Wafer transfer system, wafer transfer method, cassette exchange system and cassette exchange method

Abstract

A cassette exchange system is provided. The cassette exchange system includes a wafer temporary storage apparatus, a first cassette base, a second cassette base and a moving apparatus. The wafer temporary storage apparatus includes a plurality of wafer carrier units. The first cassette base is suitable for carrying a first cassette, and the second cassette base is suitable for carrying a second cassette. The moving apparatus connects the first cassette base with the second cassette base. Also, the moving apparatus sequentially moves the first cassette base and the second cassette base to the wafer temporary storage apparatus to simultaneously transfer the wafers stored in the first cassette to the second cassette.

1 . A wafer transfer system, comprising: 
 a movable body;    at least one wafer carrier unit, the wafer carrier unit comprising a first end and a second end opposed to the first end, wherein the first end connects with the movable body; and    at least two sensors, disposed at the second end of the wafer carrier unit.    
   
   
       2 . The wafer transfer system of  claim 1 , wherein the sensors comprise optical sensors, wireless sensors or wired sensors.  
   
   
       3 . A wafer transfer method, comprising: 
 (a) providing a cassette with at least one wafer, a determining unit and a wafer transfer system; the wafer transfer system at least comprising a wafer carrier unit, a first sensor and a second sensor;    (b) moving the wafer carrier unit to the cassette;    (c) performing a checking step to the cassette by using the first sensor and the second sensor to obtain a first signal and a second signal;    (d) transmitting the first signal and the second signal to the determining unit, wherein    when the determining unit determines that the first signal is equal to the second signal, or that the first signal and the second signal are equal to a preset signal of the determining unit, steps from the step (e) are performed; or    when the determining unit determines that the first signal is not equal to the second signal, or that the first signal and the second signal are not equal to the preset signal of the determining unit, steps from the step (e) are not performed; and    (e) unloading wafers in the cassette by the wafer carrier unit.    
   
   
       4 . The wafer transfer method of  claim 3 , wherein in the step (a) the wafers are in the cassette, and after the first wafer is unloaded, the method further repeats at least once of the steps (a)-(e) to unload other wafers in the cassette.  
   
   
       5 . The wafer transfer method of  claim 3 , wherein the first signal and the second signal comprise a height signal of a sensor or a signal informing whether a barrier is in front of the wafer carrier unit.  
   
   
       6 . A cassette exchange system, comprising: 
 a wafer temporary storage apparatus, the wafer temporary storage apparatus comprising:    a main body; and    a plurality of wafer carrier units, wherein each of the wafer carrier units comprises a first end and a second end opposed to the first end, and the first end connects with the main body;    a first cassette base, carrying a first cassette;    a second cassette base, carrying a second cassette; and    a moving apparatus, connecting with the first cassette base and the second cassette base so as to sequentially move the first cassette base and the second cassette base to the wafer temporary storage apparatus, and simultaneously to transfer a plurality of wafers in the first cassette to the second cassette by the wafer carrier units; or the moving apparatus connecting with the wafer temporary storage apparatus to move the wafer temporary storage apparatus to the first cassette base and the second cassette base in sequence, and simultaneously to transfer the wafers in the first cassette to the second cassette by the wafer carrier units.    
   
   
       7 . The cassette exchange system of  claim 6 , wherein the moving apparatus comprises at least one horizontally moving unit and at least one vertically moving unit.  
   
   
       8 . The cassette exchange system of  claim 6 , wherein the first cassette base and the second cassette base are on the same or different horizontal planes.  
   
   
       9 . The cassette exchange system of  claim 6 , further comprising at least two sensors, which are disposed at the second end of at least one of the unit carrier units.  
   
   
       10 . The cassette exchange system of  claim 9 , wherein the sensors comprise optical sensors, wireless sensors, or wired sensors.  
   
   
       11 . A cassette exchange method, comprising: 
 (a) providing a cassette exchange system, the cassette exchange system comprising a plurality of wafer carrier units, a first cassette with a plurality of wafers and a second cassette;    (b) moving the wafer carrier units to the first cassette;    (c) simultaneously unloading the wafers in the first cassette by the wafer carrier units so that the wafers are on the wafer carrier units;    (d) moving the wafer carrier units with the wafers to the second cassette; and    (e) simultaneously loading the wafers from the wafer carrier units to the second cassette by the wafer carrier units.    
   
   
       12 . The cassette exchange method of  claim 11 , wherein in the step (a) a determining unit is provided, the cassette exchange system further comprises a first sensor and a second sensor, and between the steps (b) and (c), the method further comprises the following steps: 
 (b′) performing a checking step to the first cassette by the first sensor and the second sensor to generate a first signal and a second signal; and    (b″) transmitting the first signal and the second signal to the determining unit, wherein    when the determining unit determines that the first signal is equal to the second signal, or that the first signal and the second signal are equal to a preset signal of the determining unit, steps from the step (c) are performed; or    when the determining unit determines that the first signal is not equal to the second signal, or that the first signal and the second signal are not equal to the preset signal of the determining unit, steps from the step (c) are not performed.    
   
   
       13 . The cassette exchange method of  claim 12 , wherein the first signal and the second signal comprise a height signal of a sensor or a signal informing whether a barrier is in front of the wafer carrier unit.  
   
   
       14 . The cassette exchange method of  claim 11 , further comprising the following steps between the steps (d) and (e): 
 (d′) performing another checking step to the second cassette by the first sensor and the second sensor to generate a third signal and a fourth signal; and    (d″) transmitting the third signal and the fourth signal to the determining unit, wherein    when the determining unit determines that the third signal is equal to the fourth signal, or that the third signal and the fourth signal are equal to a preset signal of the determining unit, steps from the step (e) are performed; or    when the determining unit determines that the third signal is not equal to the fourth signal, or that the third signal and the fourth signal are not equal to the preset signal of the determining unit, steps from the step (e) are not performed.    
   
   
       15 . The cassette exchange method of  claim 14 , wherein the third signal and the fourth signal comprise a height signal of a sensor or a signal informing whether a barrier is in front of the wafer carrier unit.