JP4615095B2 - Chip grinding method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for grinding a chip to a desired thickness.
[0002]
[Prior art]
Semiconductor chips such as memories are used in various electronic devices such as mobile phones and personal computers. However, in order to reduce the weight, size, and thickness of electronic devices, it is required to make the semiconductor chips thinner. ing.
[0003]
In order to meet these requirements, apart from the usual method of forming individual chips by grinding the back surface of the semiconductor wafer to a desired thickness and then dicing, the surface of the semiconductor wafer is ground before grinding the back surface of the semiconductor wafer. A method has also been developed in which dicing grooves are formed by half-cutting, the back surface is ground until reaching the dicing grooves, and divided into individual chips, and further ground to finish each chip to a desired thickness. .
[0004]
[Problems to be solved by the invention]
However, since such a technique is not widely used, many chips are distributed between device manufacturers in a relatively thick state. In addition, when this method is used, the chip can be made thinner than when the normal method is used, but the accuracy of the chip thickness is often insufficient.
[0005]
Accordingly, there is a problem in that a chip formed relatively thick can be ground to a desired thickness with high accuracy.
[0006]
[Means for Solving the Problems]
As a specific means for solving the above-mentioned problems, the present invention provides a grinding apparatus comprising at least a chuck table for holding a workpiece and a grinding means having a grinding wheel disposed to face the chuck table. A method for grinding a chip to grind the chip to a predetermined thickness using a ring, and to form a ring frame that is at least thicker than the finished thickness of the chip and has a thickness substantially equal to the thickness of the chip before grinding A process, an integrated bonding process in which a chip is accommodated in an internal space of the ring frame and a bonding member is bonded to the ring frame and the chip so that the ring frame and the chip are integrated; A chuck table holding step for holding the chuck table, and a hand for grinding the ring frame and the chip held by the chuck table. Providing a grinding step of grinding, the tip grinding method composed of the thickness detecting step of indirectly detecting the thickness of the chip is ground to measure the thickness of the ring frame by.
[0007]
In this chip grinding method, a thickness measurement gauge is disposed adjacent to the chuck table, and the grinding process is performed while measuring the thickness of the ring frame using the thickness measurement gauge. An additional requirement is that the grinding process is terminated when the measured thickness value of the ring frame reaches a predetermined value, and that the ring frame is formed of a member of the same quality as the members constituting the tip. And
[0008]
DETAILED DESCRIPTION OF THE INVENTION
An example of an embodiment of the present invention will be described with reference to the drawings. First, the circular wafer W is accommodated in the cassette 11 of the cutting apparatus 10 shown in FIG. 1, and the wafer W is carried out to the temporary placement region 13 by the carry-in / out means 12. Then, the wafer W is transferred to the holding table 15 by the transfer means 14 and is sucked and held.
[0009]
The holding table 15 is rotatable and movable in the X-axis direction, and the wafer W held on the holding table 15 is positioned immediately below the alignment means 16 as the holding table 15 moves in the + X direction. Here, after the region to be cut is detected, it is positioned in the cutting region 17 by further moving in the same direction.
[0010]
A cutting means 19 having a rotating blade 18 is disposed in the cutting region 17 so as to be movable in the Y-axis direction and the Z-axis direction. As shown in FIG. 2, the cutting means 19 includes a rotary spindle 18 mounted on a rotary spindle 21 rotatably supported by a spindle housing 20, and a cutting water supply nozzle 22 disposed on a side of the rotary blade 18. It becomes the composition.
[0011]
As shown in FIG. 2, the wafer W held on the holding table 15 moves the cutting means 19 in the Y-axis direction and the Z-axis direction with the high-speed rotation of the rotary blade 18, and the holding table 15 rotates. As a result, the ring is cut into a ring shape by the rotating blade 18 and separated into the ring frame F and the unnecessary wafer W1 remaining inside the ring frame F, and the unnecessary wafer W1 is removed to form the ring frame F (ring frame formation). Process).
[0012]
Here, an area formed inside the ring frame F after removing the unnecessary wafer W <b> 1 is referred to as an internal empty area 23. In addition, the thickness of the ring frame F is set to be thicker than the finished thickness of the chip, and is substantially the same as the thickness of the chip before grinding. The ring frame F may be formed using two core drills having different diameters.
[0013]
Next, as shown in FIG. 3, a plurality of chips C to be ground are accommodated in the internal empty region 23 of the ring frame F, and an adhesive member, for example, an adhesive tape T, is attached to the ring frame F and the chips C from the bottom surface side. By sticking, as shown in FIG. 4, the chip C is fixed by the adhesive tape T in the internal empty region 23 and integrated with the ring frame F (integrated sticking step). In this way, the object to be ground 25 is formed by integrating the chip C and the ring frame F with the adhesive tape T interposed therebetween.
[0014]
The object to be ground 25 formed by the integral attaching step is conveyed to, for example, a grinding device 30 shown in FIG. Here, a wall portion 32 is provided upright from the end portion of the base 31 of the grinding apparatus 30 shown in FIG. 5, and a pair of rails 33 are vertically arranged on the inner surface of the wall portion 32. The grinding means 35 attached to the support part 34 is moved up and down following the support part 34 moving up and down along the rail 33. Further, a turntable 36 is rotatably disposed on the base 31, and a chuck table 37 that holds the workpiece 25 is disposed on the turntable 36.
[0015]
In the grinding means 35, a mounter 39 is attached to the tip of a rotary spindle 38 having a vertical axis, and a grinding wheel 40 is attached to the lower part thereof. A grinding wheel 41 is provided below the grinding wheel 40. The grinding wheel 41 is also rotated as the rotary spindle 38 rotates. A stylus-type thickness measurement gauge 42 that measures the thickness of the workpiece held on the chuck table 37 is disposed around the turntable 36.
[0016]
As shown in FIG. 6, a ball screw 43 is disposed in the vertical direction on the back side of the wall portion 32, and a pulse motor 44 is connected to the ball screw 43 and penetrates the wall portion 32 to grind. The nut provided in the support portion 45 connected to the screw 35 is screwed, and the support portion 45 and the grinding means 35 connected thereto are moved up and down as the ball screw 43 is rotated by driving the pulse motor 44. It is the composition to do.
[0017]
The pulse motor 44 is connected to the control unit 47 via the pulse motor driver 46, and moves the grinding means 35 up and down by rotating the ball screw 43 under the control of the control unit 47. Further, the vertical position of the support portion 45 is measured by the linear scale 48 and the information is transmitted to the control portion 47 so that the vertical movement of the grinding means 35 is precisely controlled.
[0018]
The control unit 47 is connected to a servo driver 49, and the servo driver 49 is connected to an encoder 50 and a servo motor 51 provided below the chuck table 37, and the chuck table 37 rotates under the control of the control unit 47. To do.
[0019]
Further, the control unit 47 is also connected to the thickness measurement gauge 42, and is configured to be able to precisely control the vertical movement of the grinding means 35 based on the measurement value by the thickness measurement gauge 42.
[0020]
In the grinding apparatus 30, as shown in FIG. 5, the workpiece 25 is held on the chuck table 37 (chuck table holding step). When the turntable 36 is rotated to position the workpiece 25 directly below the grinding means 35, the chuck table 37 is rotated by the servo motor 51, and the grinding means 35 is lowered while rotating the rotary spindle 38. The grinding wheel 41 rotates at a high speed as the rotating spindle 38 rotates at a high speed, and the rotating grinding wheel 41 contacts the surfaces of the rotating tip C and the ring frame F to apply a pressing force. The surface is ground by the grinding wheel 41, and the thickness of the tip C and the ring frame F is gradually reduced (grinding step).
[0021]
At this time, if a plurality of chips are integrated with one frame as in the present embodiment, the plurality of chips can be ground at the same time, so that productivity is improved. In addition, even chips of different manufacturers and different types can be ground in one space inside the ring frame, so that they can be ground at a time, so that they can be flexibly adapted to low-volume production of other products. Can do.
[0022]
During grinding, the thickness of the ring frame F is measured at an appropriate timing using the thickness measurement gauge 42. At the time of measurement, as shown in FIG. 7, of the two measurement arms provided in the thickness measurement gauge 42, the lower end of one measurement arm 43 is brought into contact with the surface of the ring frame F and the surface of the ring frame F And the lower end of the other measuring arm 44 is brought into contact with the surface of the chuck table 37 to determine the height of the surface of the chuck table 37. Then, when the difference between the two obtained heights is calculated, the calculated difference in height becomes the thickness of the ring frame F.
[0023]
Further, since the tip C and the ring frame F are attached to the common adhesive tape T and are ground simultaneously by the grinding wheel 41, the thickness of the ring frame F and the thickness of the tip C are equal. In other words, the thickness of the ring frame F obtained using the thickness measurement gauge 42 can be regarded as the thickness of the chip C, and thereby the thickness of the chip C can be obtained indirectly (thickness). Detection step).
[0024]
In order to make the thickness of the tip C and the thickness of the ring frame F exactly match, it is desirable that the tip C and the ring frame F are formed of the same quality members. For example, if the chip to be ground is a silicon chip, the ring frame F is also preferably formed by cutting a silicon wafer into a ring shape.
[0025]
By performing grinding while measuring the thickness of the ring frame F in this way, it is considered that the tip C has also reached the desired thickness when the thickness of the ring frame F reaches the desired thickness. Therefore, the thickness of the chip can be finished with higher accuracy.
[0026]
When it is confirmed that the chip has a desired thickness, the object to be ground 25a in which the ring frame F1 after grinding and the chip C1 shown in FIG. 8 are integrated is removed from the chuck table 37, and the adhesive tape is further removed. By picking up a plurality of ground chips C1 from T, as shown in FIG. 9, individual chips C1 that are ground thinly to a desired thickness are obtained.
[0027]
【The invention's effect】
As described above, according to the chip grinding method of the present invention, since the thickness of the chip can be measured even during chip grinding, the chip can be finished to a desired thickness with high accuracy.
[0028]
Further, when a plurality of chips are accommodated and integrated in an internal empty area of one frame, the plurality of chips can be ground at the same time, so that productivity is improved.
[0029]
Furthermore, even chips of different manufacturers and different types can be ground in one empty space inside a single ring frame, so that they can be flexibly adapted to low-volume production of other varieties. Can do.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an example of a cutting apparatus used in a ring frame forming step constituting a chip grinding method according to the present invention.
FIG. 2 is a perspective view showing a state in which a ring frame is formed by the ring frame forming step.
FIG. 3 is a perspective view showing an integral sticking step constituting the chip grinding method according to the present invention.
FIG. 4 is a perspective view showing an object to be ground formed by the same body attaching step.
FIG. 5 is a perspective view showing an example of a grinding apparatus used in a grinding process constituting a chip grinding process according to the present invention.
FIG. 6 is an explanatory view showing a configuration of the grinding apparatus.
FIG. 7 is a perspective view showing a state in which the thickness of the ring frame is measured in the grinding apparatus.
FIG. 8 is a perspective view showing an object to be ground after grinding.
FIG. 9 is a perspective view showing the chip after grinding.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Cutting device 11 ... Cassette 12 ... Carry-in / out means 13 ... Temporary placing area 14 ... Conveyance means 15 ... Holding table 16 ... Alignment means 17 ... Cutting area 18 ... Rotary blade 19 ... Cutting means 20 ... Spindle housing 21 ... Rotary spindle 22 ... cutting water supply nozzle 23 ... internal empty area 25 ... workpiece 30 ... grinding device 31 ... base 32 ... wall part 33 ... rail 34 ... support part 35 ... grinding means 36 ... turntable 37 ... chuck table 38 ... rotating spindle DESCRIPTION OF SYMBOLS 39 ... Mounter 40 ... Grinding wheel 41 ... Grinding wheel 42 ... Thickness measuring gauge ... 43 ... Ball screw 44 ... Pulse motor 45 ... Supporting part 46 ... Pulse motor driver 47 ... Control part 48 ... Linear scale 49 ... Servo driver 50 ... Encoder 51 ... servo motor W ... wafer F ... ring frame T ... Wearing tape C ... chip

Claims (3)

The chip is ground to a predetermined thickness by using a grinding device comprising at least a chuck table for holding a workpiece and a grinding means having a grinding wheel disposed opposite the chuck table. A chip grinding method,
A ring frame forming step of forming a ring frame that is at least thicker than the finished thickness of the chip and has a thickness substantially the same as the thickness of the chip before grinding;
An integral attachment step of accommodating a chip in an internal empty region of the ring frame, attaching an adhesive member to the ring frame and the chip, and integrating the ring frame and the chip;
A chuck table holding step of holding a ring frame integrated with the chip on the chuck table;
A grinding step of grinding the ring frame and the chip held by the chuck table by the grinding means;
A chip grinding method comprising a thickness detecting step of measuring the thickness of the ring frame and indirectly detecting the thickness of the ground chip. A thickness measurement gauge is disposed adjacent to the chuck table, and the ring frame is measured by the thickness measurement gauge by performing a grinding process while measuring the thickness of the ring frame using the thickness measurement gauge. 2. The chip grinding method according to claim 1, wherein the grinding step is terminated when the thickness value reaches a predetermined value. 3. The chip grinding method according to claim 1, wherein the ring frame is formed of a member having the same quality as a member constituting the chip.

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