JPH1126558A - Pre-alignment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pre-alignment device which can reduce the signal detection time when detecting a signal by using a CCD sensor. SOLUTION: This device has a CCD sensor 9 comprising a photoelectric conversion part 9a, a charge transfer part 9b, and a light source 13 with which light is irradiated on the CCD sensor 9. The device has a light-shading part 11 which is provided to a side farther from the signal output part of the CCD sensor 9 and shades a part of light irradiated from a light source, and a drive means 25 which drives the CCD sensor 9 so as to uptate the signal of the photoelectric conversion part 9a by transferring a signal stored in the photoelectric conversion part 9a to the charge transfer part 9b, without reading the signal of the light-shading part 11 after reading a signal stored in a part except for the light-shading part 11 of the CCD sensor 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pre-alignment apparatus, and more particularly to a pre-alignment apparatus capable of reducing a signal detection time when a signal is detected using a one-dimensional or more CCD sensor.

[0002]

2. Description of the Related Art FIG. 5 is a schematic diagram showing a configuration of a conventional pre-alignment apparatus. FIG. 6 shows a CCD (Charge Coupled Device) in the pre-alignment apparatus shown in FIG.
It is the cross section which shows the constitution of the sensor and the graph which shows the profile of the electric charge which is accumulated in the sensor.

As shown in FIG. 5, a pre-alignment apparatus 100 has a CCD sensor 109. This CCD sensor 109 is, as shown in FIG.
A photoelectric conversion means (photo sensor) 109a such as a CCD is provided on the upper surface of the (CD array) 109b. The charge transfer means 109b such as a CCD is driven by a drive means 125 such as a CCD.

The CCD array 109b is connected to a wafer end detecting means 119, and the wafer end detecting means 119 is connected to an end position information storing means 121. The end position information storage means 121 is connected to the center and azimuth calculation means 123 for a wafer or the like.

[0005] Above the photo sensor 109a, a cylindrical lens 117 is provided, and above the cylindrical lens 117, a condenser lens 115 is provided. Above the condenser lens 115, a light source (LED, halogen lamp, etc.) 113 is provided.

[0006] In the vicinity of the CCD sensor 109, an end portion (outer peripheral portion) of the semiconductor wafer or the like 103 is positioned between the photo sensor 109a and the cylindrical lens 117, and the surface of the semiconductor wafer or the like 103 is parallel to the photo sensor 109a. A gripping means 105 for positioning a wafer or the like is provided. Below the wafer holding means 105, a wafer rotating means 107 for rotating the wafer 103 is provided.

Next, the operation of the pre-alignment apparatus 100 will be described. First, light emitted downward from the light source 113 to the photo sensor 109a in the vertical direction is applied to the photo sensor 109a via the condenser lens 115 and the cylindrical lens 117. At this time, part of the light is blocked by the outer periphery of the semiconductor wafer 103 and its vicinity. At this time, light not blocked by the wafer is input to the photo sensor 109a of the CCD sensor 109, and the input light is photoelectrically converted into a photocurrent, and this current is accumulated in a capacitor to become a signal charge. The profile of the accumulated charge amount is as shown in FIG. 6, for example.

Next, the accumulated signal charge of each pixel is C
The data is transferred by the CD array 109b as a transfer clock corresponding to the total number of pixels shown in the lower part of FIG.
9b. The output signal is sent to the wafer and other end detecting means 119. This edge detection means 119
In, the position of one point of the end (outer periphery) of the semiconductor wafer 103 is detected. Next, the data of the detected position is sent to the end position information storage means 121 and stored.

The detection of the position of the end of the wafer 103 as described above is performed 3000 to 10000 times while rotating the wafer 103 by the wafer or the like rotating means 107. As a result, the trajectory of the edge of the wafer 103 is stored in the edge position information storage unit 121.

Next, the accumulated data is sent to the center / azimuth calculating means 123 for the wafer or the like.
Is used to calculate the center position of the wafer 103.

[0011]

In the above-mentioned conventional pre-alignment apparatus, the CCD array sensor 10
When the edge of the wafer is detected by the method 9, the position of the edge needs to be detected 3000 to 10000 times as described above. For this reason, in order to reduce the time required for finding the center position of one wafer, it is necessary to shorten the time required for one position detection as much as possible.

As described above, according to the principle of the CCD sensor 109, after one position detection is performed, the next position detection must be performed after reading information of all the pixels of the CCD array 109b. . That is, in the CCD sensor 109 shown in FIG. 6, since the entire area of the sensor becomes the signal detection effective portion C, the next position detection cannot be performed unless information is read for all the C areas. Therefore, to shorten the time required for one position detection, it is necessary to use CC
It is better that the number of pixels of the D sensor is small.

However, when the CCD sensor 109 is used, a ready-made product (line sensor having a length of 4 to 5 cm in a longitudinal direction) supplied from a device maker is obtained. The specification of the sensor has a considerably large number of pixels. This ready-made product is considerably larger than the number of pixels required as a sensor in actual edge position detection. Therefore, this is a great constraint in detecting the position of the edge of the wafer.

That is, only a small part of the portion necessary as a sensor for detecting the position of the edge of the wafer is necessary, and the other portions are unnecessary. Time hinders the performance of electronic circuits using the sensor. If the time for reading unnecessary information for signal detection can be omitted, the processing time of an electronic circuit using the information can be reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pre-alignment apparatus capable of reducing a signal detection time when detecting a signal using a CCD sensor. It is in.

[0016]

In order to solve the above-mentioned problems, a pre-alignment apparatus according to the present invention comprises a pre-alignment device having a CCD sensor comprising a photoelectric conversion unit and a charge transfer unit, and a light source for irradiating the CCD sensor with light. A light-shielding portion provided on a side far from the signal output portion of the CCD sensor, the light-shielding portion blocking a portion of light emitted from the light source, and the light stored in a portion other than the light-shielding portion of the CCD sensor. After reading the signal, the CCD sensor is configured to transfer the signal stored in the photoelectric conversion unit to the charge transfer unit and update the signal detection of the photoelectric conversion unit without reading the signal of the light shielding unit. And driving means for driving the.

In this pre-alignment apparatus, a light-shielding portion that blocks a part of the light is provided on a side far from the signal output portion of the CCD sensor. Therefore, when a signal accumulated in a portion other than the light-shielding portion of the CCD sensor is read, The state of the sensor in the region of the light-shielding portion moves to a portion other than the light-shielding portion. Since the region of the light-shielding portion is a region in which no signal charge is accumulated, when the reading of the signal of the portion other than the light-shielding portion of the sensor is completed, CC
The D sensor can be set to a state substantially equivalent to a state where no signal is detected in all regions. Therefore, the signal stored in the photoelectric conversion unit by the driving unit can be immediately transferred to the charge transfer unit, and the detection of the photoelectric conversion unit can be updated.

It is preferable that the apparatus further includes a variable length control section for controlling the length of the light shielding section. In addition, the above CC
What is claimed is: 1. A pre-alignment apparatus further comprising a pre-alignment unit for performing a preliminary position detection before performing a position detection by a D sensor, wherein said light-shielding unit is provided by said length variable control unit according to a position detected by said pre-alignment unit. It is preferred to control the length of the part.

By performing preliminary position detection by the preliminary alignment means, it is possible to determine a certain position before performing position detection by the CCD sensor, so that the length of the light shielding portion can be further reduced.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a configuration of a pre-alignment apparatus according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing the configuration of the CCD sensor in the pre-alignment apparatus shown in FIG. 1 and a graph showing a profile of the amount of charge accumulated in the sensor.

As shown in FIG. 1, the pre-alignment device 1 has a CCD sensor 9. The CCD sensor 9 is a charge transfer means such as a CCD (CCD array) as shown in FIG.
Photoelectric conversion means (photo sensor) 9 such as CCD on the upper surface of 9b
a, and a light shielding unit 11 is provided on the photo sensor 9a. The CCD array 9b is driven by a driving means 25 such as a CCD.

The CCD array 9 is connected to a wafer end detecting means 19, which is connected to an end position information storing means 21. The end position information storage means 21 is connected to the center and orientation calculation means 23 for a wafer or the like.

A cylindrical lens 17 is provided above the photo sensor 9a, and a condenser lens 15 is provided above the cylindrical lens 17. Above the condenser lens 15, a light source (LED,
13) are provided.

In the vicinity of the CCD sensor 9, an end (outer peripheral portion) of the semiconductor wafer 3 is located between the photo sensor 9 a and the cylindrical lens 17.
There is provided a holding means 5 such as a wafer for positioning the surface of the photo sensor 9a in parallel with the photo sensor 9a. Below the gripping means 5 for wafers and the like, a rotating means 7 for wafers and the like for rotating the wafer 3 and the like is provided.

Next, the operation of the pre-alignment apparatus 1 will be described. First, light emitted downward from the light source 13 to the photo sensor 9a in the vertical direction is applied to the photo sensor 9a via the condenser lens 15 and the cylindrical lens 17. At this time, part of the light is blocked by the outer periphery of the semiconductor wafer 3 and its vicinity. At this time, light that is not blocked by the wafer 3 is applied to the photo sensor 9a of the CCD sensor 9.
The input light is photoelectrically converted into a photocurrent, and this current is accumulated in a capacitor to become a signal charge. The profile of the accumulated charge amount is shown in FIG.
It becomes as shown in. That is, no charge is accumulated in the region A where light is shielded by the light shielding portion (shielding material) 11,
Electric charges are accumulated only in the B region of the signal detection effective portion, which is a non-shielding portion. The area A is an area farther from the signal output portion of the CCD sensor 9 (a side farther from the signal readout).
The area B is an area closer to the signal output unit of the CCD sensor 9 (closer to signal reading).

Next, the signal charges accumulated in the region B are transferred as a transfer clock corresponding to a non-light-shielding portion shown in the lower part of FIG. 1 and output from the CCD array 9b. This output signal is sent to the wafer end detecting means 19. The edge detecting means 19 detects the position of one point of the edge (outer circumference) of the semiconductor wafer 3. Next, the data of the detected position is sent to the end position information storage means 21 and stored.

The signal charge accumulated in the above-mentioned B region is C
When output from the CD array 9b, the state of the area A moves to the area B. Thereafter, without outputting the signal charges in the region A, the charges of the photo sensor 9a are immediately transferred to the CCD array 9b by the driving means 25 such as a CCD, and the signal detection of the photo sensor is updated.

The detection of the position of the end of the wafer 3 as described above is performed 3000 to 10000 times while the wafer 3 is rotated by the wafer or the like rotating means 7. Thereby, the wafer 3
Are stored in the end position information storage means 21. The planar shape of the wafer 3 can be determined from the edge position information.

Next, the accumulated data is sent to the center and azimuth calculating means 23 for the wafer and the like, and the calculating means 23 calculates the center position of the wafer 3.

According to the first embodiment, the shield 1
Since the area A of the CCD sensor 9 is shielded by 1, when the light from the light source 13 irradiates the photoelectric conversion surface, charges having a signal profile as shown in FIG. 2 are accumulated.
When the signal charges are read out in this state, the signal charges accumulated in the B region are sequentially read, and the state of the A region where no signal charges are accumulated moves to the B region. Since the area A is an area where no signal is detected, when the reading of the signal in the area B is completed, the CCD sensor can be brought into a state almost equivalent to a state where no signal is detected in all areas. The drive unit 25 can update the detection of the CCD sensor. Therefore, the reading time can be reduced as compared with the case where the signal charges in all the regions of the CCD sensor are read as in the conventional pre-alignment apparatus.

That is, if half of the CCD sensor is masked by the shield 11, the reading time can be reduced to half. For example, one-dimensional CC of 2048 pixels
In the case of using the D sensor, assuming that the read cycle is 5 MHz, the time required to read all the pixels is 4
09.6 μs. In contrast, this one-dimensional CCD
When 1024 pixels, which is half of the total number of pixels of the sensor, are masked and used, the time required for reading is 204.8 μsec. As a result, light can be emitted from the light source 13 to the CCD sensor 9 at twice the period, so that the time for detecting the position of the edge of the semiconductor wafer 3 can be reduced.

FIG. 3 is a schematic diagram showing a configuration of a pre-alignment apparatus according to a second embodiment of the present invention.
The same parts as those described above are denoted by the same reference numerals, and only different parts will be described. FIG. 4 is a configuration diagram showing the preliminary alignment means shown in FIG.

The pre-alignment apparatus 10 shown in FIG. The pre-alignment means 31 includes a photoelectric conversion element 33 and an illumination means as shown in FIG. That is, a plurality of photoelectric conversion elements 33 are provided in the wafer transfer path for transferring the wafer 3 from the wafer carrier to the pre-alignment apparatus. Immediately above the photoelectric conversion element 33, an illuminating means (not shown) for illuminating the wafer 3 being carried on the carrying path is provided.

The pre-alignment means 31 is for preliminarily detecting the center of the wafer 3 before the pre-alignment device 10 detects the center position of the wafer 3. Specifically, when the wafer is being sent on the transfer path in the wafer transfer direction, light is applied to the photoelectric conversion element 33 on the transfer path by the illumination unit. Thereby, the center position of the wafer 3 is calculated from the difference in the time when the end face of the wafer 3 being conveyed passes over each photoelectric conversion element 33.

The photo sensor 9a of the CCD sensor 9
Is provided with a light shielding portion 11a.
1a is composed of, for example, an ECD, a liquid crystal, or the like. Also,
It is also possible to use a mechanical shutter as the light shielding part 11a.

The light shielding section 11a is provided with a variable length control section 11b. The variable length control unit 11b controls the light shielding unit 11a so as to shield the photoelectric conversion surface other than the necessary part from light in accordance with the center position of the wafer 3 detected by the preliminary alignment unit 31. The driving means 25 such as a CCD is also changed to a driving method corresponding to a change in the length of the light shielding portion 11a.

Note that the accuracy of the center position detected by the preliminary alignment means 31 is not good because of the insufficient control of the transfer speed of the wafer 3 and the small number of end face data obtained. As described above, it can be said that the accuracy is sufficient to determine the length of the light shielding portion 11a.

In the second embodiment, the same effects as those in the first embodiment can be obtained.

Further, by preliminarily detecting the center position of the wafer 3 by the pre-alignment means 31, the end position of the wafer 3 can be determined from this center position although there is some error. Then, by adjusting the length of the light shielding portion 11a by the variable length control portion 11b in accordance with the determined position of the end portion, it is possible to shield the portions other than the necessary portion of the CCD sensor 9 from light. As a result, the CCD sensor 9 in the pre-alignment device 10
Can be made shorter than in the first embodiment. Therefore, the reading time can be further reduced as compared with the case where the pre-alignment unit 31 is not used as in the pre-alignment apparatus according to the first embodiment.

[0040]

As described above, according to the present invention, C
A light-shielding portion that blocks a part of light is provided on a side far from the signal output portion of the CD sensor. Therefore, it is possible to provide a pre-alignment apparatus capable of shortening the signal detection time when detecting a signal using the CCD sensor.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a pre-alignment apparatus according to a first embodiment of the present invention.

FIG. 2 shows a CC in the pre-alignment apparatus shown in FIG.
It is the cross section which shows the constitution of D sensor and the graph which shows the profile of the electric charge which is accumulated in the sensor.

FIG. 3 is a schematic diagram illustrating a configuration of a pre-alignment apparatus according to a second embodiment of the present invention.

FIG. 4 is a configuration diagram showing a preliminary alignment unit shown in FIG. 3;

FIG. 5 is a schematic diagram showing a configuration of a conventional pre-alignment apparatus.

FIG. 6 shows a CC in the pre-alignment apparatus shown in FIG.
It is the cross section which shows the constitution of D sensor and the graph which shows the profile of the electric charge which is accumulated in the sensor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Pre-alignment apparatus 3 ... Semiconductor wafer etc. 5 ... Wafer etc. holding means 7 ... Wafer etc. rotation means 9 ... CCD sensor 9a ... Photoelectric conversion means (photo sensor) such as CCD 9b ... Charge transfer means such as CCD (CCD array) 11 ... Light shielding part 11a ... Light shielding part 11b ... Variable length control part 13 ... Light source 15 ... Condenser lens 17 ... Cylindrical lens 19 ... Wafer and other edge detecting means 21 ... Edge position information accumulating means 23 ... Wafer and other center / direction calculating means 25 ... CCD driving means 31 ... Preliminary alignment means 33 ... Photoelectric conversion element 100 ... Pre-alignment device 103 ... Semiconductor wafer etc. 105 ... Wafer holding means 107 ... Wafer rotation means 109 ... CCD
Sensor 109a: Photoelectric conversion means such as CCD (photo sensor) 109b: Charge transfer means such as CCD (CCD array) 113: Light source 115: Condenser lens 117: Cylindrical lens 119: Wafer edge detection means 121: Edge position information storage means 123 ... Center and azimuth calculation means for wafer etc. 125 ... Drive means for CCD etc.

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // G01N 21/27 H01L 27/14 D

Claims (3)

[Claims] 1. A CCD comprising a photoelectric conversion unit and a charge transfer unit
A pre-alignment device having a sensor and a light source for irradiating light to the CCD sensor; a light shielding unit provided on a side far from a signal output unit of the CCD sensor, for shielding a part of light emitted from the light source; After reading the signal stored in a portion other than the light-shielding portion of the CCD sensor, the signal stored in the photoelectric conversion portion is transferred to the charge transfer portion without reading the signal of the light-shielding portion. And a driving unit for driving the CCD sensor so as to update the signal detection of the photoelectric conversion unit. 2. The pre-alignment apparatus according to claim 1, further comprising a variable length control unit for controlling a length of the light shielding unit. 3. A pre-alignment apparatus further comprising preliminary alignment means for performing preliminary position detection before position detection by said CCD sensor; said length according to the position detected by said preliminary alignment means. 3. The pre-alignment apparatus according to claim 2, wherein the length of the light shielding unit is controlled by a variable control unit.