Robot apparatus

0001This invention relates to a robot apparatus especially for use in integrated circuit production.

0002Figure 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.

0003Rotatable 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.

0004In 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.

0005Outer 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.

0006Vacuum 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.

0007Inner 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.

0008Outer 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.

0009This 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.

Summary of the Invention

0010It is the object of the invention to provide an apparatus especially for use in integrated circuit production, having arranged a vacuum chamber, of about a motor chamber in the manner to permit a pressure difference to exist between the chambers.

0011The apparatus of the invention comprises the features of claim 1.

0012With the specific embodiment, the robot apparatus with a motor chamber, a first set of magnets disposed in the motor chamber for movement about a common axis, a second set of magnets disposed in the motor chamber for movement about the common axis, a vacuum robot chamber arranged about the motor chamber in a manner to permit a pressure difference to exist between the chambers, a third set of magnets disposed outside the motor chamber and within the vacuum robot chamber for movement about the common axis, the third set of magnets being magnetically coupled to the first set of magnets, and a fourth set of magnets disposed outside the motor chamber and within the vacuum robot chamber for movement about the common axis, the fourth set of magnets being magnetically coupled to the second set of magnets has a drive mechanism mounted in the motor chamber, the drive mechanism having a first drive member coupled to the first set of magnets and a second drive member coupled to the second set of magnets to independently and selectively move the third and fourth sets of magnets to cause a revolving motion and/or a linear motion of a robot coupled to the third and fourth sets of magnets.

Description of the Figures

0013<dl id="dl0001"><dt>Figure 1</dt><dd>illustrates a wafer handling system 20 that allows a robot 21 to supply wafers to any of a plurality of IC processing chambers.</dd><dt>Figure 2</dt><dd>illustrates the components of a magnetic coupler utilized in a robot manufactured by Anelva.</dd><dt>Figure 3</dt><dd>illustrates an integrated circuit processing system utilizing the magnetic coupler of Figure 2.</dd><dt>Figure 4</dt><dd>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.</dd><dt>Figure 5</dt><dd>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.</dd></dl>

Description of the Preferred Embodiment

0014Figure 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.

0015Motor 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.

0016Similarly, 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.

0017Robot 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.

0018Because 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.

0019Figure 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 1008. 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.

0020To 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.

0021Further details about the design and arrangement of the robot are disclosed in EP 90 119 433.2 which is the parent application for the present application. Its content is fully incorporated into this application by reference.