JPH0866848A - Cutting direction detection system - Google Patents

Abstract

PURPOSE: To automatically detect a cutting direction in which chipping is less likely to occur by selecting a less chipped groove through the comparison of the states of the grooves, for determining the cutting direction. CONSTITUTION: A first cut groove formed is positioned immediately below a photographing means 7, and the state of the first cut groove is detected and stored in a memory. After the direction for cutting the workpiece has been reversed by the rotation of a holding means 6 by 180 degrees, the surface of the workpiece is photographed by the photographing means 7, and an area to be cut is detected by a cutting means 9. In accordance with this alignment, at least one second groove is cut in the workpiece, and the state of the second cut groove is detected and stored in the memory. The states of the first and second cut grooves are compared, and the cutting direction is determined through the selection of the less chipped groove.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting direction determining system for cutting a workpiece such as a semiconductor wafer with a cutting device such as a dicer.

[0002]

2. Description of the Related Art Generally, in order to cut a semiconductor wafer, a rotating blade of a cutting machine cuts down along a cutting area (street) formed in a grid pattern. There is a difference in the occurrence of chipping between the case of cutting the street from right to left and the case of cutting the street from left to right. This tendency is particularly strong in compound semiconductors such as GaAs. Therefore, conventionally, only one line of the streets arranged in the parallel direction is cut, and the operator inspects the occurrence state of chipping. If the chipping is small, the cutting is continued in the same direction. Is reversed and the cutting is done from the opposite direction.

[0003]

However, the groove inspection by the operator as described above is troublesome and lowers the work efficiency, and if the cutting device is a full-automatic dicer, the manual groove inspection cannot be performed. When the cutting is performed from the direction in which a large number of defects occur, not only the quality is deteriorated but also many defective products are generated. The present invention is made in order to solve such a conventional problem, a cutting direction detection system capable of automatically detecting the cutting direction with less occurrence of chipping of a workpiece such as a wafer when cutting with a dicer. The challenge is to provide.

[0004]

As means for technically solving the above-mentioned problems, the present invention provides a holding means for holding a workpiece and a cutting for cutting the workpiece held by the holding means. In the case of cutting with a cutting device including at least a means and an imaging means for optically imaging the workpiece,
A first alignment step in which the surface of the workpiece held by the holding means is imaged by the imaging means and a cutting region to be cut by the cutting means is detected; and at least one workpiece is formed on the workpiece based on this alignment step. First to form a cutting groove
Cutting step for positioning the cutting groove directly below the image pickup means, detecting the groove state and storing it in the memory, and rotating the holding means by 180 ° to cut the workpiece. And a second alignment step in which the surface of the workpiece after the reversal is imaged by the imaging means and the cutting area to be cut by the cutting means is detected, and the workpiece is machined based on this alignment. A second cutting step of forming at least one cutting groove on the object; a second groove detecting step of positioning the cutting groove directly below the image pickup means, detecting the state of the groove, and storing it in a memory;
Cutting direction determination step configured by comparing the states of the grooves detected by the first groove detection step and the second groove detection step and selecting the one with less chipping to determine the cutting direction The system is the gist. Moreover, the state of the groove is the width of the area or the groove of the groove, to choose a smaller smaller or width of the area as the lesser of chipping, and CH ₁ of the cutting area of the workpiece, CH ₂
Determining the cutting direction for any of the cutting areas of
The subject is that the work piece is a compound semiconductor which is apt to cause chipping.

[0005]

[Operation] In the first alignment step, the blade and the street of the wafer are aligned, and in the first cutting step, at least one street is cut and the groove is
In the groove detection step, the degree of chipping is stored, and then the chuck table is rotated 180 ° to reverse the street direction in the cutting direction reversal step, and the wafer after the reversal is subjected to the second alignment step. Aligned with, and at least 1 in the second cutting step
The street of the book is cut, the groove is optically detected in the second groove detection step, and the degree of chipping is stored, and the chipping and second groove of the first groove detection step are stored in the cutting direction determination step. The chipping degree in the detection step is compared and the lesser degree of chipping is determined as the cutting direction. The degree of chipping is compared by the size of the groove area or the groove width. Since the streets have a grid pattern, the cutting direction is determined for both CH ₁ and CH ₂ . This is particularly effective for compound semiconductors that are apt to cause chipping.

[0006]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 shows an example of a dicer, in which a cassette 2 containing a plurality of wafers to be processed is placed in a cassette placing area 1, and one wafer in the cassette is placed in a standby area 4 by a loading / unloading means 3. Each of them is carried out one by one, and is conveyed to a chuck table 6 which is a holding means by a conveying means 5 having a swivel arm, and the chuck table 6 is moved and aligned by an image pickup means 7. Then, a cutting means 9 having a rotary blade 8 mounted thereon. It is designed to be cut.

As shown in FIG. 2, the wafer is fixed to a frame 11 via a resin tape 10. The wafer W has a cutting area (street) in the CH ₁ direction and in the C direction.
They are arranged in parallel in the H ₂ direction at regular intervals to form a grid.

Compound semiconductor W'of GaAs, GaP, etc.
Often has an irregular shape as shown in FIG. 3, and in such a case, a system for detecting the shape, position, and size of a workpiece disclosed in, for example, Japanese Patent Laid-Open No. 4-363047 is used together. Good to do.

When the wafer W is cut by the cutting means 9, first, as a first alignment step, the wafer W is aligned through the image pickup means 7 in order to align the rotary blade 8 and the street.

After the alignment, in the first cutting step, at least one street is down-cut by the rotary blade 8 while moving the chuck table 6 as shown in FIG. At this time, it is assumed that the street of the wafer W in the CH ₁ direction is cut from A to B as shown in FIG.

After cutting, the CH ₁ cutting groove is positioned immediately below the image pickup means 7 in the first groove detecting step,
The state of the groove is detected and an image digitally converted as shown in FIG. 5B is displayed on the monitor 12, the area of the cutting groove U ₁ is calculated based on the image, and the memory M ₁ of the CPU (not shown) is calculated. Remember.

After that, the chuck table 6 is rotated 180 ° in the cutting direction reversing step, and a second alignment step is performed in which the rotary blade 8 and the street are aligned with each other via the image pickup means 7.

Next, in the second cutting step, at least one street is down-cut by the rotary blade 8 while moving the chuck table 6 as shown in FIG. That is, as shown in FIG. 7A, the street in the CH ₁ direction of the wafer W is cut from B to A.

After cutting, the cutting grooves B to A of CH ₁ are positioned immediately below the image pickup means 7 by the second groove detecting step, and the state of the grooves is detected in the same manner as described above, and then the state shown in FIG. Display the digitally converted image on the monitor 12,
The area of the cutting groove U ₂ is calculated based on the image and the CPU
It is stored in the memory M ₂ (not shown).

Thereafter, in the cutting direction determining step, the memories M ₁ and M ₂ are compared with each other, and _one having a smaller cutting groove area, that is, one having less chipping is selected to determine the cutting direction. In the illustrated example, the cutting groove U ₁ has a smaller area than U _{2, and} therefore the cutting direction is determined from A to B. FIG. 8 is a flowchart showing the above steps.

[0016] Based on the cutting direction determination, the wafer W is all the streets respect CH ₁ direction is cut from A to B direction, but after the cutting ends are cut with respect to CH ₂ direction of the wafer W, the CH ₂ The same method as above is used to determine the cutting direction. However, as a pre-stage, it is necessary to rotate the chuck table 6 by 90 ° so that the street in the CH ₂ direction and the cutting direction of the rotary blade are parallel.

In the comparison of the chipping state of the cutting groove, the area of the groove is used as a parameter and the smaller area is selected as the less chipping, but the smaller width is selected as the parameter and the smaller one is selected as the less chipping. You may do it. Further, the present invention can be sufficiently applied to an amorphous compound semiconductor as shown in FIG. 3 in exactly the same manner.

[0018]

As described above, according to the present invention,
When the lattice street of the wafer is cut by the rotating blade, the cutting direction with less chipping can be automatically detected, so that the quality can be improved and defective products can be prevented. In particular, it has excellent effects such as being effective for a compound semiconductor which is apt to cause chipping and being suitable for a full-auto dicer.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a dicer.

FIG. 2 is a top view of wafers housed in a cassette.

FIG. 3 is a top view of an amorphous compound semiconductor.

FIG. 4 is an explanatory diagram showing a state of a first cutting step.

5A is an explanatory view showing a cutting direction at the first cutting step, and FIG. 5B is an image view of the cutting groove.

FIG. 6 is an explanatory diagram showing a state of a second cutting step.

FIG. 7A is an explanatory view showing the cutting direction at the second cutting step, and FIG. 7B is an image view of the cutting groove.

FIG. 8 is a flowchart of steps.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Cassette mounting area 2 ... Cassette 3 ... Carrying in / out means 4 ... Standby area 5 ... Conveying means 6 ... Chuck table 7 ... Imaging means 8 ... Rotating blade 9 ... Cutting means 10 ... Resin tape 11 ... Frame 12 ... Monitor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H01L 21/301 H01L 21/78 F

Claims (4)

[Claims] 1. A cutting device comprising at least holding means for holding a workpiece, cutting means for cutting the workpiece held by the holding means, and imaging means for optically imaging the workpiece. In the case of cutting, a first alignment step of capturing an image of the surface of the workpiece held by the holding means by the image pickup means and detecting a cutting region to be cut by the cutting means, and a first alignment step based on this alignment. A first cutting step of forming at least one cutting groove in the workpiece; a first groove detecting step of positioning the cutting groove directly below the imaging means, detecting a groove state, and storing the state in a memory; A cutting direction reversing step of reversing the cutting direction of the work piece by rotating the holding means by 180 °, and an image of the surface of the work piece after reversing is picked up by the image pick-up means to detect a cutting area to be cut by the cutting means. A second alignment step; a second cutting step for forming at least one cutting groove on the workpiece based on this alignment; and positioning the cutting groove directly below the image pickup means to detect the state of the groove. Cutting for determining the cutting direction by comparing the states of the grooves detected by the second groove detecting step stored in the memory, the first groove detecting step, and the second groove detecting step, and selecting the one with less chipping to determine the cutting direction. A cutting direction determination system including a direction determination step. 2. The cutting direction determining system according to claim 1, wherein the groove state is an area of the groove or a width of the groove, and one having a smaller area or one having a smaller width is selected as one having less chipping. 3. A CH ₁ cutting area of a workpiece and CH ₂
The cutting direction determination system according to claim 1, wherein the cutting direction is determined for any of the cutting regions. 4. The cutting direction determination system according to claim 1, wherein the work piece is a compound semiconductor which is apt to cause chipping.