JP2004207607A - Semiconductor wafer splitting method - Google Patents

Abstract

When dividing a semiconductor wafer which is formed thin and has low rigidity into individual semiconductor chips, the handling is facilitated without increasing the production cost, and the semiconductor wafer is prevented from being damaged.
In a case where a semiconductor wafer having a plurality of circuits formed on a surface is divided into semiconductor chips for each circuit, the surface of the semiconductor wafer W faces an upper surface of a support substrate 11 supporting the semiconductor wafer, and an adhesive is provided. The semiconductor wafer W and the support substrate 11 are integrated through the support 10, and the back surface of the semiconductor wafer W is polished while being integrated with the support substrate 11, and the semiconductor wafer W is integrated with the support substrate 11. The semiconductor chip is divided into individual semiconductor chips from the back side, and the semiconductor chips are picked up from the support substrate 11. Since the semiconductor wafer W is always supported by the support substrate, there is no damage.
[Selection] Fig. 2

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method of polishing a back surface of a semiconductor wafer and dividing the semiconductor wafer into individual semiconductor chips.
[0002]
[Prior art]
A semiconductor wafer on which circuits such as ICs and LSIs are formed on the front surface is polished on the back surface to be formed to a predetermined thickness, and then divided into individual semiconductor chips by a dividing device such as a dicing device.
[0003]
When polishing the back surface of the semiconductor wafer, a protective tape is adhered to the front surface of the semiconductor wafer in order to prevent the circuit on the front surface from being damaged. Also, when dividing the polished semiconductor wafer into individual semiconductor chips, the front side that can directly detect the street is attached to the dicing tape with the front side facing up, the semiconductor wafer is transferred, and the semiconductor wafer is separated from the dicing frame. Integrated (for example, see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-10-284449 (page 10, FIG. 9)
[0005]
[Problems to be solved by the invention]
However, in recent years, in order to reduce the size and weight of various electronic devices, it has been necessary to grind a semiconductor wafer to an extremely thin thickness of 100 μm or less and 50 μm or less. If the grinding is performed to such a degree, there is a problem that the rigidity of the semiconductor wafer is significantly reduced and handling becomes difficult. In particular, when transferring the semiconductor wafer from the protective tape to the dicing tape, there is a problem that the semiconductor wafer may be broken or damaged.
[0006]
On the other hand, after attaching the back surface of the semiconductor wafer to the dicing tape with the protective tape still attached to the front surface, a method of preventing the semiconductor wafer from cracking by peeling the protective tape from the front surface of the semiconductor wafer is also conceivable. However, there is a problem that a special device is required for that, which leads to an increase in production cost.
[0007]
Therefore, in the case of dividing a thinly formed semiconductor wafer having reduced rigidity into individual semiconductor chips, there is a problem in that it is easy to handle and prevents damage to the semiconductor wafer without increasing the production cost. I have.
[0008]
[Means for Solving the Problems]
As a specific means for solving the above problems, the present invention is a method of dividing a semiconductor wafer into semiconductor chips for each circuit, a semiconductor wafer having a plurality of circuits formed on the surface, An integration step in which the surface of the semiconductor wafer faces the upper surface of the supporting substrate to be supported and the semiconductor wafer and the supporting substrate are integrated via an adhesive, and the back surface of the semiconductor wafer integrated with the supporting substrate is polished A method for dividing a semiconductor wafer, comprising: a polishing step; a dividing step of dividing a semiconductor wafer integrated with a support substrate into individual semiconductor chips from the back side; and a pickup step of picking up semiconductor chips from the support substrate. I will provide a.
[0009]
And this semiconductor wafer dividing method is that the adhesive is a double-sided tape, the adhesive is reduced in adhesive strength by an external stimulus, of the double-sided tape, at least the surface on which the semiconductor wafer is stuck, It is an additional requirement that the adhesive strength is reduced by an external stimulus, and that the supporting substrate is formed of any one of synthetic resin, metal, glass, and ceramics.
[0010]
According to the semiconductor wafer dividing method configured as described above, the polishing step, the dividing step, and the pickup step are performed in a state where the semiconductor wafer remains attached to the support substrate. Very easy to handle.
[0011]
In addition, when the process is shifted from the polishing process to the dividing process, it is not necessary to replace the tape with a tape, so that damage to the semiconductor wafer during the replacement can be prevented without using a special device.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
An example of an embodiment of the present invention will be described with reference to the drawings. The semiconductor wafer W shown in FIG. 1 is an example of a semiconductor wafer divided according to the present invention, and has a configuration in which a plurality of circuits are formed on the surface by being divided by streets S. It is divided into individual semiconductor chips C by cutting or the like.
[0013]
The semiconductor wafer W is turned upside down so that the surface of the semiconductor wafer W faces the upper surface of the support substrate 11 as shown in FIG. 2, and the two are integrated via the double-sided tape 10 to the state shown in FIG. Integration process). Here, the double-sided tape 10 is an example of an adhesive, and for example, a liquid resin or the like can also be used.
[0014]
The support substrate 11 is made of a highly rigid member such as synthetic resin, glass, ceramics, and metal. The thickness of the support substrate 11 is 0.5 mm to 1.5 mm when formed of glass or ceramics, 0.3 mm to 1.0 mm when formed of metal (for example, stainless steel), and synthetic resin (for example, PET). When it is formed by, the thickness is preferably 0.1 mm to 0.5 mm.
[0015]
As shown in FIG. 3, the back surface of the semiconductor wafer W integrated with the support substrate 11 is polished by, for example, the polishing apparatus 20 shown in FIG.
[0016]
In the polishing apparatus 20, a wall 22 is provided upright from an end of a base 21, and a pair of rails 23 is vertically disposed on an inner surface of the wall 22. The polishing means 25 attached to the support plate 24 moves up and down as the support plate 24 moves up and down. A turntable 26 is rotatably disposed on the base 21. The turntable 26 rotatably supports a chuck table 27 for holding a semiconductor wafer.
[0017]
In the polishing means 25, a mounter 29 is mounted on a tip of a spindle 28 having a vertical axis, a polishing wheel 30 is further mounted below the mounter 29, and a polishing wheel 31 is fixed to a lower surface of the polishing wheel 30. The polishing grindstone 31 rotates with the rotation of the spindle 28.
[0018]
When grinding the back surface of the semiconductor wafer W using the polishing apparatus 20, the semiconductor wafer W integrated with the support substrate 11 is held on the chuck table 27 so that the back surface is exposed and positioned directly below the polishing means 25. Then, while rotating the chuck table 27 and rotating the spindle 28, the polishing means 25 is lowered. Then, the polishing wheel 30 rotates with the rotation of the spindle 28, and the rotating polishing grindstone 31 comes into contact with the back surface of the semiconductor wafer W to apply a pressing force, whereby the back surface is polished by the polishing grindstone 31 ( Polishing step).
[0019]
Then, as shown in FIG. 5, after the semiconductor wafer W is formed to a desired thickness (for example, 100 μm or less, 50 μm or less), the semiconductor wafer W is cut into individual semiconductor chips by, for example, a cutting device 50 shown in FIG. To divide.
[0020]
In the cutting device 50, a plurality of semiconductor wafers W integrated with the support substrate 11 are accommodated in the cassette 51. Then, the semiconductor wafer W is conveyed one by one to the temporary storage area 53 by the carrying-in / out means 52, sucked by the carrying means 54, and conveyed to the chuck table 55 by the turning movement thereof, and is suctioned in a state where the back surface of the semiconductor wafer W faces upward and is exposed. Will be retained.
[0021]
When the semiconductor wafer W integrated with the support substrate 11 is sucked and held by the chuck table 55, the chuck table 55 moves in the + X direction and is positioned immediately below the imaging means 56. The imaging means 56 takes an image of the front side by transmitting light from the back side of the semiconductor wafer W with infrared rays, for example, and scans the street S to be cut (see FIG. 1) formed on the front side by pattern matching by the alignment means 56a. Detected by processing. Then, after alignment of the cutting blade 57 having the same Y coordinate with the imaging means 56 and the detected street in the Y-axis direction is performed, the chuck table 55 further moves in the + X direction, and the cutting blade 57 rotating at a high speed rotates. Under the action, the detected street is cut.
[0022]
When the chuck table 55 is reciprocated in the X-axis direction while indexing and feeding the cutting blades 57 in the Y-axis direction at street intervals, all streets in the same direction are cut.
[0023]
Further, when the chuck table 55 is further rotated by 90 degrees and the same cutting is performed as described above, as shown in FIG. 7, all the streets are cut vertically and horizontally to form individual semiconductor chips C (see FIG. 1). It is divided (dividing step). At this time, the individual semiconductor chips C maintain the state held by the support substrate 11.
[0024]
In the above example, the street to be cut is detected by infrared imaging. However, when the support substrate 11 is formed of a transparent member such as glass or PET, the street is transmitted through the transparent support substrate 11 from below. Then, alignment can be performed by performing imaging.
[0025]
Further, not only a cutting device but also a laser cutting device may be used to cut a street by irradiating a laser beam to divide the street into individual semiconductor chips.
[0026]
As shown in FIG. 7, after the semiconductor wafer W is divided into individual semiconductor chips C while maintaining its shape, as shown in FIG. Pickup is performed one by one from 11 (pickup step).
[0027]
Here, when at least the surface of the double-sided tape 10 to which the semiconductor wafer W is adhered is a type of adhesive whose adhesive force is reduced by an external stimulus, an external stimulus is applied to the adhesive. If the pickup is performed after the adhesive force is reduced, the pickup can be performed easily and smoothly. In the illustrated example, the external stimulus is ultraviolet light, and among the double-sided tape 10, the adhesive on at least the side to which the semiconductor wafer W is adhered is of a type that can reduce the adhesive force by irradiation with ultraviolet light. Things.
[0028]
When the integration step, the polishing step, the division step, and the pickup step are performed as described above, there is no need to peel the semiconductor wafer from the support substrate and attach it to the dicing tape as in the related art, and the polishing step, the division step, Since the pickup process is performed while being supported by the support substrate 11, the semiconductor wafer W thinned by polishing can be easily handled, and the semiconductor wafer W may be cracked or chipped without using a special device. Can be prevented.
[0029]
In the above-described embodiment, the case where the outer diameter of the semiconductor wafer W is equal to the outer diameter of the support substrate 11 has been described as an example. However, as in the case of the support substrate 11a shown in FIG. When a support substrate having a large outer diameter is used, as shown in FIG. 10, in the polishing step, one of the styluses 70 is attached to the stylus 70 using a stylus-type thickness measuring device 72 having styluses 70 and 71. The thickness of the semiconductor wafer W is measured based on the difference in height between the two styluses by bringing the other stylus 71 into contact with the back surface of the semiconductor wafer W while making contact with the upper surface of the support substrate 11a. Polishing can be performed while polishing. Further, since only the support substrate 11 can be held during the transfer, there is no possibility that the semiconductor wafer W is damaged.
[0030]
【The invention's effect】
As described above, according to the method for dividing a semiconductor wafer according to the present invention, the polishing step, the dividing step, and the pickup step are performed while the semiconductor wafer is still attached to the support substrate. Even if it is thin, handling is extremely easy, and damage to the semiconductor wafer can be prevented.
[0031]
Also, since it is not necessary to replace the tape when transferring from the polishing process to the dividing process, damage to the semiconductor wafer during the replacement can be prevented without using a special device, and the safety is increased. .
[Brief description of the drawings]
FIG. 1 is a perspective view showing an example of a semiconductor wafer.
FIG. 2 is a perspective view showing an integration step.
FIG. 3 is a perspective view showing a semiconductor wafer integrated with a support substrate.
FIG. 4 is a perspective view showing an example of a polishing apparatus.
FIG. 5 is a perspective view showing a semiconductor wafer integrated with a support substrate after polishing.
FIG. 6 is a perspective view showing an example of a cutting device.
FIG. 7 is a perspective view showing a semiconductor wafer divided into individual semiconductor chips and integrated with a support substrate.
FIG. 8 is a perspective view illustrating an example of a pickup step.
FIG. 9 is a perspective view showing a second example of the support substrate.
FIG. 10 is a front view showing how the thickness of the semiconductor wafer is measured in the polishing step.
[Explanation of symbols]
W ... Semiconductor wafer S ... Street C ... Semiconductor chip 10 ... Double-sided tape (adhesive) 11 ... Support substrate 20 ... Polishing device 21 ... Base 22 ... Wall 23 ... Rail 24 ... Support plate 25 ... Polishing means 26 ... Turn table 27 ... Chuck table 28 ... Spindle 29 ... Mounter 30 ... Polishing wheel 31 ... Polishing grindstone 50 ... Cutting device 51 ... Cassette 52 ... Transport / inlet means 53 ... Temporary storage area 54 ... Transport means 55 ... Chuck table 56 ... Imaging means 56a ... Alignment Means 57 Cutting blade 60 Adsorbing collets 70, 71 Contact probe 72 Thickness measuring instrument

Claims (5)

A method of dividing a semiconductor wafer that divides a semiconductor wafer having a plurality of circuits formed on a surface into semiconductor chips for each circuit,
An integration step of integrating the semiconductor wafer and the support substrate via an adhesive with the surface of the semiconductor wafer facing the upper surface of the support substrate supporting the semiconductor wafer,
A polishing step of polishing the back surface of the semiconductor wafer integrated with the support substrate,
A dividing step of dividing the semiconductor wafer integrated with the support substrate into individual semiconductor chips from the back side,
A method for dividing a semiconductor wafer, comprising: a pickup step of picking up semiconductor chips from the support substrate. 2. The method for dividing a semiconductor wafer according to claim 1, wherein the adhesive is a double-sided tape. 3. The method for dividing a semiconductor wafer according to claim 1, wherein the adhesive has a reduced adhesive strength due to an external stimulus. The method for dividing a semiconductor wafer according to claim 2, wherein at least a surface of the double-sided tape to which the semiconductor wafer is adhered has a reduced adhesive strength due to an external stimulus. 5. The method according to claim 1, wherein the support substrate is formed of any one of synthetic resin, metal, glass, and ceramics.

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