TW202402460A - Grinding method for workpiece including a rough grinding step, a fine grinding step, and a grinding correction step - Google Patents

Abstract

The present invention provides a workpiece grinding method that can unify a grinding time period into a fixed and short time period. A grinding method for deep-feed grinding of the workpiece with a slow speed includes: a rough grinding step, a fine grinding step, and a grinding correction step. The rough grinding step includes positioning a lower surface of a first grinding stone at a first distance lower than an upper surface of the workpiece and causing a first disk table to move horizontally relative to the first grinding stone, thereby grinding the upper surface of the workpiece. The fine grinding step includes positioning a lower surface of a second grinding stone at a second distance lower than the upper surface of the workpiece and causing a second disk table to move horizontally relative to the second grinding stone, thereby grinding the upper surface of the workpiece. The grinding correction step includes grinding the thickness of the workpiece to a predetermined thickness before the fine grinding step begins.

Description

Grinding method of workpiece

The invention relates to a grinding method for grinding a workpiece into a predetermined thickness with deep feed.

As a packaging technology for integrating and miniaturizing components used in various electronic devices, there is a known technology in which a wafer on which components are formed is placed on a substrate, a Cu electrode is formed on the wafer, and the wafer is sealed with resin. After the wafer and the Cu electrode are connected to protect the element from impact, moisture, etc., the resin is ground to expose the Cu electrode, and the resin is further ground to obtain a workpiece of the desired thickness.

Then, as a grinding method for grinding a workpiece equipped with a Cu electrode to a predetermined thickness, there is a method in which a ring-shaped grinding stone is placed on the lower surface of a rotating grindstone that attracts and holds the workpiece with a chuck table. In a state where the workpiece is lowered only a predetermined distance from the upper surface of the workpiece, the workpiece and the grindstone are relatively moved horizontally to perform deep creep grinding of the upper surface of the workpiece (for example, refer to patent documents 1, 2).

In the above-mentioned deep feed grinding, the grindstone is lowered by only 100 μm, for example, and the grindstone is horizontally moved relative to the workpiece to perform rough grinding until the Cu electrode is about to be exposed. The rough grinding is The action of grinding the front side of the workpiece is only repeated a preset number of times. Then, after the rough grinding, the grindstone is lowered by only 10 μm, for example, and the grindstone is horizontally moved relative to the workpiece to perform finish grinding. The finish grinding is an action of repeatedly grinding the front surface of the workpiece. Until the thickness of the workpiece reaches the preset thickness.

That is, in rough grinding, the action of grinding the upper surface of the workpiece, for example, 100 μm, is repeated only a preset number of times. In fine grinding, the action of grinding the upper surface of the workpiece, for example, 10 μm, is repeated each time until the workpiece is The operation of grinding the upper surface of the workpiece is repeated until the thickness reaches the preset thickness. [Known technical documents] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2019-084646 [Patent Document 2] Japanese Patent Application Publication No. 2020-171977

[Problem to be solved by the invention] In the current deep-feed grinding of the workpiece, since the rough grinding of the workpiece is only performed a preset number of times, the thickness of the rough-ground workpiece is not fixed, and the time required for subsequent fine grinding will vary. It varies according to the thickness of the workpiece after rough grinding. That is, since the upper surface of the workpiece is ground by, for example, 10 μm each time in fine grinding, if the thickness of the workpiece after rough grinding is thicker, the time required for fine grinding may become longer, which may affect the next step. problem.

Therefore, an object of the present invention is to provide a grinding method that can unify the grinding time into a fixed and short workpiece.

[Technical means to solve the problem] According to the present invention, there is provided a method for grinding a workpiece, in which the lower surface of a grindstone is positioned lower than the upper surface of the workpiece on the outside of the workpiece held on a chuck table, so that the chuck The disc table moves horizontally relative to the grindstone to grind the upper surface of the workpiece, and is provided with: a rough grinding step that positions the lower surface of the first grindstone a first lower surface than the upper surface of the workpiece. distance and make the chuck table move horizontally relative to the first grinding stone, thereby grinding the upper surface of the workpiece; the correction grinding step is to change the thickness of the workpiece after performing the rough grinding step Grinding to a predetermined thickness; and a fine grinding step, which after implementing the corrective grinding step, positions the lower surface of the second grinding stone at a second distance lower than the upper surface of the workpiece and makes the chuck table and The second grindstone moves relatively horizontally to grind the upper surface of the workpiece.

[Invention effect] According to the present invention, since the workpiece that has been roughly ground in the rough grinding step is corrected and ground in the next corrective grinding step so that its thickness becomes a preset predetermined thickness, all the workpieces are processed. The thickness of the workpiece before fine grinding becomes a preset thickness and becomes fixed. Therefore, the time required for fine grinding of the workpiece in the next fine grinding step is unified to a fixed and short time, and an effect is obtained that the entire workpiece can be ground to a predetermined thickness in a fixed short time.

Hereinafter, embodiments of the present invention will be described based on the drawings.

First, the structure of a grinding device for implementing the grinding method of a workpiece (workpiece) according to the present invention will be described based on FIGS. 1 and 2 . In addition, in the following description, the arrow directions shown in FIG. 1 are respectively referred to as the X-axis direction (left-right direction), the Y-axis direction (front-back direction), and the Z-axis direction (up-down direction).

The grinding device 1 shown in Figure 1 is a device for deep-feed grinding a rectangular plate-shaped workpiece W (see Figures 5 and 6), and has the following elements as its main components: a first processing unit U1, which performs rough grinding of the workpiece W; the second processing unit U2, which performs fine grinding of the workpiece W that has been roughly ground by the first processing unit U1; and the first thickness measuring device 5, whose measurement has been The thickness and upper surface height of the workpiece W that has been roughly ground by the first processing unit U1; the second thickness measuring device 6, which measures the thickness of the workpiece W that has been finely ground by the second processing unit U2; the temporary holding part 40, It temporarily places the workpiece W in advance; the workpiece conveying means 20 transports the workpiece W between the temporary holding part 40 and the first processing unit U1 and the second processing unit U2 (see FIG. 2 ); cleaning Means 50 for cleaning the workpiece W that has been finely ground by the second processing unit U2; robot 60 for conveying between the first cassette 7 and the alignment table 9 and between the cleaning means 50 and the second cassette 8 The workpiece W; and the controller 70 that controls the grinding operation of the grinding device 1 .

Here, as shown in FIG. 7( a ), the workpiece W before grinding has a rectangular plate-shaped support substrate W1 made of resin such as a PCB and a plurality of wafers C arranged on the support substrate W1 . Elements (not shown) are formed on the front surface of each wafer C. Furthermore, a plurality of Cu electrodes P are protrudingly provided on the front surface of each element, and these wafers C and Cu electrodes P are sealed with resin F such as epoxy resin. In addition, each wafer C uses silicon, gallium arsenide, sapphire, etc. as a base material.

Next, the structure of the main components of the grinding device 1 will be described respectively. The main components are the first processing unit U1 and the second processing unit U2, the first thickness measuring device 5 and the second thickness measuring device 6, and the temporary storage unit. part 40, workpiece conveying means 20, cleaning means 50, robot 60 and controller 70.

As shown in Figure 1, the first processing unit U1 for rough grinding the workpiece W and the second processing unit U2 for fine grinding the workpiece W are arranged side by side on the base of the device along the X-axis direction (left-right direction). On the base 2, the basic structures of the first processing unit U1 and the second processing unit U2 are the same, so the following description will focus on the structure of the first processing unit U1.

The first processing unit U1 is composed of a first chuck table 3, a rough grinding means 10 as a first processing means, and a first moving mechanism (not shown) that reciprocates the first chuck table 3 in the Y-axis direction. Here, the structure of the first chuck table 3, the rough grinding means 10, and the first moving mechanism (not shown) constituting the first processing unit U1 will be described below.

The first chuck table 3 is a disk-shaped member and can move back and forth along the Y-axis direction by a first moving mechanism (not shown). A circular holding surface 3a for attracting and holding the workpiece W is formed on the upper surface of the first chuck table 3. In addition, the holding surface 3a is connected to an attraction source (not shown).

The rough grinding means 10 includes: a spindle motor 12 fixed to the holder 11; a vertical spindle 13 that is rotationally driven by the spindle motor 12; a disc-shaped mounting piece 14 mounted on the lower end of the spindle 13; and grinding The wheel 15 is removably mounted on the lower surface of the mounting member 14 . Here, a plurality of first grindstones 16 arranged in an annular shape are attached to the grinding wheel 15 .

Then, the rough grinding means 10 is supported by the lifting mechanism 30 so as to be able to move up and down. The lifting mechanism 30 is provided on the -Y-axis direction end surface (front surface) of the block-shaped cylinder 4, and the block-shaped cylinder 4 is vertically It is erected at the end (rear end) of the device base 2 in the +Y-axis direction.

The above-mentioned lifting mechanism 30 is a mechanism for lifting and lowering the rough grinding means 10 along the Z-axis direction (up and down direction), and includes a rectangular plate-shaped lifting plate 31 and a pair of left and right guide rails 32 for guiding the lifting movement of the lifting plate 31 . Here, the rough grinding means 10 is attached to the lifting plate 31 . In addition, a pair of left and right guide rails 32 are arranged perpendicularly and parallel to each other on the -Y-axis direction end surface (front surface) of the column 4 .

Then, between the pair of left and right guide rails 32, a rotatable ball screw shaft 33 is arranged vertically along the Z-axis direction (up and down direction). The upper end of the ball screw shaft 33 is connected to the driving source, that is, an electric motor that can forward and reverse. Motor 34 links. In addition, the lower end of the ball screw shaft 33 is rotatably supported by the column 4 via a bearing (not shown). The ball screw shaft 33 is horizontally protruded toward the rear (+Y-axis direction) on the back of the lift plate 31 . The nut member (not shown) is screwed together.

Therefore, when the electric motor 34 of the lifting mechanism 30 configured as above is activated to cause the ball screw shaft 33 to rotate forward and reverse, the lifting plate 31 protrudes with a nut member (not shown) screwed to the ball screw shaft 33 . It moves up and down along the pair of left and right guide rails 32, so the rough grinding means 10 installed on the lifting plate 31 also moves up and down along the Z-axis direction (up and down direction).

The first moving mechanism not shown in the figure is a mechanism that reciprocates the first chuck table 3 and the workpiece W held therein along the Y-axis direction, and is configured by a conventional mechanism disposed in the device base 3 It is composed of ball screw mechanism, etc. Therefore, further description and drawings of the first moving mechanism are omitted.

In addition, although the second processing unit U2 is provided with the second chuck table 3', the second processing means, that is, the finishing means 10', and the second moving mechanism not shown, the second chuck table 3' and the second moving mechanism The structure of the mechanism is the same as the structure of the first chuck table 3 and the first moving mechanism of the first processing unit U1, so the description thereof is omitted.

Here, a circular holding surface 3a' for attracting and holding the workpiece W is formed on the upper surface of the second chuck table 3' of the second processing unit U2.

Moreover, the fine grinding means 10' is equipped with the same as the rough grinding means 10: a spindle motor 12', which is fixed to the holder 11'; a vertical spindle 13', which is rotationally driven by the spindle motor 12'; a disc-shaped The mounting piece 14' is mounted on the lower end of the spindle 13'; and the grinding wheel 15' is detachably mounted on the lower surface of the mounting piece 14'. Here, although a plurality of second grindstones 16' arranged in an annular shape are installed on the grinding wheel 15', these second grindstones 16' are produced by using a grinding wheel that is more precise than the first grindstone 16 of the rough grinding means 10. Made of fine abrasive grains. Moreover, the second machining unit U2 is also provided with a lifting mechanism 30 for the fine grinding means 10'. This lifting mechanism 30 is the same as the lifting mechanism 30 that lifts and lowers the rough grinding means 10, so the same reference numerals are attached to these parts, and further description is omitted.

The first thickness measuring device 5 serves as both a thickness measuring device for measuring the thickness of the workpiece W rough ground by the rough grinding means 10 and a surface height measuring device for measuring the height of the upper surface of the workpiece W, and is measured by a height gauge. constituted. Specifically, this first thickness measuring instrument 5 includes a first contactor 5a that is in contact with the upper surface of the workpiece W held on the first chuck table 3, and a first contactor 5a that is in contact with the upper surface of the outer peripheral portion of the first chuck table 3. If the first thickness measuring device 5 is used to contact the second contactor 5b, the upper surface height of the workpiece W is measured through the first contactor 5a, and from the height of the workpiece W measured through the first contactor 5a The thickness of the workpiece W during rough grinding is obtained by subtracting the upper surface height of the outer peripheral portion of the first chuck table 3 measured by the second contactor 5b from the upper surface height of the workpiece W.

The second thickness measuring device 6 measures the thickness of the workpiece W finely ground by the fine grinding means 10', and is composed of a height gauge like the first thickness measuring device 5. Specifically, this second thickness measuring instrument 6 includes a first contactor 6a that is in contact with the upper surface of the workpiece W held on the second chuck table 3' and an outer peripheral portion of the second chuck table 3'. If the second contactor 6b is in contact with the upper surface and the second thickness measuring device 6 is used, the height measured by the second contactor 6b is subtracted from the height of the upper surface of the workpiece W measured by the first contactor 6a. The thickness of the workpiece W during fine grinding is determined by measuring the height of the upper surface of the outer peripheral portion of the second chuck table 3'.

The temporary holding unit 40 temporarily holds the workpiece W that has been roughly ground by the rough grinding unit 10 of the first processing unit U1 in order to transfer the workpiece W that has been roughly ground by the rough grinding unit 10 to the second processing unit U2. W, as shown in FIG. 1 , is arranged between the first processing unit U1 and the second processing unit U2 and the first cassette 7 and the second cassette 8 on the device base 2 in the Y-axis direction.

This temporary unit 40 is provided with a temporary workbench 43 on a horizontal temporary stand 41. The temporary workbench 43 can move in the X-axis direction along the guide plate 42 laid along the X-axis direction. Here, the temporary workbench is A circular holding surface 43a for attracting and holding the workpiece W is formed on the upper surface of the workpiece 43. In addition, although not shown in the figure, the temporary setting part 40 is provided with a moving mechanism that moves the temporary setting table 43 along the guide plate 42 in the X-axis direction.

The workpiece conveyance means 20 shown in Fig. 2 are respectively arranged in the spaces S1 and S2 shown by dotted lines in Fig. 1, and both have the same structure.

This workpiece conveying means 20 holds the workpiece W and conveys it to a predetermined position, and is equipped with a pair of rectangular plate-shaped conveyance pads 21 that attract and hold the workpiece W as shown in FIG. 2 . Here, a pair of conveying pads 21 are mounted parallel to each other on a reversing mechanism 22 that intermittently rotates 180°. The reversing mechanism 22 is mounted on a rotating shaft 24 extending horizontally from a block-shaped lifting block 23b. Front end. In addition, a plurality of suction cups 25 are attached to the suction surface of each transfer pad 21 .

Then, the transfer pad 21 can move in the Y-axis direction (front-rear direction) by the Y-axis moving mechanism 20A, and can move up and down in the Z-axis direction by the Z-axis moving mechanism 20B. Here, the Y-axis moving mechanism 20A is provided with: a pair of upper and lower guide rails 22a, which are arranged parallel to each other along the Y-axis direction on the side surface of the bottom plate 21a; and a slider 23a, which can move in the Y-axis direction along these guide rails 22a. A rotatable ball screw shaft 24a extending in the Y-axis direction is disposed between the pair of guide rails 22a.

One axial end of the ball screw shaft 24a is connected to the electric motor 25a which is a driving source, and the other axial end of the ball screw shaft 24a is rotatably supported by the base plate 21a via a bearing 26a. Then, the ball screw shaft 24a is screwed and inserted into the rectangular block-shaped slider 23a.

The Z-axis moving mechanism 20B is provided with: a guide rail 22b that is vertically installed along the Z-axis direction on a base plate 21b that is installed on the side of the slider 23a; and a lifting block 23b that moves along the Z-axis direction along the guide rail 22b. Lifting and lowering movement in the axis direction. Then, the first conveying pad 21 is supported by the reversing mechanism 22 at the front end. The aforementioned rotating shaft 24 extends horizontally from the lifting block 23b along the + Rotatable ball screw shaft 24b. Here, the upper end of the ball screw shaft 24b is connected to the electric motor 25b that is a rotation drive source, and the lower end of the ball screw shaft 24b is rotatably supported by the base plate 21b via a bearing 26b.

Therefore, if the electric motor 25a of the Y-axis moving mechanism 20A is started to cause the ball screw shaft 24a to rotate forward and reverse, the slider 23a screwed with the ball screw shaft 24a will move along the guide rail 22a along the Y-axis with the Z-axis moving mechanism 20B. If the electric motor 25b of the Z-axis moving mechanism 20B is started to cause the ball screw shaft 24b to move forward and reverse, the lifting block 23b screwed with the ball screw shaft 24b will move up and down along the Z-axis direction. Therefore, through the rotating shaft 24 The transfer pad 21 supported by the lift block 23b in conjunction with the reversal mechanism 22 can move in the Y-axis direction and can move up and down in the Z-axis direction.

In addition, although not shown in the figures, the grinding device 1 of this embodiment is provided with grinding water supply means that supplies the machining fluid, that is, grinding water, to the first portion of the rough grinding means 10 during the grinding process. The grinding stone 16 has a second grinding stone 16' with a fine grinding means 10'. This grinding water supply means supplies the grinding water to the grinding wheels 15 and 15' respectively through the axis centers of the spindle motors 12, 12' and the spindles 13, 13' of the rough grinding means 10 and the fine grinding means 10'. The contact surfaces between the first grindstone 16 and the second grindstone 16' and the workpiece W are respectively cooled by grinding water. Here, pure water is preferably used as the grinding water.

The cleaning means 50 cleans the workpiece W that has been finely ground by the finishing means 10' of the second processing unit U2 with washing water, and is arranged below the temporary holding portion 40 in the Y-axis direction as shown in FIG. 1 . This cleaning means 50 is equipped with: a rotating table 51 that attracts and holds the finely ground workpiece W on the upper surface and rotates around a vertical central axis at a predetermined speed; and a cleaning water nozzle 52 whose direction is maintained on the upper surface. The workpiece W of the turntable 51 is sprayed with cleaning water. In addition, it is better to use pure water as the cleaning water.

The robot 60 is a multi-jointed robot and has the following functions: taking out the processed object W contained in the first cassette 7 before grinding and transporting it to the alignment table 9 , and cleaning the object W in the cleaning means 50 . The processed product W is transported to the second cassette 8 and accommodated in the second cassette 8 .

In this robot 60, the robot hand 61 for sucking and holding the workpiece W is detachably attached to the mounting part 62. Furthermore, the robot 60 here is provided with a horizontal movement mechanism 63 that moves the robot hand 61 in the horizontal direction, and a lifting mechanism 64 that moves the robot hand 61 up and down. Here, the horizontal movement mechanism 63 includes a bendable first arm 63a and a second arm 63b, and one end of the first arm 63a is connected to the lifting mechanism 64.

The controller 70 shown in Figure 1 is equipped with: a CPU (Central Processing Unit, central processing unit) that performs calculation processing according to the control program, a ROM (Read Only Memory, read-only memory), and a RAM (Random Access Memory, random access memory). memory) and other memory, etc. As will be described later, the controller 70 controls the grinding device in such a manner that the workpiece W is ground to a predetermined thickness through rough grinding by the first machining unit U1 and fine grinding by the second machining unit U2. 1 action function, but its details will be described later.

Next, the first embodiment of the grinding method of the workpiece W of the present invention implemented in the grinding device 1 configured as above will be described.

As shown in FIG. 3 , the grinding method of the first embodiment grinds the workpiece W to a predetermined thickness through 1) rough grinding step, 2) corrective grinding step and 3) fine grinding step. However, in the 2) corrective grinding step , perform 2-1) thickness measurement step, 2-2) calculation step and 2-3) thickness correction grinding step in sequence. Each step is explained below.

In the rough grinding step, the robot 60 shown in FIG. 1 takes out a piece of workpiece W before grinding from the first cassette 7 and places it on the alignment table 9 . In this way, the workpiece W is aligned on the positioning table 9, and the aligned workpiece W is attracted and held by the conveying pad 21 of the workpiece conveying means 20 shown in Fig. 2 and is moved to the first processing. The first chuck table 3 of the unit U1 is handed over and is attracted and held by the holding surface 3 a of the first chuck table 3 .

Although the first chuck table 3 that has attracted and held the workpiece W is waiting at the rough grinding start position Y1 shown in Fig. 5(a), at this time, the controller 70 sets the number of rough grinding times n to 0 (n=0 ) as the initial setting (step S1 in Figure 4). Furthermore, the controller 70 drives the lifting mechanism 30 of the first processing unit U1 to position the first grindstone 16 of the rough grinding means 10 on its lower surface from the front of the workpiece W as shown in FIG. Only the first distance (100 μm in this embodiment) is lower (step S2 of FIG. 4 ).

From the above state, the controller 70 starts the spindle motor 12 of the rough grinding means 10 to rotate the first grindstone 16 around its central axis at a predetermined speed, and drives the first moving mechanism (not shown) to move the first grindstone 16 . The chuck table 3, together with the workpiece W held therein, moves at a predetermined speed in the direction of the arrow a from the rough grinding start position Y1 shown in Fig. 5(a) until the rough grinding start position Y1 shown in Fig. 5(b) to the grinding end position Y2. In this way, the front surface of the workpiece W (resin F) is roughly ground to a thickness of only 100 μm by deep creep grinding using the first grindstone 16 (step S3 in FIG. 4 ). Then, when the rough grinding is completed, the first chuck table 3 and the workpiece W are driven by the first moving mechanism (not shown) to move from the rough grinding end position Y2 in the direction of the arrow b in the figure, and return. Rough grinding start position Y1.

As described above, when the upper surface of the workpiece W is roughly ground only to a thickness of 100 μm by one rough grinding operation, the controller 70 counts the number of rough grinding operations n and sets n=1 (step S4 in FIG. 4 ). . In this embodiment, since the number n of rough grinding is set to 3 (that is, only three rough grindings), the controller 70 determines whether the counted number n of rough grinding has reached 3 (step S5). When the counted number of rough grinding n has not reached 3 (step S5: No), the above rough grinding (steps S2 to S5) is repeated.

Then, if the workpiece W is roughly ground three times (step S5 in Fig. 4: Yes), as shown in Fig. 7(a), the front surface of the workpiece W (resin F) is roughly ground by only 300 μm. Although the thickness of the workpiece W reaches t ₁ as shown in the figure, a correction grinding step is subsequently performed. In addition, in this embodiment, the grinding amount of one rough grinding is set to 100 μm and the number of rough grinding n is set to 3, but the grinding amount and the number of rough grinding n can be set to arbitrary values.

As mentioned above, in the thickness correction grinding step, the thickness measurement step, the calculation step and the thickness correction grinding step described below are performed in sequence (see Figure 3).

In the thickness measurement step, the thickness t ₁ of the workpiece W that has been roughly ground in the aforementioned 1) rough grinding step is measured using the first thickness measuring device 5 shown in Figure 1 (see Figure 7(a) ) (Step S6 in Figure 4).

In the calculation step _, the _difference (thickness _difference ) Δt ( =t ₁ −t ₀ ) (see FIG. 7( a )) (step S7 in FIG. 4 ). In addition, the thickness difference calculated by this calculation step is the consumption of the first grindstone 16 .

In the thickness correction grinding step, the first grinding stone 16 is lowered so that the lower surface of the first grinding stone 16 is located just below the thickness difference Δt from the front surface of the roughly ground workpiece W (step S8 in FIG. 4 ), similarly to rough grinding (refer to FIG. 5 ), the first chuck table 3 and the workpiece W are moved in the Y-axis direction by the first moving mechanism (not shown), and the workpiece W is processed by the grinding amount Δt. The front surface of object W (resin F) is ground for thickness correction (step S9 in Figure 4). In this way, as shown in Figure 7(b), although the workpiece W with the predetermined thickness _t0 is obtained, in this state, the Cu electrode P is not exposed from the front surface of the workpiece W, and It is buried inside the resin F.

Here, t is established between the thickness t ₁ of the workpiece W after rough grinding, the grinding amount Δt of the workpiece W in the thickness correction grinding step, and the thickness t ₀ of the workpiece W after thickness correction grinding. ₁ - Δt = t ₀ relationship.

If the workpiece W with a predetermined thickness t ₀ is obtained in the above rough grinding step, the workpiece W is transported by the workpiece conveying means (first workpiece conveying means) 20 shown in FIG. 2 Moving toward the temporary storage portion 40 shown in FIG. 1 , the workpiece conveying means (first workpiece conveying means) 20 shown in FIG. 2 is arranged in the space S1 shown in FIG. 1 . In this way, the workpiece W with a thickness t ₀ that has undergone thickness correction grinding is placed and held on the temporary table 43 of the temporary holding part 40 , and the temporary table 43 holding the workpiece W is It moves in the −X-axis direction along the guide plate 42 by a moving mechanism not shown in the figure.

Next, the workpiece W is conveyed to the second chuck of the second processing unit U2 by the workpiece conveyance means (second workpiece conveyance means) 20 shown in FIG. 2 which is arranged in the space S2 of FIG. 1 The workpiece W is attracted and held by the holding surface 3a' of the second chuck table 3'.

The second chuck table 3', which has attracted and held the workpiece W as described above, is waiting at the finishing start position Y3 shown in Fig. 6(a). However, at this time, the controller 70 drives the lifting and lowering of the second processing unit U2. Mechanism 30, and as shown in FIG. 6(a), the second grindstone 16' of the fine grinding means 10' is positioned on its lower surface only a second distance lower than the front surface of the workpiece W (in this embodiment is 10 μm) (step S10 in Figure 4).

From the above state, the controller 70 starts the spindle motor 12' of the fine grinding means 10' to rotate the second grindstone 16' around its central axis at a predetermined speed, and drives the second moving mechanism not shown in the figure. The second chuck table 3', together with the workpiece W held therein, is moved from the finishing grinding start position Y3 shown in Figure 6(a) to the direction of the arrow c shown in the figure at a predetermined speed until Figure 6(b) to the finishing position Y4 shown. In this way, the front surface of the workpiece W (resin F) is finely ground to a thickness of only 10 μm by the second grindstone 16' (step S11 in Fig. 4). Then, when the finishing grinding is completed, the second chuck table 3' and the workpiece W are moved in the direction of the arrow d from the finishing position Y4 by the second moving mechanism (not shown), and return to the finishing position. Grinding start position Y3.

If the upper surface of the workpiece W is finely ground to a thickness of only 10 μm in one round of fine grinding as described above, the thickness of the workpiece W is measured by the second thickness measuring device 6 shown in FIG. 1 ( Step S12 of FIG. 4 ), and the result is sent to the controller 70 . In this way, the controller 70 determines whether the measured thickness of the workpiece W has reached the predetermined thickness t ₂ (see FIGS. 7(b) and (c) ) (step S13 in FIG. 4 ).

When the measured thickness of the workpiece W is thicker than the predetermined thickness t ₂ (step S13: No), the operations of steps S10 to S13 are repeated to repeat the fine grinding of the workpiece W multiple times until the measured thickness is reached. until the thickness of the workpiece W becomes equal to the predetermined thickness _t2 . In this embodiment, as shown in FIG. 7(b) , fine grinding is repeated five times to obtain a workpiece W with a predetermined thickness t ₂ as shown in FIG. 7(c) . In addition, the number of finishing grinding is based on the amount of finishing grinding in one time and is not limited to five times.

Then, in the workpiece W having a predetermined thickness t ₂ that has been precisely ground, as shown in FIG. 7(c) , the Cu electrode P is also ground, and a part of it is exposed from the front surface of the workpiece W.

As described above, according to the grinding method of the workpiece W of the present invention, the thickness of the workpiece W that is rough-ground in the rough grinding step becomes the preset predetermined thickness t ₀ in the next correction step. Correction grinding is performed in the grinding step, so that the thickness of all the workpieces W before finishing grinding becomes the preset thickness t ₀ and becomes fixed. Therefore, the time required for fine grinding of the workpiece W in the next fine grinding step can be uniformly fixed and short, and all the workpieces W can be ground to the predetermined thickness t ₂ in a fixed short time.

When the fine grinding of the workpiece W in the second processing unit U2 is completed as described above, the finely ground workpiece W is held in the workpiece W shown in FIG. 2 arranged in the space S2 of FIG. 1 The object transport means 20 is transported to the cleaning means 50 and delivered to the turntable 51 of the cleaning means 50 .

In the cleaning means 50, the rotary table 51 is rotated and driven together with the workpiece W at a predetermined speed around a vertical central axis by a rotation mechanism not shown in the figure, and is directed from the cleaning water nozzle 52 toward the workpiece W. Spray cleaning water. In this way, the workpiece W is washed with the cleaning water, and the grinding chips adhering to the front surface of the workpiece W are removed. The workpiece W cleaned by the cleaning means 50 in this way is held by the robot 60 and transported to the second cassette 8 to be accommodated in the second cassette 8. The series of grinding processing of one piece of workpiece W is completed. .

Next, a second embodiment of the grinding method of a workpiece according to the present invention will be described below with reference to FIGS. 8 and 9 .

In the grinding method of this embodiment, as shown in FIG. 8 , the workpiece W is ground through 1) rough grinding step, 2) correction grinding step, and 3) fine grinding step in the same manner as in the first embodiment. Only the setting method of the correction grinding amount in 2) the correction grinding step is different from the first embodiment mentioned above. Therefore, only the correction grinding step 2) will be explained below, and the description of the rough grinding step 1) and the fine grinding step 3) will be omitted. In addition, in the flowchart shown in FIG. 9 , the same processing as that in the flowchart shown in FIG. 4 is denoted by the same symbols as the steps shown in FIG. 4 .

In the correction grinding step, as shown in Figure 8, 2-1) upper surface height measurement step, 2-2) calculation step, and 2-3) upper surface height correction grinding step are performed in sequence.

In the upper surface measurement step, the upper surface height h ₁ of the workpiece W that was rough ground in the 1) rough grinding step is measured using the first thickness measuring device 5 shown in Figure 1 (see Figure 7(a) ) (Step S6' in Figure 9).

In the calculation step, the height h ₁ of the upper surface of the workpiece W measured by the first thickness measuring device 5 shown in FIG. 1 is calculated to be a preset height from the holding surface 3 a of the first chuck table 3 . The difference Δh (=h ₁ −h ₂ ) between the thickness t ₃ and the height h ₂ (<h ₁ ) (refer to Fig. 7(a)) (step S7' in Fig. 9).

In the upper surface height correction grinding step, the first grinding stone 16 is lowered so that the lower surface of the first grinding stone 16 is located just a height difference Δh from the front surface of the roughly ground workpiece W (Fig. 9 Step S8'), in the same manner as in rough grinding (refer to FIG. 5), the first chuck table 3 and the workpiece W are moved in the Y-axis direction by the first moving mechanism not shown in the figure, and the grinding amount is Δh performs thickness correction grinding on the front surface of the workpiece W (resin F) (step S9 in FIG. 9 ). In this way, as shown in Fig. 7(b), the workpiece W with a predetermined thickness _t0 is obtained.

Thereafter, as in the first embodiment, the workpiece W is finely ground (steps S10 to S14 in FIG. 9 ), and the workpiece W is ground to a predetermined thickness t ₂ (see FIG. 7( c )).

In this embodiment, similarly to the first embodiment described above, the workpiece W that has been roughly ground in the rough grinding step is processed in the next correction grinding step so that its thickness becomes the predetermined thickness t ₀ set in advance. Correction grinding is performed in the process, so for all the workpieces W, the thickness of the workpiece W before finishing grinding becomes the preset thickness t ₀ and becomes fixed. Therefore, the time required for fine grinding of the workpiece W in the next fine grinding step is unified to be fixed and short, so that the entire workpiece W can be ground to the predetermined thickness t ₂ in a fixed short time. The effect.

In addition, in the above embodiment, although the first and second chuck tables 3 and 3' (workpiece W) side are moved relative to the first and second grindstones 16 and 16' on the fixed side, deep grinding is performed. Grinding is performed by slow feed, but conversely, the first and second grindstones 16 and 16' may be moved relative to the first and second chuck tables 3 and 3' (the workpiece W) to perform deep feed and slow grinding. Give grinding.

Furthermore, deep feed grinding may be performed every time the first and second chuck tables 3, 3' and the first and second grindstones 16, 16' move relative to each other.

In addition, the present invention is not limited to the embodiments described above and can be variously modified within the scope of the patent application, the technical ideas described in the specification and the drawings.

1: Grinding device 2: Device base 3: First chuck table 3a: Holding surface 3': Second chuck table 3a': Holding surface 4: Cylinder 5: First thickness gauge (thickness gauge, upper Surface height measuring device) 5a: first contact 5b: second contact 6: second thickness measuring device 6a: first contact 6b: second contact 7: first cassette 8: second cassette 9: Alignment table 10: Rough grinding means 11, 11': Holder 12, 12': Spindle motor 13, 13': Spindle 14, 14': Mounting parts 15, 15': Grinding wheel 16: First grinding stone 16' : Second grindstone 20: Workpiece conveying means 20A: Y-axis moving mechanism 20B: Z-axis moving mechanism 21: Conveying pad (second conveying pad) 21a, 21b: Bottom plate 22a, 22b: Guide rail 23a: Slider 23b: Lifting block 24a, 24b: Ball screw shaft 25a, 25b: Electric motor 26a, 26b: Bearing 25: Suction cup 30: Lifting mechanism 31: Lifting plate 32: Guide rail 33: Ball screw shaft 34: Electric motor 40: Temporary part 41: Temporary setting table 42: Guide plate 43: Temporary setting table 43a: Holding surface 50: Cleaning means 51: Rotary table 52: Cleaning water nozzle 60: Robot 61: Robot hand 62: Installation part 63: Horizontal moving mechanism 63a: First Arm 63b: Second arm 64: Elevating mechanism 70: Controller C: Wafer F: Resin h ₁ : Height of the upper surface of the roughly ground workpiece h ₂ : Height above the predetermined thickness from the holding surface P: Cu Electrodes S1, S2: Space t ₀ : Preset thickness of the workpiece t ₁ : Thickness of the roughly ground workpiece t ₂ : Predetermined thickness of the finely ground workpiece t ₃ : Preset thickness Δt: Thickness difference Δh: Height difference U1: First processing unit U2: Second processing unit W: Workpiece W1: Support substrate Y1: Rough grinding start position Y2: Rough grinding end position Y3: Fine grinding start position Y4: Fine grinding Grinding end position

FIG. 1 is a partially cutaway perspective view of a grinding device used for carrying out the grinding method of a workpiece according to the present invention. FIG. 2 is a perspective view of a workpiece conveying means of the grinding device shown in FIG. 1 . FIG. 3 is a flowchart showing steps of a method for grinding a workpiece according to the first embodiment of the present invention. FIG. 4 is a flowchart showing the procedure of the grinding method of the workpiece according to the first embodiment of the present invention. 5(a) and 5(b) are schematic side views showing a rough grinding step in the method for grinding a workpiece according to the first embodiment of the present invention. 6(a) and 6(b) are schematic side views showing the finishing step in the method for grinding a workpiece according to the first embodiment of the present invention. 7(a) to 7(c) are longitudinal sectional views of the workpiece ground by the workpiece grinding method of the present invention. FIG. 8 is a flowchart showing the steps of the grinding method of a workpiece according to the second embodiment of the present invention. FIG. 9 is a flowchart showing the procedure of the grinding method of the workpiece according to the second embodiment of the present invention.

S1: Initial setting: n=0

S2: The first grinding stone drops 100μm

S3: Rough grinding

S4:n=n+1

S5: Is n=3?

S6: Measure the thickness of the workpiece

S7: Calculate thickness difference

S8: The first grinding stone reduces the thickness difference

S9:Thickness correction grinding

S10: The second grinding stone drops by 10μm

S11: Precision grinding

S12: Measure the thickness of the workpiece

S13: Is thickness = predetermined thickness?

S14:End

Claims (3)

A method for grinding a workpiece, which includes positioning the lower surface of a grindstone lower than the upper surface of the workpiece on the outside of the workpiece held on a chuck table, so that the chuck table is in contact with the grindstone. The stone moves relatively horizontally to grind the upper surface of the workpiece, and has: The rough grinding step is to position the lower surface of the first grindstone at a first distance lower than the upper surface of the workpiece and move the chuck table horizontally relative to the first grindstone, thereby grinding the workpiece. The upper surface of the workpiece; A correction grinding step, which grinds the thickness of the workpiece to a predetermined thickness after performing the rough grinding step; and The fine grinding step is to position the lower surface of the second grindstone at a second distance lower than the upper surface of the workpiece and make the chuck table face the second grindstone after performing the corrective grinding step. Move horizontally to grind the upper surface of the workpiece. For example, the grinding method of the workpiece of claim 1, wherein the modified grinding step includes: a thickness measuring step, which uses a thickness measuring device to measure the thickness of the workpiece held on the chuck table; A calculation step that calculates the difference between the thickness measured by the thickness measurement step and the preset thickness; and A correction grinding step, which positions the lower surface of the first grinding stone lower than the upper surface of the workpiece ground by the rough grinding step by the difference calculated by the calculation step and causes the chuck to The table moves horizontally relative to the first grindstone, thereby grinding the upper surface of the workpiece. For example, the grinding method of the workpiece of claim 1, wherein the modified grinding step includes: An upper surface height measuring step, in which the upper surface height measuring device measures the upper surface height of the workpiece held on the chuck table; a calculation step that calculates the difference between the upper surface height of the workpiece measured by the upper surface height step and a height that is only higher than a preset thickness from the holding surface; and The upper surface height correction grinding step positions the lower surface of the first grinding stone only lower than the upper surface of the workpiece ground by the rough grinding step by the difference calculated by the calculation step and makes The chuck table moves horizontally relative to the first grindstone, thereby grinding the upper surface of the workpiece.