JP3963300B2 - A wafer outer peripheral position detecting method, a computer-readable recording medium storing a program for executing the method, and a wafer outer peripheral position detecting device. - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a positioning method and positioning apparatus for an opaque substantially circular wafer having a V-shaped notch called a notch or a notch called an orientation flat (orientation flat), and in particular, a CCD linear sensor. The present invention relates to a method for detecting the outer peripheral position of a wafer using the method.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a wafer pre-alignment sensor has been used in a semiconductor manufacturing apparatus for positioning a wafer center position, orientation flat or notch. As an example of the prior art, Japanese Patent Application Laid-Open No. 8-64660 discloses a method for performing positioning accurately even with a point light source instead of parallel light. Therefore, a conventional wafer positioning method will be described with reference to a block diagram of a wafer outer periphery position detection device using the CCD linear sensor of FIG. An opaque substantially circular wafer 2 is placed on the stage 1, and a light source 3 and a CCD linear sensor 4 are provided across the outer periphery of the wafer 2. When the light source 3 illuminates the outer peripheral portion of the wafer 2, the light is blocked by the wafer 2, and a bright and dark image is projected onto the CCD linear sensor 4. This image is an edge signal binarized by the signal processing unit 5 of the signal processing board 11. The value of the data at the moment when the edge signal changes from light to dark is held by a latch circuit provided therein, and is output and recorded in the memory 7 of the computer apparatus 10. The same operation is repeated until the wafer 2 is rotated once by the stage 1, and outer circumference data for one round of the wafer is recorded in the memory 7. Such operations of the signal processing unit 5 and the memory 7 are performed in cooperation with a command of the CPU 9 of the computer apparatus 10. Based on the outer circumference data of the memory 7, the data processor 8 obtains the orientation flat position or notch position of the wafer 2 and the center position of the wafer 1. When such an operation is performed, the signal processing unit 5 starts scanning from one end of the CCD linear sensor 4 and when the rising change point of the edge signal is detected, the edge position data at that time is latched, and the memory 7 Stored in The edge signal is usually like the edge signal 13 in FIG. 2, and the change point of light and darkness of the image projected on the CCD linear sensor 4 is set as the rising change point. The above-described single scanning operation is repeated many times during one rotation of the stage, and the center position, orientation flat, and notch position of the wafer 2 are calculated from the data for one round.
[0003]
[Problems to be solved by the invention]
However, in the above-described conventional outer periphery position detection method, when the particle 12 adheres to the CCD linear sensor 4 as shown in FIG. 2, the edge signal 13 changes a plurality of times like the edge positions 15 and 16 of the particle. The edge position 16 is output, and the wafer outer peripheral position cannot be detected correctly. An object of the present invention is to provide a method capable of correctly detecting the outer peripheral position of a wafer even if such particles or the like adhere to a CCD linear sensor.
[0004]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a wafer outer peripheral position detection method according to the present invention includes a light source and a CCD linear that receives light from the light source, sequentially scans from one end to the other, and outputs detection position information and detection data. And when the outer periphery of the semiconductor wafer is located between the light source and the CCD linear sensor, the outer peripheral position of the semiconductor wafer is determined by an edge at which the detection data changes from LO (or HI) to HI (or LO). In the pre-alignment sensor to detect, when the CCD sensor scans from the outer peripheral side of the wafer to the inside and sequentially outputs the detection position information and the detection data, the detection data changes from LO (or HI) to HI (or LO). to be the detection position information is recorded at the changing edge, the last of the time the edge is scanned when there are multiple The detection position information corresponding to Tsu di is characterized in that it is a peripheral position of the semiconductor wafer.
In the wafer outer peripheral position detecting method according to the present invention, when the substantially disk-shaped semiconductor wafer makes one rotation, the scan is repeated a plurality of times, and the detected position information corresponding to the edge is included in the scan. It is characterized by being recorded correspondingly.
A computer-readable recording medium having recorded thereon a program for executing the wafer outer periphery position detecting method according to claim 3 is written in such a manner that the program for executing the method according to claim 1 or 2 is read by the computer. It is characterized by that.
According to a fourth aspect of the present invention, there is provided a wafer outer peripheral position detecting device comprising: a light source; and a CCD linear sensor that receives light from the light source, sequentially scans from one end to the other end, and outputs detection position information and detection data. Provided that when the outer periphery of the semiconductor wafer is located between the light source and the CCD linear sensor, the detection position of the outer periphery of the semiconductor wafer is detected by an edge at which the detection data changes from LO (or HI) to HI (or LO). In the alignment sensor, the CCD sensor scans from the outer peripheral side of the wafer to the inside and inputs the detection position information and the detection data, and the detection data changes at the edge where the detection data changes from LO (or HI) to HI (or LO). a signal processing means for outputting said detected position information of the place, the last time the scan is obtained by scanning if it is determined to have been completed A data update unit that outputs position information, a memory that stores all the position information of the data update unit that is input for each scan, and outputs all the position information when a series of scans are completed, and the memory outputs When all the position information to be input is input, the data processing unit executes a predetermined calculation process.
As a result, the wafer outer peripheral position can be correctly detected even if particles or the like adhere to the CCD linear sensor.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a pre-alignment sensor that implements the method of the present invention, FIG. 2 is a diagram for explaining detection signals, and FIG. 3 is a flowchart showing a processing procedure of the method of the present invention.
In FIG. 1, an opaque substantially circular wafer 2 is placed on a rotatable stage 1, and a light source 3 and a CCD linear sensor 4 that is a light receiving element are arranged above and below across the outer periphery of the wafer 2. When the light from the light source 3 is blocked by the wafer 2, a bright and dark image is projected onto the CCD linear sensor 4. This image is binarized as an edge signal of the wafer 2 by the signal processing unit 5 provided on the signal processing board 11, and the rising position of the binarized edge signal is latched as the outer peripheral position.
[0006]
Here, a method of correctly detecting the outer peripheral position of the wafer 2 when the particles 12 adhere to the CCD linear sensor 4 will be described with reference to FIG. In FIG. 2, when the particle 12 is attached to the CCD linear sensor 4 or when the particle 12 is floating between the light source 3 and the CCD linear sensor 4, the light projected from the light source 3 is the particle 12 and the wafer. 2 is shielded from light. The CCD linear sensor 4 outputs cell numbers and light / dark detection data in order from right to left, and includes a binarized edge signal 13. In order to prevent erroneous detection of the edge positions 14 and 15 of the particles of the edge signal 13 as the wafer outer peripheral position, in the present invention, the scanning direction 17 of the CCD linear sensor 4 is from the outer peripheral side of the wafer 2 to the inner side, that is, from bright to dark. In the direction toward. Then, by utilizing the fact that the edge signal 13 does not change because the wafer 2 is opaque inside the outer periphery position of the wafer 2, the last edge position 14 which is the rising edge of the latest edge signal is detected as the outer periphery position data. Then, it is stored in the memory 7 as the outer peripheral position of the wafer 2.
[0007]
Specifically, the data update unit 6 in FIG. 1 determines whether or not the scan from the right end to the left end of the CCD linear sensor 4 has been completed, and if it has been completed, the signal processing unit 5 latches it as an edge position. Is stored in the memory 7 as wafer peripheral position data. This is repeated a predetermined number of times while the wafer 2 makes one round. In the data processing unit 8, the orientation flat position and the notch position of the wafer 2 are calculated using the wafer outer peripheral position data for one round of the wafer 2 obtained in this way.
[0008]
Next, the above method will be described in more detail with reference to the flowchart of FIG. First, when the opaque substantially circular wafer 2 is placed on the stage 1 by a robot (not shown) or the like and fixed by a suction mechanism (not shown) mounted on the stage 1, the light source 3 illuminates the peripheral portion of the wafer 2. . (S1) When the stage 1 starts rotating with the wafer 2 placed thereon, (S2) the write address of the memory 7 mounted on the computer apparatus 10 is reset. (S3) When the CCD linear sensor 4 receives light from the light source 3 and simultaneously detects light and dark, and holds an electric charge inside, the cell number (S4) of the light receiving cell is advanced by one from the right end to the left end in FIG. (S5) The cell number and light / dark detection value data are output to the signal processing unit 5.
[0009]
(S6) The signal processing unit 6 determines whether or not the detected value data has risen compared with the detected value data of the previous cell number, and if it has risen (S7) the linear sensor as the rising edge position. The cell number is output to the data updating unit 6 (S8), and it is determined whether or not the scanning from the right end to the left end of the CCD linear sensor 4 is completed. If it is not determined in (S6) that the system has started, the process proceeds to (S8) without passing through (S7). If it is not determined that the scan is completed in (S8), the process proceeds to (S4), the above procedure from (S4) to (S7) is repeated, and if it is determined that the scan is completed (S9) data update The unit 6 outputs the rising edge position data to the memory 7. (S10) The write address of the memory 7 is incremented by 1 (S11), and it is determined whether a series of measurements is completed. If it is determined that the measurement has not been completed, the process returns to (S3) and the above procedures from (S3) to (S10) are repeated. If it is determined that a series of measurements has been completed (S12), the rotation of the stage 1 is stopped. The (S13) A series of data stored in the memory 7 in this way is output to the data processing unit 8. (S14) A predetermined process imposed on the data processing unit 8 is performed, and the measurement is completed. Thereafter, the stage 1 is rotated to a specified position with the output orientation flat position or notch position as a reference, the wafer 2 is positioned, the wafer 2 is unfixed, and the wafer 2 is transferred to the next process. .
[0010]
A third aspect of the present invention is a magnetic disk such as a floppy (registered trademark) disk or an optical disk such as a CD-ROM in which a procedure for carrying out the method for detecting the outer peripheral position of the wafer is described as a computer program. These are various readable recording media. The computer that has read this can fulfill the above function as a data updating unit.
[0011]
【The invention's effect】
As described above, according to the present invention, even when the binarized detection data changes due to the adhesion of particles on the CCD linear sensor, the latest change point is detected at the outer periphery of the wafer. Since it can be detected as a position, a correct outer peripheral position of the wafer can be detected.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a pre-alignment sensor that implements the method of the present invention. FIG. 2 is a diagram illustrating detection signals. FIG. 3 is a flowchart illustrating a processing procedure of the method of the present invention. Block diagram showing the configuration of the pre-alignment sensor [Explanation of symbols]
1 stage, 2 wafer, 3 light source,
4 CCD linear sensor, 5 signal processor, 6 data updater,
7 memory, 8 data processing unit, 9 CPU,
10 computer equipment, 11 signal processing board, 12 particles,
13 edge signal, 14 last edge position,
15, 16 Edge position of particles, 17 Scan direction

Claims (4)

A light source and a CCD linear sensor that receives light from the light source and sequentially scans from one end to the other to output detection position information and detection data, and an outer periphery of a semiconductor wafer between the light source and the CCD linear sensor In the pre-alignment sensor that detects the outer peripheral position of the semiconductor wafer by an edge where the detection data changes from LO to HI or from HI to LO ,
When the CCD sensor scans from the outer peripheral side to the inner side of the wafer and sequentially outputs the detection position information and the detection data, the detection position information at the edge where the detection data changes from LO to HI or from HI to LO. Recorded,
A wafer outer periphery position detection method, wherein, when there are a plurality of edges, the detected position information corresponding to the last edge when scanned is an outer periphery position of the semiconductor wafer.   The detection position information corresponding to the edge is recorded corresponding to the scan while the scan is repeated a plurality of times when the substantially disk-shaped semiconductor wafer rotates once. 2. A method for detecting an outer peripheral position of a wafer according to 1.   A computer-readable recording medium having recorded thereon a program for executing a method for detecting the outer peripheral position of a wafer, wherein the program for executing the method according to claim 1 is written in a computer-readable manner. A light source and a CCD linear sensor that receives light from the light source and sequentially scans from one end to the other to output detection position information and detection data, and an outer periphery of a semiconductor wafer between the light source and the CCD linear sensor Is detected by the edge at which the detection data changes from LO to HI or from HI to LO , and this is repeated a predetermined number of times during one rotation of the wafer, and the orientation flat position of the wafer is detected. In the pre-alignment sensor that calculates the notch position ,
The detection position information and the detection data output by the CCD sensor scanned from the outer peripheral side to the inner side of the wafer are input, and the detection position information at the edge where the detection data changes from LO to HI or from HI to LO. Signal processing means for outputting,
A data updating unit that outputs the detected position information corresponding to the last edge as the outer peripheral position of the wafer when there are a plurality of the edges when the scan is completed;
A memory that stores all of the position information of the data update unit that is input every scan that is repeated a predetermined number of times during one rotation of the wafer and that outputs all the position information when a series of scans is completed;
A wafer outer peripheral position detecting apparatus comprising: a data processing unit that executes a predetermined calculation process for calculating an orientation flat position and a notch position when all the position information output from the memory is input.

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