Dual arm vacuum robot with common drive pulley

A robot for use in semiconductor vacuum chambers is disclosed. The robot may include two independently-driven arms configured for wafer handling. The robot may include three motors or drive systems and a tri-axial seal to realize independent extension/retraction of each arm and overall simultaneous rotation of the arm assembly. The robot may provide enhanced throughput efficiency over other robot designs.

BACKGROUND

Different types of tools are used to perform hundreds of processing operations during semiconductor device fabrication. Most of these operations are performed in process chambers at very low pressure, i.e., in a vacuum or partial vacuum. Such process chambers may be arranged about a central hub, and the hub and process chambers may be kept at substantially the same very low pressure. Wafers may be introduced to the process chambers by wafer handling systems that are mechanically coupled to the process chambers and/or central hub. The wafer handling systems transfer wafers from the factory floor to the process chamber. The wafer handling systems may include loadlocks to bring the wafers from atmospheric conditions to very low pressure conditions and back, and robots to transfer the wafers to various positions. Wafer handling systems may utilize robots that operate outside of the vacuum environment, e.g., robots that operate in the ambient factory floor environment, and robots that operate within the very low pressure environment of the process chambers. Throughput—the number of wafers that is processed in a period of time—is affected by the process time, the number of wafers that are processed at a time, as well as timing of the steps to introduce the wafers into the vacuum process chambers.

SUMMARY

In some implementations, a wafer-transport robot for use in semiconductor fabrication apparatus vacuum chambers may be provided. The robot may include a first arm, the first arm including a first end effector interface at one end, a second arm, the second arm including a second end effector interface at one end, and a base. The base may include a first motor, a second motor, and a third motor. The base may have a central axis. Activation of the first motor without activation of the second motor or the third motor may cause the first arm to translate the first end effector interface in a direction perpendicular to the central axis without rotation of the first end effector interface about the central axis. Activation of the second motor without activation of the first motor or the third motor may cause the second arm to translate the second end effector interface in a direction perpendicular to the central axis without rotation of the second end effector interface about the central axis. Activation of the first motor, the second motor, and the third motor simultaneously may cause the first end effector interface and the second end effector interface to rotate about the central axis without translation of the first end effector interface and the second end effector interface in directions perpendicular to the central axis.

In some further implementations of the robot, activation of the first motor without activation of the second motor or the third motor may not cause the second arm to move, and activation of the second motor without activation of the first motor or the third motor may not cause the first arm to move.

In some further implementations of the robot, the first arm may include a first mechanical input including a first primary rotational input and a first secondary rotational input. The first primary rotational input and the first secondary rotational input may both be configured to rotate substantially about the central axis. Rotation of the first primary rotational input relative to the first secondary rotational input in a first rotational direction may cause the first end effector interface to translate in a first direction perpendicular to the central axis, and rotation of the first primary rotational input and the first secondary rotational input both in the same rotational direction may cause the first end effector interface to rotate about the central axis without translating in a direction perpendicular to the central axis. The second arm may include a second mechanical input including a second primary rotational input and a second secondary rotational input. The second primary rotational input and the second secondary rotational input may both be configured to rotate substantially about the central axis. Rotation of the second primary rotational input relative to the second secondary rotational input in a second rotational direction may cause the second end effector interface to translate in a second direction perpendicular to the central axis, and rotation of the second primary rotational input and the second secondary rotational input both in the same rotational direction may cause the second end effector interface to rotate about the central axis without translating in a direction perpendicular to the central axis.

In some such implementations of the robot, the first secondary rotational input and the second secondary rotational input may be rotationally coupled and may not rotate independently.

In some implementations of the robot, the first primary rotational input may be rotationally coupled with the first motor, the second primary rotational input may be rotationally coupled with the second motor, and the first secondary rotational input and the second secondary rotational input may both be rotationally coupled with the third motor.

In some implementations of the robot, the base may further include a fourth motor, the fourth motor configured to translate the first arm and the second arm in a direction parallel to the central axis.

In some implementations of the robot, the first arm may include a first upper arm with a proximal end and a distal end opposite the proximal end of the first upper arm and a first lower arm with a proximal end and a distal end opposite the proximal end of the first lower arm. Similarly, the second arm may include a second upper arm with a proximal end and a distal end opposite the proximal end of the second upper arm and a second lower arm with a proximal end and a distal end opposite the proximal end of the second lower arm. The proximal ends of the first upper arm and the second upper arm may both be configured to rotate substantially about the central axis, the proximal end of the first lower arm may be rotatably connected with the distal end of the first upper arm, the proximal end of the second lower arm may be rotatably connected with the distal end of the second upper arm, the first end effector interface may be rotatably connected with the distal end of the first lower arm, and the second end effector interface may be rotatably connected with the distal end of the second lower arm.

In some implementations of the robot, the robot may also include a first lower arm driven pulley fixedly connected with the proximal end of the first lower arm, a second lower arm driven pulley fixedly connected with the proximal end of the second lower arm, a common drive pulley, a first upper arm drive belt rotationally coupling the first lower arm driven pulley with the common drive pulley, and a second upper arm drive belt rotationally coupling the second lower arm driven pulley with the common drive pulley.

In some implementations, the robot may further include a first upper arm drive pulley fixedly connected with the first upper arm, a second upper arm drive pulley fixedly connected with the second upper arm, a first end effector driven pulley fixedly connected with the first end effector interface, a second end effector driven pulley fixedly connected with the second end effector interface, a first lower arm drive belt rotationally coupling the first end effector driven pulley with the first upper arm drive pulley, and a second lower arm drive belt rotationally coupling the second end effector driven pulley with the second upper arm drive pulley.

In some further implementations of the robot, the robot may further include a controller including one or more processors and one or more memories and configured to control the first motor, the second motor, and the third motor. The one or more memories may store computer-executable instructions for controlling the one or more processors to activate the first motor without activating the second motor or the third motor to cause the first arm to extend the first end effector interface in a first radial direction perpendicular to the central axis without causing rotation of the first end effector interface about the central axis, activate the second motor without activating the first motor or the third motor to cause the second arm to extend the second end effector interface in a second radial direction perpendicular to the central axis without causing rotation of the second end effector interface about the central axis, and activate the first motor, the second motor, and the third motor simultaneously to cause the first end effector interface and the second end effector interface to rotate about the central axis without causing translation of the first end effector interface and the second end effector interface in directions perpendicular to the central axis.

In some further implementations of the robot, the first end effector interface and the second end effector interface may be oriented in opposing directions, and the computer executable instructions for controlling the one or more processors include instructions for controlling the one or more processors to activate the first motor without activating the second motor or the third motor by causing the first motor to provide a rotational output in a first rotational direction about a first axis substantially parallel to the central axis, activate the second motor without activating the first motor or the third motor by causing the second motor to provide a rotational output in the first rotational direction about a second axis substantially parallel to the central axis, and activate the first motor, the second motor, and the third motor by causing the first motor, the second motor and the third motor to rotate in the same rotational direction simultaneously to cause the first end effector interface and the second end effector interface to rotate about the central axis without causing translation of the first end effector interface and the second end effector interface in directions perpendicular to the central axis.

In some such further implementations of the robot, the first end effector interface and the second end effector interface may be substantially co-planar with one another.

In some other further implementations of the robot, the first end effector interface and the second end effector interface are oriented in the same direction, and the computer executable instructions for controlling the one or more processors include instructions for controlling the one or more processors to activate the first motor without activating the second motor or the third motor to extend the first arm by causing the first motor to provide a rotational output in a first rotational direction about a first axis substantially parallel to the central axis, activate the second motor without activating the first motor or the third motor to extend the second arm by causing the second motor to provide a rotational output in a second rotational direction about a second axis substantially parallel to the central axis, the second rotational direction opposite the first rotational direction, and activate the first motor, the second motor, and the third motor by causing the first motor, the second motor and the third motor to rotate in the same rotational direction simultaneously to cause the first end effector interface and the second end effector interface to rotate about the central axis without causing translation of the first end effector interface and the second end effector interface in directions perpendicular to the central axis.

In some such further implementations of the robot, the first end effector interface and the second end effector interface may be located on spaced-apart parallel planes and are configured to have substantially the same range of radial motion.

In some implementations of the robot, the robot may further include a first end effector and a second end effector. The first end effector may be affixed to the first end effector interface, and the second end effector may be affixed to the second end effector interface.

In some implementations of the robot, the first motor, the second motor, and the third motor may each have an axis of rotation and the axes of rotation of the first motor, the second motor, and the third motor may be substantially coaxial with the central axis. In some other implementations of the robot, the first motor, the second motor, and the third motor may each have an axis of rotation and at least one of the axes of rotation of the first motor, the second motor, and the third motor may be offset from the central axis.

In some further implementations of the robot, the common drive pulley may have a common drive pulley diameter, the first lower arm driven pulley and the second lower arm driven pulley may both have a lower arm driven pulley diameter, and the common drive pulley diameter and the lower arm driven pulley diameter may have a ratio to one another of 2:1, respectively.

In some further implementations of the robot, the first upper arm drive pulley and the second upper arm drive pulley may both have an upper arm drive pulley diameter, the first end effector driven pulley and the second end effector driven pulley may both have an end effector driven pulley diameter, and the upper arm drive pulley diameter and the end effector driven pulley diameter may have a ratio to one another of 1:2, respectively.

In some implementations, a wafer-transport robot for use in semiconductor fabrication apparatus vacuum chambers may be provided. The robot may include a first arm with a first end effector interface, a second arm with a second end effector interface, and a base. The first arm and the second arm may each be rotatable with respect to the base about a common axis. The first arm may be configured to translate the first end effector interface in a first direction perpendicular to the common axis without translating or rotating the second end effector interface, the second arm may be configured to translate the second end effector interface in a second direction perpendicular to the common axis without translating or rotating the first end effector interface, and the first arm and the second arm may be configured to rotate the first end effector interface and the second end effector interface about the common axis simultaneously without translating the first end effector interface and the second end effector interface in the first direction and the second direction, respectively.

DETAILED DESCRIPTION

Examples of various embodiments are illustrated in the accompanying drawings and described further below. It will be understood that the discussion herein is not intended to limit the claims to the specific embodiments described. On the contrary, it is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The present invention may be practiced without some or all of these specific details. In other instances, well-known process operations have not been described in detail in order not to unnecessarily obscure the present invention.

FIG. 1Ashows an isometric view of a robot100for use in very low pressure environments such as semiconductor fabrication process chamber environments. The robot100features an A arm137and a B arm138. The A arm137and the B arm138may each be configured with end effector A180and end effector B190, respectively, suitable for lifting and transporting semiconductor wafers from station to station. In some implementations, the end effector A180and the end effector B190may be removably connected to end effector interfaces that are part of the A arm137and the B arm138, respectively. The A arm137and the B arm138face in opposing directions in robot100, although other configurations of arms may be used as well. For example, A arm137and B arm138may face in the same direction and be stacked on top of each other.FIG. 1Bshows the robot100shown inFIG. 1A, but with various cover panels on portions of the A arm137and the B arm138removed to allow some of the inner workings of the arms to be seen.

FIG. 1Cshows an isometric exploded view of the robot100. Some of the structures shown inFIG. 1Cmay be shown in simplified form to avoid visual clutter that is not needed to understand the concepts disclosed herein. As withFIG. 1B, various cover panels have been omitted to allow for clearer viewing of other parts. The robot100may include a base101, sometimes referred to as a base unit, and an arm assembly130. Two alternate implementations of a base unit101are shown, although both may include a base plate102that may be used to mount the robot100within a semiconductor process chamber, central hub, or tool. A support structure103may be rigidly connected with the base plate102and may be used to provide support to the arm assembly130, as well as other components within the base101.

The support structure103may, for example, be rigidly connected with rails (not shown) along face105, that may allow for z-axis, e.g., vertical, movement of a motor support106. The motor support106may include glides or other hardware that may be slidably engaged with the rails and that may prevent the motor support106from moving in directions other than along the z-axis. The motor support106may be moved in the z-axis direction by a z-axis drive104. The z-axis drive104may be, for example, a linear drive assembly using a lead screw driven by a rotational motor.

The motor support106may support an A drive motor107, a B drive motor108, and a common drive motor109. The A drive motor107, the B drive motor108, and the common drive motor109may be similar motors, or may be different motors. For example, the B drive motor108may be a stepper motor that can supply 10 N-m of continuous torque and 30 N-m peak torque. The A drive motor107and common drive motor109may both, for example, be capable of supplying 5 N-m of continuous torque and 15 N-m of peak torque. In some implementations, motors with torque capabilities of approximately 50% of those discussed in the above example may be used, although such implementations may not be capable of supporting as many different sizes or types of arms as the example motor set may support.

The base unit101may also include an A drive shaft110, a B drive shaft111, and a common drive shaft112. The A drive shaft110may be rotationally driven by the A drive motor107. The B drive shaft111may be rotationally driven by the B drive motor108. The common drive shaft112may be rotationally driven by the common drive motor109. The A drive shaft110, the B drive shaft111, and the common drive shaft112may be coaxially arranged and may all rotate about substantially the same axis. The A drive shaft110, the B drive shaft111, and the common drive shaft112may all pass through a tri-axial ferro-fluidic seal116, such as those supplied by Ferrotec Corp., and an accompanying bellows coupling. The tri-axial ferro-fluidic seal116may allow for three independently driven shafts to be passed through the seal without loss of seal integrity (“tri-axial” does not refer to three orthogonal axes in this case, but to three coaxial axes). This allows the majority of the base101to be operated in an environment different from the very low pressure environments observed in the hub or the semiconductor process chambers and within which the arm assembly130will function. A base cover115may be attached to the base101to prevent damage to the internal components of the base101. While a ferro-fluidic seal is used in this implementation, other types of seals may be used in place of, or in addition to, a ferro-fluidic seal, such as magnetic couplings or friction seals.

As noted above, two alternative base unit arrangements are shown inFIG. 1C. The right-hand base unit101depicts a drive system where the A drive motor107, the B drive motor108, the common drive motor109, the A drive shaft110, the B drive shaft111, and the common drive shaft112are all coaxial with each other. In such an arrangement, the drive shafts may each be directly coupled to their respective drive motors.

The left-hand base unit101depicts a drive system where the A drive motor107, the B drive motor108, and the common drive motor109are not coaxial with each other, the A drive shaft110, the B drive shaft111, or the common drive shaft. In such an arrangement, the drive motors may be coupled to their respective drive shafts via belts, such as belts134.

The arm assembly130may include an A arm137and a B arm138. The A arm137and the B arm138may operate in a similar manner and utilize many common components, although the two arms may differ slightly in construction to allow for operating clearances and particular arm assembly configurations.

The A arm137may include an upper A arm140and a lower A arm160with and an end effector A180attached (or attachable) thereto. The B arm138may include an upper B arm150and a lower B arm170with an end effector B190attached (or attachable) thereto. The end effector A180and the end effector B190can be any type of end effectors including paddles, forks, grippers, and the like. In some implementations, the robot100may be provided to a customer without end effectors, but with end effector interfaces that can accept one or more types of end effectors, thereby allowing the customer to customize the robot for a particular application or process.

One end of the upper A arm140may be rigidly coupled with the A drive shaft110such that when the A drive shaft110is rotated by the A drive motor107, the upper A arm140rotates with respect to the base101about the rotational axis of the A drive shaft110. For example, a plate with an A drive shaft hole pattern142may be bolted to the A drive shaft110and joined via an upper A arm bellows coupling146to a load transfer plate147that is bolted to the upper A arm140that allows for a substantially rigid rotational coupling between the A drive shaft110and the upper A arm140while still allowing for minor axial misalignments during assembly. The other end of the upper A arm140may be rotationally coupled with one end of the lower A arm160. The other end of the lower A arm160may, in turn, be rotationally coupled with the end effector A180.

Similarly, one end of the upper B arm150may be rigidly coupled with the B drive shaft111such that when the B drive shaft111is rotated by the B drive motor108, the upper B arm150rotates with respect to the base101about the rotational axis of the B drive shaft111. For example, the upper B arm150may be bolted to the B drive shaft via B drive shaft hole pattern152. The other end of the upper B arm150may be rotationally coupled with one end of the lower B arm170. The other end of the lower B arm170may, in turn, be rotationally coupled with the end effector B190.

The upper A arm140and the upper B arm150may also be rotationally coupled with each other via an upper arm bearing153. The rotational axis of the upper arm bearing153may be substantially coaxial with the rotational axes of the A drive shaft110and the B drive shaft111.

The upper A arm140and the upper B arm150may both rotate about a common drive pulley assembly131, that may be housed between a first recess in the upper A arm140and a similar first recess in the upper B arm150. The common drive pulley assembly131may rotate about an axis substantially coaxial with the rotational axes of the A drive shaft and the B drive shaft with respect to the upper A arm140and the upper B arm150. The common drive pulley assembly may include a common drive plate136with a common drive shaft hole pattern135. The common drive shaft hole pattern135may be configured to allow the common drive plate136to be rigidly connected with the common drive shaft112such that rotation of the common drive shaft112causes the common drive pulley assembly131to rotate about the rotational axis of the common drive shaft112.

The common drive pulley assembly131may also include a common drive pulley A132and a common drive pulley B133, which may be rigidly connected with the common drive plate136.

The lower A arm160may include a lower A arm driven pulley162, that, when the lower A arm160is rotatably connected with the upper A arm140, may protrude into a second recess in the upper A arm140. The lower A arm driven pulley162may be rigidly connected with the lower A arm160. The diameter of the lower A arm driven pulley162may be one half the diameter of the common drive pulley A132. An upper A arm drive belt141may be stretched over both the lower A arm driven pulley162and the common drive pulley A132. The upper A arm drive belt141may be made from steel or some other material with a relatively high tensile elasticity, such as 301 high-yield stainless steel. Various belt tensioning systems may be employed to help eliminate rotational slop between the common drive pulley A132and the lower A arm driven pulley162. A pair of channels connecting the first recess and the second recess of the upper A arm140may allow the upper A arm drive belt141to span between the common drive pulley A132and the lower A arm driven pulley162.

When the upper A arm140is rotated through an angle X with respect to the common drive pulley assembly131and, consequently, the common drive pulley A132, this causes the upper A arm drive belt to circulate within the first recess and the second recess of the upper A arm140, as well as within the channels connecting those recesses, and also causes the lower A arm driven pulley162to be rotated with respect to the upper A arm140. Due to the 2:1 diameter ratio between the common drive pulley A132and the lower A arm driven pulley162in this example, the lower A arm driven pulley162, as well as the lower A arm160rigidly connected with the lower A arm driven pulley162, may be rotated through an angle of 2X and in the opposite direction of the rotation of the upper A arm140by the movement of the upper A arm drive belt141.

The end effector A180, as mentioned above, may be rotationally coupled with the end of the lower A arm160opposite the end of the lower A arm160featuring the lower A arm driven pulley162. The end effector A180may include an end effector A driven pulley181that is rigidly connected with the end effector A180, i.e., rotation of the end effector A driven pulley181with respect to the lower A arm160causes the end effector A180to rotate with respect to the lower A arm160as well. A lower A arm drive belt161may be stretched over the end effector A driven pulley181and an upper A arm drive pulley145. The upper A arm drive pulley145may be rigidly connected with the upper A arm140, and may be approximately one half the diameter of the end effector A driven pulley181. The lower A arm drive belt161may be made from material similar to that used for the upper A arm drive belt141.

When the lower A arm160is rotated through an angle Y with respect to the upper A arm140, which consequently causes the upper A arm drive pulley145to rotate with respect to the lower A arm160, this causes the lower A arm drive belt161to circulate within the lower A arm160and also causes the end effector A driven pulley181to be rotated with respect to the lower A arm160through, in this example, an angle of ½ Y and in the opposite direction of the rotation of the lower A arm160.

Because the end effector A180, the lower A arm160, and the upper A arm140may all be kinematically linked with each other by the various pulleys and belts described above, rotating the upper A arm140through an angle X with respect to common drive pulley A132may cause the lower A arm160to rotate through an angle of −2X with respect to the upper A arm140, and to cause the end effector A180to rotate through an angle of X with respect to lower A arm160. For example, if the upper A arm140is rotated by 30° CW, the lower A arm160would rotate 60° CCW with respect to the upper A arm140, and the end effector A180would rotate 30° CW with respect to the lower A arm160, which results in a net rotation of 0° of the end effector A180in absolute terms. This may result in the end effector A180translating in a linear direction with respect to the axis of rotation of the upper A arm140but with no rotation of the end effector A180about the axis of rotation of the upper A arm140.

The B arm138is constructed in a manner very similar to the manner in which the A arm137is constructed, although with some differences. The lower B arm170may include a lower B arm driven pulley172, that, when the lower B arm170is rotatably connected with the upper B arm150, may protrude into a second recess in the upper B arm150. The lower B arm driven pulley172may be rigidly connected with the lower B arm170via a spacer173, which may offset the lower B arm170from the upper B arm150sufficiently far enough to cause the lower B arm170and the lower A arm160to be co-planar. The diameter of the lower B arm driven pulley172may be one half the diameter of the common drive pulley B133. An upper B arm drive belt151may be stretched over both the lower B arm driven pulley172and the common drive pulley B133. The upper B arm drive belt151may be made from material similar to that used for the upper A arm drive belt141. A pair of channels connecting the first recess and the second recess of the upper B arm150may allow the upper B arm drive belt151to span between the common drive pulley B133and the lower B arm driven pulley172.

When the upper B arm150is rotated through an angle X with respect to the common drive pulley assembly131and, consequently, the common drive pulley B133, this causes the upper B arm drive belt to circulate within the first recess and the second recess of the upper B arm150, as well as within the channels connecting those recesses, and also causes the lower B arm driven pulley172to be rotated with respect to the upper B arm150. Due to the 2:1 diameter ratio between the common drive pulley B133and the lower B arm driven pulley172in this example, the lower B arm driven pulley172, as well as the lower B arm170rigidly connected with the lower B arm driven pulley172, may be rotated through an angle of 2X and in the opposite direction of the rotation of the upper B arm150by the movement of the upper B arm drive belt151.

The end effector B190, as mentioned above, may be rotationally coupled with the end of the lower B arm170opposite the end of the lower B arm170featuring the lower B arm driven pulley172. The end effector B190may include an end effector B driven pulley191that is rigidly connected with the end effector B190, i.e., rotation of the end effector B driven pulley with respect to the lower B arm170causes the end effector B190to rotate with respect to the lower B arm170as well. A lower B arm drive belt171may be stretched over the end effector B driven pulley191and an upper B arm drive pulley155. The upper B arm drive pulley155may be rigidly connected with the upper B arm150, and may be approximately one half the diameter of the end effector B driven pulley191.

When the lower B arm170is rotated through an angle Y with respect to the upper B arm150, which consequently causes the upper B arm drive pulley155to rotate with respect to the lower B arm170, this may cause the lower B arm drive belt171to circulate within the lower B arm170and may also cause the end effector B driven pulley191to be rotated with respect to the lower B arm170through, in this example, an angle of ½ Y and in the opposite direction of the rotation of the lower B arm170.

Because the end effector B190, the lower B arm170, and the upper B arm150may all be kinematically linked with each other by the various pulleys and belts described above, rotating the upper B arm150through an angle X with respect to common drive pulley B133may cause the lower B arm170to rotate through an angle of −2X with respect to the upper B arm150, and to cause the end effector B190to rotate through an angle of X with respect to lower B arm170. For example, if the upper B arm150is rotated by 30° CW, the lower B arm170would rotate 60° CCW with respect to the upper B arm150, and the end effector B190would rotate 30° CW with respect to the lower B arm170, which results in a net rotation of 0° of the end effector B190in absolute terms. This may result in the end effector B190translating in a linear direction with respect to the axis of rotation of the upper B arm150but with no rotation of the end effector B190about the axis of rotation of the upper B arm150

FIGS. 1D through 1Fdepict trimetric views of a partial cutaway of the robot100. To allow for easier viewing, the robot100is shown with the arm assembly130at full extension, although such a configuration of the arm assembly130may not be possible in actual operation due to limits on belt travel within the arms or due to motion-limiting hard stops. Upper A arm140, upper B arm150, lower A arm160, lower B arm170, end effector A180, and end effector B190are all shown with one half of their respective portions cut away to allow for enhanced viewing of the interior components.FIG. 1Dshows the entire robot100,FIG. 1Efocuses on A arm137, andFIG. 1Ffocuses on B arm138. Various components discussed above are indicated inFIGS. 1D through 1F.

The various components of the robot100shown inFIGS. 1A through 1Jmay be made from a variety of different materials that may be selected according to various requirements. The A arm137and B arm138may, for example, be made primarily of aluminum. Various bearing surfaces within robot100may, for example, be made from stainless steel. Other materials may be used as needed, although materials may, in general, be selected to be largely inert with respect to process gases.

FIG. 1Gdepicts a top view of the robot100in an “at-rest” position.FIG. 1Hdepicts the robot100with the upper A arm140rotated approximately 32° from the position the upper A arm is in inFIG. 1G, which causes the end effector A180to be extended away from the center of the robot100. The configuration shown inFIG. 1Hmay be achieved by rotating the A drive motor107approximately 32° counter-clockwise from the position the A drive motor107is in, and by keeping the B drive motor108and the common drive motor109stationary, with respect to the positions those drive motors are in inFIG. 1G.

FIG. 1Idepicts a top view of the robot100with both upper A arm140and upper B arm150rotated approximately 32° counter-clockwise from the position each arm is in inFIG. 1G, which causes the end effector A180and the end effector B190to extend away from the center of the arm assembly130. While the A drive motor107and the B drive motor108may both be rotated by 32° with respect to the positions those motors are in inFIG. 1G, the common drive motor109may remain stationary with respect to the position it is inFIG. 1G.

While the above discussion has focused on rotational movement of the upper arms which causes the end effectors to translate in a direction perpendicular to the axis of rotation of the upper arms, the upper arms may also be rotated to cause the end effectors to rotate about the upper arm rotational axes without translation, i.e., the entire arm assembly130may be rotated about the rotational axes of the upper arms without any movement of the arms with respect to each other.

Such rotational movement of the arm assembly may be achieved by rotating the upper A arm140, the upper B arm150, and the common drive pulley assembly131in the same direction and at the same angular rate. Since the rotational movements of the lower A arm160with respect to the upper A arm140and the end effector A180with respect to the lower A arm160are both driven by relative rotational movement of the upper A arm140with respect to the common drive pulley A132, rotating the common drive pulley assembly131at the same rotational rate as the upper A arm140results in the lower A arm160staying fixed with respect to the upper A arm140and the end effector A180staying fixed with respect to the lower A arm160while the entire A arm137rotates. Similar behavior may be observed in the B arm138. Thus, the robot100may be used to perform “pick” and “place” operations, in which the end effectors are extended and retracted, in combination with vertical displacement of the arm assembly130, in order to pick up or place wafers in wafer processing chambers or other locations. The robot100may also be rotated to allow the end effectors to be extended into and retracted from different processing chambers.

FIG. 1Jdepicts a top view of the robot100showing such rotational movement. InFIG. 1J, the A drive motor107, the B drive motor108, and the common drive motor109are all rotated by approximately 32° with respect to the positions of those motors inFIG. 1G. This results in the entire arm assembly130rotating about the centers of rotation of the upper A arm140and the upper B arm150without any translation of the end effectors away from these rotational axes.

The A arm137and the B arm138may each be actuated independently of each other, i.e., the A arm137and the B arm138are not kinematically linked with each other during end effector linear/radial translation. In a robot such as the robot100, the end effectors may be paddle or spatula type effectors that lift a wafer from underneath and may rely on friction to hold the wafer in place while the end effector is in motion. Some implementations may utilize other types of end effectors, such as vacuum-assisted friction devices. In end effectors that utilize friction, however, the maximum acceleration with which the end effector may be moved when carrying a wafer may be friction-limited, i.e., accelerating the rate of effector movement beyond a certain limit may cause the wafer that the end effector is carrying to slip because the acceleration is sufficient to overcome the friction force. When movement of an end effector does not cause movement of a wafer, there is no risk of wafer slippage due to the movement of the end effector and the maximum acceleration of the end effector may instead be torque-limited instead of friction-limited. However, in designs where end effectors are kinematically linked, e.g., translation of one end effector causes some translation of the other end effector, the maximum acceleration of an end effector may still be friction-limited even when that end effector is not carrying a wafer if the other end effector is carrying a wafer. At the least, a wafer that shifts during effector movement may not be in the optimum location when placed in the destination process chamber, and valuable process time may be lost correcting for the misplacement. In some cases, slippage may result in the wafer falling off of the effector and may cause damage to, or destruction of, the wafer in addition to lost process time.

Because the A arm137and the B arm138are not kinematically linked during end effector linear translation, each end effector is only friction limited when actually carrying a wafer during end effector linear translation. This allows a robot such as the robot100to operate at higher throughput rates. For example, consider a wafer transfer operation in which the A arm137is used to pick up a wafer using a “pick” motion while the B arm138is used to hold a different wafer using the end effector B190. A pick motion may include extending the end effector A180away from the base101of the robot100(a linear translation of the end effector A180underneath the wafer), a z-axis translation of the arm assembly130upwards (lifting the wafer clear of the wafer support), and a retraction of the end effector A180(a linear translation of the end effector A to withdraw the wafer from the process chamber). In a robot with kinematically-linked arms, the time for each of these stages is estimated to be 0.9 seconds for extension, 0.7 seconds for z-axis translation upwards, and 1.4 seconds for retraction. By contrast, the estimated time for each stage using a robot such as the robot100is 0.6 seconds for extension, 0.7 seconds for z-axis translation upwards, and 1.4 seconds for retraction. As can be seen, the last two stages for either robot have similar times because in the last two stages, both arms of the robot are carrying wafers. However, the first stage is noticeably quicker for the robot100since the A arm137may be moved at a higher rate of speed since it is not kinematically linked to the wafer-holding B arm138during the extension of the end effector A180.

Similarly, a “place” motion, in which wafers may be placed into a destination chamber, may see a similar speed increase using a robot such as the robot100. A place motion may include similar stages to those used in a pick motion, but with downwards z-axis movement instead of upwards z-axis movement. In a robot with kinematically-linked arms, the time for each of these stages is estimated to be 1.4 seconds for extension, 0.7 seconds for z-axis translation downwards, and 0.9 seconds for retraction. By contrast, the estimated time for each stage using a robot such as the robot100is 1.4 seconds for extension, 0.7 seconds for z-axis translation downwards, and 0.6 seconds for retraction.

In between the pick and place motions, the robot100may rotate the arm assembly130, for example, by 180° in order to transfer a picked wafer from one processing chamber to another processing chamber. While a rotation of greater than 180° may be performed, the same end positioning may often be achieved by rotating a lesser amount in the opposite direction, thus, 180° represents a reasonable maximum rotation angle through which the arm assembly130may be rotated in many implementations. The robot100and a robot with kinematically-linked arms may both take approximately 2.4 seconds to rotate 180°.

Thus, according to the estimates provided above, a robot with kinematically-linked arms may require 8.4 seconds to perform a single pick, rotation, and place cycle, whereas the robot100may only require 7.8 seconds to perform the same actions. Each wafer must at least be picked from a loadlock and placed into a chamber, and then picked from the chamber and placed into a loadlock, a minimum of two such complete pick-and-place cycles must be performed for each wafer—if additional process chambers are involved, the number of pick-and-place cycles per wafer may increase beyond this. This represents approximately an 8% improvement in cycle time for the robot100over a robot with kinematically-linked arms.

As mentioned previously, other implementations may feature an arm assembly with end effectors facing the same direction.FIG. 2Ashows an isometric view of robot200, which features an arm assembly230that is mounted to a base unit201. The arm assembly230has an end effector A280and an end effector B290facing the same direction.FIG. 2Bdepicts a side view of the robot200, and illustrates how the two end effectors are positioned in similar locations yet offset from one another.

In principle, the robot200may be constructed and operate in a very similar manner to the robot100discussed above. However, while largely similar in operation and construction, some differences may be observed. For example, whereas the drive motor A107and the drive motor B108may each be rotated in the same direction to translate the end effector A180and the end effector B190, respectively, in the same radial direction in the robot100, corresponding drive motors for each arm in the robot200may be rotated in opposite directions to cause the end effector A280and the end effector B290to translate in the same radial direction. To rotate the arm assembly230without translation of the end effector A280and the end effector B290away from the center of rotation, all three drive motors may be driven in the same direction.

Another difference between the robot200and the robot100is that both the A arm237and the B arm238may feature spacers273which are similar to spacer173for B arm138in the robot100. This extra spacer allows the A arm237and the B arm238to interleave with each other, as is evident inFIG. 2C.FIG. 2Dshows a top view of the robot200. Due to the end effectors both being in the same rest position but offset from each other, only the end effector A280, and not the end effector B290, is visible.

While the various internal mechanisms of robot200are not shown in the figures; they may be largely similar to the internal mechanisms of the robot100.

FIG. 3shows a schematic of a dual-arm vacuum robot according to the present disclosure. Visible inFIG. 3is an arm assembly330that includes an A arm337and a B arm338. The A arm337includes an upper A arm340, a lower A arm360, and an end effector A380. The B arm338includes an upper B arm350, a lower B arm370, and an end effector B390. The upper A arm340is rigidly connected with an A drive shaft310and the upper B arm350is rigidly connected with a B drive shaft311. A common drive shaft312may be coaxially interposed between the A drive shaft310and the B drive shaft311and may be rigidly connected with a common drive pulley assembly331. Thus, the upper A arm340may be rotated by rotating the A drive shaft310, the upper B arm350may be rotated by rotating the B drive shaft311, and the common drive pulley assembly331may be rotated by rotating the common drive shaft312.

The upper A arm340and the upper B arm350may both be configured to rotate about a substantially common axis; the ends of the A arm340and the B arm350that rotate about the substantially common axis may be referred to as proximal ends of the A arm340and the B arm350, whereas the opposing ends of the A arm340and the B arm350may be referred to as distal ends of the A arm340and the B arm350.

The upper A arm340may be rotatably connected with the lower A arm360at the distal end of the upper A arm340. A lower A arm driven pulley362that is rigidly connected with the lower A arm360may protrude into the upper A arm340, and an upper A arm drive pulley345that is rigidly connected with the upper A arm340may protrude into the lower A arm360. An upper A arm drive belt341may rotatably connect the lower A arm driven pulley362with the common drive pulley assembly331such that relative rotation between the common drive pulley assembly331and the upper A arm340causes the lower A arm driven pulley362, as well as the lower A arm360, to rotate relative to the upper A arm340. Similarly, the lower A arm360may be rotatably connected with the end effector A380. An end effector A driven pulley381may be rigidly connected with the end effector A380and may protrude into the lower A arm360. A lower A arm drive belt361may rotatably connect the upper A arm drive pulley345with the end effector A driven pulley381such that relative rotation between the upper A arm drive pulley345and the lower A arm360causes the end effector A driven pulley381, as well as the end effector A380, to rotate relative to the lower A arm360.

The portion of the lower A arm360that is rotatably connected with the distal end of the upper A arm340may be referred to as the proximal end of the lower A arm360, and the opposing end of the lower A arm360, i.e., the end that is rotatably connected with the end effector A380, may be referred to as the distal end of the lower A arm360.

In a similar fashion, the upper B arm350may be rotatably connected with the lower B arm370at the distal end of the lower arm370. A lower B arm driven pulley372that is rigidly connected with the lower B arm370may protrude into the upper B arm350, and an upper B arm drive pulley355that is rigidly connected with the upper B arm350may protrude into the lower B arm370. An upper B arm drive belt351may rotatably connect the lower B arm driven pulley372with the common drive pulley assembly331such that relative rotation between the common drive pulley assembly331and the upper B arm350causes the lower B arm driven pulley372, as well as the lower B arm370, to rotate relative to the upper B arm350. Similarly, the lower B arm370may be rotatably connected with the end effector B390. An end effector B driven pulley391may be rigidly connected with the end effector B390and may protrude into the lower B arm370. A lower B arm drive belt371may rotatably connect the upper B arm drive pulley355with the end effector B driven pulley391such that relative rotation between the upper B arm drive pulley355and the lower B arm370causes the end effector B driven pulley391, as well as the end effector B390, to rotate relative to the lower B arm370.

Similarly, the portion of the lower B arm370that is rotatably connected with the distal end of the upper B arm350may be referred to as the proximal end of the lower B arm370, and the opposing end of the lower B arm370, i.e., the end that is rotatably connected with the end effector B390, may be referred to as the distal end of the lower B arm370.

Thus, rotating the A drive shaft310without rotating the common drive shaft312or the B drive shaft311may cause the A arm337to extend or retract without extending or retracting the B arm338and without rotating either the A arm337or the B arm338. Similarly, rotating the B drive shaft311without rotating the common drive shaft312or the A drive shaft310may cause the B arm338to extend or retract without extending or retracting the A arm337and without rotating either the A arm337or the B arm338. Rotating the A drive shaft310, the B drive shaft311, and the common drive shaft312may cause the A arm337and the B arm338to rotate about the center of the arm assembly330without extending or retracting.

The ratio of the common drive pulley assembly331diameter to either the lower A arm driven pulley362diameter or the lower B arm driven pulley372diameter may be 2:1; this may cause twice as much relative rotation between the lower A arm driven pulley362and the upper A arm340as between the common drive pulley assembly331and the upper A arm340. Similarly, the ratio of the end effector A driven pulley381diameter or the end effector B driven pulley391diameter to the upper A arm drive pulley345or the upper B arm drive pulley355, respectively, may be 2:1; this may, for example, cause half as much relative rotation between the end effector A380and the lower A arm360as between the upper A arm drive pulley345and the lower A arm360.

Such arrangements allow for independent retraction and extension of either robot arm, as well as rotation of the robot arms together, with a lower number of motors as compared to two-arm systems that allow for both arms to extend, retract, and rotate with complete independence. Coupling rotational movement of the robot arms also allows for a simpler control scheme, since it is unnecessary to monitor the positions of the arms with respect to each other to prevent rotational interference with one another.

It is to be understood that the robots described above may also include other or additional components, e.g., motor controllers, sensors, anti-vibration mounts, etc. For example, a robot such as those described herein may be implemented within a central transfer chamber or hub that may be configured to interface with various loadlocks and process chambers. The central transfer chamber or hub may be configured to be environmentally controlled, e.g., sealed from the ambient environment and temperature- and pressure-controlled, and filled with a desired atmospheric gas mixture. Such an implementation, or other implementations, may also include a system controller having instructions for controlling the robot during process operations in accordance with the present invention. For example, the controller may be configured to translate a command to extend an end effector A into signals that activate drive motor A without activating drive motor B or the common drive motor. Similarly, the controller may be configured to translate a command to rotate the A arm and the B arm into drive signals that activate the A drive motor, the B drive motor, and the common drive motor in the same direction. The controller may be configured to translate other commands to the robot arm in a manner consistent with the above disclosure. The system controller will typically include one or more memory devices and one or more processors configured to execute the instructions so that the apparatus will perform a method in accordance with the present invention. Machine-readable media containing instructions for controlling process operations in accordance with the present invention may be coupled to the system controller.

It will also be understood that unless features in any of the particular described implementations are expressly identified as incompatible with one another or the surrounding context implies that they are mutually exclusive and not readily combinable in a complementary and/or supportive sense, the totality of this disclosure contemplates and envisions that specific features of those complementary implementations can be selectively combined to provide one or more comprehensive, but slightly different, technical solutions. It will therefore be further appreciated that the above description has been given by way of example only and that modifications in detail may be made within the scope of the invention.