Abstract:
An epitaxy processing system and its processing method for enhancing operation efficiency is provided. The system includes a stacked cassette, a transportation device, a reaction chamber, and a cooling device. The cooling device can rapidly cool down susceptor and processed wafers without damaging the epitaxy layer. The cluster system design minimizes the footprint of system, reduces the operation cost, and increases throughput and thereby enhances the productivity of the system.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to the field of wafer processing system. More particularly, the present invention relates to an epitaxy processing system and its processing method which comprises a transportation device which can move the susceptor out from high temperature reacting chamber to a cooling device which afterward can rapidly cool down the wafers and the susceptor to increase the production capacity. 
         [0003]    2. Description of the Prior Art 
         [0004]    In the fabrication of integrated circuit and compound semiconductor, processing system is generally employed to process semiconductor wafers. Those processing system include a reacting chamber to effectuate depositions, epitaxy, etching, and so on. 
         [0005]    The conventional processing system includes a glove box with a loadlock and a reacting chamber arranged inside the glove box. When a fabrication process is going to proceed, the operator must first put the wafer boat into the glove box via the loadlock, followed by pick and place the wafers onto the susceptor which locates in the reacting chamber by manual operation, then close the reacting chamber lid and the epitaxy process is starting to proceed. After process ends, the susceptor with wafers will not move out of the reacting chamber immediately until the nitrogen gas cycle purge inside the reacting chamber and reacting chamber temperature lower down to 150° C. However, this step occupies lots of machine time to process next one cycle and consumes lots of nitrogen gas. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention generally provides a wafer processing system and its processing method including a reacting chamber, a transportation device which provides the susceptor transportation and a cooling device which provides a quickly temperature-lowering down function and a volume minimized stacked cassette as a loadlock function. 
         [0007]    A volume minimized stacked cassette containing a plurality of susceptors, wherein each susceptor has at least a wafer placed thereon. A transportation device is utilized for transmitting those susceptors between the reacting chamber, the cooling device, and the stacked cassette. At process initial, the transportation device transmits the susceptor in stacked cassette through a chamber gate valve to reacting chamber which maintain at high temperature environment. After process ends, the transportation device transmits the susceptor from high temperature reacting chamber to cooling device for quickly cooling down. Wherein the transportation device follows up transmits another susceptor in stacked cassette to the reacting chamber for next one run processing. After that, the cooled down susceptor on the cooling device is transmitting to the stacked cassette. 
         [0008]    In one embodiment of the present invention, an epitaxy processing system including: a stacked cassette for containing a plurality of susceptors, wherein each of the susceptors has at least a wafer placed thereon; a transportation device for transporting the susceptors; a reacting chamber having a chamber gate valve, wherein the susceptor is transported by the transportation device from the stacked cassette through the chamber gate valve and the wafer is processed while the chamber gate valve is closed; and a cooling device for cooling the processed wafer transported by the transportation device from the reacting chamber under a high temperature, and the processed wafer is cooled down to a lower temperature. After transporting the processed wafer into the cooling device, the transportation device transports another susceptor from the staked cassette into the reacting chamber for next one run processing. 
         [0009]    In another embodiment of the present invention, an epitaxy processing system is provided. The epitaxy processing system includes a stacked cassette for containing a plurality of susceptors, wherein each of those susceptor has at least a wafer placed thereon. A transportation device is utilized for transmitting those susceptors. A plurality of reacting chambers are arranged around the transportation device, each of the reacting chambers having a chamber gate valve, wherein the susceptors are respectively transported by the transportation device from the stacked cassette to those reacting chambers; and for each of those reacting chambers, the susceptor is transported while the chamber gate valve is open, and the wafer is processed while the chamber gate valve is closed. And, a cooling device is utilized for sequentially cooling the processed wafers transported by the transportation device respectively from those reacting chambers under a high temperature, and the processed wafers are respectively cooled down to a lower temperature, wherein those cooled processed wafers are removed out the cooling device by the transportation device to load in the stacked cassette. Once one susceptor is removed out from one reacting chamber, another susceptor is transported from the stacked cassette to the empty reacting chamber by the transportation device. 
         [0010]    In another embodiment of the present invention, an epitaxy processing method is provided. The epitaxy processing method including: providing a plurality of susceptors disposed in a stacked cassette, wherein each of the susceptors has at least a wafer placed thereon; transporting the susceptor by a transportation device from the stacked cassette into a reacting chamber having a chamber gate valve, the susceptor is transported while the chamber gate valve is open and the wafer is processed while the chamber gate valve is closed; transporting the processed wafer by the transportation device from the reacting chamber under a high temperature into a cooling device; cooling the processed wafer to a lower temperature by the cooling device; and after transporting the processed wafer into the cooling device, transporting another susceptor from the staked cassette into the reacting chamber by the transportation device for next run processing. 
         [0011]    Other advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The foregoing aspects and many of the accompanying advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
           [0013]      FIG. 1A  is a schematic diagram showing an epitaxy processing system and its processing method in accordance with one embodiment of the present invention; 
           [0014]      FIG. 1B  is a schematic diagram showing an epitaxy processing system and its processing method in accordance with another embodiment of the present invention; 
           [0015]      FIG. 2  is a schematic diagram showing a susceptor arranged on a cooling device in accordance with one embodiment of the present invention; 
           [0016]    FIG  3 A is a schematic diagram showing one embodiment of an epitaxy processing system and its processing method in accordance with one embodiment of the present invention; 
           [0017]      FIG. 3B  is a schematic diagram showing one embodiment of an epitaxy processing system and its processing method in accordance with one embodiment of the present invention; and 
           [0018]      FIG. 4  is a schematic diagram showing another embodiment of an epitaxy processing system and its processing method in accordance with one embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    The present invention generally provides an epitaxy processing system and its processing method including a reacting chamber, a transportation device which provides the susceptor transportation and a cooling device which provides a quickly temperature-lowering function and a volume minimized stacked cassette as a loadlock function. The detailed explanation of the present invention is described as following. The described embodiments are presented for purposes of illustrations and description, and they are not intended to limit the scope of the present invention. 
         [0020]    Firstly, refer to FIG  1 A, FIG  1 A shows a schematic diagram illustrating an epitaxy processing system and its processing method in accordance, with one embodiment of the present invention. As shown in the figure, the epitaxy processing system  100  of one embodiment of the present invention includes a stacked cassette  110 , which is volume minimized, for containing a plurality of susceptors  120 , wherein each susceptor  120  has at least a wafer W placed thereon. A transportation device  130  is utilized for transporting those susceptors  120 , and one susceptor  120  is transported at a time. Those susceptors  120  are transported by the transportation device  130  from the stacked cassette  110  into a reacting chamber  140  and the wafer W is processed in the reacting chamber  140 , wherein the reacting chamber  140  has a chamber gate valve  142  and the chamber gate valve  142  is open when the transportation device  130  carries the susceptor  120  into or out from the reacting chamber  140 . And, a cooling device  150  is utilized for cooling the processed wafer W which is still in a high temperature, such as over 500° C. and transported by the transportation device  130  from the reacting chamber  140  after reacting, and then another susceptor  120  which has a un-processed wafer placed thereon is transmitted from the stacked cassette  110  to the reacting chamber  140  which remains substantially at the high temperature by the transportation device  130 . The transportation device  130  can take out the susceptor  120  with the wafer W which are still in a high temperature from the reacting chamber  140  into the cooling device  150  immediately, and then the transportation device  130  can pick another susceptor with a wafer from the stacked cassette  110  into the reacting chamber  140  to react while the reacting chamber  140  is still in the high temperature so that the processing time can be reduced to improve the throughput. It is understood that the temperature may be slightly lower down when the gate valve  142  of the reacting chamber  140  is open. However, the effects of the invention may hot be affected. 
         [0021]    Continuing the above description, in one embodiment, the transportation device  130 , the cooling device  150  and the reacting chamber  140  are arranged in a closed space, which is called a glove box, and the glove box is cycle purged with an inert gas, such as the nitrogen gas, to lower down the concentration of oxygen in the glove box to a PPM level. The stacked cassette  110  is a closed space in the system and has two cassette gate valves; one of the cassette gate valves, such as cassette gate valve  112 , is faced to an external atmospheric environment; and another, cassette gate valve  114  for example, is faced to the epitaxy processing system  100 , and the stacked cassette  110  is cycle purged with the nitrogen gas also. In another embodiment, the stacked cassette  110  can have a two-directional susceptor picking structure and can be fixed or rotated. An operator can pick those wafers which are placed on the wafer boat onto the susceptor  120  in the working area in atmospheric environment, and then load these susceptors  120  into the stacked cassette  110  from cassette gate valve  112 . Hereafter, stacked cassette  110  is purged with the nitrogen gas and those wafers W are transported into the reacting chamber  140  by the transportation device  130 . In one embodiment, the transportation device  130  can has a robot or a linear slide guide to transfer the susceptor  120  and wafer W placed thereon, especially one susceptor  120  each time. 
         [0022]    Continuously, in one embodiment, the reacting chamber  140  has a gas distribution apparatus that provides separate and uniform distribution of at least two gases and a fluid cooling pathway provided within the reacting chamber. In the gas distribution apparatus, a thin-plated susceptor made of high thermal conductivity, low thermal mass and high density material is provided to quick temperature ramp-up/down for processing equipment and automation handling. Referring to FIG.  1 B, in another embodiment, the reacting chamber  140  also can be set outside the closed space. Therefore, the transportation device  130 , the cooling device  150  and the chamber gate valve  142  are arranged in the closed space. Besides, the closed space, such as the glove box, and the stacked cassette are cycle purged with nitrogen gas. It is very convenient to the operator when the reacting chamber  140  needs to be maintained, the operator can just open the lid of the reacting chamber to check out. 
         [0023]    For easily transmitting those susceptors  120  and pick and place by the transportation device  130 , the schematic diagram of the susceptor of the present invention is shown in  FIG. 2 . As shown in the figure, the susceptor  120  has a          -type profile, and the susceptor  120  includes a plate  122  to have at least a wafer W placed thereon; an ring-like flange  124 , which is an peripherally extension of the plate  122 , for detachably contact with the transportation device  130 ; and an encircled supporting wall  126  underneath the plate  122 , the inner side  127  of the supporting wall  126  is beveled outwardly, the beveled edge is inclined so that there is an obtuse angle between the plate  122  and the inner side  127  of the supporting wall  126 , in order to mount on a rotor  152  of the cooling device  150 . In one embodiment, the transportation device  130  is utilized to hold the ring-like flange  124  of the susceptor  120  in a regular way or clip the outer lateral of the plate  122  of the susceptor  120  to move outward in changing the width of the transportation device  130 . Continuously, in one embodiment, the cooling device  150  can utilize an upper gas sparging cooling method, a lower fluid pipe conduction cooling method or a superconductor medium contact cooling method to lower down the temperature of those susceptors and wafers. In one embodiment, the cooling device  150  is designed to control the cooling rate and the susceptors and wafers which are still in the high temperature can be cooled down gradually and immediately. Besides, because of the design of the cooling device  150 , the nitrogen gas usage during the cooling can be reduced. 
         [0024]    In another embodiment, a plurality of reacting chambers  240  can be applied in the epitaxy processing system  200 , wherein the structure of the stacked cassette  210 , the susceptor  220 , the transportation device  230  and the cooling device  250  are approximately the same as last embodiment so that it is no unnecessary detailed here. The arrangement of the reacting chambers  240  and the cooling device  250  are described in the following. Please refer to  FIG. 3A , a plurality of reacting chambers  240 , each of the reacting chambers  240  having a chamber gate valve  242 , wherein those susceptors  220  are respectively transported by the transportation device  230  from the stacked cassette  210  to the reacting chambers  240 ; for each of the reacting chambers  240 , the susceptor  220  is transported while one of the chamber gate valve  242  is open and the wafer W are processed while the chamber gate valve  242  is closed; the reacting chambers  240  are arranged around the transportation device  230 . And, a cooling device  250  is utilized for sequentially cooling those processed wafers W transported by the transportation device  230  respectively from those reacting chambers  240  under a high temperature, and the processed wafers W are cooled down to a lower temperature, wherein those cooled processed wafers W are removed out the cooling device  250  by the transportation device  230  to load in the stacked cassette  210 , once susceptor  220  is removed out from those reacting chambers  240 , another susceptor  220  is transported from the stacked cassette  210  to the empty reacting chamber  240  which is still in the high temperature by the transportation device  230  for next one run processing.  FIG. 3A  and  FIG. 3B  are an in-line type arrangement, in another embodiment, those reacting chambers can be arranged in the cluster type or other type, such as shown in  FIG. 4 , those reacting chambers  340  are arranged in the cluster type. Moreover, refer to  FIG. 3A , the transportation device  230 , the cooling device  250  and the reacting chamber  240  are arranged in a closed space; and the closed space are cycle purged with nitrogen gas. In another embodiment, referring to  FIG. 3B , the transportation device  230  are arranged in a closed space; the cooling device  250  has a gate valve  252 ; the chamber gate valve  242  and the gate valve  252  are connected with the closed space; and the closed space are cycle purged with nitrogen gas.  FIG. 4 , in the embodiment, the transportation device  330  is arranged in a closed space and the cooling device  350  has a gate valve, such as gate valve  352 . As shown in the figure, the chamber gate valve  342  and the gate valve  352  are connected with the closed space and the closed space is cycle purged with nitrogen gas too. Furthermore, as shown in  FIG. 3A ,  FIG. 3B  and  FIG. 4 , the stacked cassette  210 ,  310  has two cassette gate valves  214 ,  216 ,  314 ,  316 ; one of the cassette gate valves, such as cassette gate valves  214  and  314 , face to the closed space; another cassette gate valve, such as cassette gate valves  216  and  316 , face to an external atmospheric environment; and the stacked cassette  210 ,  310  are cycle purged with nitrogen gas. 
         [0025]    In another embodiment, an epitaxy processing method is provided herein including the following step. First, providing a plurality of susceptors disposed in a stacked cassette, wherein each of those susceptors has at least a wafer placed thereon. Next, transporting the susceptor by a transportation device from the stacked cassette into a reacting chamber having a chamber gate valve, the susceptor is transported while the chamber gate valve is open and the wafer is processed while the chamber gate valve is closed. And then, transporting the processed wafer by the transportation device from the reacting chamber under a high temperature into a cooling device. Next, cooling the processed wafer to a lower temperature by the cooling device. Finally, after transporting the processed wafer into the cooling device, transporting another susceptor from the staked cassette into the reacting chamber by the transportation device for next run processing. 
         [0026]    Continuing the above description, in one embodiment, the cooling method includes an upper gas sparging purging cooling method, an underneath fluid pipe conduction cooling method or a superconductor medium contact cooling method. Besides, in another embodiment, the high temperature is over 500° C., and the lower temperature is below 150° C. The epitaxy processing method can be utilized to sequentially cool down those susceptors respectively from each reacting chamber which remains substantially at the high temperature after reacting so that the production output of the system can be improved. 
         [0027]    Continuously, in the above-mentioned embodiments, those reacting chambers can co-use at least one cooling device to cool down the susceptors and the wafers placed thereon under high temperature to provide a maximum temperature-lowering function and increase the production capacity. Besides, the function and recipe of those reacting chambers can be different. Moreover, when the number of the reacting chambers is increased to a specific amount, another cooling device can be added to the system. 
         [0028]    To sum up the foregoing descriptions, the present invention generally provides an epitaxy processing system and processing method including a reacting chamber, a transportation device which provides the susceptor transportation and a cooling device which provides a quickly temperature-lowering function and a volume minimized stacked cassette as a loadlock function. 
         [0029]    The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustrations and description. They are not intended to be exclusive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the an to best utilize the invention and various embodiments with various modifications as are suited to particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.