Displaced wafer detection systems

Abstract

A displaced wafer detection system comprises a unified pod, a pod opener, a horizontal transmission robot, and a sensor. The unified pod encloses a plurality of wafers in a first position. The pod opener opens the unified pod. The horizontal transmission robot carries the wafers from the unified pod to a second position. When one of the wafers reaches the second position, the sensor detects if any wafer slips during wafer transmission from the unified pod.

1 . A displaced wafer detection system, comprising:
 a unified pod enclosing a plurality of wafers in a first position;   a pod opener opening the unified pod;   a horizontal transmission robot carrying the wafers from the unified pod to a second position; and   a sensor, when one of the wafers has reached the second position, detecting if any wafer has slipped during wafer transmission from the unified pod.   
   
   
       2 . The system as claimed in  claim 1 , wherein the sensor is disposed between the horizontal transmission robot and the pod opener while the wafers are carried by the horizontal transmission robot from the unified pod to the second position. 
   
   
       3 . The system as claimed in  claim 2 , wherein the sensor is fixed to a first surface of the pod opener, and, when the horizontal transmission robot carrys the wafers from the unified pod, the first surface faces the horizontal transmission robot. 
   
   
       4 . The system as claimed in  claim 2 , wherein the sensor comprises at least one transmitter dispatching a signal and one receiver accepting the signal, the wafers carried by the horizontal transmission robot are substantially parallel, when no wafer slips while being carried from the unified pod, the centers of the wafers reach and lie on a second line, the transmitter and the receiver are both disposed on a third line along which the signal is transmitted from the transmitter to the receiver, and the third line is parallel to the second line. 
   
   
       5 . The system as claimed in  claim 4 , wherein the wafers when being in the opened unified pod have the centers thereof substantially lie on a first line, and the signal travels along a path on the same plane as the first and second lines. 
   
   
       6 . The system as claimed in  claim 4 , further comprising a control unit determining that at least one of the wafers slips when one of the wafers has reached the second position while the receiver does not receive the signal. 
   
   
       7 . The system as claimed in  claim 4 , wherein the control unit stops the horizontal transmission robot when at least one of the wafers slips. 
   
   
       8 . A displaced wafer detection system, comprising
 a unified pod enclosing a first lot of wafers in a first position;   a pod opener opening the unified pod;   a horizontal transmission robot carrying the wafers from the unified pod;   a vertical transmission robot, when in a first orientation, acquiring the wafers and then vertically rotating the wafers to a second orientation;   a transporter moving upward to support the wafers in a vertical orientation when the vertical transmission robot is in the second orientation; and   a sensor detecting if any wafer drops from the vertical transmission robot before the wafers are supported by the transporter.   
   
   
       9 . The system as claimed in  claim 8 , wherein the sensor is disposed between the vertical transmission robot and the transporter when the vertical transmission robot is in the second orientation, and the transporter has not supported the wafers. 
   
   
       10 . The system as claimed in  claim 9 , wherein the wafers acquired by the vertical transmission robot are substantially parallel, the centers of the wafers substantially move along a vertical plane while the vertical transmission robot rotates from the first orientation to the second orientation, the sensor comprises a transmitter dispatching a signal and a receiver accepting the signal, and the transmitter and the receiver are disposed on a line substantially parallel to the vertical plane. 
   
   
       11 . The system as claimed in  claim 10 , wherein the transmitter and the receiver are substantially disposed on the vertical plane. 
   
   
       12 . The system as claimed in  claim 10 , further comprising a control unit determining that at least one of the wafers has dropped if the signal from the transmitter to the receiver is interrupted during a period since the wafers are acquired by the vertical transmission robot until the wafers are supported by the transporter. 
   
   
       13 . The system as claimed in  claim 12 , wherein the control unit stops the transporter when at least one of the wafers drops. 
   
   
       14 . The system as claimed in  claim 12 , wherein the transporter has had a second lot of wafers disposed thereon, and the control unit determines that at least one of the wafers has dropped if the signal from the transmitter to the receiver is interrupted before the first lot of wafers and the second lot of wafers are interleaved. 
   
   
       15 . The system as claimed in  claim 14 , wherein the control unit stops the transporter when at least one of the wafers drops. 
   
   
       16 . The system as claimed in  claim 8 , wherein the horizontal transmission robot carries the wafers from the unified pod to a second position; further comprising:
 a second sensor, when one of the wafers has reached the second position, detecting if any wafer has slipped during wafer transport from the unified pod.   
   
   
       17 . The system as claimed in  claim 16 , wherein the sensor is disposed between the horizontal transmission robot and the pod opener while the wafers are carried by the horizontal transmission robot from the unified pod to a second position.