Robot apparatus

Abstract: A robot apparatus comprises a robot vacuum chamber (1003) having an outer wall (1004), a top wall (1001) and a bottom wall (1002); a robot (1008) within said vacuum chamber (1003); and a support (1005, 1006, 1007) within said vacuum chamber (1003) extending from the top wall (1001) to the bottom wall (1002), whereby when a vacuum is produced within said vacuum chamber (1003), said support (1005, 1006, 1007) significantly reduces vertical displacement of said top and bottom walls (1001, 1002) by ambient pressure.

Description: This invention relates to a robot apparatus especially for use in integrated circuit production. Figure 1 illustrates an existing wafer handling system 20 that allows a robot 21 to supply wafers to any of a plurality of IC processing chambers. Robot 21 includes an extensible arm 28 that can extend a wafer blade 29 radially into any of chambers 23-27. Arm 28 is mounted on a rotatable table 210 that enables the extensible arm to be directed at any selected one of chambers 23-27. A vacuum is maintained in chamber 211 containing the robot so that the chambers 24-27 and 211 can be carefully cleaned and purged before wafers are introduced for processing. This system enables wafers 22 to be exchanged between a wafer cassette elevator 23 and any of the chambers 24-27 without breaking vacuum in these chambers. Rotatable table 210 and robot 21 are each coupled to motors exterior to chamber 211 to prevent wafers from being contaminated by operation of such motors. These motors are typically in an atmospheric environment, so rotary seals are required to separate chamber 211 from the environment in which the motors are contained. These seals enable the motor shafts to extend between the motor and robot chambers while preserving the pressure difference between these chambers. In a robot system manufactured by Anelva, these rotary seals are replaced by a magnetic coupler 30 illustrated in Figure 2. Coupler 30 consists of an outer assembly 31, a vacuum assembly 38 and an inner assembly 313. Outer assembly 31 includes a cylindrical casing 32, a bottom cap 33 and a top cap 34. Casing 32 encloses a chamber 35 and has attached to its inner wall a set of six bar magnets 36 polarized in the radial direction of casing 32. Bottom cap 33 includes a ball bearing ring 37 into which can be fitted vacuum assembly 38. Vacuum assembly 38 includes a flange 39 and a cylindrical shell 310 enclosing an inner cavity 311. In an integrated circuit processing system using a robot such as that shown in Figure 1, wall 40 (see Figure 3) between chamber 41 containing motor 42 and chamber 211 containing the robot contains a hole of diameter slightly larger than the outer diameter of cylindrical shell 310. A vacuum ring 43 (see Figure 3) is slipped over cylindrical shell 310 which is then inserted through this hole in the wall and attached to the wall by flange bolts through range 39 with sufficient pressure against the vacuum ring to maintain the pressure difference between the motor and robot chambers. Inner assembly 313 includes a ferrite inner pole section 314 having a set of six poles 315. On one end of section 314 is a ball bearing ring 316 and on the other end is a shaft 317 over which is slipped a ball bearing ring 318. When this inner assembly is inserted into inner cavity 311, ball bearing rings 316 and 318 cooperate to center shaft 317 and inner pole section 314 within cavity 311 and to enable inner pole section 314 and shaft 317 to rotate easy within this cavity. Shaft 317 is then connected to the robot to activate various operations of that robot. Outer assembly 31 is slipped over shell 310 until shell 310 fits into ball bearing ring 37. Ball bearing rings 37, 316 and 318 enable both inner assembly 313 and outer assembly 31 to rotate relative to vacuum assembly 38. A motor is connected to outer assembly 31 to controllably rotate that assembly relative to the vacuum assembly. Pole magnets 36 within outer assembly 36 each magnetically couple to an associated pole 315 of ferrite inner pole section 314 so that the inner assembly rotates with the outer assembly. This magnetic coupler enables elimination of the rotary seals, but exhibits several deficiencies. In particular, the structure of the coupling should be such that the vertical position of the robot does not vary when a vacuum is established in the robot chamber. Such variation could produce misalignment of a robot blade with a wafer in a chamber external to chamber 211. In EP-A-0 160 305 a device is disclosed comprising a first arm rotatably attached at one end thereof to a support base, a second arm rotatably attached to the other end of the first arm. The only function of the support base of such a device is to carry the arms. The problem described concerning the effects of the vacuum, however, is not solved by the device of EP-A-0 160 305. Summary of the Invention It is the object of the invention to provide an apparatus especially for use in integrated circuit production, having arranged a robot within a vacuum chamber, the positions of said robot being maintained unchanged within that chamber upon application of a vacuum. The apparatus of the invention comprises the features of claim 1. With the specific embodiment, the motor chamber extends upward into the robot chamber so that the magnets that are attached directly to a motor are inside of the portion of the magnetic coupling that is within the robot chamber. This enables the side wall of the motor chamber to extend entirely through the robot chamber and provide support to both the top and bottom walls of the robot chamber. The utility of this can be understood by reference to Figure 3. Figure 3 illustrates a problem that occurs in a robot system, in which the drive motor 42 directly attaches to magnets that are outside of the inner pole section 314 that is attached directly to robot 44. In this illustrated embodiment, inner pole section 314 couples to a robot 44 having a wafer blade 45 that is to controllably extend through a wafer exchange slot 46 in sidewall 47 of robot chamber 211 to transfer wafers into and out of chamber 21 1. When a vacuum is created in chamber 211 this bows wall 40 inward producing a vertical displacement of blade 45 upward relative to wafers in other chambers of a wafer handling systems such as shown in Figure 1. Because outer assembly 31, which is directly attached to motor 42, is at a greater distance from the motor rotation axes than is inner pole section 314, which is attached directly to robot 44, this outer assembly 31 cannot be extended upward through chamber 211 without interfering with the operation of robot 44. However, if motor chamber 41 extended upward into the robot chamber and the power coupled from inside the motor chamber outward across the sidewall of the motor chamber into the robot chamber (instead of from outside inward as in Figure 3), then the motor chamber sidewall could extend from the bottom wall of the robot chamber to the top wall of robot chamber. For such a configuration, when a vacuum is produced in the robot chamber, the sidewall of the motor chamber prevents the bottom wall of the robot chamber from bowing upward and displacing the robot vertically relative to wafers in other chambers of the wafer handling system. Also, the motor chamber is accessible from above, thereby simplifying repair or replacement of parts within the motor chamber. Description of the Figures Figure 1 illustrates a wafer handling system 20 that allows a robot 21 to supply wafers to any of a plurality of IC processing chambers. Figure 2 illustrates the components of a magnetic coupler utilized in a robot manufactured by Anelva. Figure 3 illustrates an integrated circuit processing system utilizing the magnetic coupler of Figure 2. Figure 4 illustrates a magnetic coupler for magnetically coupling rotational motion from one or more motors in a motor chamber into another chamber surrounding the motor chamber. Figure 5 illustrates an alternate embodiment in which additional support is provided between the top and bottom walls of a robot vacuum chamber to substantially eliminate vertical displacement of a robot when vacuum is produced within this chamber. Description of the Preferred Embodiment Figure 4 illustrates a magnetic coupler suitable for magnetically coupling one or more motors 51 and 52 from a cylindrical motor chamber 53 into a second chamber 54 that radially encircles the cylindrical motor chamber 53. A sidewall 55 defines the radial extent of motor chamber 53 and enables a pressure difference to exist between chambers 53 and 54. Chamber 54 is a robot vacuum chamber in which is contained a robot that is to transfer wafers to and from a set of reaction chambers disposed circumferentially around the robot. Selection of one of these chambers for wafer transfer is achieved by rotation of the robot. Transfer of a wafer into or out of the selected chamber is achieved by linear, radial extension of a robot arm into and out of the selected chamber. Motor 51 is coupled to a reduction gear 513 to reduce the rotation speed of a typical motor to a rotation of gear output shaft 514 more appropriate for providing power to the robot. Reduction gear output shaft 514 is attached to a magnet clamp 515 that presses against a bearing 516 and that holds a set of sixteen magnets 517, each of which is closely space from sidewall 55. Similarly, motor 52 is connected through a reduction gear 518 and a gear output shaft 519 to a magnet clamp 520 that presses against a bearing 521 and that holds a set of sixteen magnets 522. Bolted to this magnet clamp above and below the magnets are a pair of magnet retainer rings that prevent vertical motion of these magnets. Robot vacuum chamber 54 is enclosed by cylindrical inner wall 55, top wall 523 and bottom wall 524 continuing in an outer wall (not shown). A vacuum seal of chamber 54 is created by vacuum rings 525 and 526. Within robot chamber 54 are a set of sixteen magnets 527 retained within the plane of the magnets by a magnet clamp 528 that is similar to clamps 515 and 520, except that the fingers extend radially inward. Magnet retainer rings above and below the magnets are bolted to clamp 528 to retain these magnets vertically. A similar set of magnet clamp 529 and retainer rings 30 hold a set of 16 magnets 530. A set of bearings 531 - 534 enable clamps 528 and 529 to rotate about motor axis A. Because side wall 55 extends between top wall 523 and bottom wall 524, when a vacuum is produced within chamber 54, there is no vertical displacement of robot blade 45 (Fig. 3) with respect to wafer rest positions within external chambers, thereby maintaining alignment of wafer blade 86 with wafers external to the robot vacuum chamber for any range of internal pressures within cavity 54. Figure 5 illustrates an alternate embodiment of providing additional support between a top wall 1001 and a bottom wall 1002 of the robot chamber 1003. This "additional" support is in addition to support by sidewall 1004. In this embodiment, the additional support is provided by a rotatable shaft 1005. In this embodiment, the robot consists of motor 1010, thrust bearings 1006 and 1007, and wafer blade. This robot has the single degree of freedom to rotate a wafer 1009 to any selected angular position about shaft 1005. Thrust bearings 1006 and 1007 enable shaft 1005 to rotate even though shaft 1005 is compressed by a force equal to twice the atmospheric pressure on top wall 1001. In an alternate of this embodiment, motor 1010 is anchored to bottom wall 1002 by support 1011 and thrust bearing 1007 is located within motor 1010. To dampen oscillations in the robot during rotation or blade extension, wall 55 should be selected to be conductive so that eddy currents therein are produced to damp such oscillations. This wall can be coated with a conductive coating to enhance these eddy currents, but preferably wall 55 is of a conductive material such as aluminum so that bulk eddy currents can be generated. Further details about the design and arrangement of the robot are disclosed in EP-A-0423608 which is the parent application for the present application.

Claims: A robot apparatus comprising: a robot vacuum chamber (54, 1003) having an outer wall (1104), a top wall (523, 1001) and a bottom wall (524, 1002); a robot (80, 1008) within said vacuum chamber (54, 1003); and a support (55, 1005, 1006, 1007) within said vacuum chamber characterized in that said support (55, 1005, 1006, 1007) within said vacuum chamber (54, 1003) is extending from the top wall (523, 1001) to the bottom wall (524, 1002), whereby when a vacuum is produced within said vacuum chamber (54, 1003), said support (55, 1005, 1006, 1007) significantly reduces vertical displacement of said top and bottom walls (523, 1001; 534, 1002) by ambient pressure; and said robot (80, 1008) is attached to said support (1005, 1006); A robot apparatus according to claim 1, wherein said support comprises a cylindrical wall (55) extending between the top and bottom walls (523, 524) of the vacuum chamber. A robot apparatus according to claim 2, wherein said cylindrical wall (55) is a wall enclosing a motor chamber (53) of the robot (80). A robot apparatus according to claim 1, wherein said support comprises a rotatable shaft (1005) and a thrust bearing (1006, 1007) between an end of said shaft (1005) an the top or bottom wall (1001, 1002) of said vacuum chamber (1003). A robot apparatus according to claim 4, wherein a motor (1010) driving said shaft is anchored to said top or bottom wall and said thrust bearing (1007) is located within said motor (1010).

Inventors: LOWRANCE ROBERT B, LOWRANCE, ROBERT B.
Applicants: APPLIED MATERIALS INC, APPLIED MATERIALS, INC.
Application year: 1990
Main classification: B25J21
IPC codes: B25J21, H01L21, B25J9, F16D7, F16H49, B25J19