JPH07335593A - Dicing method - Google Patents

Abstract

PURPOSE:To solve a problem that the surface of a wafer is damaged when a blade is returned to the X-axis due to a fact that the thickness of the wafer is a little irregular or to solve a problem that a cutting depth from the surface cannot be made uniform. CONSTITUTION:Before a wafer is diced, the thickness of the wafer is measured by an autofocus operation or the like, and the Z-axis control of a blade 10 is executed on the basis of its measured value. When the blade which has cut a street in the wafer is returned relatively to a cutting starting point in order to cut a next street, the blade 10 is retreated to the Z-axis direction on the basis of the actually measured value of the thickness of the wafer in such a way that the surface of the wafer is not damaged by the blade 10. On the basis of the actually measured value of the thickness of the wafer, the cutting depth of the blade 10 with reference to the wafer is controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dicing method which can prevent mis-dicing due to variations in wafer thickness when dicing a wafer.

[0002]

2. Description of the Related Art When dicing a wafer with a dicing machine, the thickness of several wafers in a lot is measured, the maximum value is stored in a CPU, and the blade is instructed by the CPU based on the data. Is controlled in the Z-axis direction (vertical direction) to perform dicing along the streets of the wafer.

[0003]

During the conventional dicing, a wafer thicker than the data stored in the CPU may be thrown in, and the conventional dicing device cannot detect the thickness error and the blade is When returning to the cutting starting point (X-axis return) for cutting the next street, problems such as scratching the surface of the wafer occur.
Further, if the thickness of the wafer varies, the cutting depth also varies accordingly. That is, in the case of a thick wafer, the cutting depth from the surface becomes excessive, and in the case of a thin wafer, the cutting depth from the surface becomes insufficient. Therefore, the present invention has a problem that the surface of the wafer is damaged when the blade returns to the X-axis due to a slight variation in the thickness of the wafer, or the cutting depth from the surface cannot be kept uniform. It was made for the purpose of solving the problem.

[0004]

As a means for technically solving the above-mentioned problems, the present invention measures the thickness of a wafer by autofocus etc. before dicing the wafer, and based on the measured value The gist is a dicing method for performing Z-axis control of a blade. Also, when the blade that cuts the street of the wafer returns relatively to the cutting start point for cutting the next street, the blade is moved in the Z-axis direction based on the measured value of the wafer thickness so as not to damage the wafer surface by the blade. The purpose is to retreat to, and control the cutting depth of the blade with respect to the wafer based on the measured value of the wafer thickness.

[0005]

[Operation] At the time of alignment before dicing, the thickness of each wafer is measured by autofocus, etc., and the Z axis control of the blade is performed based on the measurement data according to the command from the CPU. Even if there is a variation in the above, by sufficiently retracting in the Z-axis direction when the blade returns to the X-axis, the surface of the wafer is not damaged and the cutting depth from the surface can be kept uniform.

[0006]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In FIG. 1, reference numeral 1 denotes a cassette placed in a cassette placing area 2, and a plurality of wafers are stored in the cassette 1. The carrying-in / out means 3 places the wafers one by one in a standby area 4. Be shipped. The carried-out wafer is carried on the chuck table 6 by the carrying means 5 having a turning arm and is fixed by suction,
After that, the chuck table 6 is moved to be positioned directly below the alignment means 7.

The alignment means 7 aligns the streets of the wafer by using a known optical means such as a CCD camera, measures the thickness of the wafer by auto focus, etc., and inputs the measured data to the CPU 8 for storage. Let

After the wafer alignment and the thickness measurement, the chuck table 6 is moved and the wafer 10 is diced by the blade 10 attached to the tip of the spindle 9a of the cutting means 9.

The cutting direction of the dicing is limited to a fixed direction (right to left in the illustrated example) along each street S of the wafer W in relation to the rotating direction of the blade 10 as shown in FIG. This is because if the rotation direction of the blade 10 is the direction in which the wafer W is rolled up from the bottom with respect to the cutting direction, chipping called chipping often occurs during cutting, which is unsatisfactory.

Therefore, when cutting the next street, the blade 10 is returned to the cutting start point in the X-axis direction while being moved in the Y-axis direction while dividing the street into spaces. When the blade 10 returns to the X-axis, the blade 10 is retracted upward in the Z-axis direction as shown in FIG. 3 so as not to contact the surface of the wafer W and damage it.

Raising amount P of this blade 10 in the Z-axis direction
The (retraction amount) needs to be minimized in order to improve productivity, and the minimum value is instructed to the cutting means 9 from the CPU, and a Z-axis drive mechanism (not shown) based on the instruction signal.
Is transmitted to the blade 10 by driving.

In this way, since the minimum retreat amount of the blade 10 is instructed from the CPU 8 for each wafer, the X-axis of the blade 10 is maintained even if the thickness of the wafer varies or a particularly thick wafer is loaded. It is possible to prevent scratches on the wafer surface when returning.

To cut the next street after returning to the X-axis, the blade 1 is instructed by the CPU 8 as shown in FIG.
0 is moved downward by the amount P corresponding to the minimum retracted amount in the Z-axis direction. In this case, the blade 10
Although the example in which the tool is moved in the X-axis direction to perform cutting has been described, the chuck table 5 may be moved in the X-axis direction to perform cutting, that is, relative movement between the two.

On the other hand, as shown in FIG. 4, some wafers W'have to be cut to a certain depth D from the surface. For example, a wafer having a two-layer structure including a silicon layer and a glass layer corresponds to this. In performing such cutting, conventionally, the blade 10 was lowered and kept constant so that the cutting depth was D. However, if the thickness of the wafer W ′ varies, the cutting depth also varies accordingly.

In the present invention, the thickness is measured for each wafer, the measured data is stored in the CPU 8, and the cutting depth is always D corresponding to the thickness of each wafer by a command from the CPU 8 during dicing. Blade 10
Since the Z-axis control is performed, the cutting depth does not vary even if the wafer W ′ varies in thickness.

As the wafer thickness measuring means, there is an advantage that the measuring means does not need to be separately provided by an optical method such as auto-focusing of the alignment means. It is possible to use suitable thickness measuring means such as type measuring means.

[0017]

As described above, according to the present invention,
The thickness of each wafer is measured before dicing, the measured data is stored in the CPU, and the blade is controlled in the Z-axis direction according to a command from the CPU during dicing, so that there is some variation in the thickness of the wafer. Even if there is, it has an excellent effect that the surface of the wafer is not damaged when the blade returns to the X-axis and the cutting depth from the surface can be always kept uniform.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a procedure for dicing a wafer.

FIG. 3 is an explanatory view showing the movement of the blade.

FIG. 4 is an explanatory diagram showing a cutting depth of a wafer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Cassette 2 ... Cassette mounting area 3 ... Carrying in / out means 4 ... Standby area 5 ... Conveying means 6 ... Chuck table 7 ... Alignment means 8 ... CPU 9 ... Cutting means 9a ...
Spindle 10 ... Blade

Claims (3)

[Claims] 1. A dicing method in which the thickness of a wafer is measured by autofocus or the like before dicing the wafer and Z-axis control of a blade is performed based on the measured value. 2. When a blade that has cut a street of a wafer returns relatively to the starting point for cutting the next street, the blade is cut based on an actual measurement value of the wafer thickness so as not to scratch the wafer surface by the blade. The dicing method according to claim 1, wherein the dicing method is retracted in the Z-axis direction. 3. The dicing method according to claim 1, wherein the cutting depth of the blade with respect to the wafer is controlled based on an actually measured value of the wafer thickness.