Radiant energy – Photocells; circuits and apparatus – With circuit for evaluating a web – strand – strip – or sheet
Reexamination Certificate
1999-07-02
2001-10-16
Allen, Stephone B. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
With circuit for evaluating a web, strand, strip, or sheet
C356S614000, C250S559400, C414S935000
Reexamination Certificate
active
06303939
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor wafer mapping apparatus. More particularly, the present invention relates to a semiconductor wafer cassette mapper for detecting number and position of wafers in a wafer cassette.
2. Description of the Related Art
In order to reduce dust and contamination from a manufacturing process, an automatic mechanism is required to perform automatic processes. When a wafer cassette holding a number of wafers is placed in an appropriate position, a robotic arm transports the wafers between a wafer processing chamber and the wafer cassette. Several types of wafer cassettes are used to hold these wafers, depending on the particular process being performed. For example, Teflon wafer cassettes are employed to transport wafers while they are in chemical processes, and quartz wafer cassettes are employed to hold wafers during high temperature processes. In between these processing steps, automated transfer devices are used to transfer the wafers from one type of wafer cassette to another.
FIG. 1
is a schematic, three-dimensional illustration of the conventional semiconductor wafer cassette mapper.
Referring to
FIG. 1
, a semiconductor wafer cassette
100
, capable of holding a full complement of twenty-five wafers
101
, is shown. Each of the wafers
101
is disposed horizontally in evenly-spaced slots
103
located on each sidewall of wafer cassette
100
.
While performing the semiconductor process, number and position of the wafers in the wafer cassette depend on the process performed on the wafers. A semiconductor wafer cassette mapper for detecting number and position of wafers in a wafer cassette is required to enable a robotic arm to accurately remove and place wafers in the wafer cassette. Conventionally, an emitter apparatus is located at one side of wafer cassette
100
and a receiver apparatus is located at the opposite side thereof. The emitter apparatus is leveled with the receiver apparatus, and the wafer cassette
100
is stationary between the emitter apparatus and the receiver apparatus. The emitter apparatus and the receiver apparatus move up and down simultaneously at a constant rate to scan the wafers
101
(or the emitter apparatus and the receiver apparatus are stationary, and the wafer cassette moves up and down at a constant rate). The presence or absence of a wafer
101
in the wafer cassette
100
is determined by whether a beam from the emitter apparatus is detected by the receiver, or not. Moreover, a double slot effect that multiple wafers
101
are stacked or a cross slot effect that a wafer
101
is not placed horizontally can probably be determined by the wafer cassette mapper.
The position of the wafers is scanned by moving either the wafer cassette, or the emitter and the receiver. However, no matter which mechanism is used, the speed of moving elements must be controlled accurately to prevent deviation of mapping or sway of the wafers in the wafer cassette. As a result, a complex and accurate driving system is used.
FIG. 2
is a schematic, three-dimensional illustration of the conventional driving system for controlling a wafer cassette moving up or down. These complex parts are not described herein since they are not closely related to the scope of the present invention. The complicate mechanism fails easily, causing equipment shutdown or incorrect mapping results. For preventing deviation of mapping or sway of the wafers under mapping process, it is necessary to control cassette a slow travelling rate, thus time of wafer mapping is further increased and wafer throughput is decreased.
SUMMARY OF THE INVENTION
Accordingly, the present invention is to provide a semiconductor wafer mapping apparatus. The semiconductor wafer mapping apparatus comprises a cassette mapper with an increased mapping efficiency without the implementation of a complex driving system. Moreover, the device can increase in mapping speed and more reliable.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention provides a semiconductor wafer cassette mapper. A photo-detecting array is used as a receiver for the semiconductor wafer cassette mapper. During a mapping process, the cassette and receiver are relatively stationary, and the complex and accuracy driving system is not required, so that probability for deviation of mapping is reduced.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention provides a semiconductor wafer cassette mapper. A wafer cassette holding a number of wafers is provided. A strip light source is used as an emitter, and a photo-detecting array is used as a receiver for the semiconductor wafer cassette mapper. During a mapping process, the strip light source, the photo-detecting array and the wafer cassette do not need to move for scanning. The strip light source emits a parallel light, and the parallel light is parallel to the wafers and passes through the wafer cassette. Then, the photo-detecting array obtains an information of all wafers by receiving the parallel light at one time. Since the information is obtained at one time, the mapping time is reduced.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention provides a semiconductor wafer cassette mapper. A wafer cassette holding a number of wafers is provided. A parallel scanning light source serves as an emitter and a photo-detecting array serves as a receiver of a semiconductor wafer cassette mapper. During the mapping process, the parallel scanning light source emits a parallel beam, which means a beam with parallel scanning, and the parallel beam is incident and parallel to the wafers. The parallel scanning light source moves vertically to mapping the wafers in the wafer cassette. The photo-detecting array receives the parallel beam. Since the linear photo-detecting array is inherent position discrimination, an information of all wafers is obtained. Since it does not need complex mechanism and accuracy speed control, the parallel scanning light source can move speedily to scan the wafers. As a result, the mapping is also fast.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.
REFERENCES:
patent: 4803373 (1989-02-01), Imamura et al.
patent: 5225691 (1993-07-01), Powers et al.
patent: 5239182 (1993-08-01), Tateyama et al.
patent: 6097492 (2000-08-01), Kondo et al.
Chung Ping-Chung
Lu Tsung-Lin
Allen Stephone B.
United Microelectronics Corp.
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