Abstract:
A system includes an implantation chamber; a warming chamber, wherein the warming chamber is outside of the implantation chamber and has a sidewall shared with the implantation chamber; a first robotic arm configured to move a first wafer from the implantation chamber into the warming chamber; and a second robotic arm configured to move a second wafer into the implantation chamber.

Description:
PRIORITY DATA 
       [0001]    This is a divisional application of U.S. patent application Ser. No. 14/205,299, filed Mar. 11, 2014, which claims priority to U.S. Provisional Patent Application No. 61/785,729, filed Mar. 14, 2013, the entire disclosure of which is hereby incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    In conventional semiconductor fabrication processes, there are number of techniques for warming the wafers back to room temperature after low temperature implantation is complete. In one such technique, the wafer is warmed directly by the platen. In another, room temperature air is injected into the load lock and used to warm the wafers slowly. Lastly, a single tube-type lamp may be positioned inside the load lock to warm the wafers. 
         [0003]    However, all these conventional techniques have disadvantages. Heating the platen directly results in low wafer per hour (“WPH”) and reduces the throughput as it takes more time of the processing chamber. Injecting room temperature air into the load lock also results in low WPH and wafer spotting defects due to water condensation resulting from mist, in addition to absorbing a lot of time and negatively affecting throughput. Those techniques utilizing a single lamp to warm the wafers results in non-uniform heating, which further causes non-uniform dopant diffusion and non-uniform device behavior from wafer to wafer and from die to die. 
         [0004]    Accordingly, there is a need in the art for a wafer warming technique which alleviates or eliminates these disadvantages. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    The present disclosure is best understood from the following detailed description when read in conjunction with the accompanying figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale and are used for illustration purposes only. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. 
           [0006]      FIG. 1  is a top-side view of a semiconductor wafer fabrication system according to certain exemplary embodiments of the present invention; 
           [0007]      FIG. 2  illustrates a block diagrammatical view of single wafer warming chamber, according to certain exemplary embodiments of the present invention; 
           [0008]      FIGS. 3  is a flow chart of a high-throughput semiconductor fabrication process utilizing a post-implantation warming stage, according to certain exemplary methodologies of the present invention; and 
           [0009]      FIG. 4  illustrates a high throughput time sequence according to certain exemplary methodologies of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0010]    Illustrative embodiments and related methodologies of the present invention are described below as they might be employed in a high throughput system and method for warming a semiconductor wafer after low temperature implantation has occurred. In the interest of clarity, not all features of an actual implementation or methodology are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. Further aspects and advantages of the various embodiments and related methodologies of the invention will become apparent from consideration of the following description and drawings. 
         [0011]    As described herein, the present invention is directed to a time-efficient, high throughput system and method for warming a wafer to a desired temperature after undergoing a low temperature implantation process. In general, an exemplary system includes an implantation chamber, a wafer warming chamber configured to uniformly warm a single wafer, and a plurality of robotic arms to transfer wafers throughout the system. During an exemplary methodology, a first wafer undergoes a low temperature ion-implementation process and is transferred to the warming chamber by one of the robotic arms. While the first wafer is being transferred to the warming chamber, a second wafer is transferred to the implementation chamber using a second robotic arm. As the first wafer is being warmed to substantially room temperature in the warming chamber, the second wafer undergoes implantation. The first wafer may then be transferred out of the warming chamber while the second wafer is transferred into the warming chamber. This process may occur for any number of wafers. Thus, at each stage in the fabrication process, the system (via the robotic arms) can simultaneously work with multiple wafers and, therefore, provide a high throughput process. In addition, the warming chamber may be a vacuum environment, thus eliminating the mist-condensation problem that results in wafer spotting. Accordingly, the wafer uniformity is increased, while also alleviating those issues related to wafer spotting and non-uniform heating associated with prior art methodologies. 
         [0012]      FIG. 1  is a top-side view of a semiconductor wafer fabrication system  10  according to certain exemplary embodiments of the present invention. Wafer fabrication system  10  comprises a plurality of load ports  12  positioned adjacent a first and second load lock  14   a , 14   b.  As understood in the art, load locks  14   a , 14   b  are configured to hold a plurality of wafers during fabrication. Load locks  14   a , 14   b  are positioned adjacent an implantation chamber  16 , which includes a wafer orientor  18  and platen  20 . Implantation chamber  16  may be configured to perform a variety of implantation techniques, such as, for example, low temperature ion-implantation or room temperature implantation. 
         [0013]    In this example, a pre-implantation cooling chamber  22  is positioned adjacent implantation chamber  16  to cool the wafers prior to implantation. In one exemplary embodiment, pre-implantation cooling chamber  22  may cool the wafers to −100 C, for example, in order to form the amorphous layer for ultra-shallow junctions, RC and leakage reduction, etc., as will be understood by those ordinarily skilled in the art having the benefit of this disclosure. A low temperature cooling system  24  is communicably coupled to pre-implantation cooling chamber  22  for controlling and providing the cooling environment present within pre-implantation cooling chamber  22 . Although not shown, low temperature cooling system  24  includes at least one processor and associated circuitry to achieve its functionality. 
         [0014]    Still referring to the exemplary embodiment of  FIG. 1 , wafer fabrication system  10  further includes a single wafer warming chamber  26  positioned adjacent to implantation chamber  16 . In an alternative embodiment, however, single wafer warming chamber  26  may also be positioned inside implantation chamber  16  as an implantation stage chamber. As described herein, single wafer warming chamber  26  comprises one or more heating elements configured to uniformly heat the wafers. In addition, a robotic arm  28  is positioned adjacent load ports  12  for transferring wafers between load ports  12  and load locks  14   a , 14   b.  Robotic arms  30 , 32  are positioned inside implantation chamber  16  for simultaneously transferring wafers between load locks  14   a , 14   b,  implantation chamber  16 , pre-implantation cooling chamber  22 , and single wafer warming chamber  26 . Although three robotic arms are illustrated, those ordinarily skilled in the art having the benefit of this disclosure realize more or less arms may also be utilized as desired. 
         [0015]    Although not illustrated, exemplary embodiments of wafer fabrication system  10  may include at least one processor, non-transitory computer-readable storage, communication module, I/O devices, an optional display, etc., all interconnected via a system bus. Software instructions executable by the processor for implementing the methodologies described herein may be stored in the system storage or some other computer-readable medium, or uploaded into such memories from another storage media via wired/wireless methodologies. In addition, wafer fabrication system  10  may be connected to one or more public and/or private networks via appropriate network connections. 
         [0016]    Moreover, those ordinarily skilled in the art will appreciate that the invention may be practiced with a variety of computer-system configurations, including hand-held devices, multiprocessor systems, microprocessor-based or programmable-consumer electronics, minicomputers, mainframe computers, and the like. Any number of computer-systems and computer networks are acceptable for use with the present invention. The invention may be practiced in distributed-computing environments where tasks are performed by remote-processing devices that are linked through a communications network. In a distributed-computing environment, program modules may be located in both local and remote computer-storage media including memory storage devices. The present invention may therefore, be implemented in connection with various hardware, software or a combination thereof in a computer system or other processing system. 
         [0017]      FIG. 2  illustrates a block diagrammatical view of single wafer warming chamber  26 , according to certain exemplary embodiments of the present invention. For simplicity of understanding, not each feature of the chamber is illustrated here. However, those ordinarily skilled in the art having the benefit of this disclosure will readily understand how the described warming chamber may be fabricated and altered as desired. In one example, a thermal mechanism similar to a rapid thermal annealing (“RTA”) tool may be used in the system. However, in the present embodiment, the warming chamber  26  is incorporated in the semiconductor wafer fabrication system  10 . Nevertheless, in one exemplary embodiment, single wafer warming chamber  26  comprises a base  36  on which the wafers are positioned. Base  36  comprises a first heating element  34  configured to warm the lower surface of the wafers to a desired temperature. In the present example, such desired temperature is room temperature or substantially room temperature. 
         [0018]    A second heating element  38  is positioned above base  36  in order to warm the upper surface of the wafers. Thus, first and second heating elements  34 , 38  work in combination to uniformly heat the wafers to the desired temperature. The heating duration depends on the heating power and the initial temperature of the wafer. In one example, the heating duration may take a few seconds to a few minutes. The heating elements may be a variety of elements, such as, for example, lamp-type heaters or conventional heating elements. In one example, halogen lamps may be used as heating elements. Moreover, in certain embodiments, single wafer warming chamber may be a vacuum chamber. In such embodiments, utilizing lamp type heaters will provide for greater heating efficiency that will also eliminate mist-condensation issues. 
         [0019]    Certain exemplary embodiments of single wafer warming chamber  26  may also comprise a temperature control loop. Thus, as illustrated in  FIG. 2 , an exemplary control loop comprises a close-loop central controller  40  that is communicably coupled to a lamp power controller  42  and a heater power controller  44 . A sensor  46  (pyro sensor, for example) is communicably coupled to central controller  40  and serves as the input to detect and transmit the temperature of the wafer to central controller  40 . Thereafter, central controller  40  transmits the necessary control signals to lamp power controller  42  and heater power controller  44  to alter or maintain the temperature of the wafer as desired. 
         [0020]    Now, with reference to  FIGS. 1 and 3 , an exemplary methodology  300  of the present invention will now be described. As described herein, method  300  is a high-throughput semiconductor fabrication process utilizing a post-implantation warming stage. At block  302 , a plurality of wafers are loaded into load ports  12 , and transferred to load lock  14   a  by robotic arm  28  at block  304 . After the desired number of wafers is loaded into load lock  14   a,  wafer fabrication system  10  increases the pressure inside load lock  14   a  from atmospheric to vacuum. At block  308 , wafer fabrication system  10  then transfers a single first wafer from load lock  14   a  to pre-implantation cooling chamber  22  using robotic arm  32 . At block  310 , wafer fabrication system  10  then cools down the first wafer using cooling system  24 . At block  312 , robotic arm  32  then transfers the cooled first wafer to platen  20  of implantation chamber  16 , where the first wafer undergoes an implantation process (low temp ion-implantation, for example) at block  314 . 
         [0021]    At block  316 , wafer fabrication system  10  then transfers the first wafer to single wafer warming chamber  26  using robotic arm  30 , where the first wafer is warmed to substantially room temperature, for example, at block  318 . Although not illustrated, in one exemplary methodology, robotic arm  32  may transfer a second wafer from cooling chamber  22  to implantation chamber  16  while robotic arm  30  is transferring the first wafer to single wafer warming chamber (block  318 ). As will be discussed in more detail below, such simultaneous transference of wafers through wafer fabrication system  10  provides a high-throughput fabrication process. Nevertheless, at block  320 , the first wafer is then transferred to load lock  14   b.  The foregoing process continues on any desired number of wafers until all are transferred to load lock  14   b,  and wafer fabrication system  10  then returns the pressure from vacuum to atmospheric at block  322  using robotic arm  30 . Thereafter, wafer fabrication system  10  then transfers the wafers back to load ports  12  using robotic arm  28 . 
         [0022]      FIG. 4  illustrates a time lapse methodology  400  useful to further describe certain exemplary methodologies of the present invention. In this example, only four wafers will be described, although any number of wafers may be fabricated using method  400 . Note that not every step in this exemplary method will be described here; rather, method  400  is intended to more clearly illustrate the time efficiency, and resulting high-throughput, provided by the present invention. The exemplary time slots (T 1 ,T 2 ,TN . . . ) described herein may be any desired length as dictated by system design or otherwise (for example, 30˜500 seconds), as will be understood by those ordinarily skilled in the art having the benefit of this disclosure. 
         [0023]    With reference to  FIG. 4 , at time T 1 , a first wafer (wafer  01 ) is transferred to implantation chamber  16 . At time T 2 , the first wafer undergoes a low-temperature implantation process within implantation chamber  16 . At time T 3 , the first wafer is then transferred to single wafer warming chamber  26  while a second wafer (wafer  02 ) is transferred to implantation chamber  16 . At time T 4 , the first wafer is then warmed to the desired temperature inside single wafer warming chamber  26 , while the second wafer undergoes low temperature implantation inside implantation chamber  16 . At time T 5 , the first wafer is then transferred back to load lock  14   a , 14   b,  while the second wafer is transferred to single wafer warming chamber  26 , and a third wafer (wafer  03 ) is transferred to implantation chamber  16 . At time T 6 , the first wafer is now ready for further processing, while the second wafer is being warmed to the desired temperature inside single wafer warming chamber  26 , and the third wafer undergoes low temperature implantation inside implantation chamber  16 . 
         [0024]    At time T 7 , the second wafer is then transferred to load lock  14   a , 14   b  where it is ready for further processing, while the third wafer is transferred to single wafer warming chamber  26 , and a forth wafer (wafer  04 ) is transferred to implantation chamber  16 . At time T 8 , the third wafer is then warmed up to the desired temperature inside single wafer warming chamber  26 , while the fourth wafer undergoes low temperature implantation inside implantation chamber  16 . At time T 9 , the third wafer is then transferred back to load lock  14   a , 14   b,  while the fourth wafer is then transferred to single wafer warming chamber  26 . At time T 10 , the fourth wafer is then warmed to the desired temperature and then transferred back to load lock  14   a,b  at time T 11 . Accordingly, the wafers have been warmed from a low temperature to a desired temperature in a rapid, high-throughput fashion. 
         [0025]    An exemplary methodology of the present invention provides a method for fabricating a semiconductor wafer comprising transferring a first semiconductor wafer to an implantation chamber and performing an implantation process on the first semiconductor wafer within the implantation chamber. After the implantation process on the first semiconductor wafer is complete, the first semiconductor wafer is transferred to the warming chamber while a second semiconductor wafer is simultaneously transferred to the implantation chamber. The first semiconductor wafer is then warmed within the warming chamber while the implementation process is simultaneously performed on the second semiconductor wafer. The first semiconductor wafer is then transferred out of the warming chamber for further processing while the second semiconductor wafer is simultaneously transferred to the warming chamber where it is warmed. 
         [0026]    An exemplary embodiment of the present invention provides a system for fabricating a semiconductor wafer comprising an implantation chamber, a first and second robotic arm operably connected to the implantation chamber in order to transfer semiconductor wafers through the system, a pre-implantation cool down chamber positioned adjacent the implantation chamber, a load lock positioned adjacent the implantation chamber, and a warming chamber comprising one or more heating elements configured to warm the semiconductor wafers. In addition, the system comprises processing circuitry to implement any of the methods described herein. 
         [0027]    In addition, an exemplary methodology of the present invention provides a method for fabricating a semiconductor wafer comprising implanting a first wafer inside an implantation chamber at time T 1  and transferring the first wafer to a warming chamber at time T 2 . A second wafer is also transferred to the implementation chamber at time T 2 . At time T 3 , the first wafer is warmed inside the warming chamber and the second wafer is implanted inside the implantation chamber. At time T 4 , the first wafer is transferred out of the warming chamber for further processing and the second wafer is transferred to the warming chamber. At time T 5 , the second wafer is warmed inside the warming chamber. 
         [0028]    The foregoing outlines features of several embodiments so that those ordinarily skilled in the art may better understand the aspects of the present disclosure. Those skilled persons should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments and methodologies introduced herein. For example, although a single wafer warming chamber is described herein, those ordinarily skilled persons would realize that a multiple wafer warming chamber may also be utilized. As such, those same skilled persons should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure. Therefore, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.