Patent Publication Number: US-11049751-B2

Title: Cassette supply system to store and handle cassettes and processing apparatus equipped therewith

Description:
FIELD 
     The invention relates to a cassette supply system to store and handle cassettes for substrates and a processing apparatus equipped therewith. The cassette supply system comprising: 
     a cassette storage provided with a base plate constructed and arranged to support cassettes; and, 
     a cassette handler to transfer cassettes to and from the base plate. 
     BACKGROUND 
     When processing substrates such as semiconductor wafers in processing apparatus, the processing apparatus are adapted to and optimized for the size of the substrate to be processed. The size of the substrates are standardized in a limited number of discrete sizes where there has been a tendency towards increasing size in the past decennia in order to increase the production efficiency. The most recently introduced substrate sizes are 200 mm and 300 mm diameter. A wafer fabrication facility will normally be adopted to one substrate size. 
     To transport the substrates, cassettes may be used which may require a specific cassette supply system. The cassette supply system may be employed in the processing apparatus used in the manufacture of discrete and integrated semiconductor products on semiconductor material substrates. The cassette supply system may have a cassette storage with a base plate constructed and arranged to support cassettes to store multiple cassettes. A cassette handler may be used to transfer cassettes to and from the base plate. 
       FIG. 1  is a front/bottom perspective view of a cassette  3  having an opening  2  to receive substrates in horizontal slots (not depicted) in the interior of the cassette. The cassette may be provided with recesses such as for example the three elongated grooves  7  in the bottom  4  for handling/positioning of the cassette  3 . The ends of the grooves  7  may be closed as depicted or open ended. The grooves  7  may be constructed by a rim extending from the bottom of the cassette  3 . 
       FIG. 2  is a cross-sectional view on a base plate  1  supporting the cassette  3 . Plate pins  5  may be provided on the base plate  1  and may be matching with the elongated grooves  7  provided in the bottom of the cassettes  3  to position the cassette  3 . 
       FIG. 3  depicts a top view on the base plate  1 , an end effector  9  of a cassette handler and the grooves  7  of the cassette during transfer of the cassette from the end effector  9  to the base plate  1  or vice versa. As depicted in  FIG. 3  the end effector  9  may also be provided with three handler pins  11  which match with the three grooves  7  provided in the bottom of the cassettes. The cassette may thereby be positioned on the end effector  9  in a predetermined position by the three handler pins  11 . 
     During transfer of the cassette  3  to and from the moveable base plate  1  the three grooves  7  in the bottom of the cassette  3  may be in contact with three plate pins  5  and three handler pins  11  simultaneously. The position of the cassette  3  may thereby become overdetermined. This overdetermined position may lead to brusque movements in the transfer of the cassette  3  which may lead to particle generation. To alleviate the brusque movements the end effector  9  may need to move very slowly at high precision in the transfer of the cassette  3  to and from the base plate  1  which may deteriorate the throughput of the system and/or lead to a more expensive system. 
     Accordingly, it may be desirable to provide an improved cassette supply system which accommodates an improved transfer of the cassette to and from the base plate. 
     BRIEF SUMMARY OF THE INVENTION 
     Accordingly, there may be provided a cassette supply system to store and handle cassettes for substrates. The system may comprise a cassette storage provided with a base plate constructed and arranged to support cassettes and a cassette handler to transfer cassettes to and from the base plate. The cassette handler may comprise an end effector provided with at least one protrusion to support and position the cassette on the end effector. The base plate may be provided with a substantially flat surface to support and position the cassettes. 
     By having a substantially flat surface to support and position the cassettes on the base plate the position of the cassette will not be overdetermined during transfer of a cassette between the end effector and the base plate. 
     A processing apparatus for the manufacture of semiconductor products may be provided with a cassette supply system in accordance with the invention. The processing apparatus may further comprise a processing device to process substrates and, a substrate handler constructed and arranged to move substrates from a cassette at a substrate load/unload station to the processing device and to move the substrates from the processing device to a cassette at a substrate load/unload station after processing. The cassette supply system may comprise the cassette handler constructed and arranged to transfer cassettes to a substrate load/unload station from the base plate and vice versa. Such an system may enable products to be manufactured in large numbers and may be easy to maintain and/or install. 
     These and other embodiments will become readily apparent to those skilled in the art from the following detailed description of certain embodiments having reference to the attached figures, the invention not being limited to any particular embodiment(s) disclosed. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       It will be appreciated that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of illustrated embodiments of the present disclosure. 
         FIG. 1  is a front/bottom perspective view of a cassette according to the prior art. 
         FIG. 2  is a cross-sectional view on a base plate supporting the cassette according to the prior art. 
         FIG. 3  depicts a top view on the base plate, an end effector of a cassette handler and the grooves of a cassette during transfer according to the prior art. 
         FIG. 4  shows, diagrammatically and partially exposed, a perspective view of a substrate processing apparatus with a cassette supply system according to an embodiment. 
         FIG. 5  shows a plan view of the substrate processing apparatus of  FIG. 4 . 
         FIG. 6  depicts a top view on a portion of the base plate, an end effector of a cassette handler and the grooves of a cassette during transfer of the cassette in a cassette supply system in  FIG. 4 . 
         FIG. 7  is a cross-sectional view on a portion of a base plate supporting the cassette in the cassette supply system in  FIG. 4 . 
     
    
    
     The figures are not drawn to scale, and particularly the dimensions and the thickness direction are exaggerated for clarity. Corresponding areas bear the same reference numerals whenever possible. 
     DETAILED DESCRIPTION 
       FIG. 4  shows, diagrammatically and partially exposed, a perspective view, and  FIG. 5  shows a plan view of a substrate processing apparatus for substrates supplied in cassettes and provided with a cassette supply system according to an embodiment. Processing area  21  comprises vertical reactors, and a substrate handling chamber  22  is provided between the processing area  21  and a cassette handling area  23  to provide substrates to the reactors. The cassette supply system according to an embodiment is provided in the cassette handling area  23  to transfer and store cassettes  3 . An input/output station, to feed or remove cassettes  3  into or out of the apparatus, is indicated by  33 . 
     Substrates  13  are supplied in cassettes  3  which may be placed on input/output station  33 . A cassette handler  32  may transfer the cassettes from the input/output station  33  into the cassette store  8  located in the cassette handling area  23 . This optionally may be accomplished through a closable opening  34 . The cassette store  8  may be provided with a number of base plates  1  above each other on which the cassettes  3  may be stored. The cassette handler  32  may be provided with an elevator  35  to be movable in a vertical direction, so that many base plates  1  at different levels may be reached. The cassette handler  32  may be provided with a cassette end effector  9  may have dimensions a little smaller than those of the cut-out  26  in base plate  1 . When the cassette handler  32  has transferred the cassette  3  into the store  8 , the end effector  9  may be lowered through one of the cut-outs  26  in one of the base plates  1  to place the cassette  3  on said plate. Subsequently, the cassette handler  32  may retract its end effector  9  from cassette store  8 . 
       FIG. 6  depicts a top view on cut out portion of the base plate  1 , the end effector  9  of the cassette handler  32  and the recesses, e.g., grooves  7  of the cassette  3  during transfer of the cassette  3  from the cassette handler  32  to the base plate  1  or vice versa. As depicted in  FIG. 6 , the end effector  9  may be provided with at least a first protrusion, which may match with at least a first recess. For example, the three handler pins  11  may match with the three grooves  7  provided in the bottom of the cassettes  3 . The cassette  3  may thereby be supported and positioned on the end effector  9  with precision. 
     During transfer of the cassette  3  to and from the moveable base plate  1  the rim of the three grooves  7  in the bottom of the cassette  3  may be in contact with a substantially flat surface to support the cassettes  3 . By having the substantially flat surface to support and position the cassettes on the base plate  1 , the position of the cassette  3  may not be over determined during transfer of the cassette between the end effector and the base plate  1 , making a fast and simple transfer of the cassette possible. 
     The flat surface may comprise a flexible material, e.g., rubber to absorb energy when the cassette is transferred to the surface. The material may have a high friction to keep the cassette on its position on the flat surface when the base plate  1  is moved. 
     The base plate  1  may be provided with multiple pads  25  each provided with the flat surface to support the cassettes. The base plate  1  may be provided with three pads  25  to support one cassette around one cut out  26 . One pad  25  may be positioned closer to the center  27  of the base plate  1 . Two other pads  25  may be positioned closer to the edge of the base plate  1 . The pads may be configured on the base plate to match with the grooves  11  provided in the bottom plate of the cassette  3 . The pads may be configured in a triangular form. The triangular form may be isosceles having at least two edges with the same length or even equilateral having three edges with the same length. 
       FIG. 7  is cross-sectional view on a portion of a base plate  1  supporting the cassette  3 . Pads  25  provided on the base plate  1  may be matching with the elongated grooves  7  provided in the bottom of the cassettes  3  to support the cassette  3 . The pads  25  may have a thickness between 1 and 10 mm, preferably between 2 and 5 mm to support the cassette  3 . The height of the base plate  1  and cassette  3  combination may be lowered with 5 to 20 mm by using pads  25  instead of pins  5  (see  FIG. 2 ) which may be advantageously in an system where vertical space may be limited by the ceiling of the semiconductor manufacturing plant. 
     The base plate  1  with its pads  25  may be constructed and arranged so that the flat surface may be the only contact area with the cassette  3 . Since the contact area of the pads  25  and the cassette  3  may be larger compared to a situation where pins are used high pressure zones in the material may be avoided which makes the design more easy and less sensitive to wear and/or particle formation. 
     During transfer of the cassette  3  by the cassette handler  32 , the three handler pins  11  may determine the position of the cassette  3  in the horizontal plane. The pads  25  allow the positioning of the cassette  3  with some play in the horizontal plane. Only in the vertical direction the pads  25  may function as a hard stop. The flexibility of the material of the pads  25  however may absorb the energy of the cassettes  3  in the vertical direction so as to make a more quick movements in the transfer of the cassette possible while still avoiding particle generation. 
     The base plate  1  may be provided with visual markings for the position of the cassette  3  on the base plate  1 . An operator, during repairs for example, may be able to position the cassettes  3  in the correct position on the base plate with the visual markings such that the cassette handler  32  may be able to move the end effector  32  in the cut out  26  to take the cassette from the pads  25  with its three handler pins  11 . 
     The cassette handler  32  may be constructed and arranged such that it may be able not only to transfer cassettes between the input/output station  33  and store  8 , but that it also may be possible to transfer cassettes between store  8  and a rotatable cassette transfer platform  30  functioning as a substrate load/unload station and/or between input/output station  33  and the rotatable cassette transfer platform  30 . The rotatable cassette transfer platform  30  may be constructed, such that on rotation, the cassette  3  may be placed against a partition between cassette handling area  23  and substrate handling chamber  22 , which partition may be provided with a closure and a closure mechanism  37 . After placing the cassette  3  against the closure of the substrate handling chamber  22 , the closure mechanism may grip and unlock the closure of the cassette  3  and may remove the closure of the substrate handling chamber  22  simultaneously with the closure of the cassette  3 . The rotatable cassette transfer platform  30  functioning as the substrate load/unload station may comprise at least a first protrusion, e.g., three pins to support and position the cassette with high precision. The substrate handler  24  may then transfer the substrates from/to the cassette  3  in a smooth manner. The input/output station  33  may comprise at least a first protrusion, e.g., three pins to support and position the cassette with high precision as well, so that an Automatic Guided Vehicle or an Overhead Hoist System may automatically place or pick the cassettes from the apparatus for further processing in different semiconductor equipment in a semiconductor fabrication plant. 
     The substrate handler  24  may transfer substrates between the cassette concerned and a substrate boat  12 . After completion of the loading of substrates into substrate boat  12 , arm  16  may move substrate boat  12  through a closable opening in the substrate handling chamber  22  into processing chamber  21 . Processing chamber  21  may be provided with a rotary boat transfer platform  11 , supporting the substrate boat  12 . 
     Two reactors  6 , which may be heated, may be arranged in the processing chamber  21 . The heated reactors may be positioned vertically and substrate boats, indicated by  12 , filled with substrates  13 , may be introduced into the reactors  6  in the vertical direction from below. To this end, each reactor may have an insertion arm  14 , which may be movable in the vertical direction. 
     The treatment of a large number of substrates may be carried out as follows. The operator, shown diagrammatically in  FIG. 4 , may load the store  8  by introducing a number of cassettes on the input/output station manually or with an automated system and carrying out control operations on panel  36 . Each of the cassettes  3  may be transferred from the input/output station with the aid of cassette handler  32  into the storage compartments  31  made for these cassettes  3  in store  8 . By rotation of the base plate  1  with a moving device around the center of the base plate  1  and use of the elevator  35 , it may be possible to fill various compartments  31  with cassettes  3 . After filling store  8 , no further human interaction may be required with this automated installation. The cassettes  3  concerned may then be selected from the store  8  by rotation of the base plate  1  and removed by the cassette handler  32  and placed on cassette transfer platform  30 . 
     The cassette transfer platform  30  may comprise two levels, schematically indicated in  FIG. 4 , each level capable of receiving a cassette. The levels may be rotated independently from each other. Upon rotation of the cassette transfer platform  30  the cassette may be placed against closure  37 . After removing the closure of the cassette, together with closure  37 , the substrates may be removed by substrate handler  24  and placed in substrate boat  12 . After the substrate boat  12  has been filled with substrates it may become available for one of the reactors  6 ,  7 , the closure  19  may be opened and the substrate boat may be placed on rotary boat transfer platform  10 . The boat transfer platform then may move the substrate boat  12  to a position below the reactor  6  to be loaded. Then the insertion mechanism  14  may move the boat into the reactor. Treated substrates may execute a movement counter to the above. 
     This system is described in further detail in PCT Publication No. WO 99/38199 of applicant. Although it is described that an operator introduces the cassette on the input/output station, the system is designed such that as an alternative the cassettes can be introduced on the input/output station by means of an automated system, such as an Automatic Guided Vehicle or by an Overhead Hoist System. In such a case, the control system of the substrate processing system may be connected to a host computer system that carries out the control functions. In this way, no human interaction at the substrate processing system may be required at all. 
     The dimensions of the main plate  1  may be adapted to the dimensions of the cassette  3 , which may be a box-shaped body, with an open front side which may be closed with a closure. The dimensions of the cassette may be determined by the number and the size of substrates in the cassette. The base plate  1  may have a thickness between 0.2 and 4 mm, preferably between 0.3 and 3 mm and may be made from a metal, e.g., steel or aluminum. 
     The cassette supply system may have a computer operable connected with an optical sensor, such as a camera. The computer provided with a processor and a memory, wherein the memory is provided with machine vision software for detecting at least one of a presence and a correct orientation of the substrate cassette on the base plate. 
     The particular implementations shown and described are illustrative of the invention and its best mode and are not intended to otherwise limit the scope of the aspects and implementations in any way. Indeed, for the sake of brevity, conventional manufacturing, connection, preparation, and other functional aspects of the system may not be described in detail. Furthermore, the connecting lines shown in the various figures are intended to represent exemplary functional relationships and/or physical couplings between the various elements. Many alternative or additional functional relationship or physical connections may be present in the practical system, and/or may be absent in some embodiments. 
     It is to be understood that the configurations and/or approaches described herein are exemplary in nature, and that these specific embodiments or examples are not to be considered in a limiting sense, because numerous variations are possible. The specific routines or methods described herein may represent one or more of any number of processing strategies. Thus, the various acts illustrated may be performed in the sequence illustrated, in other sequences, or omitted in some cases. 
     The subject matter of the present disclosure includes all novel and nonobvious combinations and sub combinations of the various processes, systems, and configurations, and other features, functions, acts, and/or properties disclosed herein, as well as any and all equivalents thereof.