TWI772535B - Grinding method and grinding device of workpiece - Google Patents

Abstract

[Problem] In a grinding apparatus, the front protection member attached to the front side of the workpiece is prevented from being erroneously ground with a grinding stone. [Solution] A grinding method comprising: a step of covering the front surface of a workpiece with a protective member; a step of holding the workpiece with a holding surface of the chuck table 30; In order to measure the thickness, the thickness measurement step of calculating the change amount from the first thickness data measured and the second thickness data measured from the time when the first thickness data was measured to the second thickness data measured after an arbitrary time; and grinding the workpiece In the thickness measurement step, if the calculated change amount is below the pre-registered threshold value, it is judged that the surface of the workpiece contacted by the thickness measuring device 382 is the back surface of the workpiece, and grinding starts, and the calculated change amount is When the threshold value registered in advance is exceeded, it is determined that the surface of the workpiece with which the thickness measuring device 382 comes into contact is a front protection member, and grinding is not started.

Description

Grinding method and grinding device of workpiece

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

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

A grinding device for grinding the back surface of a workpiece (see, for example, Patent Document 1) includes: a chuck table that holds the front side of the workpiece to which the front protection member is attached; A grinding stone that grinds the back of the workpiece and grinds the workpiece more efficiently. [Prior Art Documents] [Patent Documents]

[Patent Document 1] Japanese Patent No. 5025200

[Problem to be Solved by the Invention] However, in the above grinding apparatus, when the workpiece is held by the chuck table, the back side of the workpiece not covered with the front protection member is erroneously attracted to the holding surface of the chuck table. When the rear side of the workpiece is attracted by the holding surface of the chuck table, the front side protection member of the front side of the workpiece is ground by the grinding stone, and the current value of the motor that rotates the grinding stone due to poor machining exceeds the allowable value. The automatic operation of the grinding device may stop. In this case, it is necessary to dress (grind) the grinding stone to return to a normal state, resulting in increased downtime of the grinding device.

Therefore, in the grinding apparatus, there is a problem of preventing erroneous grinding of the front protection member adhered to the front side of the workpiece with the grinding stone.

[Technical Means for Solving the Problem] In order to solve the above-mentioned problems, the present invention provides a method for grinding a workpiece having elements formed in regions divided by a plurality of planned dividing lines formed in a lattice shape, using a grinding stone to grind the back surface of a workpiece. The front side of the workpiece, the grinding method of the workpiece includes: a front side protection step, covering the front side of the workpiece with a front side protection member; a holding step, after the front side protection step is implemented, the workpiece is held by the holding surface of the chuck table, the chuck table can be Rotate around the axis of rotation with the axis direction as the vertical direction; in the thickness measurement step, after the holding step is carried out, the thickness measuring device is brought into contact with the surface on the opposite side of the workpiece and the surface held by the chuck table, and the thickness of the workpiece is measured. , calculate the amount of change from the measured first thickness data, and the time when the first thickness data was measured to the second thickness data measured after an arbitrary period of time; and the grinding step, implemented the thickness measurement After the step, the back surface of the workpiece is ground while supplying grinding water with a grinding stone rotated by a rotating shaft orthogonal to the holding surface; in the thickness measurement step, the calculated change amount is below a pre-registered threshold value. , judging 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 difficult to occur, and starts the grinding step, and if the calculated change exceeds the pre-registered threshold, it is judged that the The face of the workpiece with which the thickness gauge is in contact is the front protection member where sinking of the thickness gauge is likely to occur, and the grinding step is not started.

The aforementioned front protection member can be, for example, an adhesive film.

In addition, in order to solve the above-mentioned problems, the present invention provides a grinding apparatus including a chuck table holding a workpiece, a thickness measuring means for measuring the thickness of the workpiece held on the chuck table, and a grinding device for grinding the workpiece held on the chuck table. Grinding means, the grinding device is characterized in that: the chuck table is rotatable around a rotation axis with the vertical direction as the axis direction, and the workpiece to which the front protection member is adhered is held by the holding surface, and the thickness measuring means starts grinding of the workpiece. Before the thickness measurement device is brought into contact with the surface of the workpiece on the opposite side to the surface held by the chuck table, and thickness measurement is performed, the grinding means utilizes a grinding stone rotated by a rotation axis orthogonal to the holding surface of the chuck table. , grinding the back side of the workpiece while supplying grinding water; the grinding device is provided with: calculation means from the first thickness data measured by the thickness measuring means, and the time point when the first thickness data is measured to after an arbitrary time has elapsed Calculate the amount of change of the measured second thickness data; and control means to start grinding if the amount of change calculated by the calculation means is below a pre-registered threshold value, and when the amount of change exceeds the threshold In the case of this pre-registered threshold value, it indicates an error and does not start grinding.

The aforementioned thickness measurement 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 measurement means, when the measurement surface is a front protection member with flexibility, the subsidence of the thickness measurement device provided in the thickness measurement means to the front protection member, The variation in workpiece thickness becomes larger. On the other hand, when the measurement surface is the hard back surface of the ground surface of the workpiece, the amount of variation in the thickness of the workpiece is small because there is hardly any subsidence of the thickness measuring device provided in the thickness measuring means to the back surface. Therefore, the grinding method of the present invention includes: a front protection step of covering the front surface of the workpiece with a 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, and the chuck table can be wound around Rotate the rotation shaft with the axis direction as the vertical direction; in the thickness measurement step, after the holding step is implemented, the thickness measuring device is placed in contact with the workpiece and the surface on the opposite side of the chuck table is held, and the thickness of the workpiece is measured, from measurement to The first thickness data and the second thickness data measured after an arbitrary time have elapsed from the time when the first thickness data is measured, and the amount of change is calculated; and in the grinding step, after the thickness measurement step is performed, use and hold the surface The grinding stone rotated by the orthogonal rotation axis grinds the back surface of the workpiece while supplying grinding water; in the thickness measurement step, if the calculated change amount is less than or equal to the pre-registered threshold value, the thickness of the workpiece in contact with the thickness measuring device is judged. If the surface is the back surface of the workpiece where the thickness gauge is difficult to sink in, the grinding step is started, and if the calculated change exceeds the pre-registered threshold, it is judged that the surface of the workpiece that the thickness gauge is in contact with is prone to the thickness gauge. The front surface protection member sinks in, and the grinding step is not started, whereby when the workpiece is attracted and held in the wrong state on the chuck table, that is, when the back side of the ground surface of the workpiece is accidentally sucked by the chuck table Even in this case, the grinding step is not carried out as it is, and the front protection member is ground without causing grinding defects.

The grinding device of the present invention is provided with: calculation means from the first thickness data measured by the thickness measurement means and the second thickness data measured after an arbitrary time has elapsed from the time when the first thickness data was measured, Calculate the amount of change; and control means, if the amount of change calculated by the calculation means is below the pre-registered threshold value, start grinding, and if the amount of change exceeds the pre-registered threshold value, it will indicate an error and not. Grinding is started; thereby, when the workpiece is attracted and held on the chuck table in a wrong state, that is, when the back side of the workpiece to be ground is accidentally sucked by the chuck table, it will not be held. In the current situation, the front protection member is ground by a grinding method, and grinding failure occurs.

The thickness measurement means of the grinding device is used to measure the thickness of the workpiece before the start of grinding, and also to control the thickness of the workpiece after the start of grinding, which can try to achieve the miniaturization of the grinding device and prevent the production of the grinding device. increase in cost.

The grinding apparatus 3 of the present invention shown in FIG. 1 is an apparatus that performs grinding processing on the workpiece W sucked and held by the chuck table 30 . The workpiece W shown in FIG. 1 is, for example, a semiconductor wafer with a circular plate shape using silicon as a base material, and on the front surface Wa facing downward in FIG. 1 , a plurality of divisions that intersect vertically are formed. The planned lines S are formed on the respective regions divided into a lattice shape by the planned dividing lines S, and elements D such as ICs are formed. The front surface Wa and the back surface Wb on the opposite side of the workpiece W are ground surfaces to be ground. Furthermore, the workpiece W may be made of gallium arsenide other than silicon, sapphire, gallium nitride or silicon carbide, etc., and its shape may be non-circular, for example, rectangular.

The front (-Y direction side) on the base 3A of the grinding device 3 is an area where the workpiece W is loaded and unloaded from the chuck table 30 by the robot arm 330 capable of conveying the workpiece W, and the rear (+Y direction side) on the base 3A is ) is 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 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 arranged. 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 grinding from the first cassette 331 and carrying the ground workpiece W into the second cassette 332 is disposed.

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

The first conveyance means 335 is arranged in the vicinity of the alignment means 333 , and the second conveyance means 336 is arranged in the vicinity of the cleaning means 334 . The first conveyance means 335 has a function of conveying the workpiece W before grinding placed on the alignment means 333 to any one of the chuck tables 30 as shown in FIG. A function of conveying the retained ground workpiece W to the cleaning means 334 .

A turntable 34 is arranged on the rear side (+Y direction side) of the first conveyance means 335 on the substrate 3A, and three chucks, for example, are arranged on the upper surface of the turntable 34 at equal intervals in the circumferential direction. Desk 30. At the center of the turntable 34, a rotation shaft (not shown) is arranged for rotating the turntable 34, and the turntable 34 can be rotated on the base 3A around the rotation shaft. In addition, any one of the chuck tables 30 is positioned in the vicinity of the first conveyance means 335 and the second conveyance means 336 by the rotation of the turntable 34 .

The chuck table 30 is rotatably supported by the rotary table 34 . In addition, 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, which is composed of a motor or the like, whereby the chucking is performed. The table 30 is rotatable around a rotation axis in the vertical direction on the turntable 34 . The chuck table 30 has, for example, a circular outer shape, and includes a suction portion 300 that suctions and holds the workpiece W made of a porous member or the like, and a frame 301 that supports the suction portion 300 . The suction part 300 communicates with a suction source (not shown), and the suction force generated by the suction source is transmitted to the holding surface 300 a of the exposed surface of the suction part 300 , and the chuck table 30 sucks and holds the workpiece W on the holding surface 300 a.

A column 3B and a column 3C are erected side by side on the rear side of the base 3A, and a first grinding feed means 35 is arranged on the side face on the -Y direction side of the column 3B. The first grinding feed means 35 uses the rough grinding means 31 to borrow The workpiece W held by the chuck table 30 is ground and fed, and a second grinding and feeding means 36 is arranged on the side face of the column 3C on the -Y direction side. The disc table 30 grinds and feeds the held workpiece W.

The first grinding and feeding means 35 is composed of: a ball screw 350 having a vertical axis; a pair of guide rails 351 arranged in parallel with the ball screw 350; and a motor 352 connected to the ball screw 350 to rotate the ball screw 350 and the lifting part 353, the inner nut is screwed with the ball screw 350 and the side part is in sliding contact with the guide rail 351, and the first grinding and feeding means 35 becomes the following structure: when the motor 352 makes the ball screw 350 rotate and the lifting part 353 is guided by the guide rails 351 to ascend and descend. The lifting portion 353 supports the rough grinding means 31 , and the rough grinding means 31 is also lifted and lowered by the lifting and lowering of the lifting portion 353 .

The second grinding and feeding means 36 is composed of: a ball screw 360 having a vertical axis; a pair of guide rails 361 arranged in parallel with the ball screw 360; and a motor 362 connected to the ball screw 360 to rotate the ball screw 360 And the lifting part 363, the inner nut and the ball screw 360 are screwed and the side part is in sliding contact with the guide rail 361, and the second grinding and feeding means 36 becomes the following structure: When the motor 362 makes the ball screw 360 rotate and accompanied by the lifting part 363 is guided by guide rails 361 to ascend and descend. The lift portion 363 supports the fine grinding means 32 , and the fine grinding means 32 is also raised and lowered by the lift of the lift portion 363 .

The rough grinding means 31 includes a rotating shaft 310 whose axial direction is a vertical direction (Z-axis direction) perpendicular to the holding surface 300 a of the chuck table 30 , a housing 311 that rotatably supports the rotating shaft 310 , and a motor 312 that is rotatably driven The rotating shaft 310 ; the mounting piece 314 is mounted on the lower end of the rotating shaft 310 ; the grinding wheel 313 is detachably connected to the mounting piece 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 diamond abrasive grains or the like with a vitrified bond or the like. In addition, the shape of the rough grinding stone 313a may be integrally formed in a ring shape. The rough grinding grindstone 313a is, for example, a grindstone used for rough grinding, and a grindstone with large abrasive grains is contained in the grindstone.

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

The fine grinding means 32 can perform fine grinding with high flatness on the workpiece W that has been thinned to a finished thickness by rough grinding. That is, the fine grinding means 32 further grinds the back surface Wb of the workpiece W ground by the rough grinding means 31 by the grinding wheel 313 provided with the fine grinding stone 323a and rotatably installed. The abrasive grains contained in the finishing grinding stone 323 a are abrasive grains having a smaller particle size than the abrasive grains contained in the rough grinding grinding stone 313 a of the rough grinding means 31 . The structure other than the finishing grinding stone 323 a of the finishing grinding means 32 is the same as that of the rough grinding means 31 .

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

The first thickness measuring device 381 and the second thickness measuring device 382 are each provided with a contactor that is raised and lowered in the up-down direction at each tip thereof to contact each measurement surface. The root side of the first thickness gauge 381 (second thickness gauge 382 ) is supported by the first support portion 383 (second support portion 384 ). The first support portion 383 (the second support portion 384 ) supports the first thickness gauge 381 (the second thickness gauge 382 ) so as to be movable up and down, and is capable of, for example, a pressing force generated by a built-in spring. The first thickness gauge 381 (the second thickness gauge 382 ) is pressed against each measurement surface with an appropriate force. The first thickness measuring means 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, and also That is, the height of the workpiece W and the surface held by the chuck table 30 are on the opposite side, and by calculating the difference between the detected values, the thickness of the workpiece W can be measured at any time before or after grinding.

The grinding apparatus 3 is provided with the control means 9 which controls the whole apparatus, for example. The control means 9 includes a CPU for performing calculation processing of a control program, a ROM for storing control programs, etc., and a RAM for storing calculation results and other information, etc., and the first grinding feeding means 35 or the first grinding feed means 35 or The rotation means etc. which rotate the chuck table 30 are not shown in figure. In addition, under the control of the control means 9, the rotation operation of the chuck table 30 by the rotation means (not shown) or the grinding feed in the Z-axis direction of the rough grinding means 31 by the first grinding and feeding means 35 is performed. The operation of each configuration of the grinding device 3 such as the operation is controlled.

Hereinafter, each procedure in the case of grinding the workpiece W shown in FIG. 1 using the grinding apparatus 3 of the present invention will be described.

(1) Front Protection Step First, a circular front protection member T having substantially the same diameter as the workpiece W is adhered to the front surface Wa of the workpiece W, and the front surface Wa is covered and protected by the front protection member T. The front protection member T is, for example, an adhesive film having a base material layer and an adhesive layer, and the base material layer is composed of a resin having a certain degree of flexibility, but it is not limited to this, and a liquid resin may also be coated on the front side Wa. Then, the resin is cured by heating or irradiating ultraviolet rays, etc., to form a protective member which has a certain degree of flexibility and covers the front surface Wa of the workpiece W. As shown in FIG.

(2) Holding Step The turntable 34 shown in FIG. 1 rotates clockwise when viewed from the +Z axis direction, and the chuck table 30 moves to the vicinity of the first conveyance means 335 . The robot arm 330 extracts one workpiece W to which the front protection member T is adhered 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 conveyance means 335 conveys the workpiece W on the alignment means 333 onto the holding surface 300 a of the chuck table 30 . And the attraction|suction force by the attraction|suction source which is not shown in figure is transmitted to the holding surface 300a, and the workpiece|work W is attracted and held by the chuck table 30 by this. Here, if the workpiece W is correctly conveyed to the chuck table 30 and held by suction, the surfaces of the workpiece W held by the chuck table 30 are the front surface Wa covered with the front protection member T and the surface held by the chuck table 30 The back surface Wb on the opposite side is exposed upward. On the other hand, the workpiece W may be transported to the chuck table 30 in an incorrect state and held by suction. That is, there is a possibility that the surface held by the chuck table 30 of the workpiece W is the back surface Wb, and the front surface Wa covered by the front protection member T on the opposite side to the surface held by the chuck table 30 may face upward.

(3) Thickness Measurement Step In the case where the workpiece W is sucked and held by the chuck table 30 in an incorrect state as described above, in order to prevent the occurrence of poor grinding caused by starting grinding while maintaining the status quo, the grinding device 1 of the present invention implements the following description. thickness measurement steps. As shown in FIG. 1 , the turntable 34 rotates clockwise when viewed from the +Z axis direction, thereby moving the chuck table 30 holding the workpiece W to below the first thickness measuring means 38A. And, for example, the chuck table 30 is rotated around the rotation shaft 30b at a predetermined rotational speed, and the thickness measurement of the workpiece W is started by the first thickness measurement means 38A. In addition, the thickness measurement of the workpiece|work W can also be started in the state which the chuck table 30 is not rotating.

FIG. 3 shows a state in which the workpiece W is sucked and held by the chuck table 30 in a correct state. Therefore, the first thickness gauge 381 is pressed with a predetermined pressing force on the upper surface of the casing 301 serving as the reference surface of the rotating chuck table 30, and the second thickness gauge 382 is pressed with a predetermined pressing force On the back surface Wb of the surface on which the front surface Wa of the workpiece|work W and the surface held by the chuck table 30 is the opposite side. On the other hand, FIG. 4 shows the case where the workpiece W is sucked and held by the chuck table 30 in a wrong state. Therefore, the first thickness gauge 381 is pressed with a predetermined pressing force on the upper surface of the casing 301 serving as the reference surface of the rotating chuck table 30, and the second thickness gauge 382 is pressed with a predetermined pressing force The front protection member T to which the back surface Wb of the surface held by the chuck table 30 of the workpiece|work W and the front surface Wa of the opposite side is stuck.

In the case shown in FIG. 3, the height position of the upper surface of the frame body 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 of the values is taken as the thickness of the workpiece W. Then, information on the calculated thickness of the workpiece W is transmitted to, for example, the control means 9 and stored in the RAM. The curve G1 shown in FIG. 5 is a graph showing the thickness change of the workpiece W from the time when the thickness measurement of the workpiece W by the first thickness measuring means 38A shown in FIG. an example of . 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 frame body 301 is measured by the first thickness measuring device 381 , and the front protection attached to the front surface Wa of the workpiece W is measured by the second thickness measuring device 382 . The height position of the member T, the difference between the two measured values is calculated as the thickness of the workpiece W. Then, information on the calculated thickness of the workpiece W is transmitted to, for example, the control means 9 and stored in the RAM. The curve G2 shown in FIG. 5 shows an example of the thickness change diagram of the workpiece W from the time when the thickness measurement of the workpiece W by the first thickness measuring means 38A shown in FIG. .

Since the back surface Wb of the workpiece W is silicon having a certain degree of hardness, when the thickness of the workpiece W is measured by the first thickness measuring means 38A in FIG. small amount. As a result of this, the thickness of the workpiece W indicated by the difference between the measurement value of the first thickness measuring device 381 and the measurement value of the second thickness measuring device 382 is, as shown in FIG. There is almost no difference between the thickness M1 of the workpiece W and the thickness M2 of the workpiece W from the time when the thickness measurement of the workpiece W is started until an arbitrary time t1 elapses. On the other hand, since the front protection 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 Subsidence to the front protection member T is large. As a result of this, the thickness of the workpiece W indicated by the difference between the measurement value of the first thickness measuring device 381 and the measurement value 2 of the second thickness measuring device 382 is compared with the curve G1 as shown in the curve G2 in FIG. 5 . 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 from the start of the measurement of the thickness of the workpiece W to an arbitrary time t1 have a certain degree of difference.

The control means 9 includes, for example, a calculation means 90 as shown in FIG. 1 . The calculation means calculates the amount of change from the first thickness data measured by the first thickness measurement means 38A and the time point when the first thickness data is measured to the second thickness data measured after an arbitrary time has elapsed. In the thickness measurement 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 in FIG. 5 , and the second thickness data is the curve The thickness M2 of the workpiece W at the time point from the start of the measurement to the elapse of an arbitrary time t1 indicated by G1. Then, the calculation means 90 calculates the difference ( M1 - M2 ) between the thickness M1 of the workpiece W and the thickness M2 of the workpiece W as a variation (difference) of the thickness of the workpiece W, for example. 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 the measurement shown by the curve G2, and the second thickness data is, as shown by the curve G2 The thickness M3 of the workpiece W at the time point from the start of the measurement to the elapse of an arbitrary time t1. Then, the calculation means 90 calculates, for example, 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 in the thickness of the workpiece W (difference).

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 gauge 382 contacts is the back surface Wb of the workpiece W where the sinking of the second thickness gauge 382 is unlikely to occur. In other words, it is the back surface Wb for judging whether the surface of the workpiece W on the opposite side from the surface held by the chuck table 30 is the surface to be ground. 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 (a difference amount in this embodiment) exceeds the threshold value Mc or is equal to or less than the threshold value Mc. Furthermore, depending on the type of the workpiece W and the type of the front protection member T, the pre-registered threshold value Mc corresponds to the workpiece W due to the difference in the sinking amount of the second thickness gauge 382 to the back surface Wb or the front protection member T of the workpiece W. The values of the back surface Wb and the type of the front protection member T are selected based on experiments, experience or theory.

In the case shown in FIG. 3 , as shown by the curve G1 in FIG. 5 , since the amount of change ( M1 - M2 ) is smaller than the threshold value Mc, the control means 9 can also determine the size of the workpiece W that the second thickness measuring device 382 is in contact with. The surface is the back surface Wb of the workpiece W where the sinking of the second thickness gauge 382 is unlikely to occur. That is, it is determined that the workpiece W is sucked and held by the chuck table 30 in a correct state, and grinding can be started as it is. In the case shown in FIG. 4 , as shown by the curve G2 in FIG. 5 , since the amount of change ( M1 - M3 ) is a value exceeding the threshold value Mc, the control means 9 judges that the surface of the workpiece W that the second thickness measuring device 382 is in contact with is an occurrence The sunk front holding member T of the second thickness measuring device 382, that is, it is judged that the workpiece W is sucked and held by the chuck table 30 in an incorrect state, and grinding cannot be started as it is.

When the control means 9 judges that the grinding cannot be started, under the control of the control means 9, the transition to the grinding step described later in the grinding device 3 is stopped, and grinding of the workpiece W is not started. Furthermore, the control means 9 notifies the operator of the judgment by sounding an alarm sound from the speaker or displaying an error on the screen. For example, the workpiece W is adjusted so that the back surface Wb is exposed upward on the holding surface 300a of the chuck table 30 or the workpiece W is removed from the chuck table 30 by manual operation of the operator notified of the judgment.

The thickness measurement step is not limited to the above-described embodiment, and may be implemented, for example, as described below (the following are other embodiments of the thickness measurement step). In another embodiment of the thickness measurement step, as shown in FIG. 3 , the amount of change calculated by the calculation means 90 is the inclination (differential amount of the tangent line L1 of the curve G1 at an arbitrary time point t2 in the measurement time) ). That is, the calculating means 90 calculates the first thickness data measured by the first thickness measuring means 38A after the start of the thickness measurement, and the time when the first thickness is measured until an arbitrary time has elapsed (only a short time has elapsed). After) the difference value of the measured second thickness data, and further calculate the change amount (inclination of the tangent L1) by differentiating the calculated difference value. Furthermore, when the change amount is not the inclination of the tangent line L1, it may be at any two time points within the thickness measurement time (for example, when the measurement starts and when the time t1 elapses, or when the time t2 elapses and when the time t1 elapses). the slope of the curve G1. Similarly, in the case shown in FIG. 4 , the amount of change calculated by the calculation means 90 is the inclination (differential amount) of the tangent line L2 of the curve G2 at an arbitrary time point t2 within the measurement time. That is, the calculating means 90 calculates the first thickness data measured by the first thickness measuring means 38A after the start of the thickness measurement, and the time when the first thickness is measured until an arbitrary time has elapsed (only a short time has elapsed). After) the difference value of the measured second thickness data, and further calculate the change amount (the inclination of the tangent L2) by differentiating the calculated difference value. Furthermore, when the change amount is not the inclination of the tangent line L2, it may be at any two time points within the thickness measurement time (for example, when the measurement starts and when the time t1 elapses, or when the time t2 elapses and when the time t1 elapses). the slope of the curve G2.

The threshold value registered in the ROM of the control means 9 is used to judge whether or not the surface of the workpiece W that the second thickness gauge 382 comes into contact with is the back surface Wb of the workpiece W where the sinking of the second thickness gauge 382 is unlikely to occur, in other words, it is It is used to judge whether or not the surface of the workpiece W on the opposite side from the surface held by the chuck table 30 is the back surface Wb of the surface to be ground. Then, the control means 9 judges that the amount of change (in other embodiments, the differential amount) calculated by the calculation means 90 exceeds the threshold value or is equal to or less than the threshold value.

In the case shown in FIG. 3 , if the inclination (change amount) of the tangent line L1 of the curve G1 in FIG. 5 is smaller than the registered threshold value, for example, the control means 9 may determine the surface of the workpiece W that the second thickness measuring device 382 is in contact with The back surface Wb of the workpiece W in which the sinking of the second thickness gauge 382 is unlikely to occur, that is, it is judged that the workpiece W is sucked and held by the chuck table 30 in a correct state, and grinding can be started. In the case shown in FIG. 4 , when the inclination (change amount) of the tangent line L2 of the curve G2 in FIG. 5 exceeds, for example, a registered threshold value, the control means 9 determines that the surface of the workpiece W with which the second thickness measuring device 382 comes into contact is The front holding member T of the second thickness measuring device 382 , that is, it is judged that the workpiece W is sucked and held by the chuck table 30 in an incorrect state, and grinding cannot be started.

(4) Grinding Step The thickness measurement step as described above is carried out. 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. 3 , it is determined that the workpiece is a workpiece. This grinding step is carried out when the chuck table 30 is sucked and held in a correct state. As shown in FIG. 1 , the rotary table 34 rotates clockwise when viewed 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, and aligning the grinding wheel 313 with the workpiece W . As an example of alignment, as shown in FIG. 6 , the alignment is performed to deviate the rotation center of the grinding wheel 313 with respect to the rotation center of the workpiece W by a predetermined distance in the +X direction, and to pass the rotational orbit of the rough grinding stone 313 through the workpiece W the center of rotation.

When the rotary shaft 310 is driven to rotate, the grinding wheel 313 is rotated along with it. The rough grinding means 31 is conveyed in the −Z direction by the first grinding feeding means 35 shown in FIG. In addition, since the rotation of the chuck table 30 is accompanied by the rotation of the workpiece W held on the holding surface 300a, the entire surface of the back surface Wb of the workpiece W is ground. In addition, grinding water is supplied to the contact portion of the rough grinding grindstone 313a and the workpiece W through a flow path not shown in the rotating shaft 310, and the contact portion is cooled and cleaned. In addition, 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 thickness of the workpiece W is controlled to have a desired thickness (eg, the thickness before the finished thickness).

The workpiece W before the finished thickness is ground by rough grinding, and then ground to the finished thickness. After the rough grinding means 31 shown in FIG. 1 is separated from the workpiece W, the turntable 34 rotates clockwise as viewed in the +Z direction, whereby the chuck table 30 moves below the fine grinding means 32 . Then, after the grinding wheel 313 included in the fine grinding means 32 is aligned with the workpiece W, the fine grinding means 32 is conveyed in the −Z direction, the rotating fine grinding stone 323 a abuts 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. Moreover, grinding water is supplied to the contact part of the finish grinding stone 323a and the workpiece W, and the contact part is cooled and cleaned. In addition, 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 thickness of 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 turntable 34 rotates clockwise as viewed in the +Z direction, and the workpiece W1 with high flatness ground to the back surface Wb of the finished thickness is thereby moved to the vicinity of the second conveying means 336 . Then, the second conveyance means 336 conveys the workpiece W on the chuck table 30 to the cleaning means 334 . Then, after the workpiece W is cleaned by the cleaning means 334 , the workpiece W is accommodated in the second cassette 332 by the robot arm 330 .

The grinding method of the present invention as described above includes: a front protection step of covering the front surface of the workpiece with a front protection member; and a holding step of holding the workpiece W by the holding surface 300a of the chuck table 30 after the front protection step is performed. It can be rotated around the rotating shaft 30b whose axial direction is the vertical direction; in the thickness measurement step, after the holding step is implemented, the second thickness measuring device 382 is brought into contact with the workpiece W and the surface on the opposite side of the surface held by the chuck table 30 , and measure the thickness of the workpiece W, from the first thickness data measured, and the time point when the first thickness data was measured to the second thickness data measured after an arbitrary time, calculate the amount of change; and the grinding step , after the thickness measurement step is performed, the back surface Wb of the workpiece W is ground while supplying grinding water by the rough grinding grindstone 313a rotated by the rotating shaft 310 orthogonal to the holding surface 300a; in the thickness measurement step, the calculated change If the amount is less than or equal to the pre-registered threshold value, the surface of the workpiece W that the second thickness gauge 382 contacts is judged to be the back surface Wb of the workpiece W where the sinking of the second thickness gauge 382 is unlikely to occur, and the grinding step is started to calculate If the amount of change exceeds the pre-registered threshold value, it is determined that the surface of the workpiece W that the second thickness gauge 382 comes into contact with is the front protection member T where the sinking of the second thickness gauge 382 is likely to occur, and the grinding step is not started. Therefore, when the workpiece W is sucked and held by the chuck table 30 in a wrong state, that is, when the back surface Wb of the ground surface of the workpiece W is sucked by the chuck table 30, the current state is not implemented. In the grinding step, the front protection member T is ground and a grinding defect occurs.

As described above, the grinding device 3 of the present invention is provided with the calculating means 90 for measuring from the first thickness data measured by the first thickness measuring means 38A and the time when the first thickness data is measured to an arbitrary time elapsed. and the control means 9 starts grinding if the change amount calculated by the calculation means 90 is below the pre-registered threshold value, and when the change amount exceeds the pre-registered threshold value In the case of , it indicates an error and does not start grinding; thereby, when the workpiece W is attracted and held on the chuck table 30 in a wrong state, that is, when the back surface Wb of the ground surface of the workpiece W is on the chuck table 30 Even in the case of adsorption by 30, the front protection member T is not ground by the rough grinding means 31 as it is, and grinding failure occurs.

The first thickness measuring means 38A of the grinding device 3 is used to measure the thickness of the workpiece W before the start of grinding, and also to control the thickness of the workpiece W after the start of grinding, so that the grinding device 3 can be reduced in size. , and 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 accompanying drawings is not limited to this, and can be appropriately changed within the scope of the effect of the present invention. . For example, the grinding device 3 is not limited to a two-axis grinding device as the grinding means in the present embodiment, and the grinding means may be a one-axis grinding device. In addition, for example, the first thickness measurement means 38A is not limited to the configuration including the first thickness measurement 381 and the second thickness measurement device 382 as in the present embodiment. For example, the thickness of the workpiece W may be measured by one thickness measurement device. , which includes a second thickness measuring device 382 , a tray holding the second thickness measuring device 382 movably in the vertical direction, and a displacement detection means for measuring the position of the tray.

W‧‧‧Workpiece Wa‧‧‧Front surface of workpiece Wb‧‧‧Back surface of workpiece T‧‧‧Front protection member 3‧‧‧Grinding device 3A‧‧‧Base 3B, 3C‧‧‧Column 30‧‧‧Chuck Table 300‧‧‧Suction part 300a‧‧‧Holding surface 301‧‧‧Frame body 31‧‧‧Rough grinding means 310‧‧‧Rotating shaft 311‧‧‧Enclosure 312‧‧‧Motor 313‧‧‧Grinding wheel 313a‧ ‧‧Rough Grinding Grinding Stone 32‧‧‧Fine Grinding Means 323a‧‧‧Fine Grinding Grinding Stone 330‧‧‧Robot Arm 331‧‧‧First Cartridge 332‧‧‧Second Cartridge 333‧‧‧Aligning Means 334‧‧‧Cleaning Means 335‧‧‧First Conveying Means 336‧‧‧Second Conveying Means 34‧‧‧Rotary Tables 35‧‧‧First Grinding Feeding Means 350‧‧‧Ball Screws 351‧‧‧Guideways 352 ‧‧‧Motor 353‧‧‧Elevating part 36‧‧‧Second grinding feed means 360‧‧‧Ball screw 361‧‧‧Guide 362‧‧‧Motor 363‧‧‧Elevating part 38A‧‧‧First thickness measurement Means 381‧‧‧First Thickness Measuring Device 382‧‧‧Second Thickness Measuring Device 38B‧‧‧Second Thickness Measuring Means 9‧‧‧Control Means 90‧‧‧Calculating Means

FIG. 1 is a perspective view showing an example of a grinding apparatus. FIG. 2 is a perspective view showing a state in which the front surface of the workpiece is covered with a front protection member. 3 is a cross-sectional view showing a state in which the second thickness measuring instrument is brought into contact with the back surface opposite to the front side of the sticking front protection member held by the chuck table of the workpiece, and the thickness of the workpiece is measured. 4 is a cross-sectional view showing a state where the second thickness measuring device is brought into contact with the front surface protection member attached to the front surface opposite to the back surface held by the chuck table, and the thickness of the workpiece is measured. 5 is a diagram showing a change in the thickness of the workpiece when the second thickness measuring device is brought into contact with the back surface and the thickness of the workpiece is measured, and the thickness of the workpiece when the second thickness measuring device is brought into contact with the front protection member and the thickness of the workpiece is measured. Graph of thickness change. 6 is a cross-sectional view showing a state in which the thickness of the workpiece is controlled and rough grinding is performed by rough grinding means.

G1‧‧‧curve

G2‧‧‧curve

L1‧‧‧Tangent

L2‧‧‧Tangent

M1‧‧‧Thickness

M2‧‧‧Thickness

M3‧‧‧Thickness

Mc‧‧‧Threshold

t1‧‧‧any time

t2‧‧‧any time

Claims (4)

A method for grinding a workpiece, wherein a grinding stone is used to grind a back surface of a workpiece, the workpiece having a front surface forming an element in an area divided by a plurality of predetermined dividing lines forming a lattice shape, and the grinding method of the workpiece includes: a front surface protection step, to The front protection member covers the front surface of the workpiece to form a protected workpiece; in the holding step, after the front protection step is performed, the protected workpiece is held by the holding surface of the chuck table, and the chuck table can revolve around the axis The rotation axis is rotated in the vertical direction; in the thickness measurement step, after the holding step is implemented, the thickness measuring device is brought into contact with the surface on the opposite side of the protected workpiece and the surface held by the chuck table, and the thickness of the workpiece is measured. The first thickness data combined with the thickness of the front protection member covering the front surface of the workpiece, from the measurement of the first thickness data and the time when the first thickness data is measured to an arbitrary time after the elapse of time The obtained second thickness data of the thickness of the workpiece and the thickness of the front protection member covering the front surface of the workpiece are combined, and the amount of change is calculated; A grinding stone rotated by a rotating shaft whose plane is perpendicular to the surface grinds the back surface of the workpiece while supplying grinding water; in the thickness measurement step, if the calculated variation is less than or equal to a pre-registered threshold value, the thickness measurement is determined. The surface on the opposite side of the protected workpiece contacted by the measuring device is the back surface of the workpiece where the sinking of the thickness measuring device is difficult to occur, and the grinding step is started, and the calculated change is beyond the pre-registered If the threshold value is 0, it is judged that the surface on the opposite side of the protected workpiece with which the thickness gauge is in contact is the front protection member where sinking of the thickness gauge is likely to occur, and the grinding step is not started. The grinding method of claim 1, wherein the front protection member is an adhesive film. A grinding apparatus including a chuck table holding a workpiece, thickness measuring means for measuring the thickness of the workpiece held on the chuck table, and grinding means for grinding the workpiece held on the chuck table, the grinding apparatus is characterized by: : The chuck table can be rotated around the vertical axis of rotation, and is held by the holding surface On the protected workpiece formed by pasting the front protection member to the workpiece, the thickness measuring means makes the thickness measuring device contact the surface of the protected workpiece opposite to the surface held by the chuck table before the grinding of the protected workpiece starts. the side surface, and implement thickness measurement; the grinding means uses a grinding stone rotated by a rotating shaft orthogonal to the holding surface of the chuck table to grind the back of the workpiece while supplying grinding water; the grinding device is provided with: Calculation means, before grinding starts, from the first thickness data combined with the thickness of the workpiece measured by the thickness measurement means and the thickness of the front protection member covering the front surface of the workpiece, and the measured first thickness From the time point of the data to the second thickness data obtained by combining the thickness of the workpiece and the thickness of the front protection member covering the front surface of the workpiece, measured after any time has elapsed, and calculating the amount of change; and the control means, in the If the amount of change calculated by the calculation means is less than or equal to a pre-registered threshold value, grinding is started, and when the amount of change exceeds the pre-registered threshold value, an error is indicated and grinding is not started. The grinding device according to claim 3, wherein the thickness measuring means is a thickness obtained by combining the thickness of the workpiece before the start of grinding and the thickness of the front protection member covering the front surface of the workpiece. Simultaneously with the measurement, it is also used for thickness control of the workpiece after grinding has started.

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