck table 30. The workpiece W shown in FIG. 1 is, for example, a semiconductor wafer having a circular shape as a base material, and a plurality of divisions perpendicular to each other are formed on the front side Wa facing the lower side in FIG. The predetermined line S forms an element D such as an IC on each of the areas divided into a lattice shape by the division planned line S. The front surface Wa of the workpiece W and the back surface Wb on the opposite side are the ground surfaces subjected to the grinding process. Further, the workpiece W may be made of gallium arsenide, sapphire, gallium nitride or tantalum carbide other than niobium, and its outer shape may be non-circular, and may be formed in a rectangular shape as an example.

The front side (the -Y direction side) of the base 3A of the grinding device 3 is a region where the workpiece W is attached to and detached from the chuck table 30 by the robot arm 330 that can transport the workpiece W, and the rear side of the base 3A (+Y direction side) The area where the workpiece W held on the chuck table 30 is ground by the rough grinding means 31 for rough grinding the workpiece W or the fine grinding means 32 for fine grinding of the workpiece W.

On the front side of the base 3A, a first cassette 331 for accommodating the workpiece W before grinding and a second cassette 332 for accommodating the ground workpiece W are disposed. In the vicinity of the first cassette 331 and the second cassette 332, a robot arm 330 having a function of carrying out the workpiece W before the grinding from the first cassette 331 and carrying the ground workpiece W into the second cassette 332 is disposed.

In the movable region of the robot arm 330, an alignment means 333 for aligning the workpiece W before machining to a predetermined position and a cleaning means 334 for cleaning the ground workpiece W are disposed. The cleaning means 334 is, for example, a single wafer processing cleaning machine, and is provided with a cleaning table that sucks and holds the workpiece W that has been ground.

The first conveyance means 335 is disposed in the vicinity of the alignment means 333, and the second conveyance means 336 is disposed in the vicinity of the cleaning means 334. The first transport means 335 has a function of transporting the workpiece W before the grinding by the alignment means 333 to any of the chuck tables 30 as shown in FIG. 1, and the second transport means 336 has any of the chuck tables 30. The retained workpiece W is transported to the cleaning means 334.

A rotary table 34 is disposed on the rear side (+Y direction side) of the first conveyance means 335 on the base 3A, and three chucks are disposed on the upper surface of the rotary table 34 at equal intervals in the circumferential direction. Taiwan 30. A rotating shaft (not shown) for rotating the turntable 34 is disposed at the center of the turntable 34, and the turntable 34 is rotated on the base 3A around the rotating shaft. Further, by the rotation of the rotary table 34, any of the chuck tables 30 is positioned in the vicinity of the first conveyance means 335 and the second conveyance means 336.

The chuck table 30 is reversibly supported by the rotary table 34. Further, a rotating shaft 30b whose axial direction is a vertical direction (Z-axis direction) is connected to the bottom surface side of the chuck table 30, and the rotating shaft 30b is rotated by a rotating means (not shown) composed of a motor or the like, thereby chucking The stage 30 is rotatable around the rotary shaft in the vertical direction on the rotary table 34. The chuck table 30 has, for example, a circular shape, and includes an adsorption portion 300 that adsorbs and holds a workpiece W composed of a porous member or the like, and a frame 301 that supports the adsorption portion 300. The adsorption unit 300 communicates with a suction source (not shown), and the suction force generated by the suction of the suction source is transmitted to the holding surface 300a of the exposed surface of the adsorption unit 300, and the chuck table 30 sucks and holds the workpiece W on the holding surface 300a.

A column 3B and a column 3C are arranged side by side on the rear side of the base 3A, and a first grinding feed means 35 is disposed on the side surface of the column 3B on the -Y direction side, and the first grinding feed means 35 borrows the rough grinding means 31 The workpiece W that is held by the chuck table 30 is ground and fed, and a second grinding feed means 36 is disposed on the side surface on the -Y direction side of the column 3C, and the second grinding feed means 36 causes the fine grinding means 32 to pass the card. The disk table 30 grinds and feeds the held workpiece W.

The first grinding feed means 35 is composed of a ball screw 350 having a shaft center in the vertical direction, a pair of guide rails 351 disposed in parallel with the ball screw 350, and a motor 352 coupled to the ball screw 350 and rotating the ball screw 350. And the lifting portion 353, wherein the inner nut and the ball screw 350 are screwed and the side portion is in sliding contact with the guide rail 351, and the first grinding feed means 35 has a configuration in which the motor 352 rotates the ball screw 350 with the lifting portion. 353 is guided by the guide rail 351 to ascend and descend. The lifting portion 353 supports the coarse grinding means 31, and the coarse grinding means 31 also moves up and down by the elevation of the lifting portion 353.

The second grinding feed means 36 is composed of a ball screw 360 having a shaft center in the vertical direction, a pair of guide rails 361 disposed in parallel with the ball screw 360, and a motor 362 coupled to the ball screw 360 and rotating the ball screw 360. And the lifting portion 363, the inner nut and the ball screw 360 are screwed together and the side portion is in sliding contact with the guide rail 361, and the second grinding feed means 36 is configured such that the motor 362 rotates the ball screw 360 with the lifting portion The 363 is guided by the guide rail 361 to ascend and descend. The lifting portion 363 supports the fine grinding means 32, and the fine grinding means 32 also moves up and down by the raising and lowering of the lifting portion 363.

The rough grinding means 31 includes a rotating shaft 310 whose axial direction is a vertical direction (Z-axis direction) orthogonal to the holding surface 300a of the chuck table 30. The outer casing 311 rotatably supports the rotating shaft 310, the motor 312, and is rotationally driven. The rotating shaft 310; the mounting member 314 is mounted on the lower end of the rotating shaft 310; and the grinding wheel 313 is detachably coupled to the mounting member 314. On the bottom surface of the grinding wheel 313, a plurality of rough grinding stones 313a having a substantially rectangular parallelepiped shape are annularly arranged. The rough grinding stone 313a is formed by, for example, fixing a diamond abrasive grain or the like with a ceramic bond or the like. Further, the shape of the rough grinding stone 313a may be integrally formed in a ring shape. The rough grinding stone 313a is, for example, a grindstone for rough grinding, and the grindstone contains a grindstone having a large abrasive grain.

For example, in the inside of the rotating portion 310, a flow path (not shown) that communicates with the grinding water supply source and serves as a passage for grinding water is formed in the axial direction (Z-axis direction) of the through-rotation shaft 310, and the flow path is in the grinding wheel. The bottom surface opening of the 313 is sprayed with the grinding water toward the rough grinding stone 313a.

The fine grinding means 32 can perform high-flatness fine grinding of the workpiece W which is roughly roughened to a finished thickness. In other words, the fine grinding means 32 further grinds the back surface Wb of the workpiece W which is ground by the rough grinding means 31 by the grinding wheel 313 which is provided with the grinding grinding stone 323a and rotatably mounted. The abrasive grains included in the fine grinding stone 323a are abrasive grains smaller than the particle diameter of the abrasive grains contained in the rough grinding stone 313a of the rough grinding means 31. The configuration other than the lapping stone 323a of the fine grinding means 32 is the same as that of the rough grinding means 31.

The first thickness measuring means 38A and the second thickness measuring means 38B for respectively measuring the thickness of the contact type measuring workpiece W are respectively disposed at positions adjacent to the rough grinding means 31 and the fine grinding means 32 which are lowered to the grinding position. . Since the first thickness measuring means 38A and the second thickness measuring means 38B have the same structure, only the first thickness measuring means 38A will be described below. The first thickness measuring means 38A is provided with, for example, a pair of thickness measuring devices (height meters), that is, a first height measuring device 381 for measuring the height position of the holding surface 300a of the chuck table 30 and for measuring the workpiece W. The second height measuring device 382 having a height position on the surface (the surface to be ground) on the opposite side is the surface to be held by the chuck table 30.

The first thickness measuring device 381 and the second thickness measuring device 382 have contactors that are raised and lowered in the vertical direction and contact the respective measuring surfaces at the respective distal ends thereof, and the contactors are formed in a sharp shape such that the diameter gradually decreases toward the lower side. The root side of the first thickness measurer 381 (second thickness measurer 382) is supported by the first support portion 383 (second support portion 384). The first support portion 383 (second support portion 384) supports the first thickness measuring device 381 (second thickness measuring device 382) so as to be movable up and down, and can be pressed by, for example, a spring generated by a spring built therein. The first thickness measurer 381 (second thickness measurer 382) presses an appropriate force on each measurement surface. The first thickness measuring device 38A detects the height position of the upper surface of the frame body 301 serving as the reference surface by the first thickness measuring device 381, and detects the ground surface of the workpiece W to be ground by the second thickness measuring device 382. That is, the surface of the workpiece W and the surface held by the chuck table 30 is the height position of the surface on the opposite side, and by calculating the difference between the detected values of the two, the thickness of the workpiece W can be measured at any time before or after the grinding.

The grinding device 3 is, for example, a control means 9 that controls the entire apparatus. The control means 9 includes a CPU that processes the control program, a ROM that stores a control program, and the like, and a RAM that stores calculation results or other information, etc., and connects the first grinding feed means 35 or the wiring (not shown). A rotating means or the like that rotates the chuck table 30. Further, under the control of the control means 9, the rotation means (not shown) causes the rotation operation by the chuck table 30 or the grinding of the coarse grinding means 31 by the first grinding feed means 35 in the Z-axis direction. The operation of each configuration of the grinding device 3 such as an operation is controlled.

The respective steps of the case where the workpiece W shown in Fig. 1 is ground using the grinding device 3 of the present invention will be described below.

(1) Front surface protection step First, the front surface Wa of the workpiece W is adhered to the circular front surface protection member T having substantially the same diameter as the workpiece W, and the front surface Wa is covered and protected by the front surface protection member T. The front surface protective member T is, for example, an adhesive film having a base material layer and an adhesive layer, and the base material layer is made of a resin having a certain degree of flexibility. However, the resin is not limited thereto, and a liquid resin may be applied to the front surface Wa. Thereafter, the resin is cured by heating or irradiating ultraviolet rays or the like to form a protective member having a certain degree of flexibility and covering the front surface Wa of the workpiece W.

(2) Holding Step The rotating table 34 shown in Fig. 1 is rotated in the clockwise direction as seen from the +Z-axis direction, and the chuck table 30 is moved to the vicinity of the first conveying means 335. The robot arm 330 draws a workpiece W adhered to the front surface protection member T from the first cassette 331 and moves the workpiece W to the alignment means 333. After the workpiece W is positioned at a predetermined position in the alignment means 333, the first conveying means 335 conveys the workpiece W on the alignment means 333 to the holding surface 300a of the chuck table 30. Further, the suction force generated by the suction source (not shown) is transmitted to the holding surface 300a, whereby the chuck table 30 sucks and holds the workpiece W. Here, when the workpiece W is correctly conveyed to the chuck table 30 and sucked and held, the surface held by the chuck table 30 of the workpiece W is the front surface Wa covered by the front surface protection member T, and the surface held by the chuck table 30. The back surface Wb on the opposite side is in a state of being exposed upward. On the other hand, there is a possibility that the workpiece W is transported to the chuck table 30 in an erroneous state and sucked and held. In other words, the surface on which the chuck table 30 of the workpiece W is held is the back surface Wb, and the front surface Wa covered by the front surface protective member T on the surface on the opposite side to the surface on which the chuck table 30 is held is in the upward direction.

(3) Thickness Measurement Step In the case where the workpiece W is sucked and held by the chuck table 30 in an erroneous state, the grinding device 1 of the present invention performs the following description in order to prevent the grinding from occurring due to the prevention of the grinding of the current state. Thickness measurement steps. As shown in Fig. 1, the rotary table 34 is rotated in the clockwise direction as viewed in the +Z-axis direction, thereby moving the chuck table 30 holding the workpiece W to the lower side of the first thickness measuring means 38A. Further, for example, the chuck table 30 is rotated about the rotation shaft 30b at a predetermined rotation speed, and the thickness of the workpiece W is measured by the first thickness measuring means 38A. Furthermore, the thickness of the workpiece W can also be measured in a state where the chuck table 30 is not rotated.

FIG. 3 shows a case where the workpiece W is sucked and held by the chuck table 30 in the correct state. Therefore, the first thickness measuring device 381 is pressed against the upper surface of the frame body 301 which is the reference surface of the rotating chuck table 30 with a predetermined pressing force, and the second thickness measuring device 382 is pressed with a predetermined pressing force. The front surface Wa of the surface of the workpiece W and the chuck table 30 is on the back surface Wb of the surface on the opposite side. On the other hand, FIG. 4 shows a case where the workpiece W is sucked and held by the chuck table 30 in an erroneous state. Therefore, the first thickness measuring device 381 is pressed against the upper surface of the frame body 301 which is the reference surface of the rotating chuck table 30 with a predetermined pressing force, and the second thickness measuring device 382 is pressed with a predetermined pressing force. The front surface protection member T adhered to the front surface Wa of the surface of the workpiece W held by the chuck table 30 and the front surface Wa of the surface on the opposite side.

In the case shown in FIG. 3, the height position of the upper surface of the casing 301 is measured by the first thickness measuring device 381, and the height position of the back surface Wb of the workpiece W is measured by the second thickness measuring device 382, and the two measurements are calculated. The difference in value is taken as the thickness of the workpiece W. Then, the calculated information of the thickness of the workpiece W is transmitted, for example, to the control means 9 and stored in the RAM. The curve G1 shown in FIG. 5 is a graph showing the thickness variation of the workpiece W from the start of the thickness measurement of the workpiece W by the first thickness measuring means 38A shown in FIG. 3 until the elapse of an arbitrary time t1. An example. In Fig. 5, the vertical axis represents the thickness of the workpiece W, and the horizontal axis represents the elapsed time.

On the other hand, as shown in FIG. 4, the height position of the upper surface of the casing 301 is measured by the first thickness measuring device 381, and the front surface protection of the front surface Wa of the workpiece W is measured by the second thickness measuring device 382. The height position of the member T is calculated as the difference between the measured values of the two as the thickness of the workpiece W. Then, the calculated information of the thickness of the workpiece W is transmitted, for example, to the control means 9 and stored in the RAM. The curve G2 shown in FIG. 5 is an example of a thickness change map of the workpiece W from the start of the thickness measurement of the workpiece W by the first thickness measuring means 38A shown in FIG. 4 to the time point when the arbitrary time t1 elapses. .

Since the back surface Wb of the workpiece W is a crucible having a certain degree of hardness, when the thickness of the workpiece W is measured by the first thickness measuring means 38A in FIG. 3, the sinking of the back surface Wb of the workpiece W by the second thickness measuring device 382 is A small amount. As a result, the thickness of the workpiece W indicated by the difference between the measured value of the first thickness measuring device 381 and the measured value of the second thickness measuring device 382 is as shown in FIG. 5 as the curve G1 hardly changes, at the beginning of the measurement. When the thickness M1 of the workpiece W is different from the thickness M2 of the workpiece W at the time point from the start of the thickness measurement of the workpiece W to the lapse of an arbitrary time t1, there is almost no difference. On the other hand, since the front surface protective member T is an adhesive film composed of a resin having a certain degree of flexibility, when the thickness of the workpiece W is measured by the first thickness measuring means 38A in FIG. 4, the second thickness measuring device 382 The sinking of the front protective member T is large. As a result, the thickness of the workpiece W indicated by the difference between the measured value of the first thickness measurer 381 and the measured value 2 of the second thickness measurer 382 is as compared with the curve G1 as shown by the curve G2 shown in FIG. There is a large change, as shown by the curve G2, the thickness M1 of the workpiece W at the start of the measurement and the thickness M3 of the workpiece W at the time point from the start of the thickness measurement of the workpiece W to the lapse of an arbitrary time t1.

The control means 9 is, for example, a calculation means 90 as shown in FIG. The calculation means calculates the amount of change from the first thickness data measured by the first thickness measuring means 38A and the second thickness data measured from the time point when the first thickness data is measured to the elapse of an arbitrary time. In the thickness measuring step of the case shown in FIG. 3 of the present embodiment, the first thickness data is, for example, the thickness M1 of the workpiece W at the start of measurement shown by the curve G1 of FIG. 5, and the second thickness data is a curve. The thickness M2 of the workpiece W at the time point from the start of the measurement to the lapse of an arbitrary time t1 indicated by G1. Further, the calculation means 90 is, for example, calculating the difference (M1 - M2) between the thickness M1 of the workpiece W and the thickness M2 of the workpiece W as the amount of change (difference amount) of the thickness of the workpiece W. In the thickness measurement step in the case shown in FIG. 4 of the present embodiment, the first thickness data is, for example, the thickness M1 of the workpiece W at the start of measurement shown by the curve G2, and the second thickness data is shown by the curve G2. The thickness M3 of the workpiece W at the time point from the start of the measurement to the lapse of an arbitrary time t1. Further, the calculation means 90 is, for example, calculating the difference (M1 - M3) between the thickness M1 of the workpiece W and the thickness M3 of the workpiece W as the amount of change (difference amount) of the thickness of the workpiece W.

For example, the threshold value Mc is registered in the ROM of the control means 9 to determine whether or not the surface of the workpiece W that the second thickness measuring device 382 is in contact with is the back surface Wb of the workpiece W where the sinking of the second thickness measuring device 382 is hard to occur. In other words, it is used to determine whether or not the surface on the opposite side of the surface of the workpiece W and the chuck table 30 is the back surface Wb of the ground surface. Then, the control means 9 determines whether or not the amount of change in the thickness of the workpiece W calculated by the calculation means 90 (the difference amount in the present embodiment) exceeds the threshold value Mc or is equal to or less than the threshold value Mc. In addition, the type of the workpiece W and the type of the front surface protection member T are different in the amount of sinking of the back surface Wb of the workpiece W or the front surface protection member T by the second thickness measuring device 382, and the threshold value Mc registered in advance becomes the corresponding workpiece W. The type of back Wb and front protective member T is selected based on experimental, empirical or theoretical values.

In the case shown in FIG. 3, as shown by the curve G1 in FIG. 5, since the amount of change (M1-M2) is a value smaller than the threshold value Mc, the control means 9 can also determine the workpiece W to which the second thickness measurer 382 is in contact. The surface is the back surface Wb of the workpiece W where the sinking of the second thickness measuring device 382 is hard to occur, that is, it is determined that the workpiece W is sucked and held by the chuck table 30 in the correct state, and the grinding can be started while maintaining the current state. In the case shown in FIG. 4, as shown by the curve G2 of FIG. 5, since the amount of change (M1 - M3) is a value exceeding the threshold value Mc, the control means 9 determines that the surface of the workpiece W which the second thickness measurer 382 is in contact with is generated. The sunken front holding member T of the second thickness measuring device 382, that is, the workpiece W is judged to be sucked and held by the chuck table 30 in an erroneous state, and the grinding is not maintained as it is.

When the control means 9 determines that the grinding is not possible, under the control of the control means 9, the conversion of the grinding step described later in the grinding device 3 is stopped, and the grinding of the workpiece W is not started. Further, the control means 9 notifies the operator of the determination by emitting an alarm sound from the speaker or displaying an error on the screen. For example, by the manual operation of the worker who has been notified of the determination, the workpiece W is adjusted to be exposed to the upper surface of the holding surface 300a of the chuck table 30, or the workpiece W is removed from the chuck table 30.

The thickness measuring step is not limited to the above embodiment, and may be carried out, for example, as described below (hereinafter, other embodiments of the thickness measuring step). In other embodiments of the thickness measuring step, the amount of change calculated by the case calculating means 90 shown in FIG. 3 is the inclination (differential component) of the tangent L1 of the curve G1 at an arbitrary time point t2 during the measuring time. ). In other words, the calculation means 90 calculates the first thickness data measured by the first thickness measuring means 38A after the thickness measurement is started, and the time point from the measurement of the first thickness to the elapse of an arbitrary time (only after a short time) The difference between the measured second thickness data is further calculated, and the calculated difference is further calculated by the differential (the inclination of the tangent L1). Further, when the amount of change is not the inclination of the tangent line L1, it may be any two time points in the thickness measurement time (for example, when the measurement starts, when the t1 time elapses, or when the t2 time elapses and the t1 time elapses) The slope of the curve G1. Similarly, the amount of change calculated by the case calculation means 90 shown in FIG. 4 is the inclination (differential component) of the tangent L2 of the curve G2 at an arbitrary time point t2 during the measurement time. In other words, the calculation means 90 calculates the first thickness data measured by the first thickness measuring means 38A after the thickness measurement is started, and the time point from the measurement of the first thickness to the elapse of an arbitrary time (only after a short time) After the difference of the measured second thickness data, and further the calculated difference is calculated by the differential (the inclination of the tangent L2). Further, when the amount of change is not the inclination of the tangent line L2, it may be any two time points in the thickness measurement time (for example, when the measurement starts, when the t1 time elapses, or when the t2 time elapses and the t1 time elapses) The slope of the curve G2.

The threshold value is registered in the ROM of the control means 9 to determine whether or not the surface of the workpiece W that the second thickness measuring device 382 is in contact with is the back surface Wb of the workpiece W in which the sinking of the second thickness measuring device 382 is hard to occur, in other words, It is judged whether the surface of the workpiece W and the surface held by the chuck table 30 on the opposite side is the back surface Wb of the ground surface. Further, the control means 9 judges that the amount of change calculated by the calculation means 90 (in other embodiments, the component is a threshold value or a threshold value or less).

In the case shown in FIG. 3, the inclination (change amount) of the tangent L1 of the curve G1 in FIG. 5 is, for example, smaller than the threshold value of the registration, and the control means 9 can also determine the surface of the workpiece W that the second thickness measurer 382 is in contact with. The back surface Wb of the workpiece W in which the sinking of the second thickness measuring device 382 is hard to occur, that is, the workpiece W is determined to be sucked and held by the chuck table 30 in the correct state, and the grinding can be started. In the case shown in FIG. 4, when the inclination (change amount) of the tangent L2 of the curve G2 of FIG. 5 is, for example, a threshold value exceeding the registration, the control means 9 determines that the surface of the workpiece W that the second thickness measurer 382 is in contact with is generated. The sunken front holding member T of the second thickness measuring device 382, that is, the workpiece W is judged to be sucked and held by the chuck table 30 in an erroneous state, and the grinding is not started.

(4) The grinding step performs the thickness measuring step as described above, and as a result, when the so-called control means 9 determines that the grinding of the workpiece W is started, that is, as shown in FIG. This grinding step is carried out by the fact that W is sucked and held by the chuck table 30 in the correct state. As shown in Fig. 1, the rotary table 34 is rotated in the clockwise direction as seen from the +Z-axis direction, thereby moving the chuck table 30 holding the workpiece W to the lower side of the rough grinding means 31, aligning the grinding wheel 313 with the workpiece W. . The alignment is exemplified as shown in FIG. 6, and is performed to shift the center of rotation of the grinding wheel 313 from the center of rotation of the workpiece W by a predetermined distance in the +X direction, and to pass the rotating track of the rough grinding stone 313 through the workpiece W. The center of rotation.

When the rotary shaft 310 is rotationally driven, the grinding wheel 313 rotates. Further, the rough grinding means 31 is conveyed in the -Z direction by the first grinding feed means 35 shown in Fig. 1, and the rough grinding grindstone 313a of the rotating grinding wheel 313 abuts against the back surface Wb of the workpiece W to perform rough grinding. Further, the rotation of the chuck table 30 is accompanied by the rotation of the workpiece W held on the holding surface 300a, so that the entire surface of the back surface Wb of the workpiece W is ground. Further, the grinding water is supplied to a contact portion between the rough grinding stone 313a and the workpiece W through a flow path (not shown) in the rotary shaft 310, and the contact portion is cooled and cleaned. Further, in the rough grinding of the workpiece W, the thickness of the workpiece W is measured by the first thickness measuring means 38A, and the workpiece W is controlled to have a desired thickness (for example, the thickness before the thickness is completed).

The workpiece W before the completion thickness is ground by rough grinding, and then ground to the finished thickness. After the coarse grinding means 31 shown in FIG. 1 is separated from the workpiece W, the rotary table 34 is rotated clockwise as seen from the +Z direction, whereby the chuck table 30 is moved below the fine grinding means 32. Then, when the grinding wheel 313 provided in the fine grinding means 32 is aligned with the workpiece W, the fine grinding means 32 is conveyed in the -Z direction, and the rotating lapping stone 323a abuts against the back surface Wb of the workpiece W, and the chuck table The rotation of 30 is accompanied by the rotation of the workpiece held on the holding surface 300a, so that the entire surface of the back surface Wb of the workpiece W is finely ground. Further, the grinding water is supplied to the contact portion of the lapping stone 323a and the workpiece W, and the contact portion is cooled and cleaned. Further, in the rough grinding of the workpiece W, the thickness of the workpiece W is measured by the second thickness measuring means 38B, and the workpiece W is controlled to have a desired thickness (finished thickness).

After the fine grinding means 32 is separated from the workpiece W, the rotating table 34 is rotated in the clockwise direction as seen from the +Z direction, and the workpiece W1 of the high flatness of the back surface Wb ground to the finished thickness is moved to the vicinity of the second conveying means 336. . Further, the second conveyance means 336 conveys the workpiece W on the chuck table 30 to the cleaning means 334. Further, after the workpiece W is cleaned in the cleaning means 334, the workpiece W is accommodated in the second cassette 332 by the robot arm 330.

The grinding method according to the present invention described above includes a front surface protecting step of covering the front surface of the workpiece with the front surface protective member, and a holding step of holding the workpiece W by the holding surface 300a of the chuck table 30 after the front surface protecting step is performed, the chuck table 30 The rotation axis 30b that is perpendicular to the axial direction can be rotated. The thickness measurement step is performed after the holding step, and the second thickness measurer 382 is brought into contact with the surface of the workpiece W and the surface held by the chuck table 30 is opposite. And measuring the thickness of the workpiece W, calculating the amount of change from the measured first thickness data, the time point from the measurement of the first thickness data to the second thickness data measured after an arbitrary time; and the grinding step After the thickness measurement step is performed, the rough grinding grindstone 313a rotated by the rotating shaft 310 orthogonal to the holding surface 300a is used to grind the back surface Wb of the workpiece W while supplying the grinding water, and the calculated change is performed in the thickness measuring step. When the amount is less than or equal to the threshold value registered in advance, it is determined that the surface of the workpiece W that the second thickness measuring device 382 is in contact with is the back surface Wb of the workpiece W where the sinking of the second thickness measuring device 382 is less likely to occur, and is opened. When the grinding step is performed, and the calculated amount of change exceeds the threshold value registered in advance, it is determined that the surface of the workpiece W that the second thickness measuring device 382 is in contact with is a front surface protective member T in which the sinking of the second thickness measuring device 382 is likely to occur. And the grinding step is not started, whereby the workpiece W is attracted and held by the chuck table 30 in an erroneous state, that is, when the back surface Wb of the ground surface of the workpiece W is sucked by the chuck table 30. In the meantime, the grinding step is not performed, the front protective member T is ground and the grinding failure occurs.

The grinding device 3 according to the present invention described above includes the calculation means 90 for measuring the first thickness data measured by the first thickness measuring means 38A and the time point from the measurement of the first thickness data until an arbitrary time has elapsed. The second thickness data is used to calculate the amount of change; and the control means 9 causes the grinding to start when the amount of change calculated by the calculating means 90 is equal to or less than the threshold value registered in advance, and the amount of change is a threshold exceeding the pre-registered value. In the case of the case, the error is not caused to start the grinding; thereby, when the workpiece W is attracted and held in the wrong state by the chuck table 30, that is, when the back surface Wb of the ground surface of the workpiece W is on the chuck table In the case of the adsorption of 30, the front protective member T is not ground by the rough grinding means 31, and the grinding failure occurs.

The first thickness measuring means 38A of the grinding device 3 is used for thickness measurement of the workpiece W before the start of grinding, and also for thickness control of the workpiece W after the start of grinding, thereby attempting to achieve miniaturization of the grinding device 3. And to prevent an increase in the manufacturing cost of the grinding device 3.

In addition, the grinding method of the present invention is not limited to the above-described embodiment, and the configuration of the grinding device 3 shown in the drawings is not limited thereto, and can be appropriately changed within the range in which the present invention can be exerted. . For example, the grinding device 3 is not limited to the grinding device in which the grinding means of the present embodiment is a two-axis, and the grinding means may be a one-axis grinding device. In addition, for example, the first thickness measuring means 38A is not limited to include the first thickness measuring 381 and the second thickness measuring device 382 according to the present embodiment. For example, the thickness of the workpiece W may be measured by one thickness measuring device. The second thickness measuring device 382 includes a tray that movably holds the second thickness measuring device 382 in the vertical direction, and a displacement detecting means that measures the position of the tray.

W‧‧‧Workpiece

The front of the Wa‧‧‧ workpiece

Wb‧‧‧ back of the workpiece

T‧‧‧ front protective members

3‧‧‧ grinding device

3A‧‧‧Base

3B, 3C‧‧ ‧ column

30‧‧‧ chuck table

300‧‧‧Adsorption Department

300a‧‧‧ Keep face

301‧‧‧ frame

31‧‧‧ rough grinding means

310‧‧‧Rotary axis

311‧‧‧ Shell

312‧‧‧Motor

313‧‧‧ grinding wheel

313a‧‧‧Rough grinding stone

32‧‧‧Skilled means

323a‧‧‧ fine grinding stone

330‧‧‧Machine arm

331‧‧‧ first card

332‧‧‧Second card

333‧‧‧Alignment means

334‧‧‧Washing means

335‧‧‧First means of transport

336‧‧‧Second transport means

34‧‧‧Rotating table

35‧‧‧First grinding and feeding means

350‧‧‧Ball screw

351‧‧‧rail

352‧‧‧Motor

353‧‧‧ Lifting Department

36‧‧‧Second grinding feed means

360‧‧‧Rolling screw

361‧‧‧rail

362‧‧‧Motor

363‧‧‧ Lifting Department

38A‧‧‧1st thickness measurement means

381‧‧‧1st thickness measurer

382‧‧‧2nd thickness measurer

38B‧‧‧2nd thickness measurement means

9‧‧‧Control means

90‧‧‧ Calculation means

Fig. 1 is a perspective view showing an example of a grinding device. Fig. 2 is a perspective view showing a state in which the front surface of the workpiece is covered by the front surface protective member. 3 is a cross-sectional view showing a state in which the thickness measurement of the workpiece is performed by bringing the second thickness measuring device into contact with the back surface of the front surface of the front surface protection member held by the chuck table. 4 is a cross-sectional view showing a state in which the thickness of the workpiece is measured by bringing the second thickness measuring device into contact with the front surface of the workpiece which is adhered to the front surface opposite to the back surface held by the chuck table. 5 is a view showing a change in thickness of a workpiece in a case where the second thickness measuring device is brought into contact with the back surface and thickness measurement of the workpiece, and a workpiece in a case where the second thickness measuring device is brought into contact with the front surface protective member and thickness measurement of the workpiece is performed. A graph of thickness changes. Fig. 6 is a cross-sectional view showing a state in which thickness control of a workpiece is performed and rough grinding is performed by a rough grinding means.

Claims (4)

A grinding method of a workpiece for grinding a back surface of a workpiece by grinding a grinding stone having a front surface of a component formed in a region defined by a plurality of predetermined dividing lines formed in a lattice shape, the grinding method of the workpiece having: a front protection step, The front protection member covers the front surface of the workpiece; the holding step, after the front protection step is performed, the workpiece is held by the holding surface of the chuck table, and the chuck table is rotatable about a rotation axis that is perpendicular in the axial direction; thickness measurement Step, after performing the holding step, the thickness measuring device is brought into contact with the surface of the workpiece and the surface held by the chuck table is opposite side, and the thickness of the workpiece is measured, from the measured first thickness data, and the measurement to the first 1 the thickness data is measured from the time point of the data to the second thickness data measured after any time; and the grinding step is performed, and after the thickness measurement step is performed, the rotation axis orthogonal to the holding surface is rotated Grinding the grindstone, grinding the back side of the workpiece while supplying the grinding water; in the thickness measuring step, the calculated amount of the change is pre-registered If the threshold value is less than or equal to the threshold value, it is determined that the surface of the workpiece contacted by the thickness measuring device is the back surface of the workpiece where the sinking of the thickness measuring device is hard to occur, and the grinding step is started, and the calculated amount of change is beyond the pre-registered value. In the case of the threshold, it is judged that the face of the workpiece which the thickness measurer is in contact with is the front face protection member which is liable to cause sinking of the thickness measurer, and the grinding step is not started. The grinding method according to the first aspect of the invention, wherein the front protective member is an adhesive film. A grinding device comprising a chuck table for holding a workpiece, a thickness measuring means for measuring a thickness of a workpiece held on the chuck table, and a grinding means for grinding a workpiece held by the chuck table, the grinding device characterized by: The chuck table is rotatable about a rotation axis in the direction of the vertical direction, and the workpiece is adhered to the front protection member by the holding surface, and the thickness measuring means contacts the thickness gauge to the workpiece and the card before the grinding of the workpiece starts. The surface held by the disk table is a surface on the opposite side, and thickness measurement is performed. The grinding method grinds the back surface of the workpiece while supplying grinding water by using a grinding grindstone that rotates on a rotating shaft orthogonal to the holding surface of the chuck table; The grinding device includes: a calculating means for calculating the first thickness data measured by the thickness measuring means, and the second thickness data measured after the time from the measurement of the first thickness data to the elapse of an arbitrary time The amount of change; and the control means, if the amount of change calculated by the calculation means is equal to or less than a threshold value registered in advance, the grinding starts OK, at the threshold of the amount of change is beyond the pre-registered, an error without the grinding start. The grinding device according to claim 3, wherein the thickness measuring means is used for thickness measurement of the workpiece before the start of the grinding, and also for thickness control of the workpiece after the grinding start.