JP2021137942A - Processing device - Google Patents

Abstract

To provide a processing device that detects a crack quickly.SOLUTION: A grinding device 1 comprises; a chuck table 3 that can rotate while adsorbing and holding a work-piece W; a measurement device 4 that measures a distance up to a surface of the work-piece W in a non-contact manner; and control means 5 that can adjust a rotation period for the chuck table 3 and a sampling period for the measurement device 4 so that a measurement point P of the measurement device 4 covers an approximate whole circumference in a circumferential direction of the work-piece W.SELECTED DRAWING: Figure 1

Description

The present invention relates to a processing apparatus for processing the surface of a work.

In the field of semiconductor manufacturing, a grinding device that grinds a work by pressing the grinding surface of a rotating grinding wheel against the work is known as a device that grinds a semiconductor wafer such as a silicon wafer (hereinafter referred to as "work") thinly and flatly. Has been done.

Patent Document 1 discloses an apparatus for processing a workpiece in the order of rough grinding and fine grinding.

JP-A-2009-117648

By the way, when the work is ground or polished, groove-shaped cracks may occur on the surface (surface to be processed) of the work. In particular, in rough grinding using a coarse grinding wheel, cracks tend to occur. When cracks occur, debris peeled off from the work may bite into the grindstone, causing serious damage such as scratches on the work to be processed thereafter.

However, in the past, since the operator visually inspects the workpiece after processing, it is only possible to confirm the occurrence of cracks after the fact, and further, it is not clear at what timing the cracks were formed. There was a problem that it took time to investigate the cause of crack occurrence.

Therefore, a technical problem to be solved arises in order to detect a crack promptly, and an object of the present invention is to solve this problem.

In order to achieve the above object, the processing apparatus according to the present invention is a processing apparatus for processing the surface of a work, and is a distance between a chuck table that can rotate while sucking and holding the work and the surface of the work. And a control means capable of adjusting the rotation cycle of the chuck table and the sampling cycle of the measuring device so that the measuring point of the measuring device covers substantially the entire circumference in the circumferential direction of the work. And have.

According to this configuration, since the measurement points of the measuring device spread on the work substantially in the circumferential direction, cracks generated on the surface of the work can be immediately detected during machining of the work.

Further, in the processing apparatus according to the present invention, it is preferable that the measuring apparatus is an optical interferometry type displacement sensor.

Further, in the processing apparatus according to the present invention, it is preferable that the measuring apparatus is a light quantity measuring sensor.

INDUSTRIAL APPLICABILITY The present invention can immediately detect cracks generated on the surface of a work during machining of the work.

The front view which shows the grinding apparatus which concerns on one Embodiment of this invention. The plan view which shows the arrangement relationship of a chuck table and a measuring device. The schematic diagram which shows how the measuring point of a measuring device increases every time the chuck table rotates. A schematic diagram showing a state in which the distance between the measurement points of the measuring device is wide with respect to the spot diameter, and a graph showing the measured values of the measuring device. A schematic diagram showing a state in which the distance between points of the measuring device is narrow with respect to the spot diameter, and a graph showing the measured values of the measuring device. FIG. 6 is a schematic view showing how to determine the presence or absence of cracks in a modified example of the present invention.

An embodiment of the present invention will be described with reference to the drawings. In the following, when referring to the number, numerical value, quantity, range, etc. of components, it is limited to the specific number unless it is clearly stated or in principle it is clearly limited to the specific number. It is not a thing, and it may be more than or less than a specific number.

In addition, when referring to the shape and positional relationship of components, etc., unless otherwise specified or when it is considered that this is not the case in principle, those that are substantially similar to or similar to the shape, etc. shall be used. include.

In addition, the drawings may be exaggerated by enlarging the characteristic parts in order to make the features easy to understand, and the dimensional ratios and the like of the components are not always the same as the actual ones. Further, in the cross-sectional view, hatching of some components may be omitted in order to make the cross-sectional structure of the components easy to understand.

The grinding device 1 grinds the work W thinly and flatly. The work W is a semiconductor wafer such as a silicon wafer. The grinding device 1 includes a grinding means 2 and a chuck table 3.

The grinding means 2 includes a grinding wheel 21, a grindstone spindle 22, and a spindle feed mechanism 23.

The grinding wheel 21 is, for example, a # 600 cup-shaped grindstone, and the lower surface thereof constitutes a grinding surface 21a for grinding the work W. The grinding wheel 21 is attached to the lower end of the grinding wheel spindle 22.

The grindstone spindle 22 is configured to rotationally drive the grinding wheel 21 around the rotation shaft 2a in the direction of arrow A in FIG. The rotation direction of the grinding wheel 21 is not limited to the direction of the arrow A in FIG. 2, and may be the opposite direction (clockwise).

The spindle feed mechanism 23 raises and lowers the grindstone spindle 22 in the vertical direction. The spindle feed mechanism 23 has a known configuration, and includes, for example, a plurality of linear guides for guiding the moving direction of the grindstone spindle 22, and a ball screw slider mechanism for raising and lowering the grindstone spindle 22. The spindle feed mechanism 23 is interposed between the grindstone spindle 22 and the column 24.

The chuck table 3 includes a chuck spindle 31. The chuck spindle 31 is configured to be rotationally driven around the rotation shaft 3a in the direction of arrow B in FIG. The rotation direction of the chuck spindle 31 is not limited to the direction of the arrow B in FIG. 2, and may be in the opposite direction (counterclockwise).

An adsorbent (not shown) made of a porous material such as alumina is embedded in the upper surface of the chuck table 3. The chuck table 3 includes a conduit (not shown) that extends through the interior to the surface. The pipeline is connected to a vacuum source, compressed air source or water supply source via a rotary joint (not shown). When the vacuum source is activated, the work W placed on the chuck table 3 is attracted and held by the chuck table 3. Further, when the compressed air source or the water supply source is activated, the adsorption between the work W and the chuck table 3 is released.

The grinding device 1 includes a measuring device 4. The measuring device 4 is arranged above the chuck table 3. The measuring device 4 is an optical interferometry type displacement sensor, for example, an Opti-meter manufactured by Tokyo Seimitsu Co., Ltd. or the like.

The measuring device 4 irradiates the surface of the work W with irradiation light and receives the reflected light reflected by the surface of the work W so that the distance (displacement) between the measuring device 4 and the surface of the work W is non-contact. measure. That is, the measuring device 4 measures the distance to the work W at the measuring point P set immediately below the measuring device 4.

The measurement point P is preferably set near the periphery of the work W where cracks are relatively likely to occur (for example, about 5 mm inside from the outer circumference of the work W). The measurement point P on the work W moves in the circumferential direction of the work W along the circular locus L in FIG. 2 by the rotational drive of the chuck table 3.

The operation of the grinding device 1 is controlled by the control device 5. The control device 5 controls each of the components constituting the grinding device 1. The control device 5 is composed of, for example, a CPU, a memory, and the like. The function of the control device 5 may be realized by controlling using software, or may be realized by operating using hardware.

Next, a procedure for grinding the work W with the grinding device 1 will be described.

First, the work W is sucked and held on the chuck table 3. Next, the grinding wheel 21 is moved above the work W by the slider of the spindle feed mechanism 23. Then, the work W is ground by pressing the grinding surface 21a of the grinding wheel 21 against the work W while rotating the grinding wheel 21 and the chuck table 3, respectively.

Next, the measuring device 4 measures the distance to the measuring point P on the work W and sends the measured value to the control device 5. Further, as the work W rotates around the rotation axis 3a, the measurement point P on the work moves in the circumferential direction of the work W.

Further, the control device 5 repeatedly rotates the work W so that the measurement point P covers the entire circumference of the locus L, and the control device 5 has a phase difference between the rotation cycle of the chuck table 3 and the sampling cycle of the measuring device 4. To adjust. An example of the measurement conditions of the chuck table 3 and the measuring device 4 is shown below.

[Measurement condition]
・ Outer diameter of work W: 12 inch
-Work W thickness: 25 μm
-Rotation speed of chuck table 3: 201 rpm
-Period of chuck table 3: 3.35 Hz
・ Position of measurement point P: 5 mm inward from the outer circumference of the work
-Measurement point P spot diameter: Approximately 50 μm
-Sampling cycle of measuring device 4: 1025 Hz

3 (a) to 3 (c) are schematic views showing how the measurement point P increases according to the rotation speed of the chuck table 3. FIG. 3A shows the positional relationship of the measurement points P when the work W rotates once, and FIG. 3B shows the positional relationship of the measurement points P when the work W rotates twice. (C) shows a state in which the measurement point P extends over the entire circumference of the work W. The spot diameter of the measurement point P in FIG. 3 is larger than the actual spot diameter for convenience of explanation.

Under the above-mentioned measurement conditions, as shown in FIG. 3A, the number of measurement points P when the work W makes one round is about 306, and the distance between the measurement points P is about 2978 μm. Similarly, as shown in FIG. 3B, the number of measurement points P when the work W makes two rounds is about 612, and the distance between the measurement points P is about 1489 μm. As described above, when the rotation speed of the work W is low, the distance between the measurement points P exceeds the spot diameter of the measurement point P, and the measurement points P of the measurement device 4 are sparsely scattered on the locus L. It is in a state of being.

After that, when the work W continues to rotate and the work W makes 67 laps, the number of measurement points P becomes about 20500 points and the distance between the measurement points P becomes 44.4 μm as shown in FIG. 3C. , It is smaller than the spot diameter (50 μm) of the measurement point P, and the measurement point P is set without a gap over the entire circumference of the locus L.

Next, the control device 5 determines whether or not a crack (small step) is generated on the surface of the work W based on the measured value of the measuring device 4.

Specifically, as shown in FIG. 4A, when the distance between adjacent measurement points P on the work W is significantly longer than the diameter of the measurement points P, cracks occur between the adjacent measurement points P. If it is formed, the measured value of the measuring device 4 does not fluctuate as shown in FIG. 4B, so that the control device 5 cannot detect the crack based on the fluctuation of the displacement. The measured value of the measuring device 4 shown in FIG. 4B is obtained by differentiating the fluctuation of the distance between the measuring device 4 and the surface of the work W, and there is no fluctuation in the distance between the measuring device 4 and the surface of the work W. Therefore, the measured value is substantially constant.

On the other hand, as shown in FIG. 5A, when adjacent measurement points P spread over substantially the entire circumference of the locus L, and the distance between adjacent measurement points P on the work W is shorter than the diameter of the measurement points P. Since at least one measurement point P is arranged in the crack, the measured value of the measuring device 4 fluctuates according to the position of the crack as shown in FIG. 5 (b), so that the control device 5 is displaced. Cracks can be detected based on the fluctuation of. The measured value of the measuring device 4 shown in FIG. 5B is a derivative of the fluctuation of the distance between the measuring device 4 and the surface of the work W, and the measured value increases before and after the crack and then decreases.

In this way, the control device 5 can immediately detect the crack formed on the surface of the work W during the grinding process of the work W.

Then, when the work W is ground to a desired thickness, the rotation of the grinding wheel 21 and the chuck table 3 is stopped, the slider of the spindle feed mechanism 23 is activated, and the grinding wheel 21 is separated from the work W. Then, the suction and holding of the work W by the chuck table 3 is released, and the grinding process of the work W by the grinding device 1 is completed.

Instead of the above-described configuration, the measuring device 4 may be a light amount measuring sensor that measures the light intensity of the reflected light reflected on the surface of the work W. In this case, as shown in FIGS. 6A and 6B, the measured value of the measuring device 4 fluctuates so as to decrease in the crack, so that the control device 5 fluctuates the light intensity of the reflected light. The presence or absence of cracks can be detected based on. As such a measuring device 4, it is conceivable to use the spectroscope of the displacement sensor described above, but the present invention is not limited to this.

Further, the present invention can be modified in various ways other than the above as long as it does not deviate from the spirit of the present invention, and it is natural that the present invention extends to the modified ones.

In this embodiment, the case where the measuring device 4 is applied to the grinding device 1 has been described as an example, but it is also possible to apply the measuring device 4 to the polishing device that polishes the work W with the polishing pad.

1: Grinding equipment (processing equipment)
2: Grinding means 21: Grinding wheel 21a: Grinding surface 22: Grindstone spindle 23: Spindle feed mechanism 24: Column 3: Chuck table 3a: Rotating shaft 31: Chuck spindle 4: Measuring device (measuring means)
5: Control device (control means)
L: Trajectory P: Measurement point W: Work

Claims (3)

It is a processing device that processes the surface of the work.
A chuck table that can rotate while sucking and holding the work,
A measuring means for measuring the distance to the surface of the work in a non-contact manner,
A control means capable of adjusting the rotation cycle of the chuck table and the sampling cycle of the measuring device so that the measuring point of the measuring device covers substantially the entire circumference in the circumferential direction of the work.
A processing device characterized by being equipped with. The processing device according to claim 1, wherein the measuring device is an optical interferometry type displacement sensor. The processing device according to claim 1, wherein the measuring device is a light amount measuring sensor.

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