JPH10340943A - Wafer position detecting equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the timing of position detection accurate and improve throughput, in the position detection of a wafer and an orientation flatness or a notch. SOLUTION: In this equipment, a semiconductor wafer 1 is mounted on a retaining member 2, light from a light source 6 is casted on the peripheral part of the semiconductor wafer 1, while the semiconductor wafer 1 is rotated together with the rotation of a motor 3. Positions of the wafer and an orientation flat or a notch are detected by receiving the light with a CCD line sensor 4. In this case, the CCD line sensor 4 is driven synchronously with positional information of the semiconductor wafer 1. An electronic shutter function is mounted on the CCD line sensor 4, and detection is performed during only a certain fixed time. Detection is performed during acceleration deceleration of the semiconductor wafer 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor manufacturing apparatus,
In particular, the present invention relates to a wafer position detecting device for detecting a position of a semiconductor wafer and a position of an orientation flat or a notch in a processing apparatus.

[0002]

2. Description of the Related Art In recent years, in the world of semiconductors, the diameter of wafers and the pattern processing have become finer, and the degree of cleanliness of wafers has been required more than ever before.
Further, the reference indicating the crystal orientation of the wafer has shifted from an orientation flat (hereinafter, referred to as an orientation flat) to a notch.

[0003] In a semiconductor manufacturing apparatus, an apparatus for detecting the position of a wafer has conventionally been used for aligning the center position of the wafer and the orientation flat or notch.
Japanese Patent Application Laid-Open No. 6-45226 discloses a technique of rotating a wafer that has been vacuum-sucked, obtaining an edge position detection signal of the wafer, and driving an XY stage based on the detection signal to align the wafer. I have. Further, Japanese Unexamined Patent Publication No.
Japanese Patent Publication No. 218179 discloses that when a notch is detected by a CCD line sensor asynchronously with the rotation of a stepping motor for rotating a wafer, the wafer is rotated in a coarse step, the periphery of the notch is detected, and then the wafer is notched in a fine step again. There is disclosed a technique for detecting in detail by driving in the periphery.

Further, Japanese Patent Application Laid-Open Nos. 8-264606 and 5-291383 disclose a multi-chamber cluster for consistently processing a wafer in a vacuum without exposing the wafer to the atmosphere in order to prevent foreign matter from adhering. Technology is disclosed.

[0005]

However, when the detection is performed in the constant rotation region of the wafer, when the wafer placed on the support member is rotated at a high speed in a vacuum, the friction coefficient of the support member in the vacuum is increased. Is smaller than the coefficient of friction in the atmosphere, so the possibility of the wafer slipping increases.Therefore, it is necessary to slow down the rotation speed of the wafer or start / stop the wafer slowly. Had been an obstacle. In addition, since the conventional CCD line sensor performs detection asynchronously with the detection position of the wafer, there is a problem that a deviation occurs between the detection position and the detection timing, and accurate detection cannot be performed.

On the other hand, when the measurement is performed in the rotation range of the acceleration and deceleration of the wafer, the detection positions of the wafer are usually provided at regular intervals in the rotation of the wafer. The light receiving amount of the CCD is not constant because the time interval changes, and even if the CCD is adjusted to the optimum light receiving amount at the top speed of the wafer, the CCD output may be saturated in the acceleration / deceleration rotation range. is there. For this reason, it is difficult to detect the wafer in the acceleration / deceleration region, and it is necessary to wait until the wafer rotates at a constant speed.
This was an obstacle to improving the throughput.

SUMMARY OF THE INVENTION The present invention has been made in view of the above background, and an object of the present invention is to provide a wafer position detecting device with improved throughput, and to perform accurate wafer position detection. It is an object of the present invention to provide a wafer position detecting device which can perform the above.

[0008]

In order to achieve the above object, a first wafer position detecting apparatus of the present invention holds a wafer horizontally and rotates the wafer around a vertical rotation axis with the wafer. By detecting the holding means configured to rotate the wafer, the rotation angle of the holding means,
Converting means for converting the light into electric signals; light projecting means for projecting light onto the peripheral portion of the wafer held by the holding means; and detecting a position of a projected image of the wafer by the light projected by the light projecting means. A line sensor that outputs as an electrical signal, and a signal processing unit that processes a signal from the line sensor,
Control means for controlling the line sensor to drive and detect the line sensor in synchronization with the wafer being positioned at a plurality of predetermined rotation angles.

According to a second wafer position detecting device of the present invention, in the first wafer position detecting device of the present invention, at the time of driving, the line sensor is driven from an initial state and starts detecting light. The light is detected only for a predetermined period of time within a range where the output is not saturated.

In a third wafer position detecting device according to the present invention, in the first or second wafer position detecting device according to the present invention, the control means may control the detection positions to be at equal intervals on the circumference of the wafer. To control.

A fourth wafer position detecting device according to the present invention is a holding means configured to hold a wafer horizontally, and to rotate the wafer by rotating about a vertical rotation axis with the wafer. A conversion unit that detects a rotation angle of the holding unit and converts the rotation angle into an electric signal; a light projection unit that emits light to a peripheral portion of the wafer held by the holding unit; Is a line sensor that detects the position of the projected image of the wafer by the emitted light and outputs it as an electrical signal. A line sensor that detects light only in time, a signal processing unit that processes a signal from the line sensor, and a control unit that controls the line sensor to be driven at a predetermined detection timing. A.

In a fifth wafer position detecting device according to the present invention, in the first, second, third or fourth wafer position detecting device according to the present invention, the line sensor is a CCD line sensor having an electronic shutter function.

(Operation) In the first wafer position detecting device according to the present invention, the line sensor is driven and detection is performed in synchronization with the rotation angle of the wafer reaching a predetermined rotation angle.

In the second wafer position detecting device of the present invention, in addition to the operation of the first wafer position detecting device of the present invention, when the line sensor is driven, the output of the line sensor falls within a range where the output is not saturated. Detection is performed only for a predetermined fixed time interval. At this time, since the line sensor is driven from the initial state, it is not affected by light reception before driving.

According to the third wafer position detecting device of the present invention, in addition to the operation of the first or second wafer position detecting device of the present invention, furthermore, at the detecting positions arranged at equal intervals on the circumference of the wafer. Detection is performed.

In the fourth wafer position detecting apparatus according to the present invention, when the line sensor is driven, the line sensor performs detection for a predetermined fixed time interval within a range where the output is not saturated. Since the sensor is driven from the initial state, it is not affected by light reception before driving.

In the fifth wafer position detecting device of the present invention, in addition to the operation of the first, second, third or fourth wafer position detecting device of the present invention, a CCD line having an electronic shutter function as a line sensor is further provided. Detection is performed by a sensor.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) A first embodiment in which a wafer position detecting device of the present invention is applied to a semiconductor wafer position detecting device used in a processing apparatus will be described with reference to the drawings.

FIG. 1 is a block diagram of a semiconductor wafer position detecting apparatus according to the first embodiment. The semiconductor wafer 1 is placed horizontally on a support member 2 serving as a holding means, and the support member 2 is disposed on a vertical rotation axis of a motor 3, and is rotated with the semiconductor wafer 1 by the rotation of the motor 3. It is configured to be. Motor 3 with motor 3
An encoder 13 is provided, which is a conversion unit that detects the rotation angle of the motor and converts the rotation angle into an electric signal.

A light source 6 serving as a light projecting means is provided connected to a CPU 10 serving as a control means. A lens 5 is provided between the light source 6 and the semiconductor wafer 1, and a semiconductor wafer 1 is provided.
Is a line sensor CCD on the opposite side of the light source 6
A line sensor 4 is provided.

The CCD line sensor 4 is connected to a signal processing circuit 7 serving as signal processing means and a timing pulse generating circuit 8, and the signal processing circuit 7 includes a timing pulse generating circuit 8
And the CPU 10. The timing pulse generator 8 is connected to the CPU 10. CPU1
0 is a motor driver 9, an external controller 12,
The storage circuit 11 is connected to an external controller 12. Further, the motor driver 9 is connected to the motor 3.

When the semiconductor wafer 1 is placed on the support member 2 by a robot arm (not shown) in the processing apparatus, a signal is sent from the external controller 12 to the CPU 10.
And the position detection of the semiconductor wafer 1 is started. A command pulse signal is output from the external controller 12 to the motor driver 9, and a driving signal from the motor driver 9 is output to the motor 3 formed integrally with the encoder 13, and the motor 3 starts rotating.

The support member 2 is formed on the rotating shaft of the motor 3, and the semiconductor wafer 1 is mounted on the support member 2. The semiconductor wafer 1 rotates with the rotation of the motor 3. By detecting the rotation angle of the motor 3, the rotation angle of the semiconductor wafer 1 can be known.

At this time, the rotation angle of the motor 3 is converted by the encoder 13 into an encoder signal which is a position signal. The encoder signal is fed back to the motor driver 9 and used for a servo mechanism for controlling the motor 3 with high accuracy, and is also input to the CPU 10. CP
U10 monitors the encoder signal. When the rotation angle indicated by the encoder signal coincides with the rotation angle corresponding to the detection position set in advance on the circumference of the semiconductor wafer 1, the timing signal is passed through the timing pulse generation circuit 8. To drive the CCD line sensor 4 to perform detection. The above-described detection position is determined based on the semiconductor wafer 1 in consideration of the simplicity of the subsequent calculation processing.
Are set at equal intervals on the circumference of.

Now, the CC driven by the CPU 10
The D-line sensor 4 has an electronic shutter mechanism, and starts detecting light immediately by a drive signal, and detects light only at a predetermined time at each detection position. At this time, the light receiving state before the start of the detection is structured so as not to affect the detection result. The structure of the CCD line sensor 4 will be described later in detail.

When the semiconductor wafer 1 is placed on the support member 2, the light source 6 starts emitting light in response to a command from the CPU 10,
Until a series of position detection operations of the semiconductor wafer 1 are all completed, a stable light amount is provided. The light from the light source 6 is collimated by the lens 5, applied to the periphery of the semiconductor wafer 1, and received by the CCD line sensor 4.
At this time, the position shaded by the semiconductor wafer 1 is referred to as CC.
The position of the edge of the semiconductor wafer 1 is obtained by knowing from the output of the D line sensor 4. In the first embodiment, the edge position of the semiconductor wafer 1 is obtained by using the position of the shadow due to the parallel rays, but is not limited to this.
For example, using a lens, an image of the semiconductor
An image may be formed on the pixel surface of the line sensor 4.

The output from the CCD line sensor 4 driven by the CPU 10 enters the signal processing circuit 7 and is processed into an edge signal indicating the position of the edge of the semiconductor wafer 1.
It is input to the CPU 10. The CPU 10 records the edge position at the detection position in the recording circuit 11 and, after the semiconductor wafer 1 completes one rotation and completes the detection at all the detection positions, transmits the data recorded in the recording circuit 11 to the external circuit 12 via the external controller 12. Output to Externally, the data is taken into, for example, a process controller and the wafer 1
And the position of the orientation flat or notch are calculated. In the first embodiment, the calculation is performed externally, but the calculation may be performed internally and the result may be output to the outside.

Referring to the flowchart of FIG.
The operation of the semiconductor wafer position detecting device according to the embodiment will be described in detail. When a signal from the external controller 12 enters the CPU 10 and the operation of the semiconductor wafer position detecting device is started, CP
U10 initializes various registers included in the CPU 10 (step S1). Next, a signal indicating that the detection operation is being performed is output to the external controller 12 (step S2). Next, the external controller 12 issues a rotation command to the motor driver 9 to start driving the motor 3 (step S3). With the rotation of the motor 3, the support member 2 formed on the rotating shaft also rotates, thereby the support member 2
The semiconductor wafer 1 placed on the wafer also rotates. In the first embodiment, the motor 3 uses a direct drive type AC servomotor integrally formed with the encoder 13, but is not limited to this as long as it can be controlled to rotate with required accuracy.

The driving pattern of the motor 3 at this time is called trapezoidal driving and is shown in FIG. 3, the vertical axis represents the rotation speed of the motor 3, and the horizontal axis represents the time from the start of the rotation of the motor. Looking at the relationship between the time from the start of rotation of the motor 3 and the rotation speed, an acceleration region where the speed is increasing, a constant-speed rotation region where the rotation speed is constant, and a deceleration region where the rotation speed is decreasing, It can be seen that it has a trapezoidal shape. In the first embodiment, since the rotation of the motor 3 is the rotation of the semiconductor wafer 1, the relationship between the time from the start of the rotation and the rotation speed also applies to the semiconductor wafer 1.

In the first embodiment, the rotation of the semiconductor wafer 1 by 360 degrees, that is, one rotation,
Control is performed so that the acceleration region, the constant speed rotation region, and the deceleration region come, and the detection operation is performed in the acceleration region and the deceleration region without waiting for the semiconductor wafer 1 to rotate at a constant speed. , Semiconductor wafer 1
One rotation completes the detection operation.

Returning to the flowchart of FIG. 2, when the motor 3 starts rotating, an encoder signal representing the rotation angle of the motor 3, that is, the rotation angle of the semiconductor wafer 1 is sent from the encoder 13 via the motor driver 9 to the CPU 10.
Is output to The CPU 10 analyzes the contents of the encoder signal (step S4) and determines whether the rotation angle of the semiconductor wafer 1 matches the rotation angle corresponding to the preset detection position (step S5).
4, the monitoring of the rotation angle of the semiconductor wafer 1 is continued.
If they match, the CPU 10 issues a command to the timing pulse generation circuit 8 to drive the CCD line sensor 4 (step S6). In the first embodiment, the CPU 10 controls the semiconductor wafer 1 in such a manner that the semiconductor wafer 1 is positioned at a plurality of predetermined rotation angles.
The CCD line sensor 4 is driven to perform detection.

Here, the structure of the CCD line sensor 4 will be described with reference to FIG. 4, and the encoder signal and the drive signal of the CCD line sensor 4 will be described with reference to FIG. 4A is a schematic diagram when electric charges are accumulated in the CCD, FIG. 4B is a schematic diagram when electric charges are accumulated and discarded, and FIG. 4C is a schematic diagram when electric charges of the CCD output are read. In the figure, the hatched portions indicate the accumulated charges, and the vertical direction indicates the height of the potential. In the state in which the electric charge is accumulated by receiving the light, as shown in (a), since the potential of the shutter gate 301 and the lead-out gate 302 is high, the electric charge generated by the photoelectric conversion is accumulated when the light strikes the CCD sensor 303. Is done. The amount of charge stored is proportional to the amount of incident light.

In this state, when the potential of the shutter gate 301 is lowered as shown in FIG.
All the data is not accumulated in the sensor 303 and is discarded in the shutter drain 304, and is eventually discarded in the sub-board of the sensor. Thus, by lowering the potential of the shutter gate 301, the CCD sensor 303
Even when light is incident on the CCD, the CCD can be kept in an initial state in which charges are not accumulated. Also,
When the potential of the readout gate 302 is lowered from the state of (a), the accumulated electric charge moves to the CCD register 305 as shown in (c), and an output can be obtained by transferring this electric charge.

FIG. 5 is an explanatory diagram of an encoder signal and a drive signal of the CCD line sensor 4. In FIG. 5, the one shown at the top is an encoder signal. When the motor 3 rotates, the encoder 13 outputs a pulse-like encoder signal at every predetermined minute rotation angle. The encoder signal is counted by the CPU 10, and when a count number corresponding to a plurality of predetermined detection positions is counted, the CPU 10 outputs a count-up signal to the timing pulse generation circuit 8 to drive the CCD line sensor 4. The count-up signal is shown second from the top in FIG. When receiving the count-up signal, the timing pulse generating circuit 8 changes the shutter pulse from a low level which is a normal state to a high level.

In the CCD line sensor 4, when the shutter pulse is low, the potential of the shutter gate 301 is low as shown in FIG. 4B, and no charge is accumulated even when light enters. All shutter drain 3
04 was thrown away. In this state, when the shutter pulse goes high, the potential of the shutter gate 301 increases at the rising timing of the shutter pulse, as shown in FIG. 4A, and the accumulation of electric charge according to the incident light starts.

In FIG. 5, after a predetermined period of time elapses after the shutter pulse changes from low to high,
The timing pulse generation circuit 8 includes the CCD line sensor 4
And outputs the readout pulse to the normal state, and returns the shutter pulse to the normal state from high to low. As shown in the fourth from the top in FIG. 5, the readout pulse is a pulse in which the normally high potential temporarily changes to the low level.

At the falling timing of the readout pulse, as shown in FIG. 4C, the potential of the readout gate drops, and all the electric charges accumulated so far move to the CCD register 305. This charge is CC
The signal is read out in synchronization with the D clock and input to the signal processing circuit 7 as the output of the CCD line sensor 4. The CCD clock is shown at the bottom of FIG.

As described above, the accumulation of the electric charge according to the incident light starts at the timing of the rising edge of the shutter pulse, and the accumulated electric charge is read out at the timing of the falling edge of the readout pulse. This is a section where the sensor 4 is effectively detecting light,
In other intervals, the charge is applied to the shutter drain 30 shown in FIG.
4, the CCD line sensor 4 does not detect light even if it receives light.

As described above, the shutter drain 3 determines whether or not detection is performed even during light reception by the CCD.
The function controlled by the potential 04 is called an electronic shutter function. In the readout pulse diagram of FIG. 5, the portion indicated as exposure time is a portion where light is detected by the electronic shutter function, and corresponds to the time during which the camera opens the shutter and exposes the film. In the first embodiment, the length of the section where the CCD line sensor 4 effectively detects light is made constant within a range where the output of the CCD is not saturated in consideration of the intensity of light applied to the CCD. You have set.

As described above, in the first embodiment, C
During driving, the CD line sensor 4 is driven from an initial state and starts detecting light, and uses a function of detecting light only for a predetermined period of time within a range where output is not saturated, using an electronic shutter function. However, it is a matter of course that the present invention is not limited to the electronic shutter. For example, a mechanical shutter controlled to open only for a certain period of time for detection between the CCD line sensor 4 and the semiconductor wafer 1 may be provided, and the CCD line sensor 4 may receive light only for the detection time. In this case, a circular gear-type rotary shutter in which a tooth portion of a gear becomes a shutter may be rotated in synchronization with the semiconductor wafer 1.

Returning to the flowchart of FIG. The output from the CCD line sensor 4 is a signal processing circuit 7
, The signal processing circuit 7 analyzes where the edge of the semiconductor wafer 1 is located (step S7), and outputs an edge signal (step S8). FIG. 6 shows an edge signal according to the position of the semiconductor wafer 1, where the horizontal axis represents the pixel position and the vertical axis represents the output level. FIG. 6A shows a case where the edge of the semiconductor wafer 1 is out of the detection range of the CCD line sensor 4. Since there is no shadow of the semiconductor wafer 1, all pixels of the CCD line sensor 4 receive light.
The output which was initially at a low level becomes a high-level output throughout the detection range, and becomes a low-level output again outside the detection range. FIG. 6B shows a case where the semiconductor wafer 1 is an opaque wafer such as a silicon wafer. The output which was initially at the low level enters the detection range of the CCD line sensor 4 and once goes to the high level, and then goes to the low level again at the edge position of the semiconductor wafer 1.

FIG. 6C shows that the semiconductor wafer 1 is made of glass,
This is the case for a transparent wafer such as quartz or sapphire. When the output which was initially at the low level enters the detection range of the CCD line sensor 4, the output goes to the high level, and once at the edge position of the semiconductor wafer 1, goes to the low level. Since the semiconductor wafer 1 is transparent, it goes high again after passing through the edge position, and returns to low level again outside the detection range. The length of the low level at the edge position of the transparent wafer is about 500 microns, and can be sufficiently detected with the resolution of the CCD line sensor.

The edge signal output in step S8 of the flowchart of FIG.
0 records the edge position in the recording circuit 11 (step S9). Next, it is determined whether the detection has been completed for one round of the semiconductor wafer 1 (step S10). If the detection has not yet been completed for one round of the semiconductor wafer 1, the process returns to step S4, and enters a cycle of detection at the next detection position.

When the detection has been completed for one round of the semiconductor wafer 1, the edge data recorded in the recording circuit 11 is output to the outside via the external controller 12 (step S11), and the position of the semiconductor wafer 1 is determined. The position of the orientation flat or notch is calculated. The motor 3 stops rotating, and the CPU 10 waits for a command (step S12).

FIG. 7 shows an example of edge data detected for one round of the semiconductor wafer 1. FIG. 7A shows the case of the semiconductor wafer 1 having the orientation flat, and FIG. 7B shows the case of the semiconductor wafer 1 having the notch. The amount of eccentricity of the semiconductor wafer is d / 2, the eccentric direction is angle θ1 or θ3, and the direction of the orientation flat is θ2.
Determined by As described above, the position of the semiconductor wafer 1 and the position of the orientation flat or the notch can be easily calculated from the edge data.

As described above, in the first embodiment, since the CCD line sensor 4 is driven in synchronization with the rotation angle of the semiconductor wafer 1, it is possible to detect each detection position at an accurate timing. . Further, since the CCD line sensor 4 immediately starts detecting light in response to the drive signal, it is possible to detect the light at more accurate timing at each detection position. Further, since the detection time of the CCD line sensor 4 is kept constant at each detection position, the acceleration / deceleration is performed without waiting for the semiconductor wafer 1 to rotate at a constant speed.
Detection can be performed in the entire rotation region including the deceleration region, and the throughput can be improved.

(Second Embodiment) A second embodiment in which the wafer position detecting device of the present invention is applied to a semiconductor wafer position detecting device used in a processing apparatus will be described with reference to the drawings.

In the second embodiment, the position of the wafer is detected at a timing independent of the rotation angle of the wafer. Since the second embodiment is similar to the first embodiment, the same portions will not be described, and only different portions will be described.

The block diagram of the second embodiment is the same as that of the first embodiment shown in FIG. The details of the operation in the second embodiment are different only in how to take the timing for performing the detection operation. The trapezoidal drive pattern shown in FIG. 3, the structure of the CCD line sensor shown in FIG. 4, and the structure shown in FIG. 6, the edge signal shown in FIG. 6, and the edge data obtained for one round of the semiconductor wafer shown in FIG.

The semiconductor wafer 1 shown in FIG.
The second embodiment is the same as the first embodiment until the semiconductor wafer 1 starts to rotate with the rotation of the motor 3 after being placed on the first embodiment, but in the second embodiment, C
The drive of the CD line sensor 4 is performed over one rotation of the semiconductor wafer 1 at a fixed time interval immediately after the rotation of the semiconductor wafer 1 is started. Therefore, the drive timing of the CCD line sensor 4 is not determined in synchronization with the rotation angle of the semiconductor wafer. Conversely, at the timing when the CCD line sensor 4 is driven, the rotation angle of the semiconductor wafer at that time is obtained as data from the encoder signal output from the encoder 13, and the corresponding rotation angle is stored in the storage circuit 11 together with the edge position. Keep it.

The second embodiment is the same as the first embodiment in that data is output to the outside after the semiconductor wafer makes one rotation and detection is completed, and the rotation of the semiconductor wafer is stopped. The operation of the second embodiment will be described in detail with reference to the flowchart of FIG. When a signal is input from the external controller 12 to the CPU 10 and the operation of the semiconductor wafer position detecting device is started, the CPU 10 initializes various registers included in the CPU 10 (Step S21). Next, a signal indicating that the detection operation is being performed is output to the external controller 12 (step S22). Next, the external controller 12 issues a rotation command to the motor driver 9 to start driving the motor 3 (step S23). With the rotation of the motor 3, the support member 2 formed on the rotating shaft also rotates, and accordingly, the semiconductor wafer 1 mounted on the support member 2 also rotates. In the second embodiment, the motor 3 uses a direct drive type AC servomotor integrally formed with the encoder 13, but the present invention is not limited to this as long as it can be controlled to rotate with required accuracy.

When the motor 3 starts rotating, the CPU 10
It is determined whether or not the detection timing is predetermined at predetermined time intervals (step S24). If it is not the timing of detection, it waits. If it is the detection timing, the CPU 10 obtains the rotation angle of the semiconductor wafer 1 from the encoder signal output from the encoder 13 (step S25). Also,
The CPU 10 controls the CCD at the same timing as in step S25.
The line sensor 4 is driven (Step S26). This time interval is set at the top rotation speed of the semiconductor wafer 1 as well.
CCD so that orientation flat or notch can be detected
It is determined from the relationship between the resolution of the line sensor 4 and the top rotation speed of the semiconductor wafer 1.

As described above, since the detection is performed at a constant time interval, the interval between the detection positions on the semiconductor wafer 1 during the acceleration rotation and the deceleration rotation of the semiconductor wafer 1 is determined by the acceleration / deceleration.
It is not constant due to the effect of deceleration. Further, the interval between the detection positions on the semiconductor wafer 1 is constant during the constant speed rotation, but longer than during the acceleration / deceleration.

As described above, the interval between the detection positions is not constant over the entire detection area, but at each detection timing,
The CCD line sensor 4 uses an electronic shutter function,
As soon as it is driven, it starts detecting light from the initial state and detects light only for a predetermined period of time within the range where the output does not saturate, so it takes in the encoder signal at the same time as driving the CCD line sensor and rotates it If the angle is obtained, a rotation angle corresponding to the edge signal can be obtained. Therefore, by collecting this data over one circumference of the semiconductor wafer, the position of the semiconductor wafer 1 and the position of the orientation flat or the notch can be calculated.

In the second embodiment, the CCD line sensor 4 is driven and starts detecting light from an initial state, and has a function of detecting light only for a predetermined period of time within a range where the output is not saturated. It is realized using an electronic shutter, but it is needless to say that the present invention is not limited to the electronic shutter. For example, a similar effect can be obtained by rotating a mechanical rotary shutter at a constant speed in front of the light source.

In the second embodiment, C is set at fixed time intervals.
Although the CD line sensor 4 is driven, the time interval need not be constant as long as the orientation flat or the notch can be detected. For example, detection of orientation flat or notch is C
The CCD line sensor 4 may be driven at a relatively short time interval until the orientation flat or the notch is detected by detecting the orientation flat or the notch, and the time interval may be extended after the orientation flat or the notch is detected. With this configuration, when calculating the wafer position and the position of the orientation flat or the notch in a later process, the calculation amount can be reduced.

When the output from the CCD line sensor 4 is input to the signal processing circuit 7, the signal processing circuit 7 analyzes where the edge of the semiconductor wafer 1 is located (step S2).
7) Output an edge signal (step S28). This edge signal is input to the CPU 10, and the CPU 10 records the position of the edge in the recording circuit 11 together with the corresponding rotation angle (step S29). Next, it is determined whether detection has been completed for one round of the semiconductor (step S30). If the detection has not yet been completed for one round of the semiconductor wafer 1, the process returns to step S24, and enters a detection cycle at the next detection timing.

When the detection of one round of the semiconductor wafer 1 is completed, the data of the rotation angle corresponding to the edge position recorded in the recording circuit 11 is output to the outside via the external controller 12 (step S31). Outside, the position of the semiconductor wafer 1 and the position of the orientation flat or notch are calculated. The motor 3 stops rotating, and the CPU 10 waits for a command (step S32).

As described above, in the second embodiment, the CCD
Since the line sensor 4 immediately starts detecting light in response to the drive signal, detection can be performed at an accurate timing. Further, since the detection time of the CCD line sensor 4 is kept constant, the detection can be performed in the entire rotation region including the acceleration / deceleration region without waiting for the semiconductor wafer 1 to rotate at a constant speed. Can be improved.

[0060]

As described above, according to the wafer position detecting apparatus of the present invention, the wafer position can be detected at each detection position at an accurate timing.

According to the wafer position detecting device of the present invention according to the second aspect, in addition to the effect of the wafer position detecting device according to the first aspect, detection can be performed at more accurate timing and throughput is improved. I do.

According to the wafer position detecting device of the present invention according to claim 3, in addition to the effect of the wafer position detecting device according to claim 1 or 2, the wafer position and the position of the orientation flat or notch can be calculated by a simple calculation. Can be requested.

According to the wafer position detecting device of the present invention, the detection can be performed at each detection position at an accurate timing, and the throughput is improved.

According to the wafer position detecting device of the present invention, the effect of the wafer position detecting device according to the first, second, third, or fourth aspect is obtained by using a CCD having an electronic shutter function.
It can be obtained by using a line sensor.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a wafer position detecting device according to first and second embodiments of the present invention.

FIG. 2 is a flowchart for explaining the operation of the wafer position detection device of the first embodiment in detail.

FIG. 3 is a view showing a driving pattern of a wafer according to the first and second embodiments.

FIG. 4 is a view for explaining an electronic shutter function of the CCD line sensors of the first and second embodiments.

FIG. 5 is a diagram illustrating encoder signals and signals related to a CCD line sensor according to the first and second embodiments.

FIG. 6 is a diagram illustrating a relationship between a wafer position / type and an edge signal according to the first and second embodiments.

FIG. 7 is a diagram illustrating an example of a detection result over one circumference of a wafer according to the first and second embodiments.

FIG. 8 is a flowchart illustrating in detail the operation of the wafer position detection device according to the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor wafer (wafer) 2 Support member (holding means) 3 Motor 4 CCD line sensor (line sensor) 5 Lens 6 Light source (light emitting means) 7 Signal processing circuit (signal processing means) 8 Timing pulse generating circuit 9 Motor driver 10 CPU (control means) 11 Storage circuit 12 External controller

Claims (5)

[Claims] 1. A holding means configured to hold a wafer horizontally and rotate the wafer about a vertical rotation axis with the wafer, thereby detecting the rotation angle of the holding means. Converting means for converting the signal into an electric signal; light projecting means for projecting light onto a peripheral portion of the wafer held by the holding means; and a position of a projected image of the wafer by the light projected by the light projecting means. A line sensor for detecting and outputting as an electrical signal; a signal processing means for processing a signal from the line sensor; and synchronizing the position of the wafer at a plurality of predetermined rotation angles with the line sensor. Control means for driving and controlling to perform detection. 2. The apparatus according to claim 1, wherein the line sensor is driven when
2. The wafer position detecting device according to claim 1, wherein the device is driven from an initial state and starts detecting light, and detects light only for a predetermined period of time within a range where output is not saturated. 3. The wafer position detecting device according to claim 1, wherein the control means controls the detection positions so as to be at equal intervals on the circumference of the wafer. 4. A holding means configured to hold a wafer horizontally and rotate the wafer around a vertical rotation axis with the wafer, thereby detecting the rotation angle of the holding means. Converting means for converting the signal into an electric signal; light projecting means for projecting light onto a peripheral portion of the wafer held by the holding means; and a position of a projected image of the wafer by the light projected by the light projecting means. A line sensor that detects and outputs light as an electric signal, and is driven and starts detecting light from an initial state, and detects light only for a predetermined period of time within a range where output is not saturated, A signal processing unit for processing a signal from the line sensor; and a control unit for controlling the line sensor to be driven at a predetermined detection timing. Position detection device. 5. A wafer position detecting device according to claim 1, wherein said line sensor is a CCD line sensor having an electronic shutter function.