VACUUM ELEVATOR

Technical Field

The present invention relates to an extension apparatus or elevator which is operable within a chamber, for example, a vacuum chamber, as well as to an apparatus for rotating a structure within such a chamber. Such an extension apparatus is useful for moving objects such as semiconductor wafers within a sealed environment such as a vacuum chamber.

Background Of The Invention

Elevators which operate within vacuum chambers or other controlled sealed environments generally require some type of a sliding fit between the bottom of the vacuum chamber and a structure which is attached to the elevator and which passes through the chamber bottom and is moved linearly by an appropriate motor external of the chamber. This creates a serious problem of leaks at the seal area. Such leaks can be very detrimental during vacuum processing and can also be very detrimental if the atmosphere within the controlled chamber is, for example, maintained dust free as is generally necessary for semiconductor processing operations. In particular, leakage at the sliding seal can lead to the introduction of minute particles of dust into the chamber where they can interfere with wafer processing. Similar problems occur when a structure, e.g., an elevator is to be rotated within a controlled environment chamber.

The present invention is directed to overcoming one or more of the problems as set forth above.

Disclosure Of Invention

In accordance with an embodiment of the present invention an extension apparatus is set forth. The apparatus comprises a linearly extending tubular member having first and second end portions. A rod is located within the tubular member and extends parallel to it. The rod extends from the first end portion of the tubular member to adjacent its second end portion. A linearly extending moveable member is provided having first and second end portions and being located within and parallel to the tubular member with the first and second end portions of the tubular member and of the moveable member extending in corresponding directions. The moveable member has a central cavity extending along it, the cavity fitting in close fitting slidable relation to the rod. The moveable member is shorter than the rod. A first magnetic structure is provided in contact with the first end portion of the moveable member. The first magnetic structure fits within and in close fitting slidable relation to the first end portion of the tubular member. The structure has a longitudinal hole through it which is positioned about the rod. A second magnetic structure is located about the tubular member opposite the first magnetic structure. Magnet moving means are provided for moving the second magnetic structure linearly along the tubular member to move the first magnetic structure and the moveable member linearly along the tubular member. An extension apparatus is also set forth in accordance with another embodiment of the present

invention. The apparatus comprises a linearly extending tubular member having a central passage and first and second end portions. A first magnetic structure having first and end portions is in close fitting slidable relation within the passage. A linearly extending moveable member has a proximal portion which supports the first magnetic structure. The proximal portion is within and in close fitting but slidable relation to the inner passage. The moveable member extends to a distal end portion a selected distance out of the passage. The distal end portion of the moveable member has a threaded bore through it parallel to the tubular member. A threaded shaft extends through the bore in threaded relation to it. Rotating means are provided for rotating the shaft to move the first magnetic structure linearly along the passage. A second magnetic structure is located about and in close fitting slidable relation to the tubular member opposite the first magnetic structure. A linearly extending support structure extends from the second magnetic structure past the first end portion of the tubular member.

An extension apparatus comprises yet another embodiment of the present invention. The apparatus comprises a linearly extending tubular member having an inner passage extending longitudinally along it. The inner passage is in communication with a first set of atmospheric conditions. An outer surface of the tubular member is in communication with a second set of atmospheric conditions. A linearly extending relatively moveable member is located within and extends in parallel relation to the inner passage. A first magnetic structure is in contact with the relatively moveable member. The first magnetic structure fits within and in close fitting slidable

relation to the inner passage. A second magnetic structure is located about the tubular member opposite the first magnetic structure. Magnet moving means serve for moving a respective one of the first and second magnetic structures longitudinally to move a respective other of such structures longitudinally. Communication preventing means serves for selectively preventing communication of the first set of atmospheric conditions with the second set of atmospheric conditions.

Another embodiment yet of the present invention is an apparatus for rotating an enclosed structure. The apparatus comprises a wall structure defining an interior chamber, the wall structure having a support wall having an inner side facing the chamber and an outer side facing away from the chamber. An inner magnetic structure is mounted for rotation about an axis which passes through the wall. An outer magnetic structure is located outside of the chamber. The outer magnetic structure is mounted for rotation about the axis at a location opposite the inner magnetic structure. Rotating means serves for rotating a respective one of the outer and inner magnetic structures about the axis to rotate a respective other thereof about the axis. A rotatable structure is mounted for rotation with and extends from the respective other of the magnetic structures. The present invention provides apparatus for both moving an elevator up and down and for rotating the elevator about its longitudinal axis within a chamber having a controlled environment, for example a vacuum. The required motions are provided and are carefully and precisely controlled without any mechanical connection between the controlled

atmosphere and the surrounding space. In this manner, exchange of atmosphere between the chamber and the surrounding space is prevented and the generation of dust particles within the chamber is minimized.

Brief Description Of Drawings

The invention will be better understood by reference to the figures of the drawings wherein like numbers denote like parts throughout and wherein:

Figure 1 illustrates, in side sectional view, an apparatus in accordance with an embodiment of the present invention; Figure 2 illustrates, in a view similar to

Figure 1, an apparatus in accordance with another embodiment of the present invention; and

Figure 3 illustrate, in a view similar to Figures 1 and 2, still another embodiment in accordance with the present invention.

Best Mode'For Carrying Out Invention

Figure 1 illustrates an extension apparatus

10 in accordance with an embodiment of the present invention. The extension apparatus 10 of the embodiment of Figure 1 includes a linearly extending tubular member 12 having a first end portion 14 and a second end portion 16. A rod 18 is located within the tubular member 12 and extends parallel to it. The rod 18 extends from the first end portion 14 of the tubular member 12 to adjacent its second end portion 16.

A linearly extending moveable member 24 is located within and parallel to the tubular member 12. The linearly extending moveable member 24 has a first end portion 26 and a second end portion 28.

The first end portion 26 of the moveable member 24 extends in the same direction as does the first end portion 14 of the tubular member 12 and the second end portion 28 of the moveable member 24 extends in the same direction as does the second end portion 16 of the tubular member 12. The moveable member 24 has a central cavity 30 which extends therealong. The cavity 30 fits in close slidable relation to the rod 18. The moveable member 24 is shorter than is the rod 18.

A first magnetic structure 32 is in force transmitting communication with the first end portion 26 of the moveable member 24. In the embodiment of Figure 1 the communication is via intermediate bearing structure 33. The first magnetic structure 32 fits within and in close fitting slidable relation to the tubular member 12. The first magnetic structure 32 has a longitudinal hole 34 through it. The hole 34 is positioned about the rod 18.

A second magnetic structure 36 is located about the tubular member 12 opposite the first magnetic structure 32. Magnet moving means 38 is provided for moving the second magnetic structure 36 linearly along the tubular member 12 in order to move the first magnetic structure 32 and the moveable member 24 linearly along the tubular member 12.

Figure 1 illustrates magnet moving means 38 which includes a collar 40 which fits about and holds the magnet 36. A first protrusion 42 extends from the collar 40 away from the tubular member 12. The first protrusion 42 has a bore 44 through it which is parallel to the tubular member 12. A post 46 is rigidly mounted in parallel relation to the tubular member 12. The post 46 is positioned in

close fitting slidable relation to the bore 44. In the particular embodiment illustrated the bore 44 includes bearing means 47 packing against the post 46. Collar moving means 48, which form a portion of the magnet moving means 38, is provided for moving the collar 40 linearly along the tubular member 12. In the particular embodiment illustrated the collar moving means 48 comprises a second protrusion 50 extending from the collar 40 away from the tubular member 12 and having a threaded bore 52 through it which is parallel to the tubular member 12. A threaded shaft 54 extends through the threaded bore 52 and is in threaded relation thereto. Rotating means 56 which form a part of the moving means 48 is provided, in the embodiment illustrated, by a motor 58. It serves for rotating the threaded shaft 54.

In operation as the threaded shaft 54 is rotated the threaded bore 52 moves up or down along the threaded shaft 54 depending upon the direction of rotation. Since the threaded bore 52 is in the second protrusion 50 extending from the collar 40, and since the threaded bore 52 is parallel to the rod 18, it follows that the collar 40 is moved upwardly or downwardly in this manner. This carries the second magnetic structure 36 along with it.

The post 46 and the bore 44 in the first protrusion 42 serve for assuring that the motion of the second end portion 28 of the moveable member 24 is precisely controlled and is moved precisely up or down in Figure 1.

The first magnetic structure 32 moves along with the second magnetic structure 36 and the linearly extending moveable member 24 moves along with the first magnetic structure 32. In view of

the close fitting slidable relationship of the first magnetic structure 32 (or the portion of the moveable member 24 which holds it) to the first end portion 14 of the tubular member 12, and due to the presence of the rod 18 and the fact that the linearly extending moveable member 24 has a cavity 30 which fits in close fitting slidable relation to the rod 18, movement of a platform 60 attached to the moveable member 24 is very precisely controlled to be straight up and down. Furthermore, the threaded shaft 54 provides very precise movement of the collar 40 thereby leading to very precise positioning of the platform 60.

The embodiment of Figure 1 also provides means for rotating the platform 60 relative to an enclosure 62. The rotating means comprises a motor 64 which drives a belt 66 thereby causing the extension apparatus 10, including the motor 64 to rotate about a bearing 68. Sealing is provided by appropriate packing 70.

Another embodiment of an extension apparatus 10 ' is shown in Figure 2. The extension apparatus 10' includes a linearly extending tubular member 112 having an inner passage 72, a first end portion 114 and a second end portion 116. A first magnetic structure 132 has a first end portion 74 and a second end portion 76. The first magnetic structure 132 is within the passage 72. A linearly extending moveable member 124 has at least a portion 125 within and extending in parallel, suitably close fitting sliding relation to, the inner passage 72. The member 124 supports and has the portion 125 thereof about the first magnetic structure 132.

The moveable member 124 extends to a distal end portion 80 thereof a selected distance out of the passage 72. The distal end portion 80 of the

moveable member 124 has a threaded bore 82 therethrough which is parallel to the tubular member 112.

A threaded shaft 84 extends through the threaded bore 82 in threaded relation to it.

Rotating means 158 is provided for rotating the shaft 84 to move the first magnetic structure 132 linearly along the passage 72. In the particular embodiment illustrated the rotating means 158 includes a motor 86 and a belt and pulley arrangement 88.

A magnetically moveable second magnetic structure 90 is located about and in close fitting slidable relation to the tubular member 112 opposite the first magnetic structure 132. A linearly extending platform supporting structure 159 extends from the second magnetic structure 90 past the second end portion 116 of the tubular member 112. A platform 160 is supported by the supporting structure 159.

In operation the motor 86, via the pulley and belt arrangement 88, causes the threaded shaft 84 to rotate. Through its interaction with the threaded bore 82 this causes the moveable member 124 to move upwardly or downwardly in Figure 2. This moves the first magnetic structure 132 upwardly or downwardly since it is carried by the moveable member 124. As the first magnetic structure 132 is moved upwardly or downwardly this causes the second magnetic structure 90 to move up or downwardly with it due to the magnetic coupling. This in turn causes the supporting structure 159 to move upwardly or downwardly carrying the platform 160 upwardly or downwardly. Because of the close fit of the proximal portion 125 of the moveable member 124 within the passage 72 very precise movement results.

Also, through use of the threaded shaft 84 very careful incremental control of the raising and lowering of the platform 160 results.

In order to assure even more careful control of the positioning of the platform 160 restraining means 134 can be provided for restraining the second magnetic structure 90 to move only linearly along the tubular member 112. In accordance with the embodiment illustrated in Figure 2 the restraining means 134 comprises a protrusion 150 extending from the second magnetic structure 90 away from the tubular member 112 and having a bore 92 therethrough parallel to the tubular member 112 along with a post 146 which is rigidly mounted in parallel relation to the tubular member 112, the post 146 being positioned in close fitting slidable relation to the bore 92. The bore 92 and the post 146 may suitably have non-circular cross-sections so as to more closely control the linearity of the motion of the platform 160.

The embodiments of Figures 1 and 2 have several things in common. Each includes a linearly extending tubular member, 12 or 112, having an inner passage 72, extending longitudinally therealong. The inner passage 72, in each embodiment, is in communication with a first set of atmospheric conditions. Also, in each embodiment an outer surface 94 of the tubular member 12,112 is in communication with a second set of atmospheric conditions. For example, in Figure 1 the inner passage 72 of the tubular member 12 is in communication with an inner chamber 96 enclosed by a wall 62. The outer surface 94 of the tubular member 112 is in contact with the atmospheric conditions external of the chamber 96. In the embodiment of Figure 2 it is the inner passage 72 which is in

com unication with the enclosed chamber 196 while the outer surface 94 of the tubular member 112 is in communication with the atmosphere exterior of the chamber 196. In the embodiments of both Figures 1 and 2 there is a linearly extending moveable member 24 or 124 which extends in parallel relation to the inner passage 72 of the tubular member 12 or 112.

In both the embodiments of Figures 1 and 2 a first magnetic structure 32 or 132 fits within the inner passage 72. In both embodiments a second magnetic structure 36 or 90 is located about the tubular member 12 or 112 opposite the first magnetic structure 32 or 132. The term "magnetic structure" as used herein includes permanent magnets, ferromagnetic materials and electromagnets. It will be apparent that at least one of 32 and 36, and at least one of 90 and 132, must be a permanent magnet or an electromagnet while the other may also be such or may be merely a ferromagnetic material.

In the embodiments of Figures 1 and 2 there is magnetic moving means 38 or 138 which serves for moving either the first magnetic structure 32 or 132 or the second magnetic structure 36 or 90 longitudinally to move the other of such magnetic structures longitudinally.

In each of the embodiments of Figures 1 and 2 there is communication preventing means in the nature of the walls 62, 162, for selectively preventing communication of the first set of atmospheric conditions with the second set of atmospheric condition.

Furthermore, in each embodiment it is useful to include constraining means such as the constraining means 134 for constraining a selected one of the tubular member 12 or 112 and the

relatively moveable member 24 and 124 to move parallel to a selected other thereof. In the embodiment of Figure 1 the post 46 and bore 44 provides the necessary constraining means. In the embodiment of Figure 2 the required constraining means is provided by the bore 92 and the post 146.

Let us turn now to the embodiment of Figure 3. The embodiment of Figure 3 is substantially like that of Figure 1 with the exception that an apparatus 200 has been included for rotating an enclosed structure in the nature of the platform 260. The apparatus 200 includes a wall structure 262 which defines an interior chamber 296, the wall structure 262 having a support wall 202 having an inner side 204 facing the chamber 296 and an outer side 206 facing away from the chamber 296.

A rotatable member, namely the platform 260 (which can be the bottom of an elevator) is inside the chamber 296 and is mounted for rotation about an axis which passes through the wall 202. An inner magnetic structure 208 is mounted to the rotatable member 260, and more specifically to a rod 209 which extends from the rotatable member or platform 260. The inner magnetic structure 208 which is mounted to the rod 209 is symmetrically placed about the axis. An outer magnetic structure 211 is located outside of the chamber 296 adjacent the outer side of the wall 202. The outer magnetic structure 211 is symmetrically placed about the axis at a location opposite the inner magnetic structure 208. Rotating means 213 are provided for rotating the outer magnetic structure 211 about the axis to rotate the inner magnetic structure 208 about the same axis. In the particular embodiment illustrated the rotating means 213 includes a motor 215 along with a pulley and belt arrangement 217 and appropriate

bearings 219 and 221. Generally the rod 209 will have a non-circular cross-section and means will be provided, such as the bearings 223, to assure that when the inner magnetic structure 208 rotates the rod 209 must also rotate along with it.

The embodiment of Figure 3 provides both rotational and linear motion of the platform 260 within the chamber 296. It should be noted that there are no sliding connections between the atmosphere exterior of the chamber 296 and the atmosphere interior of the chamber 296. Thus, contamination of anything being positioned by the platform 260, for example semiconductor wafers or the like, is prevented.

Industrial Applicability

The present invention provides both an extension apparatus 10,110 and a rotating apparatus 200 for moving a member such as a platform 60,160,260 within an enclosed chamber 96,196,296. Such is particularly useful for serving as an elevator for moving cassettes which carry semiconductor wafers for processing.