JPH0818329B2 - Wafer cutting failure detection method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a wafer cutting failure detection method when a large number of wafers are manufactured by sequentially cutting a semiconductor single crystal ingot by an inner peripheral blade.

[Conventional technology]

Generally, warpage and thickness defect of a silicon wafer for semiconductor devices occur as follows. That is, the warp of the wafer is caused by the inner peripheral blade bending during cutting. And, the curvature of the inner peripheral blade at the time of cutting, the symmetry of the cutting edge shape on both side surfaces of the inner peripheral blade, the balance of the cutting resistance,
When the balance of the ease of escape of cutting particles is lost, a large stress is applied to one side of the cutting edge. In this case, the above-mentioned curvature is generally maximum in the diameter part of the ingot,
The cutting surface of the ingot has an annular lens shape because it is in a substantially restored state at the cutting start point and the cutting end point. In addition, there are various cases in which the direction of the curve is reversed during cutting, the blade edge slides in the direction opposite to the curve, and the cutting surface becomes a saddle shape. In particular, the occurrence or restoration of abrupt curvature near the cutting start point and the cutting end point causes local warping, and even if lapping is performed, the slide surface cannot be partially removed. Moreover, the change in the shape of the warp causes variations in the thickness of the wafer and defective taper, as shown in FIG. In the figure, reference numerals 1 to 10 are cutting numbers, A to I are wafers, 11
Indicates the inner peripheral blade.

[Problems to be solved by the invention]

The present invention intends to solve the problems of defective wafer thickness and defective taper which are obstacles in the subsequent wafer chamfering process and lapping process.

The present invention has been made in view of the above circumstances, and an object thereof is to detect a change in the shape of the warp, thereby reliably and smoothly causing a thickness defect and a taper defect of the wafer based on this. Provided is a wafer cutting failure detection method capable of detecting a defective wafer that has been cut, capable of quickly detecting a defective wafer, suppressing the amount of defective wafers generated, and preventing the defective product from being sent to the next step. Especially.

[Means for solving problems]

In order to achieve the above object, the present invention, when cutting the semiconductor single crystal ingot, detects the cutting shape of the wafer, takes the difference between one cutting shape and the next cutting shape, the difference is a set value When the above is the case, the cutting operation of the semiconductor single crystal ingot is stopped.

[Work]

In the wafer cutting failure detection method of the present invention, each time the semiconductor single crystal rod is cut, the cutting shape is detected, one cutting shape is compared with the next cutting shape, and the difference is set. When the value exceeds the value, it is judged that the cut wafer has defective thickness or defective taper, and the cutting operation is interrupted.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 6.

1 and 2 show an example of a cutting apparatus for carrying out the method of the present invention. FIG. 1 is a perspective view showing a schematic structure, and FIG. 2 is a block diagram. In these figures, reference numeral 11
Is a blade (inner peripheral blade), and this blade 11 is a thin plate donut-shaped base metal 12 having a grindstone portion 13 formed on the inner peripheral portion thereof. Then, the cylindrical single crystal semiconductor rod 14 of silicon or the like is cut by the grindstone portion 13 to obtain a large number of wafers A.
.About.I (see FIG. 4). In addition, 15
Is an attachment member such as carbon for holding the cut wafers together.

A magnetic sensor 16 for detecting a curved state of the base metal 12 (cut shape of a semiconductor single crystal rod) is disposed facing the base metal 12 of the blade 11 at a boundary between the base metal 12 and the grindstone portion 13. . The detection signal of the magnetic sensor 16 is input to the tracking device 17, and the tracking device 17
Based on this detection signal, 17 compares one cutting shape with the next cutting shape, and if there is a difference, outputs an alarm signal to the main controller 18, and as shown in FIG. As shown, the tracking curves corresponding to the cutting numbers 1 to 10 are displayed. Further, the main controller 18 is
The disconnection is interrupted by an alarm signal from the tracking device 17.

Next, a case where the cutting failure detection method of the present invention is carried out using the cutting device configured as described above will be described with reference to the flow chart shown in FIG.

First, in the above cutting device, as in the conventional case, the blade
By inserting the semiconductor single crystal ingot 14 into the center of 11 and moving it up and down, the semiconductor single crystal ingot 14 is cut and the wafers A to I are sequentially obtained.

In this case, each time the semiconductor single crystal ingot 14 is cut, the cutting shape (tracking curve) is detected by the magnetic sensor 16.
Is detected. Then, this detection signal is input to the tracking device 17, is subjected to analog-digital conversion, and is stored (see step SP1 in FIG. 3). Next, as shown in step SP2, it is determined whether or not there is previously collected data. That is, in the case of the disconnection number 1 (at the time of the first disconnection), since there is no previous data, step SP5
As shown in, the following cutting operation is performed. If the previously collected data is stored, the previous cutting shape data and this cutting shape data are compared (step
See SP3), take the difference. At this time, if the difference is less than or equal to the predetermined value, it is determined to be normal, the process proceeds to step SP5,
If the difference exceeds a predetermined value, it is determined that the cutting is defective and a cycle stop (cutting operation interruption) processing is performed (step
See SP6). This determination process is specifically shown in the sixth
In this figure, wafers B, D, E, G, and I are judged to be defective because the difference between the two tracking curves is large, and wafers A, C, F, and H are judged to be good because there is no difference. Has been done.

〔The invention's effect〕

As described above, according to the present invention, when cutting the semiconductor single crystal ingot, the cutting shape of the wafer is detected, the difference between one cutting shape and the next cutting shape is taken, and this difference is the set value. When the above operation is to stop the semiconductor single crystal ingot cutting operation, it is possible to reliably and smoothly detect a wafer thickness defect and a taper defect, and to quickly detect a defect in the cut wafer. This has an excellent effect that it can be detected and the amount of defective wafers can be suppressed, and that defective products can be prevented from being sent to the next process.

[Brief description of drawings]

1 to 6 show an embodiment of the present invention,
FIG. 1 is a perspective view, FIG. 2 is a block diagram, FIG. 3 is a flowchart, FIG. 4 is an explanatory view showing a cut shape, FIG. 5 is an explanatory view showing a tracking curve, and FIG. 6 is a cut shape and a wafer. It is explanatory drawing which shows a shape. 11 …… Blade (inner peripheral blade), 14 …… Semiconductor single crystal rod, 16 …… Magnetic sensor, 17 …… Tracking device, AI… Wafer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenji Ieiri 314 Nishi-Migata Kinuchi, Noda City, Chiba Prefecture Nihon Silicon Co., Ltd. Noda Plant (56) References JP-A-57-168854 (JP, A)

Claims (1)

[Claims] 1. When manufacturing a large number of wafers by sequentially cutting a semiconductor single crystal ingot by an inner peripheral blade, the cutting shape of each wafer is detected, and the difference between one cutting shape and the next cutting shape is detected. Then, when the difference exceeds a set value, the semiconductor single crystal ingot cutting operation is stopped, and a wafer cutting failure detection method is characterized.