Abstract:
A set of lift pins defines a storage location for a substrate in a substrate processing chamber. Each lift pin has an actuating mechanism including a translating mechanism that translates vertical actuation into horizontal motion. The actuating mechanism may include a base, a mechanism adapted to raise and lower the base, and a lever pivotally mounted on the base. The lift pin may be fixedly mounted on the lever. A stop may be adjacent the base and adapted to engage the lever to pivot the lever as the base is lowered.

Description:
FIELD OF THE INVENTION 
     The present invention relates to semiconductor manufacturing of thin substrates or wafers and, more particularly, to the transfer and loading of semiconductor wafers, glass plates and the like into and out of processing chambers. 
     BACKGROUND OF THE INVENTION 
     Semiconductor manufacturing generally requires that a number of different processes be applied to a substrate such as a wafer. Typically, each process is applied to a wafer in a different chamber dedicated to a respective process. Thus the manufacturing process involves not only a sequence of processes carried out in the respective chambers, but also transporting wafers among the processing chambers, and loading and unloading wafers into and out of the processing chambers. Most semiconductor processing is carried out in chambers configured to process one wafer at a time, in a very high vacuum capable environment. Thus, a process to be performed in a particular chamber cannot be carried out while wafers are being loaded into or removed from the processing chamber. Consequently, reducing the time required to load and unload wafers into and out of processing chambers is a significant factor in maximizing manufacturing throughput. 
     It is therefore desirable to provide for rapid and reliable transfer of wafers to and from processing chambers. It is also desirable that chamber components which aid in the transfer of wafers be simple and inexpensive to manufacture. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the invention, a lift pin/actuating assembly includes a lift pin and an actuating mechanism having an actuator configured to generate movement by the lift pin along a first axis, and a translation mechanism coupled to the actuator and configured to translate movement of the actuator along the first axis into movement by the lift pin along a second axis. 
     According to a second aspect of the invention, a method of operating a substrate lift pin includes applying vertical actuation to the pin, moving the pin vertically a first distance, contacting a vertical motion stop after moving the first distance, and translating further vertical actuation into horizontal movement of the pin. 
     According to a third aspect of the invention, a lift pin/actuating assembly for a semiconductor processing chamber includes a lift pin adapted to hold a semiconductor substrate in the processing chamber. Also included in the lift pin/actuating assembly are a base on which the lift pin is mounted, a first mechanism adapted to raise and lower the base, and a second mechanism adapted to convert vertical motion of the base into pivoting motion of the lift pin. 
     According to a fourth aspect of the invention, a method of operating a semiconductor processing chamber includes providing a lift pin, mounting the lift pin so that it extends upwardly into the processing chamber, lowering a base on which the lift pin is mounted, and converting the lowering motion of the base into pivoting motion of the lift pin. 
     Other objects, features and advantages of the present invention will become more fully apparent from the following detailed description of the preferred embodiments, the appended claims and the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a somewhat schematic cross-sectional view of a processing chamber provided in accordance with an aspect of the invention, showing a lift pin in storage position; 
     FIG. 2 is a view similar to FIG. 1, showing the lift pin in a retracted position; and 
     FIGS.  3 ( a )- 3 ( l ) are partial cross-sectional views of the processing chamber of FIGS. 1 and 2, showing an exemplary sequence of steps for a substrate exchange procedure. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     An embodiment of the invention includes a lift pin/actuating assembly that employs a single actuator and a translation mechanism configured to translate actuation along a first axis into movement along a second axis (“movement along an axis” should be understood to include linear motion in the direction of the axis, or pivotal motion about the axis.) The actuating assembly is configured to allow actuation along the first axis to result in a predetermined range of lift pin movement along the first axis. Beyond the predetermined range of lift pin movement, further actuation along the first axis is translated into movement along the second axis. The translation mechanism may include a motion stop which defines the predetermined range of lift pin movement and a motion translator (e.g., a lever or an appropriately configured link such as a four bar link, etc.). 
     An aspect of the invention that employs a vertical motion actuator, a vertical motion stop, and a lever configured to translate vertical linear motion into horizontal pivoting motion is shown and described with reference to FIGS.  1 - 3 ( l ). 
     FIG. 1 is a schematic cross-sectional view of a semiconductor processing chamber  10  provided in accordance with an aspect of the invention. The processing chamber  10  includes an enclosure  12  defined by side wall  14 , chamber floor  16  and chamber top  18 . 
     A heated pedestal  20  is mounted in the processing chamber  10  on a shaft  22 . A lift mechanism  24  is associated with the shaft  22  to selectively raise and lower the pedestal  20 . The pedestal  20  is provided to support a wafer in the chamber  10  during processing. 
     Conventional lift pins (of which only one pin  26  is shown) are provided to selectively lift a wafer from the pedestal  20  or to deposit a wafer on pedestal  20 . The lift pins are raised and lowered via a lift plate  28  and a lift mechanism  30 . 
     Reference numeral  32  represents a robot blade that has entered the processing chamber  10  via a slit valve  34  while carrying a wafer  36 . A so-called “showerhead”  38  is suspended from the chamber top  18  and allows process gas to flow toward the pedestal  20  during processing. 
     In accordance with an aspect of the invention, a plurality of lift pins, and associated actuating mechanisms, are provided to define a wafer storage position within the enclosure  12 . For clarity, only one lift pin  40  and its associated actuating mechanism  42  are shown. Note in the exemplary embodiment shown, the actuating mechanism  42  is positioned below the floor  16  of the processing chamber  10 , and the lift pin  40  extends into the enclosure  12  via an opening  43  in the floor  16 . The lift pin  40  has a horizontally extending upper section  44 , on which a wafer is supported during storage. The lift pin  40  may be mounted directly to a lever  48  or may be held in a holder  46  which in turn is mounted on the lever  48 . The lift pin  40  may be fixedly coupled to the lever  48  such that the angle therebetween remains fixed. The lever  48  is mounted by means of a pivot  50  on a moveable base  52 . A lift mechanism or actuator  54  is associated with the base  52  to selectively raise and lower the base  52 . 
     A spring  56  is connected between the base  52  and a free end  58  of the lever  48 . The spring  56  biases the free end  58  of the lever  48  in a downward direction (counter-clockwise about the pivot  50  in FIG.  1 ). A step  60  on the base  52  defines a horizontal position of the lever  48  by limiting the downward motion of the lever  48  relative to the base  52 . A stop  62  is suspended from the chamber floor  16  and is positioned under the free end  58  of the lever  48 . A bellows  64  accommodates translational and angular motion of the lift pin  40  and its holder  46  while preventing particles from the external environment from entering the enclosure  12  via the opening  43 . 
     Those who are skilled in the art will appreciate that a controller (not shown) is associated with processing chamber  10  to control operation of lift mechanisms  24 ,  30 ,  54 , slit valve  34 , and other components of processing chamber  10  which are not shown. 
     The inventive lift pin/actuating assembly is shown in its storage position in FIG.  1 . Because of the relative positioning of the base  52  and the stop  62 , stop  62  does not come into play when the base is positioned as shown in FIG. 1, and the position of the lever  48 , as biased downwardly by the spring  56 , is determined by the step  60  of the base  52 . Lever  48  is in substantially a horizontal orientation, and lift pin  40  is in substantially a vertical orientation with the upper section  44  of lift pin  40  obstructing a path of travel of pedestal  20 . 
     Lift pin  40  is shown in its retracted position in FIG.  2 . To move the lift pin  40  from its storage position (FIG. 1) to its retracted position (FIG. 2) the base  52  is moved downwardly from the position shown in FIG.  1 . The movement of base  52  in the downward direction is actuated by lifting mechanism  54 . As the base  52  is moved downwardly, the stop  62  comes in contact with the free end  58  of the lever  48 , pushing the free end  58  of the lever  48  upwardly relative to the base  52 , against the biasing force of the spring  56 . The lever  48 , in response to contact with stop  62 , thus pivots on pivot  50 , causing holder  46  and lift pin  40  to be inclined or tilted from the vertical, thereby bringing lift pin  40  to its retracted position shown in FIG.  2 . In its retracted position lift pin  40  does not obstruct the path of travel of pedestal  20 . 
     It will be recognized from FIGS. 1 and 2 that base  52  may be considered to have two ranges of movement. In a first range of movement at and above its position in FIG. 1, movement of base  52  raises or lowers lift pin  40  without pivoting lift pin  40  (as the lever  58  does not contact the stop  62 ). In a second range of movement between its respective positions in FIGS. 1 and 2, movement of base  52  results in pivoting of lift pin  40  (as the lever  58  contacts the stop  62  and pivots in response to contact therewith). 
     With the lift pin actuating mechanism  42  shown in FIGS. 1 and 2, a single lift mechanism or actuator  54  is employed both to translate the lift pin  40  in a vertical direction and to impart angular motion to the lift pin  40  (by means of the interaction between the lever  48  and the stop  62 ). That is, the single lift mechanism  54  both raises and lowers lift pin  40  and pivots lift pin  40  between the storage position and the retracted position. Consequently, the inventive actuating mechanism  42  provides a relatively simple and cost effective arrangement for both raising and pivoting the lift pin  40 . 
     FIGS.  3 ( a )- 3 ( l ) illustrate steps performed during an exemplary wafer exchange operation with respect to the processing chamber  10 . 
     FIG.  3 ( a ) shows a condition that is in effect at a time when processing of wafer  36  is complete. It will be observed that wafer  36  is supported on the pedestal  20  in a processing position near the top of the processing chamber. The lift pin  40  is in its retracted (non-storage) position so that it does not obstruct the path of travel of the pedestal  20 . 
     After the condition of FIG.  3 ( a ), the pedestal  20  is lowered and the lift pin  26  lifts the wafer  36  from the pedestal  20 , to produce the position shown in FIG.  3 ( b ). The pedestal  20  is now in a loading position. 
     Next, the lift pin  40  is actuated, i.e. moved from its retracted position (FIG.  3 ( b ), FIG. 2) to its storage position (FIG.  3 ( c ), FIG.  1 ). The lift pin  40  is no longer inclined, but rather is upright or vertical and hence positioned to support the wafer  36  on the upper section  44  of the lift pin  40 . From the foregoing discussion of FIGS. 1 and 2, it will be recognized that the pivoting of the lift pin  40  from its retracted position to its storage position is accomplished by raising the base  52  so as to free the lever  48  from contact with the stop  62 , thereby leaving lever  48  free to pivot downwardly in response to the biasing force of spring  56 . 
     Next, the lift pin  40  is raised (by further raising the base  52 ) so that the lift pin  40  lifts the wafer  36  from the lift pin  26 . The resulting position is shown in FIG.  3 ( d ). In the condition shown in FIG.  3 ( d ) the wafer  36  is held in a storage position by the upper section  44  of the lift pin  40 . 
     At the next step, robot blade  32  enters the chamber  10  carrying a new wafer  36 ′ which is to be processed in the chamber. The resulting condition is shown in FIG.  3 ( e ). The lift pin  26  is then raised to lift the wafer  36 ′ from the robot blade  32  (FIG.  3 ( f )). The robot blade  32  then retracts from the processing chamber  10 , to result in the condition shown in FIG.  3 ( g ). 
     At the next step of the exchange operation, lift pin  26  is lowered to place the new wafer  36 ′ on the pedestal  20 , as shown in FIG.  3 ( h ). The robot blade  32  then reenters the processing chamber  10 , this time without a wafer being carried on the robot blade  32 . The resulting condition is shown in FIG.  3 ( i ). Lift pin  40 , which supports the processed wafer  36 , is then lowered (by lowering the base  52 ) to place the wafer  36  on the robot blade  32  (FIG.  3 ( j )). The robot blade  32  is then retracted from the processing chamber  10 , carrying the processed wafer  36  out of the chamber  10 . The exchange of wafers is now complete, resulting in the condition shown in FIG.  3 ( k ). Lift pin  40  is then moved from its storage position to its retracted position (FIG.  3 ( l )), by further lowering the base  52  to cause stop  62  to contact and pivot lever  48  (and the lift pin  40  fixedly coupled thereto), so that the path of travel of the pedestal  20  is no longer obstructed by the lift pin  40 . Accordingly, the pedestal  20  supporting the wafer  36 ′ may be raised to the processing position, which was initially shown in FIG.  3 ( a ). 
     The foregoing description discloses only a preferred embodiment of the invention; modifications of the above disclosed apparatus and method which fall within the scope of the invention will be readily apparent to those of ordinary skill in the art. For example, the invention has been illustrated in the context of a chemical vapor deposition (CVD) chamber. The invention may also be applied in a physical vapor deposition (PVD) chamber, an etching chamber, a photolithography chamber, a loadlock chamber, a degassing chamber, a heating chamber, a cooling chamber or at any location where substrates are exchanged. The invention may also be employed in connection with substrates other than semiconductor wafers (e.g., glass plates and the like). 
     It will be understood that the embodiment shown in FIGS.  1 - 3 ( l ) is merely exemplary and that the configuration of the lift pin/actuating assembly may vary and still function in accordance with the invention. For instance, a horizontal actuator may move the lift pin to the retracted position, contact a motion stop and translate further horizontal actuation into vertical motion. Further the specific operation of the assembly may change and still function in accordance with the invention. For example, the position of the stop and the motion translator may be reversed such that the motion translator is raised to contact the stop, rather than lowered to contact the stop, etc. 
     Accordingly, while the present invention has been disclosed in connection with the preferred embodiments thereof, it should be understood that other embodiments may fall within the spirit and scope of the invention, as defined by the following claims.