JPH06224298A - Dicing method - Google Patents

Abstract

PURPOSE:To continuously cut a wafer without generating a defective part when cutting is restarted even if the wafer is once removed from a dicing table by once stopping the cutting by so cutting the wafer as to generate a partial cut rest in two crossing directions and then cutting the rest. CONSTITUTION:A semiconductor wafer 10 is so cut as to generate a partial cut rest on a set cutting line(CL) 12 of a first direction set on the wafer 10. Then, the wafer 10 is so sequentially cut as to subsequently continuously form a semiconductor wafer part 17 having a cut rest continuously to a part having an initial cut rest for all the set CL 12 of the first direction. Then, the wafer 10 is sequentially cut along a set CL 20 of a second direction crossed with the set CL 12 of the first direction similarly to a cutting operation along the set CL 12 of the first direction. Thereafter, cut rests 30 are cut along the set CLs 12, 20 of the first and second directions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for dicing a semiconductor wafer, and more specifically, even if the cutting is stopped and the semiconductor wafer is once removed from the dicing table and then the cutting is restarted, a defective portion is generated. The present invention relates to a semiconductor wafer full-cut dicing method improved to a small number.

[0002]

2. Description of the Related Art In the manufacture of a semiconductor device, a semiconductor wafer (hereinafter, simply referred to as a wafer for simplicity) obtained after a series of processes for forming a semiconductor element is shaped like a grid in a dicing process. And cut into chips of desired size. In the dicing process, a wafer dicing apparatus as shown in FIG. 4A is used to rotate the dicing blade at a high speed to cut the wafer. In FIG. 4, reference numeral 100 denotes a dicing device, and 10
Reference numeral 2 denotes a dicing blade having a cutting edge on its peripheral edge (hereinafter, abbreviated as a blade for simplicity), and 104 denotes a wafer being dicing. Wafer 104 is generally shown in FIG.
For convenience of dicing, the tape 108 is adhered onto a dicing tape (hereinafter abbreviated as tape for simplicity) 108 having an adhesive layer on its surface for convenience of dicing.
Through the vacuum suction hole 109 through the dicing table 1
It is adsorbed and held on 05.

Incidentally, the dicing method includes a half-cut or semi-full-cut dicing method and a full-cut dicing method. In the half-cut dicing method, as shown in FIG. 5A, a cutting groove 106 is formed in the wafer 104 by the blade 102 up to about half the wafer thickness, and the wafer 104 is later braked to divide it into desired chips. is there. On the other hand, in the full-cut dicing method, as shown in FIG. 5B, the kerf 10 cut by the blade 102 beyond the wafer thickness to the tape 108.
6 is made and the wafer 104 is completely cut. Recently, a full-cut dicing method that does not require a braking process is often used because the chip surface damage or the chip damage that occurs in a later braking process is disliked.
Has been adopted.

[0004]

By the way, in the dicing process, the cutting edge of the blade is worn or damaged during dicing, and it is often necessary to replace the blade with a new one. Occurs. After replacing the blade, before restarting the dicing of the wafer that has been cut by the replaced blade, the cutter setting work to adjust the blade height by contacting the blade with the dicing table surface that holds and holds the semiconductor wafer. Also, the pre-cutting work of cutting the dummy wafer to break in the teeth of the blade must be performed. Therefore, the wafer that has been cut and stopped by being held on the dicing table is temporarily removed from the dicing table, and after the above-mentioned cutter setting work and precut work are performed,
It becomes necessary to hold the wafer on the dicing table again.

The individual chips or wafer slices cut are strongly adsorbed and held on the dicing table via the tape during the dicing, so that the mutual positional relationship between them and the kerf is the same as the original setting at the time of setting. The condition is maintained correctly. However, in the conventional full-cut dicing method, when the wafer being cut is removed from the dicing table as described above, the cut individual chips or wafer slices are only adhered to the soft tape, Due to the expansion and contraction of the tape itself or the adhesive layer, they move into a positional relationship of dimensions different from the dimensions at the time of cutting,
The prescribed dimensional accuracy could not be maintained.

For this reason, as shown in FIG. 6A, the wafer 104, which had been cut along the set cutting line on the dicing table, is interrupted at point A due to the damage of the blade, and then the dicing table is restarted. It was actually very difficult to place the tape on the substrate and resume the cutting from the point A, for example, because the dimension of the kerf 106 or the mutual positional relationship is different from the original state and is different. Also, if the blade is damaged while cutting in the X-axis direction, X
Since the positional relationship of the kerfs in the axial direction is changed and the cutting in the Y-axis direction is performed next time, the chip size becomes different from the predetermined one, so that the cutting in the Y-axis direction cannot be performed. Therefore, re-cutting is often not possible, and the part that was cut before the blade replacement (shadow part in Fig. 6 (b)) is a defective part that does not pass the dimensional specifications and cannot be commercialized, so it must be discarded. As a result, the yield of chips decreased. Further, in the state of being removed from the dicing table, the cut chips or wafer pieces were only held by adhesion with the tape, and were in an unstable state because of insufficient holding force. Therefore, during the work of removing the wafer from the dicing table or remounting it on the dicing table for the replacement of the blade, the chips and the wafer pieces often move and come into contact with each other and are often damaged. This further reduced the chip yield.

In view of the above problems, it is an object of the present invention to continue cutting even if a wafer is temporarily cut and removed from the dicing table when the cutting is restarted without causing a defective portion. It is another object of the present invention to provide an improved full-cut semiconductor wafer dicing method.

[0008]

In order to achieve the above-mentioned object, the dicing method according to the present invention is designed so that some uncut portions are left on the set cutting line in the first direction set on the semiconductor wafer. To cut the semiconductor wafer,
Then, for all of the set cutting lines in the first direction, a step of sequentially cutting the semiconductor wafer so as to continuously form a semiconductor wafer portion having an uncut portion following the portion having the first uncut portion, and A step of sequentially cutting the semiconductor wafer along a setting cutting line in a second direction that intersects the setting cutting line in the first direction, similarly to the operation of cutting along the setting cutting line in the first direction; And cutting each uncut portion along the set cutting lines in the first and second directions.

In the method of the present invention, the semiconductor wafer is cut by the full cut method. That is, in the method of the present invention, the semiconductor wafer is completely cut by making a cut groove in the semiconductor wafer that exceeds the thickness of the wafer and is cut by the dicing blade up to the dicing tape. In the present invention, the shape of the semiconductor wafer portion having the uncut portion is not limited as long as it is continuously formed so that the semiconductor wafer can be integrally held. For example, a portion having an uncut portion is formed in an annular shape on the periphery of the semiconductor wafer or in a cross shape in the central portion.

The set cutting line referred to in the present invention is a line for cutting a semiconductor wafer along this line, and does not necessarily mean a cutting line actually described on the semiconductor wafer, and it is a dicing machine. It means the cutting line set in the control device of. The dicing start point and the dicing end point have the same meaning. The method of the present invention can be applied regardless of the size, shape and material of the semiconductor wafer and the shape and size of the chip formed by cutting the semiconductor wafer.

A dicing method according to a preferred embodiment of the present invention is characterized in that a position on a set cutting line in a first direction set on a semiconductor wafer is located inward from a peripheral edge of the semiconductor wafer and a position opposite to the position. A cutting start point and a cutting end point are set respectively, the semiconductor wafer is cut from the cutting start point to the cutting end point along the set cutting line, and then all of the setting cutting lines in the first direction are performed in the same manner as the above operation. Regarding the step of sequentially cutting the semiconductor wafer and the operation of cutting along the setting cutting line in the first direction, along the setting cutting line in the second direction that intersects the setting cutting line in the first direction. And sequentially cutting the semiconductor wafer, and starting cutting from the peripheral edge along the set cutting lines in the first and second directions. It is characterized in that it comprises up to and a step of cutting each uncut semiconductor wafer to the peripheral edge from the cutting end point.

A dicing method according to another preferred embodiment of the present invention sets two cutting start points spaced apart from each other in a central portion on a set cutting line set in a first direction on a semiconductor wafer. , Cutting outward from the respective cutting start points along the set cutting line in the first direction to the peripheral edge of the semiconductor wafer, and then sequentially performing the same operation as described above for all of the set cutting lines in the first direction. Similarly to the step of cutting the semiconductor wafer and the cutting operation along the setting cutting line in the first direction, the semiconductor wafer is sequentially cut along the setting cutting line in the second direction intersecting the setting cutting line in the first direction. Cutting step and half along the set cutting lines in the first and second directions from one set cutting line start point to the other cut start point It is characterized by comprising the step of cutting the body wafer uncut respectively.

[0013]

With the above-described structure of the dicing method according to the present invention, the uncut semiconductor wafer portion functions as a strength member that integrally maintains the semiconductor wafer including the dicing tape, and the dicing tape and its adhesive layer expand and contract. Can be significantly suppressed. Therefore, by leaving the uncut portion on the semiconductor wafer, the positional relationship of the cut grooves formed by cutting the semiconductor wafer does not change even if the semiconductor wafer is once removed from the dicing table, and is maintained as it is. Can be done. This allows the semiconductor wafer to be temporarily removed from the dicing table in order to replace the dicing blade during cutting, and then placed on the dicing table again, and when the cutting is restarted, the cutting is continued from the position where the cutting was stopped. You can continue. As a result, the defective portion that would occur when the conventional dicing method is applied does not occur. In addition, during the work of removing the semiconductor wafer from the dicing table and placing it on the dicing table, the ratio of the cut chips colliding with each other and being damaged is greatly reduced.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the accompanying drawings. Example 1 FIGS. 1 (a), 1 (b) and (c) and FIGS. 2 (a), 2 (b) and 2 (c) are explanatory views showing the dicing method according to Example 1 step by step. As shown in FIG. 1A, a distance d from a peripheral point 13 along a set cutting line 12 (virtual line) in the X-axis direction set on a semiconductor wafer (hereinafter, simply referred to as a wafer for simplicity) 10. point 1 a distance of only ₁
4 and the cutting start point and the cutting end point are set at a point 16 (a point separated by a distance d ₂ from the peripheral point 15) opposite to the point 14 on the setting cutting line 12. still,
The peripheral points 13 and 15 indicate the positions of the peripheral edge of the wafer which intersects with the set cutting line 12, respectively.
As described above, the cutting start point and the cutting end point are set for all the set cutting lines in the X-axis direction.

Next, as shown in FIG. 1 (b), a dicing blade (hereinafter simply referred to as a blade for simplicity).
18 is set at the cutting start point 14, and the wafer 10 is cut along the set cutting line 12 to the cutting end point 16. In addition, cutting means cutting by a full-cut method. The same applies below. In the figure, 19 is a wafer 1.
This means a kerf formed by cutting 0, and the portions from the peripheral edge 13 to the cutting start point 14 and the cutting end point 16 to the peripheral edge point 15 are the uncut portions. Further, since the speed at which the blade is lowered to the cutting start point 14 affects the cutting quality at the cutting start point 14, it is desirable to provide the dicing apparatus with a mechanism capable of controlling the descending speed of the blade. Hereinafter, the wafer 10 is sequentially cut in the same manner for all of the set cutting lines 12 in the X-axis direction. FIG. 1C is a perspective view schematically showing the wafer 10 cut along a set cutting line in the X-axis direction, and reference numeral 19 denotes an actually cut kerf in the X-axis direction. In the figure, reference numeral 17 denotes an annular portion formed of a portion left uncut on the periphery of the wafer 10.

Next, a dicing table (not shown) on which the wafer 10 is placed is rotated by 90 °, and as shown in FIG. 2A, a set cutting line 20 in the Y-axis direction set on the wafer 10. A point 22 that is separated from the peripheral point 21 by a distance d ₃ and a point 24 that faces the point 22 on the set cutting line 20 (a distance d ₄ from the peripheral point 23).
Set a cutting start point and a cutting end point respectively at points (distances). It should be noted that the peripheral points 21 and 23 indicate the positions of the peripheral edge of the wafer which intersects with the set cutting line 20, respectively. Next, the blade 18 is set at the cutting start point 22 and the wafer 10 is cut along the set cutting line 20 to the cutting end point 24 as shown in FIG. Reference numeral 25 in the drawing denotes a kerf in the Y-axis direction formed by cutting the wafer 10. The wafer portion from the peripheral point 21 to the cutting start point 22 and the cutting end point 24 to the peripheral point 23 is the uncut portion. .

Thereafter, the wafer is sequentially cut in the same manner for all of the set cutting lines in the Y-axis direction. Figure 2
(B) is a perspective view schematically showing the wafer 10 cut along the set cutting lines in the X-axis direction and the Y-axis direction. In the figure, reference numeral 30 denotes an annular portion formed by the uncut portion left on the peripheral portion of the wafer 10. The distances d ₁ and d ₃ along the set cutting from the peripheral point to each cutting start point and the distances d ₂ and d ₄ along the set cutting from each cutting end point to the peripheral point may be slightly different values, respectively. The same value may be used. Further, the width of the uncut portion 30 shown by an imaginary line on the wafer periphery in FIG. 2B (distance from the periphery toward the center of the wafer) may be the same width.

Next, a cutting line 1 in the X-axis direction
2 and along the cutting line 20 in the Y-axis direction, from the cutting start point to the peripheral point and from the cutting end point to the peripheral point,
Similarly, cutting is performed by a blade to complete dicing. FIG. 2C shows the wafer 10 in which the dicing is completed and the cut grooves 19 and 25 are cut along the entire length of the set cutting line.

The uncut portion 30 at the peripheral portion of the wafer 10 shown in FIG. 2 (b) serves as a strength member for integrally holding the cut wafer 10 and greatly expands and contracts the tape and its adhesive layer. Can be suppressed. Therefore, by leaving the uncut portion 30 on the wafer 10, the positional relationship between the cut grooves 19 and 25 does not change even if the wafer 10 is once removed from the dicing table (not shown), and remains in its original state. Can be maintained. Even if the wafer 10 is interrupted during the cutting, the cutting can be continued as it is from the position where the cutting is stopped along the predetermined cutting line, so that the ratio of defective wafer portions is extremely low.

Embodiment 2 FIG. 3 shows a wafer 40 for each dicing step in the case where the wafer is cut so that the uncut portion is left in the central portion, as an alternative to the first embodiment. As shown in FIG. 3A, in the wafer 40, the uncut portion 42 is left in a cross shape in the X-axis direction and the Y-axis direction in the central portion of the wafer 40. In the method of the second embodiment, first, two cutting start points 46 and 48 are separated at the center of the set cutting line 44 in the X-axis direction.
From the peripheral edge point 5 of the semiconductor wafer to the outside along the set cutting line 44 in the X-axis direction.
Cut to 0,52. Next, the wafer 40 is sequentially cut on all of the set cutting lines in the X-axis direction by the same operation as described above.

Next, a dicing table (not shown) on which the wafer 40 is placed is rotated by 90 °, and two cutting start points 56 and 58 are set apart from each other at the center of the set cutting line 54 in the Y-axis direction. Then, the semiconductor wafer is cut outward along the Y-axis direction set cutting line 54 to the peripheral points 60 and 62 of the semiconductor wafer. Next, the wafer 40 is sequentially cut on all of the set cutting lines in the Y-axis direction by the same operation as described above. Figure 3 (a) shows
A wafer 40 having an uncut portion 42 after being cut in this manner is shown. In the figure, 64 is a kerf in the X-axis direction, and 66 is a kerf in the Y-axis direction. Then, the uncut portion 42 is sequentially cut along the set cutting line to complete the dicing. FIG. 3B shows the wafer 40 after the dicing is completed and the cut groove 64 in the X-axis direction and the cut groove 66 in the Y-axis direction are cut along the entire length of the set cutting line. .

In the method of the second embodiment, similarly to the method of the first embodiment, the uncut portion 42 functions as a strength member for integrally holding the cut wafer 40, and the wafer 40 is diced on the dicing table (see FIG. Even if it is removed from (not shown) or placed again, the positional relationship of the kerf of the cut portion can be correctly maintained in the original size. Therefore, even if the wafer 40 is interrupted during the cutting, the cutting can be continued from the position where the cutting is stopped along the set cutting line, and the ratio of defective wafer portions is extremely low.

Desirably, as a modification of the second embodiment, as shown in FIG. 3C, a cross-shaped uncut portion 42 is left in the central portion of the wafer 40 and the peripheral portion of the wafer 40 is also cut into an annular shape. Leave the remaining portion 17. This makes it possible to maintain the integrity of the wafer during dicing more firmly. In order to leave the uncut portion in such a shape, the dicing methods described in the first and second embodiments are applied together.

[0024]

According to the method of the present invention, the dicing process is divided into the first step and the second step. In the first step, the uncut portion is continuously formed on the semiconductor wafer, and the uncut portion is left in the second step. The part is cut. In the first stage, the uncut portion is used to integrally hold the semiconductor wafer being cut, and the expansion and contraction of the dicing tape and its adhesive layer are significantly suppressed. By leaving the uncut portion on the semiconductor wafer, even if the semiconductor wafer is removed from the dicing table or put on the dicing table again, the positional relationship of the cut grooves of the cut portion does not change and the original dimensions are correctly maintained. be able to. Accordingly, even when the semiconductor wafer once removed from the dicing table is placed on the dicing table again during the cutting and the cutting is restarted, the cutting can be continued from the position where the cutting was stopped along the set cutting line. Therefore, unlike the conventional dicing method, the part cut before restarting becomes a defective product, and by applying the dicing method according to the present invention,
The yield in the dicing process can be improved.

[Brief description of drawings]

FIG. 1A, FIG. 1B, and FIG. 1C are explanatory diagrams showing a dicing method according to an embodiment of the present invention step by step.

2 (a), (b) and (c) are explanatory views showing the method of the embodiment following FIG. 1 step by step.

3 (a) and 3 (b) are explanatory views showing a dicing method according to another embodiment of the present invention step by step. FIG. 3C shows an uncut portion according to still another embodiment.

FIG. 4A is a perspective view of a dicing device, and FIG. 4B is a schematic cross-sectional view showing a state in which a cut semiconductor wafer is placed on a dicing table.

5A and 5B are diagrams illustrating a dicing method.

FIGS. 6A and 6B are views for explaining that a defective portion is generated in the conventional dicing method.

[Explanation of symbols]

 10 Semiconductor Wafer 12 X-Axis Setting Cutting Lines 13, 15 Peripheral Point 14 Cutting Start Point 16 Cutting End Point 17 Uncut Part 18 Dicing Blade 19 X-Axis Groove 20 Y-Axis Setting Cutting Line 21, 23 Peripheral Point 22 Cutting start point 24 Cutting end point 25 Y-axis kerf 30 Uncut portion 40 Semiconductor wafer 42 Uncut portion 44 X-axis setting cutting line 46, 48 Cutting start point 50, 52 Peripheral point 54 Y-axis setting cutting line 56 , 58 Cutting start point 60, 62 Peripheral point 64 X-axis kerf 66 Y-axis kerf

Claims (3)

[Claims] 1. A semiconductor wafer is cut such that a part of the cutting is left on a setting cutting line in the first direction set on the semiconductor wafer, and then all of the setting cutting lines in the first direction are cut. A step of sequentially cutting the semiconductor wafer so that a semiconductor wafer portion having an uncut portion is continuously formed following the first portion having an uncut portion; and a step of cutting along the set cutting line in the first direction. In the same manner as the operation, the step of sequentially cutting the semiconductor wafer along the setting cutting line in the second direction that intersects the setting cutting line in the first direction, and the setting cutting lines in the first and second directions are performed. And a step of cutting each of the uncut portions along the same. 2. A cutting start point and a cutting end point are respectively set at a position inward of a peripheral edge of the semiconductor wafer and a position opposite thereto on a set cutting line set in the first direction on the semiconductor wafer. A step of cutting the semiconductor wafer from the cutting start point to the cutting end point along the set cutting line, and then sequentially cutting the semiconductor wafer on all of the set cutting lines in the first direction in the same manner as the above operation, A step of sequentially cutting the semiconductor wafer along a setting cutting line in a second direction that intersects the setting cutting line in the first direction, similarly to the operation of cutting along the setting cutting line in the first direction; and Semiconductor wafer from the peripheral edge to the cutting start point and from the cutting end point to the peripheral edge along the set cutting lines in the first and second directions Dicing method according to claim 1, characterized in that it comprises a step of cutting uncut respectively. 3. On a set cutting line in a first direction set on a semiconductor wafer, the center line is spaced apart from the set cutting line 2.
Individual cutting start points are set, and each cutting start point is cut outward along the set cutting line in the first direction to the peripheral edge of the semiconductor wafer, and then, in the same manner as the above operation, in the first direction. Similarly to the step of sequentially cutting the semiconductor wafer for all of the set cutting lines and the operation of cutting along the set cutting line in the first direction, the cutting in the second direction intersecting the set cutting line in the first direction is performed. A step of sequentially cutting along the set cutting line, and a step of cutting the uncut portion of the semiconductor wafer from one set cutting line starting point to the other cut starting point along the set cutting lines in the first and second directions, respectively. The dicing method according to claim 1, further comprising: