Techniques for wafer prealignment and sensing edge positions
원문보기
IPC분류정보
국가/구분 |
United States(US) Patent
등록
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국제특허분류(IPC7판) |
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출원번호 |
US-0415733
(2001-11-01)
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우선권정보 |
JP-2000-335530(2000-11-02); JP-2000-338601(2000-11-07); JP-2000-352309(2000-11-20) |
국제출원번호 |
PCT/JP01/009609
(2001-11-01)
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§371/§102 date |
20031014
(20031014)
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국제공개번호 |
WO02/037555
(2002-05-10)
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발명자
/ 주소 |
- Inenaga,Masamichi
- Arinaga,Yuji
- Katsuda,Shinichi
- Imanaka,Takayuki
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출원인 / 주소 |
- Kabushiki Kaisha Yaskawa Denki
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대리인 / 주소 |
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인용정보 |
피인용 횟수 :
1 인용 특허 :
3 |
초록
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A wafer prealignment apparatus comprising a CCD linear sensor and a wafer prealignment method which facilitate the sensing of wafer presence, improvement in precision of position sensing, and edge sensing adapted to the material of the wafer even of the material is transparent or not. A photodiode (
A wafer prealignment apparatus comprising a CCD linear sensor and a wafer prealignment method which facilitate the sensing of wafer presence, improvement in precision of position sensing, and edge sensing adapted to the material of the wafer even of the material is transparent or not. A photodiode (27) is provided in a vicinity of the first pixel from the center shaft of the wafer rotation means of a CCD linear sensor (5) to detect a wafer (1) on the basis of the luminous energy value. The time from the issuance of a measurement command to the sensor (5) to that of an ROG signal for transmitting the detection timing of the sensor (5) is measured to correct the angular error of a measurement position due to the rotation during this measurement. For sensing an edge position of the wafer ( 1), the scan start point of the sensor (5) is set on the opposite side of the center shaft of the wafer rotation means. When the wafer is transparent a sense signal is binarized to set its change point as the edge position. When the wafer is not transparent, information on a position lastly sensed as an edge is judged to be correct so that a particle may not be misrecognized as the edge.
대표청구항
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What is claimed is: 1. A wafer prealignment apparatus comprising: a wafer rotation means that can rotate a substantially circular wafer while holding the wafer on a table having a vertical rotational axis; a rotation sensing means for sensing a rotational angle of the wafer rotation means and trans
What is claimed is: 1. A wafer prealignment apparatus comprising: a wafer rotation means that can rotate a substantially circular wafer while holding the wafer on a table having a vertical rotational axis; a rotation sensing means for sensing a rotational angle of the wafer rotation means and transforming it into an electrical signal; a light projecting means for projecting light onto an edge of the wafer held by the wafer rotation means; a CCD linear sensor that consists of a great many pixels linearly arranged each of which has a fixed order and that reads a stored electric charge in order from a first pixel in accordance with a transfer pulse signal and then sequentially outputs stored electric charges of all pixels as electrical signals; and a signal processing means that repeatedly senses an edge position of the wafer at a plurality of arbitrary points over an outer circumference of the wafer and stores it in a built-in memory when a signal of the CCD linear sensor and a signal of the rotation sensing means are received, and, based on a sensed value thereof, calculates at least one of an orientation flat position, a notch position, and a center position of the wafer; wherein a photodiode is provided within a range where the light projecting means projects light and in the vicinity of the first pixel of the CCD linear sensor, and the signal processing means includes a luminous energy signal processing section for receiving a signal of the photodiode and sensing a quantity of light, a wafer edge sensing section for receiving a signal of the CCD linear sensor and sensing an edge of the wafer, a comparison judgment means for determining the presence or absence of the wafer by making a comparison between a luminous energy value of the photodiode and a signal of the wafer edge sensing section, and an output means for imparting a result thereof to an outside element. 2. A wafer prealignment apparatus as set forth in claim 1, wherein the signal processing means further includes a light emission drive section for turning on or off the light projecting means. 3. The wafer prealignment apparatus as set forth in claim 1, wherein the signal processing means determines that: the wafer is absent if the luminous energy value of the photodiode is equal to a value obtained when the light is admitted thereto when the edge of the wafer cannot be sensed; the wafer is present if the luminous energy value of the photodiode is equal to a value obtained when the light is blockshielded; and an unnecessary object adheres to the CCD linear sensor if the luminous energy value of the photodiode is equal to a value obtained when light is admitted thereto when the edge of the wafer can be sensed. 4. A wafer prealignment apparatus comprising: a wafer rotation means that can rotate a circular wafer while holding the wafer on a table having a vertical rotational axis; a rotation sensing means for sensing a rotational angle of the wafer rotation means and transforming it into an electrical signal; a light projecting means for projecting light onto an edge of the wafer held by the wafer rotation means; a CCD linear sensor that consists of a great many pixels linearly arranged each of which has a fixed order and that reads a stored electric charge in order from a first pixel in accordance with a transfer pulse signal and then sequentially outputs stored electric charges of all pixels as electrical signals; and a signal processing means that repeatedly senses an edge position of the wafer at a plurality of predetermined sensed positions over an outer circumference of the wafer and stores it in a built-in memory when a signal of the CCD linear sensor and a signal of the rotation sensing means are received, and, based on a sensed value thereof calculates at least one of an orientation flat position, a notch position, and a center position of the wafer; wherein the signal processing means includes a first timer for measuring time from measurement commands corresponding to the plurality of predetermined sensed positions over the outer circumference of the wafer to an ROG signal that is a timing signal used when the stored electric charge of the pixel is transformed into an electrical signal in the CCD linear sensor; and a second timer for measuring time between the measurement commands corresponding to the plurality of predetermined measurement positions over the outer circumference of the wafer. 5. A wafer prealignment apparatus as set forth in claim 4, wherein the signal processing means has a function to correct an angular error between a position in a circumferential direction where the stored electric charge of the CCD linear sensor has been output and a measured position by use of the time measured by the first timer and the time measured by the second timer when the signal processing means receives the ROG signal. 6. A wafer prealignment apparatus as set forth in claim 5, wherein an angular error φ[deg] between the plurality of predetermined measurement positions over the outer circumference of the wafer and the position where the stored electric charge of the CCD linear sensor has been output by the ROG signal is defined as: description="In-line Formulae" end="lead" φ=θ횞(τ/T)description="In-line Formulae" end="tail" where φ[deg] is an angle between the plurality of predetermined measurement positions over the outer circumference of the wafer, τ[sec] is time measured by the first timer, and T[sec] is time measured by the second timer, and an error of a rotational angle where an electric charge of the CCD linear sensor has been read is corrected by adding φ to the plurality of predetermined sensed positions over the outer circumference of the wafer. 7. A wafer-edge-position-sensing method, in which a wafer prealignment apparatus for sensing a wafer edge position comprising: a wafer rotation means that can rotate a substantially circular wafer while holding the wafer on a table having a vertical rotational axis; a rotation sensing means for sensing a rotational angle of the wafer rotation means and transforming it into an electrical signal; a light projecting means for projecting light onto an edge of the wafer held by the wafer rotation means; a CCD linear sensor that consists of a great many pixels linearly arranged each of which has a fixed order and that reads a stored electric charge in order from a first pixel occupying a scan start point in accordance with a transfer pulse signal and then sequentially outputs stored electric charges of all pixels as electrical signals; and a signal processing means in which, when a signal of the CCD linear sensor is received, the signal is binarized, and the number of transfer pulses to a change point where the binarized data is first changed from an L-level (or H-level) to an H-level (or L-level) while scanning from the scan start point is regarded as an edge position of the wafer; wherein an edge position of an opaque wafer is sensed while directing the scan start point toward a center axis of the wafer rotation means; and an edge position of a transparent wafer is sensed under the condition that the scan start point is directed in a direction opposite to a center axis of the wafer rotation means and under the condition that, when the signal processing means receives a signal of the CCD linear sensor, the signal is binarized and then reversed, and the number of transfer pulses to a change point where the reversed data is first changed from an L-level (or H-level) to an H-level (or L-level) while scanning from the scan start point is regarded as an edge position of the wafer. 8. A wafer prealignment apparatus comprising: a wafer rotation means that can rotate a substantially circular wafer while holding the wafer on a table having a vertical rotational axis; a rotation sensing means for sensing a rotational angle of the wafer rotation means and transforming it into an electrical signal; a light projecting means for projecting light onto an edge of the wafer held by the wafer rotation means; a CCD linear sensor that consists of a great many pixels linearly arranged each of which has a fixed order and that reads a stored electric charge in order from a first pixel occupying a scan start point in accordance with a transfer pulse signal and then sequentially outputs stored electric charges of all pixels as electrical signals; and a signal processing means for receiving a signal of the CCD linear sensor and sensing an edge position of the wafer; wherein the signal processing means has a function by which, when a linear-sensor-mount-direction reversing signal is input, a signal of the CCD linear sensor is received, is then binarized, and is reversed, and the number of transfer pulses to a change point where a reversed signal is first changed from an L-level (or H-level) to an H-level (or L-level) while scanning from the scan start point is set as an edge position of the wafer.
이 특허에 인용된 특허 (3)
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Igaki, Seigo; Nakakuki, Tadao; Inagaki, Takefumi; Oikawa, Shuetsu; Fujimura, Takashi, Apparatus for detecting edge of semitransparent plane substance.
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Yamamoto Satoshi (Kyoto JPX) Kamei Kenji (Kyoto JPX), Apparatus for detecting position of a notch in a semiconductor wafer.
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Perkins John D. ; Mohr David, Wafer orientation sensor.
이 특허를 인용한 특허 (1)
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Osada, Keiji; Nishinakayama, Yasuhiko; Ikeda, Gaku; Takahashi, Hiroyuki, Substrate positioning device, substrate positioning method and program.
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