JP2003007649A - Semiconductor wafer splitting method - Google Patents

Abstract

(57) Abstract: A so-called pre-dicing, in which after forming a cutting groove that does not penetrate to the back surface on a front surface of a semiconductor wafer, the back surface is ground and etched to expose the cutting groove, thereby dividing into individual semiconductor chips. In this case, the circuit surface is prevented from being damaged by the etching agent. SOLUTION: A half-cutting step 11 for forming a cutting groove that does not penetrate to the back surface in a street formed on the front surface of the semiconductor wafer, and the back surface in a state where the front surface of the semiconductor wafer having the cutting groove is supported by a protective member. A grinding step 12 for grinding and an etching step 13 for etching and removing a grinding distortion layer generated on the back surface by grinding with an etching agent are included in the grinding step 12 before the semiconductor wafer is divided into individual semiconductor chips. The grinding of the back surface is completed to form a remaining grinding layer having a thickness of about 5 μm to 50 μm. In the etching step, the remaining grinding layer is removed by etching and divided into individual semiconductor chips.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor wafer dividing method in which a cutting groove that does not penetrate to the back surface is formed on the front surface of a semiconductor wafer, and then the back surface is ground to expose the cutting groove to divide the semiconductor wafer into individual semiconductor chips. Regarding the method.

[0002]

2. Description of the Related Art As a technique for thinly forming a semiconductor chip, a relatively shallow cutting groove that does not penetrate to the back surface is formed in a street that divides a plurality of semiconductor circuits formed on the front surface of the semiconductor wafer, and then the semiconductor wafer is formed. The present applicant has developed a technique called pre-dicing in which a cutting groove is exposed from the back surface side by grinding the back surface and is divided into individual semiconductor chips.

According to the above-mentioned dicing technique, it is possible to process the chip so as to have a thickness of 100 μm or less, so that it is possible to meet the demand for miniaturization and thinning of various devices such as a mobile phone.

However, by grinding the back surface of the semiconductor wafer, grinding marks are formed on the back surface of the semiconductor chip, and a grinding strain layer having a thickness of about 0.1 to 10 μm is formed inside. However, there is a problem in that the bending strength of the semiconductor chip is reduced and the semiconductor chip is easily damaged.

In view of this, an attempt has been made to improve the bending strength by removing the grinding marks and the grinding strain layer on the back surface of each semiconductor chip after grinding by treatment by chemical etching or the like.

[0006]

However, when the semiconductor wafer is divided into individual semiconductor chips by grinding and then the etching solution is supplied to the ground surface for etching, the etching solution enters from the cutting groove exposed on the back surface. There is a problem that it wraps around and damages the circuit formed on the surface. Also,
Even in the case of dry etching performed by supplying the etching gas, the etching gas may enter from the cutting groove to cause the same problem. Further, there is a problem that the side surface of the semiconductor chip is contaminated with grinding dust.

Therefore, in so-called pre-dicing, there are problems in that the circuit surface is not damaged by the etching treatment agent and the side surface of the semiconductor chip is not contaminated.

[0008]

As a concrete means for solving the above-mentioned problems, the present invention divides a semiconductor wafer formed by dividing a plurality of semiconductor circuits by streets into individual semiconductor chips for each semiconductor circuit. A method of dividing a semiconductor wafer, comprising: a half-cutting step of forming a cutting groove that does not penetrate to a back surface on a street formed on the front surface of the semiconductor wafer; and a surface of the semiconductor wafer on which the cutting groove is formed is supported by a protective member. In a grinding step, at least a grinding step of grinding the back surface, and a treatment step of removing a grinding strain layer generated on the back surface by grinding by a treatment process.
Before the cutting groove is exposed and the semiconductor wafer is divided into individual semiconductor chips, grinding of the back surface is completed to form a residual grinding layer, and in the treatment process, the residual grinding layer is removed and divided into individual semiconductor chips. A method for dividing a semiconductor wafer is provided.

The method of dividing the semiconductor wafer is
In the grinding step, the grinding residual layer is formed to be thicker than the grinding distortion layer, the grinding distortion layer is completely removed in the treatment step, and the thickness of the grinding residual layer is 5 μm to 50 μm as additional requirements.

In the method of dividing a semiconductor wafer configured as described above, the grinding is completed to form a grinding residual layer before the semiconductor wafer is divided into individual semiconductor chips in the grinding step, and the grinding residual is left in the etching step. Since the layers are configured to be removed by etching and divided into semiconductor chips, it is possible to prevent the etching solution from being blocked by the unground layer and from penetrating into the surface of the semiconductor wafer through the cutting grooves to damage the circuit.

Further, the grinding-strained layer can be completely removed by forming the grinding-residual layer to be thicker than the grinding-strained layer in the grinding step and completely removing the grinding-residual layer in the etching step.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to the flowchart of FIG. The semiconductor wafer W shown in FIG. 2 is an example of a semiconductor wafer divided according to the present invention, and has a configuration in which a plurality of semiconductor circuits C formed on the surface are divided by streets S. First, in the half-cut step 11, for example, the street S of the semiconductor wafer W is half-cut using the dicing device 20 shown in FIG. 3 to form a cutting groove that does not penetrate to the back surface.

In the dicing apparatus 20 of FIG. 3, the semiconductor wafer W to be half-cut is the cassette 2
A plurality of sheets are stored in one unit, and the sheets are taken out one by one by the carry-in / carry-out means 22 to the temporary placement area 23, and then transported to the chuck table 25 by the first transport means 24, and suction-held.

Next, by moving the chuck table 25 in the + X direction, the semiconductor wafer W is positioned immediately below the alignment means 26, and the street where the cutting groove is to be formed is detected here, and the street and the rotary blade 27 are detected. Is aligned in the Y-axis direction.

Further, the chuck table 25 holding the semiconductor wafer W moves in the + X direction, and the cutting means 28 provided with the rotating blade 27 rotating at a high speed descends to cut into the street on the surface of the semiconductor wafer W. At this time, the cutting depth is precisely controlled so that the tip portion of the rotary blade 27 does not reach the back surface.
Form a cutting groove on the surface.

The chuck table 25 is fed while the cutting means 28 is indexed and fed in the Y-axis direction by the street distance.
By reciprocally moving in the X-axis direction, cutting grooves having a substantially constant depth are formed on all streets in the same direction.

Further, by rotating the chuck table 25 by 90 degrees and then performing the same cutting as described above, as shown in FIG. 4, all the streets provided in the vertical and horizontal directions are slightly deeper than the finished thickness of the chip. The groove 29 is formed.

The semiconductor wafer W thus half-cut is supported by the protective member 30 as shown in FIGS. The protection member 30 is composed of a ring-shaped frame 32 having an opening 31 in the center and a tape 33 attached to the back surface of the frame 32 to close the opening 31.
By sticking the surface of the semiconductor wafer W to the adhesive surface of the tape 33, the half-cut semiconductor wafer W is supported integrally with the protection member 30, as shown in FIGS. 5 and 6.

Here, the semiconductor wafer W and the protection member 30.
For the integration with the, a tape attaching device 35 as shown in FIGS. 7A and 7B is used, for example. First, the frame 32 is mounted on the mounting table 36 of the tape adhering device 35 with the back surface facing upward, and the semiconductor wafer W is mounted on the opening 31 with the surface facing upward. Then, as shown in FIG. 7A, the tape 33 is simultaneously attached to the frame 32 and the semiconductor wafer W by using the roller 37, and then the cutter 38 is rotated as shown in FIG. 7B. While adhesive tape 33
Is applied to the back surface of the frame 32 and cut into a circle.

For the half-cut semiconductor wafer W supported by the protective member 30 in this manner, for example, FIG.
The grinding process 12 is performed using the grinding device 40 shown in FIG.
In this grinding device 40, the half-cut semiconductor wafer W supported by the protection member 30 is housed in the cassette 41a with the back surface thereof facing upward. Then, the sheets are taken out one by one by the carry-in / out means 42, placed on the centering table 43, and aligned at a fixed position.

The turntable 44 is rotatable and has four chuck tables 45, 46, 4
7 and 48 are rotatably supported, and turntable 4
By the rotation of 4, the chuck tables 45, 46, 47,
48 can be positioned in any desired position.

The semiconductor wafer W aligned on the centering table 43 is transferred to the chuck table 45 by the first transfer means 49. Then, the semiconductor wafer W is positioned immediately below the first grinding means 50 by rotating the turntable 44 counterclockwise by 90 degrees.

Here, the first grinding means 50 has a wall portion 51.
A support portion 54 which is vertically moved by the driving of a drive source 53 while being guided by a pair of guide rails 52 arranged in the vertical direction.
It is configured to move up and down as the support portion 54 moves up and down. In this first grinding means 50,
A grindstone 57 is mounted on the tip of a rotatably supported spindle 55 via a mounter 56. As shown in FIG. 9, the grindstone 57 has a structure in which a grindstone piece 59 for rough grinding is annularly fixed to a lower portion of a wheel base 58.

On the other hand, the second grinding means 60 is supported by a pair of guide rails 61 arranged vertically on the wall portion 51 and supported by a support portion 63 which moves up and down by the driving of a drive source 62. It is configured to move up and down as the portion 63 moves up and down. In the second grinding means 60, the mounter 6 is attached to the tip of a spindle 64 rotatably supported.
A grinding wheel 66 is attached via 5. As shown in FIG. 9, the grindstone 66 has a structure in which a grindstone piece 68 for finish grinding is fixed in an annular shape to a lower portion of a wheel base 67.

On the back surface of the semiconductor wafer W positioned directly below the first grinding means 50, the first grinding means 50 descends as the spindle 55 rotates, and the whetstone piece 5 rotates.
When 9 comes into contact with the back surface, rough grinding is performed.

Next, the turntable 44 is rotated counterclockwise by 90.
The semiconductor wafer W is positioned immediately below the second grinding means 60 by rotating once. Then, the second grinding means 60 descends with the rotation of the spindle 64 to rotate the grindstone piece 6
Finish grinding is performed by the contact of 8 with the back surface.
Here, grinding is performed until just before the cutting groove 29 is exposed. Specifically, as shown in FIG. 10, when the layer from the bottom of the cutting groove 29 to the back surface is the residual grinding layer 71, for example, finish grinding is performed so that the thickness T of the residual grinding layer 71 is 5 μm to 50 μm. To do.

When the rough grinding and the finish grinding are performed in this manner, the grinding stone pieces 59, 68 are formed on the back surface of the semiconductor wafer W.
Grinding marks are formed along the direction of rotation, and a grinding strain layer having a thickness of about 0.1 to 10 μm is further formed therein. That is, the grinding residual layer 71 includes a grinding strain layer.

The grinding device 40 of FIG. 8 has two grinding means.
Therefore, the case where two steps of grinding, rough grinding and finish grinding, are performed in the grinding process has been described here. However, in the case of a grinding apparatus having only one grinding means, one grinding unit is used.
The grinding is performed until the unfinished grinding layer T having a desired thickness is formed by grinding once.

The semiconductor wafer W on which the unremoved layer 71 has been formed by grinding the back surface of the semiconductor wafer W rotates the turntable 44 by 90 degrees, so that the chuck table 4 in FIG.
In the state of being positioned at the position 6 and being supported by the protection member 30, it is conveyed to the cleaning means 70 by the second conveying means 69. Then, after the grinding dust is removed by cleaning, the carry-in / out means 42 stores the waste in the cassette 41b.

For the semiconductor wafer W housed in the cassette 41b and supported by the protection member 30, for example, FIG.
The treatment process 13 such as etching is performed using the wet etching apparatus 80 shown in FIG.

In the wet etching apparatus 80 of FIG. 11, a holding table 81 holding the semiconductor wafer W is held.
Is driven by a drive unit 82 to be rotatable, and is held on a holding table 81 with the back surface of the semiconductor wafer W supported by the protection member 30 facing upward. By etching solution such as hydrofluoric acid or nitric acid as an etching treatment agent from 83 onto the back surface of the semiconductor wafer W, a predetermined amount of the entire back surface is etched. Then, when all of the grinding residual layer on the back surface is removed, as shown in FIG.
9 is exposed and divided into individual semiconductor chips C.

In the wet etching performed in this way, the cutting groove 29 does not penetrate to the back surface, so that the etching liquid enters from the cutting groove 29 and wraps around to the surface where the circuit is formed unlike the conventional case. The circuit will not be damaged.

In this embodiment, the case of performing wet etching as the treatment process has been described as an example, but the same applies to the case of dry etching.
It is possible to prevent the etching gas, which is an etching treatment agent, from entering the surface through the cutting grooves 29.

Further, in the treatment process for removing the unground layer by a felt grindstone in which felt is impregnated with abrasive grains, there is no risk of damaging the circuit on the surface, but there is a risk of promoting contamination of the side surface of the semiconductor chip. However, according to the present invention, such contamination can be prevented.

If the grinding residual layer is formed thicker than the grinding distortion layer, the grinding distortion layer can be completely removed by removing the grinding residual layer. The strength can also be improved.

Further, in the past, since grinding was performed until the cutting groove was exposed in the grinding process, grinding debris could enter the cutting groove and adversely affect the quality of the semiconductor chip. Since the grinding is not performed until the cutting groove is exposed, the grinding dust does not enter the cutting groove, and the deterioration of the quality of the semiconductor chip can be prevented.

[0037]

As described above, in the method of dividing a semiconductor wafer according to the present invention, the grinding is completed to form a residual grinding layer before the semiconductor wafer is divided into individual semiconductor chips in the grinding step, Since the residual grind layer is removed by etching in the etching step and divided into the semiconductor chips, it is possible to prevent the etching solution from being blocked by the residual grind layer and entering the surface of the semiconductor wafer through the cutting groove. Therefore, since the circuit is not damaged by the etching solution, the yield can be improved.

The thickness of the grinding strain layer formed on the back surface of the semiconductor wafer in the grinding process is 0.1 to 10 μm.
5 μm thicker than the thickness of this grinding strain layer
If a grinding residue layer of about 50 μm is formed, the grinding distortion layer can be completely removed by removing the grinding residue layer in the etching step. Therefore, the bending strength can be increased while not damaging the circuit.

Further, since the side surface of the semiconductor chip is not contaminated by the grinding dust, it is possible to produce a high quality semiconductor chip.

[Brief description of drawings]

FIG. 1 is a flowchart showing a method for dividing a semiconductor wafer according to the present invention.

FIG. 2 is a plan view showing a semiconductor wafer divided by the same semiconductor wafer dividing method.

FIG. 3 is a perspective view showing an example of a dicing apparatus used in a half-cutting step of the semiconductor wafer dividing method.

FIG. 4 is a front view showing a semiconductor wafer whose surface is half-cut by the same half-cutting step.

FIG. 5 is a schematic cross-sectional view showing a semiconductor wafer whose front surface is half-cut and whose back surface is supported by a protective member.

FIG. 6 is a perspective view showing the semiconductor wafer.

FIG. 7A is a front view showing how the tape is attached to the semiconductor wafer and the frame, and FIG. 7B is a front view showing how the attached tape is cut.

FIG. 8 is a perspective view showing an example of a grinding apparatus used in a grinding step of the semiconductor wafer dividing method according to the present invention.

FIG. 9 is a perspective view showing a grinding wheel that constitutes the grinding apparatus.

FIG. 10 is a schematic sectional view showing a semiconductor wafer ground by grinding.

FIG. 11 is a perspective view showing an example of a wet etching apparatus used in the etching step of the method for dividing a semiconductor wafer according to the present invention.

FIG. 12 is a schematic cross-sectional view showing a semiconductor chip divided and formed by the same etching process.

[Explanation of symbols]

11 ... Half-cut process 12 ... Grinding process 13 ... Etching process 20 ... Dicing device 21 ... Cassette 22 ... Carry-in / out means 23 ... Temporary storage area 24 ... 1st conveyance means 25 ... Chuck table 26 ... Alignment means 27 ... Rotating blade 28 ... Cutting means 29 ... Cutting groove 30 ... Protective member 31 ... Opening 32 ... Frame 33 ... Tape 35 ... Tape sticking device 36 ... Mounting table 37 ... Roller 38 ... Cutter 40 ... Grinding device 41a, 41b ... Cassette 42 ... Carry-in / out means 43 ... Centering table 44 ... Turntable 45, 46, 47, 48 ... Chuck table 49 ... First conveying means 50 ... First grinding means 51 ... Wall part 52 ... Guide rail 53 ... Drive source 54 ... Support part 55 ... Spindle 56 ... Mounter 57 ... Grinding wheel 58 ... Wheel base 59 ... Wheel piece 60 ... Second grinding means 61 ... Guide rail 62 ... Drive source 63 ... Support part 64 ... Spindle 65 ... Mounter 66 ... Grinding wheel 67 ... Wheel base 68 ... Whetstone piece 69 ... Second conveying means 70 ... Cleaning means 80 ... Wet etching device 81 ... Holding table 82 ... driving unit 83 ... dripping unit

Claims (3)

[Claims] 1. A method of dividing a semiconductor wafer, which is formed by dividing a plurality of semiconductor circuits by streets into individual semiconductor chips for each semiconductor circuit, which is formed on a surface of a semiconductor wafer. A half-cutting step of forming a cutting groove that does not penetrate to the back surface on the street, a grinding step of grinding the back surface with the front surface of the semiconductor wafer having the cutting groove formed supported by a protective member, and a grinding step of grinding the back surface to the back surface. And a treatment step of removing the generated grinding strain layer by a treatment treatment, in which the grinding of the back surface is finished before the cutting grooves are exposed and the semiconductor wafer is divided into individual semiconductor chips. To form a residual grinding layer, and in the treatment step, the residual grinding layer is removed to Semiconductor wafer dividing method for dividing the conductor chip. 2. The method for dividing a semiconductor wafer according to claim 1, wherein in the grinding step, the grinding residual layer is formed thicker than the grinding strain layer, and the grinding residual layer is completely removed in the treatment step. 3. The method for dividing a semiconductor wafer according to claim 1, wherein the thickness of the unground layer is 5 μm to 50 μm.