Abstract:
A substrate processing apparatus having a supply of substrates, a substrate transport module, and a substrate processing module. The transport module has a movable arm assembly and two substrate holders mounted to the movable arm assembly. The substrate holders each have two separate holding areas for simultaneously holding two substrates. The movable arm assembly has two pairs of driven arms. Each pair of driven arms is connected to a separate one of the holders for extending and retracting the holders along a radial path relative to a center of the movable arm assembly.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This is a continuation-in-part application of U.S. patent application Ser. No. 08/549,995, filed Oct. 27, 1995, and now U.S. Pat. No. 5,647,724. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a substrate processing apparatus and, more particularly, to a substrate transport with substrate holders each capable of transporting more than one substrate at the same time. 
     2. Prior Art 
     Mattson Technology has a system known as its ASPEN system that moves two semi-conductor wafers into and out of a process chamber at the same time. Batch systems, single wafer systems and cluster tool systems are also known in the prior art. U.S. Pat. No. 4,951,601 discloses a substrate processing apparatus with multiple processing chambers and a substrate transport apparatus. U.S. Pat. No. 5,180,276 discloses a substrate transport apparatus with two substrate holders. U.S. Pat. No. 5,270,600 discloses a coaxial drive shaft assembly of a substrate transport apparatus. U.S. Pat. No. 4,094,722 discloses a rotatable palette that holds four wafers. U.S. Pat. No. 4,381,965 discloses a multi-planar electrode plasma etcher. U.S. Pat. No. 4,675,096 discloses a take-in-and-out chamber with side-by-side take-in and take-out positions. Other related art include the following: 
     U.S. Pat. No.: 1,190,215 U.S. Pat. No.: 2,282,608 
     U.S. Pat. No.: 3,730,595 U.S. Pat. No.: 3,768,714 
     U.S. Pat. No.: 3,823,836 U.S. Pat. No.: 3,874,525 
     U.S. Pat. No.: 4,062,463 U.S. Pat. No.: 4,109,170 
     U.S. Pat. No.: 4,208,159 U.S. Pat. No.: 4,666,366 
     U.S. Pat. No.: 4,721,971 U.S. Pat. No.: 4,730,975 
     U.S. Pat. No.: 4,907,467 U.S. Pat. No.: 4,909,701 
     U.S. Pat. No.: 5,151,008 U.S. Pat. No.: 5,333,986 
     U.S. Pat. No.: 5,447,409 
     EPO Publication No.: 0423608 
     Japanese Publication No.: 2-292153 
     SUMMARY OF THE INVENTION 
     In accordance with one embodiment of the present invention, a substrate transport apparatus is provided comprising a movable arm assembly and two substrate holders. The movable arm assembly has two pairs of driven arms. The two substrate holders include a first holder which is suitably sized and shaped to simultaneously hold at least two spaced substrates thereon. Each substrate holder is individually connected to a separate one of the pairs of driven arms. 
     In accordance with another embodiment of the present invention, a substrate processing apparatus is provided comprising a supply of substrates, a substrate transport module, and a substrate processing module. The substrate transport module is connected to the supply of substrates and includes a movable arm assembly and two substrate holders mounted to the movable arm assembly for extension and retraction relative to a center of the movable arm assembly. A first one of the holders has two separate holding areas for simultaneously holding two substrates. The substrate processing module is connected to the substrate transport module and is suitably sized and shaped to simultaneously receive two substrates transported into the processing module by the movable arm assembly and the first holder. The substrate transport module can move more than two substrates without rotating the substrate holders about a center axis of the transport module. 
     In accordance with another embodiment of the present invention, a substrate transport apparatus is provided comprising a movable arm assembly and two substrate holders. The movable arm assembly has two drive arms and two pairs of driven arms. Each pair of driven arms has a first driven arm connected to a first one of the drive arms and a second driven arm connected to a second one of the drive arms. The two pairs of driven arms are generally located on opposite sides of the drive arms. The two substrate holders are individually connected to separate ones of the pairs of driven arms. The two substrate holders each have more than one separate substrate holding area for each of the holders to simultaneously hold more than one substrate at the same time. 
     In accordance with another embodiment of the present invention, a substrate holder for use with a substrate transport apparatus is provided comprising a frame member and a mount. The frame member has a general flat planar shape with two spaced apart recesses into a front end of the frame member. The mount is connected to the frame member for attaching the frame member to the transport apparatus. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     The foregoing aspects and other features of the invention are explained in the following description, taken in connection with the accompanying drawings, wherein: 
     FIG. 1 is a schematic top plan view of a substrate processing apparatus having a substrate transport apparatus incorporating features of the present invention; 
     FIG. 2 is a top plan view of an X-shaped section of a movable arm assembly of the substrate transport apparatus shown in FIG. 1; 
     FIG. 3 is an end view of the X-shaped section shown in FIG. 2 with a partial cut away section; 
     FIGS. 4A-4E are schematic top plan views of the substrate transport apparatus shown in FIG. 1 showing the movable arm assembly and the substrate holders at five different positions; 
     FIG. 5 is an end view with partial cut away sections of an alternate embodiment of the present invention; 
     FIG. 6 is a top plan view of an alternate embodiment of a substrate holder; 
     FIG. 7 is a schematic top plan view of a substrate processing apparatus using two of the holders shown in FIG. 6; 
     FIG. 8 is an enlarged top plan view of the transport apparatus shown in FIG. 7 having four substrates thereon; 
     FIG. 9A is a schematic top plan view of the transparent apparatus shown in FIG. 8 at a first extended position; 
     FIG. 9B is a schematic top plan view as in FIG. 9A showing the transport apparatus at a second extended position; 
     FIG. 10 is a schematic top plan view of an alternate embodiment of a transport apparatus having two different types of substrate holders; and 
     FIG. 11 is a perspective view of another alternate embodiment of a substrate holder. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, there is shown a schematic top plan view of a substrate processing apparatus  10  having a substrate transport apparatus  12  incorporating features of the present invention. Although the present invention will be described with reference to the embodiments shown in the drawings, it should be understood that the present invention may be embodied in many forms of alternative embodiments. In addition, any suitable size, shape or type of materials or elements could be used. 
     In addition to the substrate transport apparatus  12 , the substrate processing apparatus  10  includes multiple substrate processing chambers  14  and substrates cassette elevators  16  connected to a chamber  15 . The transport apparatus  12  is located, at least partially, in the chamber  15  and is adapted to transport planar substrates, such as semiconductor wafers or flat panel displays, between and/or among the chambers  14  and elevators  16 . In alternate embodiments, the transport apparatus  12  could be used in any suitable type of substrate processing apparatus. 
     Referring also to FIGS. 2,  3  and  4 E, the transport apparatus  12  generally comprises a movable arm assembly  18 , a coaxial drive shaft assembly  20 , and two substrate holders  22 ,  23 . The coaxial drive shaft assembly  20  includes a first shaft  24  rotatably located inside a second shaft  26 . The two shafts  24 ,  26  are axially rotatable in unison with each other in same directions and in opposite directions relative to each other and, are movable up and down with each other as indicated by arrow Z. One such coaxial drive shaft assembly is disclosed in U.S. Pat. No. 5,270,600 which is hereby incorporated by reference in its entirety. However, any suitable type of drive assembly could be used including a non-coaxial drive assembly or a coaxial drive assembly with more than two drive shafts. 
     The movable arm assembly  18  comprises a general X-shaped section  28  and four distal arms  30 ,  31 ,  32 ,  33 . The distal arms  30 ,  31 ,  32 ,  33  connect the substrate holders  22 ,  23  to the X-shaped section  28 . The X-shaped section  28  has three arm members  34 ,  35 ,  36  that form four proximal arm section  38 ,  39 ,  40 ,  41  of the two crossed arms  42 ,  43 . The section  28  is referred to as being X-shaped. However, the two arms  42 ,  43  are movable relative to each other at their center connection to the drive shaft assembly  20 . Thus, the X-shaped section  28  is a movable or reconfigurable X-shape. In one position, shown in FIGS. 1 and 4C, the X-shaped section looses its general X-shape because the two arms  42 ,  43  are directly aligned with each other. However, in all other non-aligned positions the section  28  has a general X-shaped profile. Thus, the section  28  is referred to herein as an X-shaped section for lack of a better descriptive term. The two crossed arms  42 ,  43  form the general X-shape. The first arm  42  comprises the first arm member  34  which forms the first and third arm sections  38 ,  40 . The second arm  43  comprises the second and third arm members  35 ,  36  which form the second and fourth arm sections  39 ,  41 . 
     As seen best in FIG. 3, the first arm member  34  is fixedly attached to the first drive shaft  24  by screw  44 . The first arm section  38  has a pivot  46  at its distal end and is connected to the shaft assembly  20  at a first height. A stop  48  extends below the first arm section  38 . The third arm section  40  is integral with the first arm section  38 . The third arm section  40  has an aperture  50  that allows the drive shaft assembly  20  to pass therethrough. The third arm section  40  extends from the drive shaft assembly  20  at a third height on the assembly  20 . Located at a distal end of the third arm section  40  is an upward extension  51  with an upper overhang section  52  having a pivot  54 . The overhang section  52  extends inward towards the center of the X-shape. The second arm section  39  has an aperture  58  that allows the drive shaft assembly  20  to pass therethrough. The second arm section  39  is fixedly attached to the second drive shaft  26  by a screw  56 . The second arm section  39  extends from the drive shaft assembly  20  at a second height on the assembly  20 . Located at the distal end of the second arm section  39  is a pivot  60  on an upstanding post  62 . The fourth arm section  41  has an aperture  64  that allows the drive shaft assembly  20  to pass therethrough. The fourth arm section  41  is fixedly attached to the second drive shaft  26  by a screw  66 . The distal end of the fourth arm section  41  has an upward extension  69  with an upper overhang section  68  having a pivot  70 . The fourth arm section  41  extends from the drive shaft assembly at a fourth height on the assembly  20 . Thus, the four arm sections  38 ,  39 ,  40 ,  41  extend from the drive shaft assembly  20  at four different heights on the assembly  20 . The third arm section  40  and the fourth arm section  41  form channels  72 ,  74  to allow the distal ends of the first and second arm sections  38 ,  39  to pass through. 
     As seen best in FIG. 4E, the first distal arm  30  has one end pivotably mounted on the first pivot  46  of the first arm section  38  and an opposite end pivotably mounted to the first substrate holder  22 . The second distal arm  31  has one end pivotably mounted on the second pivot  60  of the second arm section  39  and an opposite end pivotably mounted to the first substrate holder  22 . Thus, the first holder  22  is pivotably mounted to the pair of pivots  46 ,  60 ; one pivot from each of the crossed arms  42 ,  43  of the X-shaped section  28 . The third distal arm  32  has one end pivotably mounted on the third pivot  54  of the third arm section  40  and an opposite end pivotably mounted to the second substrate holder  23 . The fourth distal arm  33  has one end pivotably mounted on the fourth pivot  70  of the fourth arm section  41  and an opposite end pivotably mounted to the second substrate holder  23 . Thus, the second holder  23  is pivotably mounted to the pair of pivots  54 ,  70 ; one pivot from each of the crossed arms  42 ,  43  of the X-shaped section  28 . In alternate embodiments other types of connections of the distal arms to the X-shaped section  28  and/or the holders  22 ,  23  could be provided. Connectors or a connecting assembly different than the distal arms  30 ,  31 ,  32 ,  33  could also be provided. 
     The first pair of pivots  46 ,  60  and their corresponding distal arms  30 ,  31  are located in a first relative lower plane of movement. The first substrate holder  22  is also located in this first relative lower plane. The second pair of pivots  54 ,  70  and their corresponding distal arms  32 ,  33  are located in a second relative upper plane of movement. The second substrate holder  23  is also located in this second relative upper plane. In a preferred embodiment the first pair of distal arms  30 ,  31  has intermeshed gear sections at holder  22  for registry of movement to keep the holder  22  in a constant orientation. The second pair of distal arms  32 ,  33  also preferably has intermeshed gear sections at holder  23  for registry of movement to keep the holder  23  in a constant orientation. However, any suitable type of system to keep the holders  22 ,  23  properly orientated could be used. 
     The substrate holders  22 ,  23  are adapted to be inserted and removed from the chambers  14  and elevators.  16 . The holders  22 ,  23  are adapted to hold substrates thereon and thereby allow the substrates to be moved between and/or among the chambers  14  and elevators  16 . Suitable means are provided (not shown) for keeping the substrate holders aligned with the movable arm assembly  18  such that the holders  22 ,  23  are always pointed in an outward direction for proper straight insertion into a chamber or elevator. This can include the ends of the distal arms  30 ,  31 ,  32 ,  33  at the holders  22 ,  23  having intermeshed gear teeth or an S-band joint constraint, such as described in U.S. patent application Ser. No. 08/421,533 entitled “Articulated Arm Transfer Device”, which is hereby incorporated by reference in its entirely. In alternate embodiments any suitable type of substrate holders or orientation constraint could be used. 
     Referring now to FIGS. 4A-4E, the operation of the substrate movement apparatus  12  will be described. FIG.  4 C and FIG. 1 show the apparatus  12  at a home position. In this home position both drive shafts  24 ,  26  can be rotated in the same direction to rotate the holders  22 ,  23  in front of a selected one of the chambers  14  or elevators  16 . In this home position, the upper holder  23  is located above the lower holder  22 . Distal arm  33  is located over distal arm  30 . Distal arm  32  is located over distal arm  31 . First arm section  38  is located over the fourth arm section  41  except for overhang section  68 . Second arm section  39  is located over the third arm section  40  except for overhang section  52 . 
     FIG. 4A shows the upper holder  23  in an extended position with the lower holder  22  in a retracted position. FIG. 4B shows an intermediate position of the apparatus  12  between the home position shown in FIG.  4 C and the upper holder extended position shown in FIG.  4 A. In order to move between these two positions, the two drive shafts  24 ,  26  are axially rotated in reverse directions relative to each other. FIG. 4E shows the lower holder  22  in an extended position with the upper holder  23  in a retracted position. FIG. 4D shows an intermediate position of the apparatus  12  between the home position shown in FIG.  4 C and the lower holder extended position shown in FIG.  4 E. The two holders  22 ,  23  are moved in opposite unison between their extended positions and their home positions with the upper holder  23  moving in a plane above the lower holder  22 . The movable arm assembly  18  allows sufficient room for the holder being retracted to move closer to the center of the X-shaped section. The stop  48  limits axial rotation of the two crossed arms  42 ,  43  relative to each other. The movable arm assembly  18  is designed to allow each arm  42 ,  43  to rotate about 160°. However, in alternate embodiments other degrees of rotation could be provided. The X-shaped section  28  has been designed to allow unobstructed movement of the arm sections  38 ,  39 ,  40 ,  41  between the positions shown in FIGS. 4A and 4E and unobstructed movement of the distal arms and holders in their two different relative planes of motion. This allows the two holders  22 ,  23  to be positioned on the same side of the assembly  18 . The two pairs of distal arms  30 ,  31  and  32 ,  33  function as forearm sections for their respective substrate holders  22 ,  23 . In alternate embodiments more than two substrate holders could be provided and/or, could be located on additional sides of the assembly  12 . The drive shaft assembly  20  vertically moves the holders  22 ,  23  in direction Z (see FIG. 3) to align the holder to be extended with the opening of the intended receiving chamber  14  or elevator  16 . Positioning the two holders  22 ,  23  on the same side of the assembly can speed-up throughput in the substrate processing apparatus  10 . Positioning of the holders  22 ,  23  on the same side of the apparatus  12  is accomplished by allowing the holders to move along substantially parallel paths, one holder above the other, with one moving in a plane over the other. 
     Referring now to FIG. 5, there is shown an alternate embodiment of the present invention. The transport apparatus  112  has a coaxial drive shaft assembly  120  with two drive shafts  124 ,  126 . The movable arm assembly  118  has four drive arms  138 ,  139 ,  140 ,  141  and four driven arms or forearms  130 ,  131 ,  132 ,  133 . Two holders  122 ,  123  are attached to ends of the forearms  130 ,  131 ,  132 ,  133 . In this embodiment, the second and fourth drive arms  139  and  141  are fixedly connected to each other by fasteners  156  (only one of which is shown). The fourth drive arm  141  is fixedly attached to the top of the outer drive shaft  126  by fasteners  166  (only one of which is shown). Thus, when the outer drive shaft  126  is moved, the second and fourth drive arms  139 ,  141  are moved. The third drive arm  140  has a section  140   a  that fasteners  140   b  are attached to. The fasteners  140   b  are also attached to section  138   a  of the first drive arm  138 . This fixedly attaches the first drive arm  138  to the third drive arm  140 . The fourth drive arm  141  has a pocket  180  to allow the section  140   a  to move therethrough. The first drive arm  138  is fixedly attached to the top of the inner drive shaft  124  by fasteners  144  (only two of which are shown). The third drive arm  140  has an extension  151  attached to it that has the pivot  154  thereon. Likewise, the fourth drive arm  141  has an extension  169  attached to it that has the pivot  170 . The first and second drive arms  138 ,  139  also have pivots  146 ,  160 , respectively. The four forearms  130 ,  131 ,  132 ,  133  are mounted on the pivots  146 ,  154 ,  160 ,  170  with suitable bearings. This embodiment is more compact than the embodiment shown in FIG.  3  and is easier to manufacture. There is also virtually no chance that the drive arms will move relative to their respective drive shafts. 
     In another alternate embodiment, two drive shaft assemblies could be used; one extending upward into the chamber  15  and one downward into the chamber  15 . Referring to FIG. 1, because the driven arms can extend and retract in a single radial direction on one side of the drive shaft, the substrate holders can withdraw a substrate from one of the chambers  14  or elevator  16  and insert a substrate into the same chamber  14  or elevator  16  without rotating the substrate holders about the center axis of the drive shaft assembly. This can obviously save time in transporting substrates. The ability to have the driven arms and substrate holders on the same side of the drive shaft assembly is an important feature and improvement for the present invention. 
     Referring now to FIG. 6, an alternate embodiment of a substrate holder  200  is shown. The holder  200  generally comprises a frame  202  and a mount  204 . The frame  202  has a general flat planar shape with two spaced apart recesses  206 ,  208  into a front end  210  of the frame  202 . The frame  202  also has a third recess  212  in its front end  210  between the first and second recesses  206 ,  208 . The front end  210 , thus, has four forwardly extending arms  214 ,  216 ,  218 ,  220 . Mounted to the frame  202  are six point contacts  222 . The point contacts  222  are preferably comprised of quartz or diamond and extend above the top surface of the frame  202 . Three point contacts  222  are provided at each of the first and second recesses  206 ,  208 . Each arms  214 ,  216 ,  218 ,  200  has one of the point contacts  222  proximate its end. A point contact  222  is also located at the rear ends of each of the first and second recesses  206 ,  208 . Substrates placed on the holder  200  rest on the point contacts  222 ; not directly on the frame  202 . However, in alternate embodiments any suitable type of system can be used to locate or mount substrates to the holder  200 . The frame and point contacts, in the embodiment shown, are suitably configured to hold up to two substrates at the same time; one above the first recess  206  and another above the second recess  208 . The holder  200  is adapted to hold the two substrates in a same plane above and parallel to the frame  202  and in a side-by-side configuration. In alternate embodiments, the frame  202  could have other shapes dependent upon how many substrates it can carry and the shape of the processor and elevator modules it is intended to be inserted into. The mount  204  is fixedly connected to the rear end  224  of the frame  202 . In an alternate embodiment the mount could be an integral part of the frame rather than a member attached to the frame. The mount  204  has two driven arms  226 ,  228  pivotably connected to it. Preferably, suitable means (not shown) are provided at the mount  204  for constraining the driven arms  226 ,  228  such that they move in registration with each other, such as intermeshing gear teeth or a dual S-band constraint. 
     Referring also to FIG. 7, there is shown a substrate processing apparatus  230  having a substrate transport apparatus  232  with two of the substrate holders  200 . The processing apparatus  230  is similar to the apparatus  10  shown in FIG. 1, but has two dual substrate cassette elevators  234 ,  235 , four dual substrate processing chambers  236 , a dual aligner  238 , a dual incooler  240 , and two dual substrate transports  242 ,  243 . The first transport  242  transports two subsubstrates at a time from the first elevator  234  to the aligner  238 . The second transport  243  transports two substrates at a time from the incooler  240  to the cassettes in the second elevator  235 . 
     Referring also to FIG. 8, the substrate transport apparatus  232  is shown holding four substrates S. The transport apparatus  232 , in the embodiment shown, includes a drive  244  and a movable arm assembly with two drive arms  246 ,  247  and four driven arms  248 ,  249 ,  250 ,  251 . Preferably, the drive is a coaxial drive shaft assembly such as described in U.S. patent application Ser. No. 08/434,012, now U.S. Pat. No. 5,720,590, which is hereby incorporated by reference in its entirety. However, any suitable type of drive could be used. A similar drive arm assembly is described in U.S. Pat. No. 5,180,276 which is hereby incorporated by reference in its entirety. In the embodiment shown in FIG. 8, mounted to the ends of the two sets of driven arms  248 ,  249  and  250 ,  251  are the two substrate holders  200   a  and  200   b . FIGS. 7 and 8 shows the transport apparatus  232  at a home position. Referring to FIGS. 9A and 9B the transport apparatus is shown at two different extended positions. In the first extended position shown in FIG. 9A, the first holder  200   a  is moved into the aligner  238  to remove the two substrates S 1  and S 2 . In the second extended position shown in FIG. 9B the first holder  200   a  has been retracted out of the aligner  238  and the second holder  200   b  has been inserted into the processing chamber  236  to deliver the two substrates S 3  and S 4 . This illustrates that the transport apparatus  232  and holders  200  can move more than two substrates without rotating the holders  200  about a center axis of the transport apparatus. 
     From the foregoing description it should be evident that the holder  200  allows for twice the substrate throughput as a single substrate holder. However, the expected increase in size of the footprint of the substrate processing apparatus is only about 40%. In addition, the increase in cost for manufacturing this type of substrate processing apparatus is expected to be only about 30% more than an apparatus with single substrate holders. Thus, throughput can be increased 100% with an increase in footprint of only 40% and increase in cost of only 30%. In addition, the dual substrate holder  200  in combination with the same side transport apparatus  12  can further increase throughput more than 100% due to the fact that the movable arm assembly  18  does not need to be rotated to remove substrates from a chamber and insert new substrates into the chamber. 
     Referring now to FIG. 10, there is shown an alternate embodiment of the present invention. In this embodiment the transport apparatus  232  includes two different substrate holders  200  and  201 . The second substrate holder  201  is for carrying a single substrate. Referring to FIG. 11, there is shown a perspective view of another embodiment of a substrate holder  260  for carrying two substrates. However, in this embodiment, the frame  262  is suitably configured to hold the substrates in a vertically offset parallel or stacked configuration; one on bottom frame section  264  and one on top frame section  266 . However, any suitable frame configuration could be used. 
     It should be understood that the foregoing description is only illustrative of the invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the spirit of the invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.