JPH0644588B2 - Orientation flat mark position detector - Google Patents

Description

The present invention detects the position of an orientation flat mark (hereinafter abbreviated as OF mark) attached to an end face of a single crystal ingot in a semiconductor manufacturing process. To a detection device for.

(Prior Art) A semiconductor wafer used as a substrate of a semiconductor electronic device is obtained by slicing a single crystal ingot of silicon or the like at a right angle to the rod axis direction, and further lapping and etching the sliced product. And at least one surface is formed into a thin disk shape with a mirror surface by polishing or the like, and a so-called orientation flat (hereinafter abbreviated as OF) for positioning an optical pattern is usually formed on a part of the circumference thereof. Is provided in at least one place. This OF is composed of a plane perpendicular to the mirror surface of the wafer, and for this, high azimuth accuracy and processing accuracy are required.

In terms of manufacturing, OF mechanically (in some cases, further chemically) a semiconductor single crystal ingot into a cylinder with a predetermined dimensional accuracy.
After the processing, the single crystal ingot is processed by grinding the side surface of the single crystal ingot in parallel with the rod axis by, for example, a cylindrical polishing machine without rotating.

By the way, conventionally, a constant crystallographic orientation and a permissible tolerance thereof are specified for the OF plane, so that an OF mark is attached to one end surface of the single crystal ingot. The OF mark is composed of, for example, coloring on one end surface of the single crystal ingot, other markings, or a similar means. Conventionally, while checking the OF mark with the naked eye, the OF mark is formed on the polishing surface of a polishing grindstone. The OF was processed by aligning the positions.

(Problems to be Solved by the Invention) However, according to such a method, the grindstone polishing surface and the OF
Since the alignment of the marks is done visually, the accuracy is lacking and time loss cannot be avoided.

The present invention has been made in view of such a problem, and an object of the present invention is to detect an OF mark provided on an end surface of a workpiece photoelectrically and use a simple signal processing circuit to achieve high accuracy. Orientation flat that enables OF processing
It is to provide a mark position detecting device.

(Means for Solving the Problem) In order to achieve the above-mentioned object, the present invention is directed to a linear orientation flat-shape attached to an end face of a single crystal ingot while rotating the single crystal ingot around its central axis.
A device for detecting the position of the mark, a plurality of photoelectric sensors that are arranged in a straight line and output a high level signal by receiving the reflected light from the orientation flat mark, and the photoelectric sensors that are the orientation flats of the single crystal ingot. A high-level signal from all photoelectric sensors output when the orientation flat mark coincides with a straight line connecting the light receiving portion of the photoelectric sensor and a detecting portion including a scanning unit that scans a predetermined range including the mark. It is characterized in that it is configured to include a detection circuit for detecting.

Further, in the present invention, the photoelectric sensor is arranged in a straight line on a sensor member that rotates around an axis orthogonal to the central axis of the single crystal ingot, and the scanning means of the detection unit is arranged on the central axis of the sensor member. It is configured to include a swing arm that is bound, an eccentric cam that is in sliding contact with the swing arm, and a motor that rotationally drives the eccentric cam.

Further, in the present invention, the detection circuit is operated by a high-level signal output from one of the photoelectric sensors, and a high-level signal from all other photoelectric sensors during operation of the one-shot circuit. It is configured to include an AND circuit that operates when is input, and a latch circuit that holds an output signal of the AND circuit.

(Operation) According to the present invention, the position of the OF mark attached to the semiconductor ingot is optically detected by the photoelectric sensor, and whether the OF mark is at a predetermined position or not is detected by the output from the photoelectric sensor. Is detected by
The OF processing for the semiconductor ingot can be performed with high accuracy.

(Embodiment) An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a perspective view of a position detecting device according to the present invention, FIG. 2 is a plan view of the device, FIG. 3 is a circuit configuration diagram of the device, and FIG. 4 is a process chart of a position detecting operation by the device. Fifth
FIG. 7 to FIG. 7 are explanatory views of the position detecting operation by the device.

In FIGS. 1 and 2, W is a columnar single crystal ingot, the outer periphery of which is polished by a cylindrical grinder, and a linear OF mark 1 is attached to its end surface Wa with red magic ink. .

On the other hand, in the vicinity of the end surface Wa of the ingot W, a cylindrical sensor member 1 constituting the position detecting device according to the present invention.
Are arranged vertically and rotatably, and three circular holes 1a, 1b, 1c are formed through the sensor member 1 in the vertical direction. And these circular holes 1a, 1b, 1c
Photoelectric switches PH1, PH0 and PH2 are housed therein. The photoelectric switches PH1, PH0, P
H2 is a photoelectric sensor that receives reflected light emitted from these and converts it into an electric signal.

A DC motor 2 is arranged near the sensor member 1, and a disc-shaped eccentric cam 3 is connected to the upper end of an output shaft 2a of the DC motor 2. The eccentric cam 3 has an outer peripheral surface slidably in contact with the other end of a swing arm 5 whose one end is connected to the central shaft 4 of the sensor member 1. The spring 6 constantly presses the outer peripheral surface of the eccentric cam 3 with a constant pressure.

By the way, as shown in FIG.
0 is electrically connected to the one-shot circuit 7, and the one-shot circuit 7 is connected to the AND circuit 8.

Further, the photoelectric switches PH1 and PH2 are both connected to an AND circuit 8, the AND circuit 8 is connected to a latch circuit 9, and the latch circuit 9 is connected to a warning buzzer 10 and a reset switch 11. Incidentally, in FIG. 3, 12
Is a sensor for detecting one rotation of the single crystal ingot W.

Next, based on FIG. 4 to FIG.
The position detecting operation of the F mark 1 will be described.

First, the detection unit composed of the sensor member 1, the DC motor 2, the eccentric cam 3 and the like shown in FIG. 1 is lowered to the ingot W (step 1 in FIG. 4), and the detection unit is shown in FIG. As shown, the ingot W is positioned near the end surface Wa. In the ingot W, the OF mark 1 attached to the end surface Wa of the ingot W has the photoelectric switch PH1,
It is preliminarily rotated so as to substantially coincide with the line connecting the centers of PH0 and PH2.

Next, slide the detector in the direction of the arrow in FIG.
Step 2) of the figure, this is the OF mark l of the ingot W
It is determined whether or not it has reached the vicinity of (step 3), and if the determination result is Yes, the detection unit is stopped (step 4), and if No, the detection unit continues to slide.

As described above, when the detection unit is located near the OF mark 1,
The sensor member 1 is swung around the central axis 4 (step 5).

Then, the swing of the sensor member 1 is performed as follows.

That is, when the DC motor 2 is driven to rotate the eccentric cam 3 in the direction of the arrow in FIG. 1, the swing arm 5 sliding on the outer peripheral surface of the eccentric cam 3 swings about the central axis 4. ,
As a result, the sensor member 1 is also swung about the central axis 4.

Here, as shown in FIG. 2, the end surface Wa of the ingot W is
Letting S be the distance between the swinging center of the sensor member 1 and θ, and θ be the swinging angle of the sensor member 1, the photoelectric switches PH1, PH0, PH2 mounted on the sensor member 1 are provided on the ingot end face Wa. The scanning range L is represented by the following formula: L = 2S · tan (θ / 2) ≈S · θ (when θ is small), and the OF mark 1 is included in this scanning range L.

By swinging the sensor member 1 as described above, the photoelectric switches PH1, PH0, PH2 are caused to scan the range L (see FIG. 2) on the end surface Wa of the ingot W, while rotating the ingot W (step 6), O
It is detected whether or not the F mark 1 coincides with a line (perpendicular) m connecting the centers of the photoelectric switches PH1, PH0, PH2 (step 7 in FIG. 4). Is done like.

That is, as the posture that the OF mark 1 can take with respect to the perpendicular m, the modes shown in FIGS. 5 (a), 6 (a) and 7 (a) are conceivable, and FIG. And FIG. 6 (a) shows OF
The case where the mark 1 does not match the perpendicular m is shown, and FIG. 7A shows the case where the OF mark 1 matches the perpendicular m. Incidentally, in FIG. 5, FIG. 6 and FIG. 7, (b),
(C) and (d) are photoelectric switches PH0 and PH, respectively.
1, PH2, and (e), (f), and (g) show the signal waveforms of the one-shot circuit 7, AND circuit 8, and latch circuit 9, respectively.

Thus, when the OF mark 1 intersects with the perpendicular m as shown in FIG. 5 (a), and the angle α formed by the OF mark 1 and the horizontal line is α <90 °, the perpendicular to the perpendicular m. If the aligned photoelectric switches PH0, PH1, PH2 are scanned in the direction of the arrow shown, the photoelectric switches PH0, PH1, PH2
Receives the reflected light from the OF mark l, and FIG.
The signals as shown in (c) and (d) are output. That is, the photoelectric switch PH0 outputs the high level signal H in agreement with the trigger position shown by the broken line in FIG. 5 (b), and the photoelectric switches PH1 and PH2 are as shown in FIGS. 5 (c) and 5 (d). The high level signal H is output earlier and later than the trigger position indicated by the broken line.

As described above, when the photoelectric switch PH0 detects the OF mark 1 and the signal changes from the low level L to the high level H, the one-shot circuit 7 operates as shown in FIG. 5 (e). A pulse is generated at the timing of the output rise of. The width t of this pulse
Is determined by the constant of the one-shot circuit 7, and the narrower the width t, the higher the measurement accuracy.

Thus, if the outputs of the photoelectric switches PH1 and PH2 are both at the high level H within the pulse width t of the one-shot circuit 7, the output of the AND circuit 8 also indicates the high level H.
In this case, since the outputs of the photoelectric switches PH1 and PH2 are both at the low level L, the outputs of the AND circuit 8 and the latch circuit 9 are both at the low level L as shown in FIGS. 5 (f) and (g). It is detected that the OF mark 1 does not match the perpendicular m.

Similar to the above, as shown in FIG.
Intersects with the vertical line m and makes an angle α> 90 between it and the horizontal line.
Even in the case of .degree., The outputs of the photoelectric switches PH1 and PH2 are both at the low level L within the pulse width t of the one-shot circuit 7 (FIGS. 6 (b), (c), (d)).
As shown in FIGS. 6 (f) and 6 (g), the outputs of the AND circuit 8 and the latch circuit 9 both show a low level L,
It is detected that the OF mark 1 does not match the perpendicular m.

On the other hand, as shown in FIG.
Is α = 90 °, which coincides with the vertical line m, as shown in FIGS. 7 (b), (c), and (d), the photoelectric switches PH0, PH are turned on within the pulse width t of the one-shot circuit 7.
Since the outputs of 1 and PH2 are both at the high level H, the output of the AND circuit 8 is at the high level H as shown in FIG.
This output signal is maintained by the latch circuit 9 (see FIG. 7 (g)), and this signal causes the buzzer 10 to operate, and the buzzer sound informs that the OF mark 1 matches the perpendicular line m. The operation of the buzzer 10 is stopped by the reset switch 11.

As described above, the position of the OF mark 1 is detected, and it can be known that the OF mark 1 coincides with the perpendicular m. However, as shown in FIGS. 5 and 6, the OF mark 1 coincides with the perpendicular m. If not, the operations of steps 6 to 7 shown in FIG. 4 are repeated, and the rotation of the ingot W is stopped when the OF mark 1 coincides with the perpendicular m as shown in FIG. After the step 8), the detector is raised (step 9), and a series of position detecting operations is completed (step 10).

Thus, the position of the OF mark 1 is the photoelectric switch PH1,
After being set so as to coincide with the line m connecting the centers of PH0 and PH2, the polishing surface of the polishing grindstone is OF as it is or at the fixed end of the ingot W rotated in the cylindrical polishing machine with reference to the perpendicular m. The ingot W is fixed so as to be parallel to the polishing surface, and a part of the outer periphery of the ingot W is polished along the OF mark 1 to form a desired OF.

When the work is done manually, the rotation speed of the ingot W is set so that the worker can accurately rotate the ingot W by a signal such as a buzzer emitted when the OF mark 1 coincides with the vertical line m. It is better to be late so that you can stop.
Further, in the case of automatic, the coincidence symbol may be input to the rotary positioning control section 11 shown in FIG. 3 to automatically position the ingot W by this.

By the way, the OF mark 1 attached to the end face Wa of the ingot W should produce a change in the light energy of the reflected light from the other parts of the ingot W depending on the color tone, the glossiness, and the spectrum of the projection light source used. Therefore, various variations are possible. Further, as another example of the OF mark, it is conceivable to attach a reflection tape having a reflectance different from that of the ingot, or to engrave a marking line with a straight diamond pen or the like on the end face of the ingot.

(Effects of the Invention) As is clear from the above description, according to the present invention, the position of the orientation flat mark provided on the end face of the single crystal ingot is optically detected by the photoelectric sensor, and the output signal from the photoelectric sensor is detected. Since the detection circuit determines whether or not the orientation flat mark is located at a predetermined position, the effect that the orientation flat can be processed with high precision with respect to the single crystal ingot is obtained.

[Brief description of drawings]

FIG. 1 is a perspective view of a position detecting device according to the present invention, FIG. 2 is a plan view of the device, FIG. 3 is a circuit configuration diagram of the device, and FIG. 4 is a process chart of a position detecting operation by the device. Fifth
FIG. 7 to FIG. 7 are explanatory views of the position detecting operation by the device. 1 ... Sensor member, 2 ... DC motor, 3 ... eccentric cam, 4 ... swing arm, 7 ... one-shot circuit, 8
... AND circuit, 9 ... Latch circuit, l ... Orientation flat mark (OF mark), m ... Vertical line, PH0, PH1, PH2 ... Photoelectric switch (photoelectric sensor), W ... Single crystal ingot.

Claims (3)

[Claims] 1. A device for detecting the position of a linear orientation flat mark attached to an end face of a single crystal ingot while rotating the single crystal ingot about its central axis, the device being arranged in a straight line. A plurality of photoelectric sensors that receive reflected light from the orientation flat mark and output a high-level signal, and a detection unit that scans the photoelectric sensor within a predetermined range including the orientation flat mark of the single crystal ingot. Section, and a detection circuit for detecting this by a high level signal from all photoelectric sensors output when the orientation flat mark coincides with a straight line connecting the light receiving sections of the photoelectric sensor. Orientation flat mark position detection device. 2. The photoelectric sensor is linearly arranged on a sensor member that rotates around an axis orthogonal to the central axis of the single crystal ingot, and the scanning means of the detection unit is connected to the central axis of the sensor member. 2. The position detection of an orientation flat mark according to claim 1, further comprising: a mounted swinging arm, an eccentric cam with which the swinging arm makes sliding contact, and a motor for rotationally driving the eccentric cam. apparatus. 3. The one-shot circuit operated by a high-level signal output from one of the photoelectric sensors, and the detection circuit receives high-level signals from all other photoelectric sensors during operation of the one-shot circuit. 3. An orientation flat mark position detecting device according to claim 1, further comprising an AND circuit that operates when input, and a latch circuit that holds an output signal of the AND circuit.