Device for the detection of substrates stacked with a specific spacing
View Patent ↗For a device for the detection of substrates stacked at an opening of a wall element, there existed the problem of constructing the detection device in such a way that the detection of the position of the substrates can be performed more flexibly with respect to the course of measurement and the measuring method employed and a defined approach of a sensor system to the semiconductor substrate to be detected is ensured in a definite position of measurement with a lowered risk of particle generation. A transmitting and receiving device ( 11 ) consists of a vertical drive mechanism ( 10 ) mounted on the wall element ( 1 ) and a sensor head ( 13 ) that can be adjusted between a lower and an upper position by means of the vertical drive mechanism ( 10 ), said sensor head being arranged so as to pivot on the vertical drive mechanism ( 10 ) in order to pivot into the opening ( 4 ). The device finds application, in particular, in the semiconductor industry for recording the state of occupancy of cassettes or containers with substrates, such as semiconductor wafers, flat-screen displays, or masks.
1. A device for the detection of substrates stacked with a specific spacing at an opening of a wall element with a closure for the opening, it being possible for this closure to be adjusted in at least two different directions relative to the wall element by means of a drive mechanism that is positioned below the opening and having a transmitting and receiving device for transmitting and receiving a horizontally directed measuring beam, characterized in that the transmitting and receiving device comprises of a vertical drive mechanism mounted on the wall element independent from the drive mechanism, and a sensor head that can be adjusted between a lower and an upper position by means of the vertical drive mechanism, said sensor head being pivoted on the vertical drive mechanism so that it can pivot into the opening.
2. The device according to claim 1 , further characterized in that the vertical drive mechanism is mounted below the opening and outside of the region of movement of the closure on the wall element.
3. The device according to claim 2 , further characterized in that the vertical drive mechanism supports the sensor head on a pivoting head that has a horizontally directed pivot axis and is mounted on an arm that can be extended vertically.
4. The device according to claim 3 , further characterized in that the pivot axis runs through a hollow shaft, on which the sensor head is placed and which can pivot between two terminal positions.
5. The device according to claim 1 , further characterized in that the sensor head is designed as a forked light barrier, in which, at one end of the fork, a transmitter is mounted for emitting a measuring beam directed along a measuring beam path towards the other end of the fork and, at the other end of the fork, there is provided a beam deflection device, from which a coupled optical fiber leads outside of the measuring beam pathway by means of optics to a receiver at the one end of the fork in a lighttight manner.
6. The device according to claim 5 , further characterized in that the forked light barrier is arranged so as to pivot around a horizontally directed pivot axis, which runs parallel to and at a spacing from the measuring beam path, so that the ends of the fork pass through the opening in the wall element when pivoting occurs around the pivot axis.
7. The device according to claim 6 , further characterized in that the transmitter is designed as a laser.
8. The device according to claim 1 , further characterized in that the transmitting and receiving device is equipped with its own electronic control and analysis unit, which is connected to a bus system of a central logic control.
9. The device according to claim 8 , further characterized in that the vertical drive mechanism is constructed as a motor-spindle combination, which has an encoder for identifying the vertical positions, the encoder being linked to the electronic control and analysis unit of the transmitting and receiving device, the measured signals obtained from a receiver thereby being assigned to the positions determined.
10. The device according to claim 1 , further characterized in that the sensor head is designed as a reflection measuring device, in which the transmitter and receiver are arranged next to each other on the sensor head.