Patent Description:
<CIT> discloses substrate transport systems and robot apparatus. The systems are adapted to pick or place a substrate at a destination by independently rotating an upper arm, a forearm, and dual wrist members relative to each other and a base.

<CIT> discloses a workpiece transporting robot that includes a robot body, a plurality of arms connected to the robot body in order via joint sections in a relatively rotatable manner, a wrist block mounted on tip side arms of the plurality of arms in the relatively rotatable manner, a linking means for activating each of the plurality of arms rotatably, and a drive means for driving the linking means in a predefined linked relation.

<CIT> discloses a manipulator device installed in a vacuum chamber, wherein vacuum dust seals are laid among first and second arms, a hand and a base to prevent the outflow of dust arising from inside connections and a disk member is provided at a distribution port mounted with a filter open to the exteriors of the first and second arms which is put in slide contact with an opening/closing pin on the ceiling of the vacuum chamber to open/close the distribution port.

<CIT> discloses a transfer robot that includes a first arm having a base end portion rotatably connected to an arm base, a second arm having a base end portion rotatably connected to a tip end portion of the first arm, and a hand having a hand base rotatably connected to a tip end portion of the second arm, the hand serving to hold a substrate.

<CIT> discloses a workpiece carrying device that is equipped with a supporting base, a supporting arm coupled to the supporting base so as to swivel around a main swiveling shaft, a hand holding arm coupled to the supporting arm so as to rotate around an elbow joint shaft, and hands coupled to the hand holding arm so as to rotate around a wrist joint shaft.

According to the present invention there is provided a wafer handling system as specified in claim <NUM>.

In some additional implementations, the first rotational encoder and the second rotational encoder may each have a resolution selected from the group consisting of: <NUM> bits or more and <NUM> micro-degrees or more.

In some additional implementations, the first rotational joint may include a first ferrofluidic seal between the base and a portion of the first movable link that extends into the base, and the second rotational joint may include a second ferrofluidic seal between the first movable link and a portion of the second movable link that extends into the first movable link.

In some additional implementations, the robot arm may further include a third movable link in which a first end of the third movable link is rotatably connected to a second end of the second movable link via a third rotational joint, a second rotational drive transfer mechanism that includes a third pulley, a fourth pulley, and one or more second belts spanning between the third pulley and the fourth pulley, and a third rotational encoder with a first portion fixedly connected with the second movable link and a second portion fixedly connected with the third movable link. In such an implementation, the third pulley may be fixedly connected with the first movable link, the fourth pulley may be fixedly connected with the third movable link, and the second rotational drive transfer mechanism may be configured such that rotation of the third pulley relative to the second movable link causes the fourth pulley and the third movable link to rotate relative to the second movable link about a center axis of the third rotational joint.

In some implementations, the robot arm may further include a third motor, a third movable link in which a first end of the third movable link is rotatably connected to a second end of the second movable link via a third rotational joint, a second rotational drive transfer mechanism including a third pulley, a fourth pulley, and one or more second belts spanning between the third pulley and the fourth pulley, and a third rotational encoder with a first portion fixedly connected with the second movable link and a second portion fixedly connected with the third movable link. In such an implementation, the third motor may be configured to cause the third pulley to rotate about a rotational axis of the second rotational joint, the fourth pulley may be fixedly connected with the third movable link, and the second rotational drive transfer mechanism may be configured such that rotation of the third pulley about the center axis of the second rotational joint relative to second movable link causes the fourth pulley and the third movable link to rotate relative to the second movable link about a center axis of the third rotational joint.

In some implementations, the first rotational joint may include a first ferrofluidic seal between the base and a portion of the first movable link that extends into the base, the second rotational joint may include a second ferrofluidic seal between the first movable link and a portion of the second movable link that extends into the first movable link, and the third rotational joint may include a third ferrofluidic seal between the second movable link and a portion of the third movable link that extends into the second movable link.

In some implementations, the first movable link may include a third rotational drive transfer mechanism that includes a fifth pulley, a sixth pulley, and one or more third belts spanning between the fifth pulley and the sixth pulley.

In some implementations, the third motor may be located within the first movable link.

In some implementations, the robot arm may further include a fourth motor, a fourth movable link in which a first end of the fourth movable link is rotatably connected to a second end of the second movable link via the third rotational joint, a fourth rotational drive transfer mechanism including a seventh pulley, an eighth pulley, and one or more fourth belts spanning between the seventh pulley and the eighth pulley, and a fourth rotational encoder with a first portion fixedly connected with the second movable link and a second portion fixedly connected with the fourth movable link. In such an implementation, the fourth motor may be configured to cause the seventh pulley to rotate about a rotational axis of the second rotational joint, the eighth pulley may be fixedly connected with the fourth movable link, and the fourth rotational drive transfer mechanism may be configured such that rotation of the seventh pulley about the center axis of the second rotational joint relative to the second movable link causes the eighth pulley and the fourth movable link to rotate relative to the second movable link about a center axis of the third rotational joint.

In some implementations, the first movable link may further include a fifth rotational drive transfer mechanism that includes a ninth pulley, a tenth pulley, and one or more fifth belts spanning between the ninth pulley and the tenth pulley.

In some implementations, the fourth motor may be located within the first movable link.

In some implementations, the one or more first belts may be made of stainless steel and may include at least two first belts, and each belt of the at least two first belts may have a first end fixedly attached to one of the first pulley of the first rotational drive transfer mechanism and the second pulley of the first rotational drive transfer mechanism and a second end fixedly attached to the other of the first pulley of the first rotational drive transfer mechanism and the second pulley of the first rotational drive transfer mechanism.

In some implementations, each of the one or more first belts may be a continuous belt.

In some implementations, the wafer handling system may further include a chamber having a nominal width, length, and height. The chamber may have a plurality of wafer stations arranged along opposing walls, each wafer station having a wafer center point. In such implementations, the width may define the nominal distance between the opposing walls and the base may be located with a center axis of the first rotational joint located within <NUM>% to <NUM>% of the width from one of the opposing walls.

In some implementations, the wafer handling system may further include an end effector configured to support a semiconductor wafer and connected to the robot arm such that the end effector is supported by the first movable link and the second movable link. In such implementations, the wafer handling system may also include a controller having a memory and one or more processors that are communicatively connected. The memory may store computer-executable instructions for controlling the one or more processors to
receive rotational position data from the first rotational encoder, receive rotational position data from the second rotational encoder, and determine a horizontal location of a point fixed in space relative to the end effector based, at least in part, on the rotational position data from the first and second rotational encoders.

In some implementations, the memory may further store computer-executable instructions for further controlling the one or more processors to control the first motor, the second motor, or the first motor and the second motor to activate for one or more periods of time to cause the point fixed in space relative to the end effector to move from a first location to a second location.

The various implementations disclosed herein are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings, in which like reference numerals refer to similar elements.

Importantly, the concepts discussed herein are not limited to any single aspect or implementation discussed herein, nor to any combinations and/or permutations of such aspects and/or implementations. Moreover, each of the aspects of the present invention, and/or implementations thereof, may be employed alone or in combination with one or more of the other aspects and/or implementations thereof without departing from the scope of the invention as defined by the appended claims. For the sake of brevity, many of those permutations and combinations will not be discussed and/or illustrated separately herein.

Semiconductor wafer handling robots are expected to move quickly, precisely, and with little noise, vibration, or potential for particulate generation. Accordingly, such robots are typically designed such that the drive elements (motors) of the robot arm or arms are located in a base (thereby reducing weight in the moving components and increasing the speed with which the robots may operate), and the motive force provided by those motors is then transferred through the arm links to the driven links using some form of mechanical drive, e.g., steel belts.

Such steel belt drive mechanisms are preferred in semiconductor processing equipment for a variety of reasons. As a first matter, stainless steel belts may be much less susceptible to chemical attack than timing belts (which are usually made of combination of polymeric and textile materials; such materials are much more likely to be damaged by chemicals that may be encountered in semiconductor processing facility environments). Stainless steel belts are much less likely to produce particulates during operation, whereas timing belts may produce both particulates (due to their lower strength) and outgassing (due to the polymeric materials used)-both of these side effects are potentially problematic in a semiconductor processing environment since they can affect wafer processing and cleanliness. In a vacuum environment, timing belts also tend to become thermally stressed since they lose the ability to shed heat through convection (due to the lack of atmosphere). When timing belts get hot, they generally become more susceptible to thermal breakdown and may exhibit higher failure rate and particulate generation.

Steel belt drive mechanisms typically feature two non-continuous steel belts that are attached to two sets of pulleys that operate in parallel, e.g., each set is connected to a common shaft. Each belt will be rigidly connected to one of the pulleys in the set, with each belt located on an opposite side of the pulleys from the other belt. This is illustrated, in concept, in <FIG>. In <FIG>, a two-pulley drive mechanism is shown in which a first pulley <NUM> and a second pulley <NUM> are linked by two first belts <NUM> (172A and 172B). The upper figure in <FIG> shows the first pulley <NUM>, the second pulley <NUM>, and the first belt 172A in isolation; as can be seen, the first belt 172A is not continuous-it is pinned to the first pulley <NUM> and the second pulley <NUM> by, in this example, a pin. In actual practice, such attachments may be more complex and may provide, for example, the ability to adjust the tension of the first belt 172A between the two pulleys.

As will be readily apparent, rotating the first pulley <NUM> counter-clockwise by approximately <NUM> degrees will cause the second pulley <NUM> to rotate counterclockwise as well. In this case, since the first pulley <NUM> is approximately twice as large as the second pulley <NUM>, the second pulley <NUM> will rotate twice as fast as the first pulley <NUM>-such belt systems may also be used in differently proportioned pulley systems, e.g., <NUM>:<NUM> ratio pulleys.

Rotating the first pulley <NUM> clockwise, however, does not result in corresponding clockwise movement in the second pulley <NUM> since the first belt 172A is not placed into tension in this mode of rotation. To allow for such clockwise movement, a first belt 172B (see middle part of <FIG>) may be affixed to the first pulley <NUM> and the second pulley <NUM> in much the same manner as the first belt 172A, but with the first belt 172B generally connected to the pulleys in different locations as compared with the second belt 172B. The resulting rotational drive transfer mechanism may provide for precise rotational positioning that is quite and lightweight. However, a key limitation of such a system is that the amount of rotational movement that such steel-belt systems may provide is less than <NUM>° since the belts typically cannot be allowed to overlap the connection points between the belts and the pulleys. Thus, there is typically at least a <NUM>° to <NUM>° dead zone (shown with the cross-hatched pie segment in the lowermost portion of <FIG>, which shows both belts on the pulleys simultaneously) through which the pulleys cannot rotate. This limits the range of rotational motion for robots that use such steel belt rotational drive transfer mechanisms, although in most typical implementations, this is not an issue since the available space within the environment where the robot arms operate is typically large enough to avoid having to undergo rotation that would conflict with such a limited range of motion.

For example, in a vacuum environment, it is common to locate the base of a wafer handling robot near at the center of the vacuum environment so that semiconductor processing chambers, load locks, and other stations/locations where wafers may be placed or retrieved from are equidistant from the robot arm base-this can reduce the length of the robot arm, allows for an easier control setup (as robot arm movements may be substantially identical for interacting with each station), and allows the robot to operate without undergoing large joint rotations. <FIG> depicts an example of a radially-arranged transfer chamber, which is a chamber that is typically kept at vacuum and that has a plurality of wafer processing chambers connected with it at various positions around it circumference or perimeter. In this example, the transfer chamber <NUM> (which may also be thought of as a wafer handling system <NUM>) has four wafer processing chambers <NUM> arranged along four different sides, and two load lock chambers <NUM>, which act as airlocks to allow wafers to enter and exit the vacuum environment of the transfer chamber without disturbing it, arranged along two other sides. As can be seen, the robot arm is able to easily access any of the processing chambers or load locks from its centrally-mounted location.

Even in non-radially arranged transfer chambers, it is typical to mount the base of a wafer handling robot generally at the center of such chambers. For example, <FIG> depicts an example rectangular-format transfer chamber in which two sets of three processing chambers <NUM> are arranged along opposing sides of the transfer chamber <NUM>. A centrally-located robot arm <NUM> is able to reach all of the processing stations <NUM> without the rotations of any of the rotational joints of the robot arm <NUM> exceeding <NUM>°.

The present inventor sought to create a new type of transfer chamber in which a robot arm, e.g., similar to the belt-driven robot arms discussed earlier, or variants thereof that are discussed in more detail below, was mounted in an off-center location. Since the drive motors and other electronics (including any vertical lift capability) of such robot arms are typically located in the robot arm base, the bases of such robot arms can be quite large, e.g., a foot in diameter and two or more feet long. For vacuum transfer chambers, the robot arm base is typically mounted in the transfer chamber such that the base protrudes out of the bottom of the chamber so that the chamber volume does not need to include head room for the base. This reduces the volume of the transfer chamber, which makes it less expensive to manufacture, easier to seal, and reduces the amount of time required to pump the transfer chamber down to a vacuum. However, when the base of the robot arm extends through the floor of the transfer chamber, it may intrude into, for example, a walkway or other personnel access passage under the transfer chamber. Such walkways or passages may allow for personnel to service or access components of the processing stations that may be located beneath the processing chambers themselves. The present inventor realized that such arrangements make it difficult for personnel to perform such maintenance or otherwise access such components, and determined that moving the robot arm so that the base of the robot arm is positioned close to one side or the other of the transfer chamber results in a less cramped arrangement underneath the transfer chamber. Instead of having the robot arm base bisect whatever walkway or passage runs beneath the transfer chamber, the base is instead offset to one side, leaving a single open path past it that is twice as wide as the paths past it would be if it were centrally located.

<FIG> depicts an example of such a new type of transfer chamber. In <FIG>, the transfer chamber <NUM> is similar to the transfer chamber <NUM> of <FIG>, except that the base of the robot arm <NUM> has been shifted to one side, placing it adjacent to one side of the transfer chamber <NUM>. In practice, it may be desirable to place the base of the robot arm <NUM> as close as possible to one side or the other, although allowances may be made for tolerances, safety clearances, moving component clearances, and so forth. More generally, the base may be centered on a location that is within <NUM>% of the width of the transfer chamber from one of the walls defining the width. For example, if the width of the transfer chamber (left-right dimension in <FIG>) is <NUM> inches, then the base of the robot arm <NUM> may be centered on a location within <NUM> inches of one of the left or right sides (per the perspective of <FIG>) of the transfer chamber <NUM>, e.g., at approximately <NUM> inches from such a side. For a typical robot arm base having a diameter of approximately <NUM> inches in such an example implementation, this leaves a gap of approximately <NUM> inches between the base and the opposite side of the transfer chamber <NUM>. Thus, even if equipment underneath the processing chambers <NUM> extends all the way up to the sides of the transfer chamber, there would still be a passageway under the transfer chamber of at least two feet in width between the robot arm base and such equipment-thereby allowing easier personnel access.

<FIG> depicts a front view of the transfer chamber <NUM> of <FIG>. In <FIG>, the transfer chamber <NUM> is elevated off of the floor. Each processing chamber <NUM> has chamber support equipment 303A below it, e.g., vertical lift devices for moving a wafer pedestal up and down within the processing chamber <NUM>, cooling systems, power supplies, etc., that may extend down to the floor (or at least partway to the floor). As can be seen, the base <NUM> is positioned to one side of the transfer chamber <NUM>, leaving a gap "X" for personnel access past the base <NUM>. The dashed outline to the right of the base <NUM> depicts the base in a centered location, as would typically be done with existing transfer chambers. As can be seen, the centered location drastically reduces the access beneath the transfer chamber <NUM>.

The present inventor also realized, however, that if traditional steel belt-driven wafer handling robot arms were used in such an off-center location, the robot arm might need to undergo larger than normal rotations for some of its links in order to access some process chambers; these rotations would result in the robot arm exceeding the maximum allowable rotation that such steel belt systems permit.

By designing a new type of wafer handling robot arm that utilizes technologies and approaches typically not seen in wafer handling robots, the present inventor was able to overcome this issue. Generally speaking, such wafer handling robot arms replace the steel belt systems that are normally used with a continuous belt system, e.g., using polymeric or polymeric and textile-based timing belts. This allows for a full <NUM>° of rotation without being limited by the rotational drive transfer mechanism used. At the same time, the present inventor determined that rather than using rotational encoders located at the drive motor outputs, as is typically done in such robots, it would be preferable to mount rotational encoders at each rotational joint in the robot arm-even when there is no motor located at that rotational joint. In a traditional wafer handling robot arm system, the rotational encoders are collocated with the motors (or even built into the motors as an integrated unit, e.g., a servomotor) since this allows the wiring for the rotational encoders and the motors to be commonly routed. It also avoids the need, for many robot arm joints, to pass wiring for the encoders through the rotational joints (or at least, avoids the need to pass wiring for the encoders through any rotational joints that do not already have electrical feed-throughs or cabling for controlling any motors that could potentially be located in, for example, the robot arm link segment adjacent to the base), thereby simplifying the robot arm design. In contrast, the new wafer handling robot arms that are the subject of this disclosure may route wiring to the rotational encoders through the various kinematic joints of the robot arm that are interposed between the base of the arm and the locations where the rotational encoders are located. Thus, the rotational joints are hollow along their centerlines in order to allow such cabling to pass through them without being exposed to the environment outside of the arms and to reduce the amount of movement that such cables experience during movement of the robot arms. In some alternative such designs, the cables themselves may not be continuous or may not even be cables. For example, flexible or inflexible printed circuit substrates may be used to provide conductive paths for the signals to and from the rotational encoders, and slip rings or other similar mechanisms for providing electrical continuity across a rotating interface may be used to electrically connect the rotational encoders to a controller. Such slip rings or similar mechanisms may be located within, for example, the sealed portions of the rotational joints in order to protect the electrically conductive paths and also prevent any particulates that are generated by such mechanisms from escaping the robot arm (other than through the base).

For the purposes of this disclosure, the phrases "directly driven," "direct drive," "directly drive," and variants thereof refer to a relationship between a rotating part and the motor that provides rotational input to the rotating part in which the motor has a center of rotation that is generally coaxial with the axis of rotation of the rotating part (there may be some minor misalignment due to manufacturing tolerances, and some systems may use a rotational flex coupler to accommodate such misalignment, but the motor rotational axis and the rotating part rotational axis will still be understood to be "generally coaxial with one another"). Rotating parts that are directly driven by their respective motors are also rotated at the same speed as the rotational output of those motors; there is no intermediate gear reduction or other speed reduction/enhancer interposed between the motor and the rotating part.

Similarly, the phrases "indirectly driven," "indirect drive," "indirectly drive," and variants thereof refer to a relationship between a rotating part and the motor that provides rotational input to the rotating part in which the motor has a center of rotation that is offset (by some designed-in amount, as opposed to offsets that occur due to assembly or manufacturing tolerances) from the axis of rotation of the rotating part in a direction perpendicular to that axis of rotation. In the context of this application, mechanisms that enable such indirect drives are referred to as "rotational drive transfer mechanisms. " Such rotational drive transfer mechanisms generally include two pulleys, each of which is attached to either the driving rotating part (which may be the output of a motor or may be driven by some other rotational input, e.g., the rotational output of another rotational drive transfer mechanism) or the driven rotating part. In practice, each rotating part may have a single pulley or may have multiple pulleys that are connected with the same shaft or other common portion of the rotating part. In such multiple-pulley scenarios, the term pulley may be understood to apply to a pulley individually or to the pulleys, in aggregate, that rotate in unison about the same axis.

Thus, the wafer handling robots described below, which are simply examples of robot arms embodying the concepts set forth herein and are not intended to limit the application of these concepts to other robot arms, may be generally described as having at least one rotational drive transfer mechanism and at least one rotational joint in between movable links of the robot arms that is driven by such a rotational drive transfer mechanism and that has a rotational encoder that is associated with that rotational joint. Such robot arms may also include additional rotational drive mechanisms and rotational joints, as well as additional rotational encoders at those additional rotational joints.

The wafer handling robots described below, and other robots embodying similar concepts, may also be able to achieve positioning accuracy that is currently unheard of in the robot arm industry. For example, for a typical robot arm having a maximum extended length (measured from the center of rotation of the arm to the center of the wafer being transported by the arm) of approximately <NUM> meters, the concepts discussed herein, including placement of rotational encoders at each rotational joint, may allow for such a robot arm to have a wafer-positioning accuracy or repeatability of as low as ±<NUM>, which is nearly two-thirds less than many state-of-the-art wafer handling robots (which may have wafer-positioning accuracy or repeatability of ±<NUM>). The improved wafer-positioning accuracy may allow wafers to be placed or centered on receiving wafer pedestals or chucks in the semiconductor processing chambers with higher accuracy, allowing for smaller feature sizes to be processed on the wafer.

A further benefit to the wafer handling robots discussed below is that the placement of the encoders at the rotational joints, as opposed to at the rotational inputs (motors) allows for any increased imprecision that may result from using timing belts or other non-steel belts to be accounted for and removed through a closed-loop control system. For example, if a timing belt stretches somewhat while being used, such stretching will result in the driven pulley being in a slightly different rotational orientation than the driving pulley (assuming a <NUM>:<NUM> pulley diameter ratio), which would lead to increased inaccuracy regarding where the movable links are in the robot arm if the driving pulley is where the rotational encoder is located.

<FIG> depicts a diagram of an example wafer handling robot arm. In <FIG>, an example robot arm <NUM> is depicted. The robot arm <NUM>, in this example, has a base <NUM>, a first movable link <NUM>, a second movable link <NUM>, and a third movable link <NUM>. The third movable link <NUM> terminates in a first end effector <NUM>, which may be a blade-type end effector that may be placed underneath a semiconductor wafer, like a spatula, in order to lift it from below. A first end 606A of the first movable link <NUM> may be rotatably connected with the base <NUM> via a first rotational joint <NUM>, which may include one or more sets of rotational bearings <NUM>. Similarly, a first end 608A of the second movable link <NUM> may be rotatably connected with a second end 606B of the first movable link <NUM> by a second rotational joint <NUM> and a first end 610A of the third movable link <NUM> may be rotatably connected with a second end 608B of the second movable link <NUM> by a third rotational joint <NUM>. The first rotational joint <NUM> may be configured to allow the first movable link <NUM> to rotate about a first rotational axis <NUM> relative to the base <NUM> responsive to a rotational input received from a first motor <NUM> located in the base <NUM>. Similarly, the second rotational joint <NUM> may be configured to allow the second movable link <NUM> to rotate about a second rotational axis <NUM> relative to the first movable link <NUM>, and the third rotational joint <NUM> may be configured to allow the third movable link <NUM> to rotate about a third rotational axis <NUM> relative to the second movable link <NUM>. The rotational joints discussed herein may also be referred to as rotational interfaces herein.

The depicted example robot arm <NUM> has only two degrees of freedom-extension and retraction of the first end effector <NUM> along an axis intersecting with, and perpendicular to, the first rotational axis <NUM>. Accordingly, there are only two motors shown, the first motor <NUM> and a second motor <NUM>. Both motors are housed within the base to avoid having the weight of the motors be located in the movable links.

In this example robot arm, the first motor <NUM> directly drives the first movable link <NUM>, as is shown by the tubular shaft that extends down into the first motor <NUM>. The second motor <NUM>, however, indirectly drives the second movable link <NUM> through a first rotational drive transfer mechanism <NUM>, which includes a first pulley <NUM>, a second pulley <NUM>, and a first belt <NUM>. The first belt <NUM> is, in this example, a timing belt or other continuous-loop belt. The first pulley <NUM> is directly driven by the second motor <NUM>, and the second pulley <NUM> is fixedly connected with the second movable link <NUM> such that the second movable link <NUM> and the second pulley <NUM> move in unison. When the first pulley <NUM> is rotated about the first rotational axis <NUM> relative to the first movable link <NUM>, e.g., by actuating the second motor <NUM> without actuating the first motor <NUM> (or by actuating both motors at different speeds and/or directions), the relative rotational motion may be transferred to the second pulley <NUM> by way of the first belt <NUM>, thereby causing the second pulley <NUM>, and the second movable link <NUM> connected therewith, to rotate relative to the first movable link <NUM>.

In addition to the first rotational drive transfer mechanism <NUM> located in the first movable link <NUM>, the robot arm <NUM> may also have a second rotational drive transfer mechanism <NUM> that is located in the second movable link <NUM>. The second rotational drive transfer mechanism <NUM> may include a third pulley <NUM> (which, in this case, is simply the outside of a tubular shaft that extends through the second rotational joint <NUM>), a fourth pulley <NUM>, and a second belt <NUM>. In this particular implementation, the third pulley <NUM> is fixedly connected with the first movable link <NUM>. As a result, relative rotational movement about the second rotational axis <NUM> between the first movable link <NUM> and the second movable link <NUM> (as may be caused by operation of the first rotational drive transfer mechanism <NUM>) may, in turn, cause the second rotational drive transfer mechanism <NUM> to operate. Such relative rotational movement may thus be transferred to the third movable link <NUM> via the fourth pulley <NUM>, which may be connected with the third movable link <NUM> and therefore directly drive the third movable link <NUM>.

In this example, the first pulley <NUM> and the second pulley <NUM> have a <NUM>:<NUM> diameter ratio, which will cause the second pulley <NUM> to rotate twice as fast and far as the first pulley <NUM>; such a ratio may be used to cause the first movable link <NUM> and the second movable link <NUM> to "scissor" outwards and inwards while the third rotational axis <NUM> translates along a radius extending away from the first rotational axis <NUM>. Correspondingly, the third pulley <NUM> and the fourth pulley <NUM> have a <NUM>:<NUM> diameter ratio, which causes the third movable link <NUM> and the first end effector <NUM> to rotate about the third rotational axis <NUM> at half the speed at which the first movable link <NUM> and the second movable link <NUM> rotate about the second rotational axis <NUM> relative to one another. This causes the first end effector <NUM> to remain aligned with the previously mentioned radius during extension and retraction of the robot arm <NUM>.

As mentioned above, the robot arm <NUM> also includes rotational encoders located at each rotational joint. For example, a first rotational encoder <NUM> may be located at the first rotational joint <NUM>, a second rotational encoder <NUM> may be located at the second rotational joint <NUM>, and a third rotational encoder may be located at the third rotational joint <NUM>. A rotational encoder, as the term is used herein, refers to a sensor device that is configured to measure rotational displacement about an axis between two components. Such devices include two portions, each of which is affixed to a different one of the two components. The two portions are free to rotate relative to one another, of course, and may, in some instances, be coupled together into a single, integrated unit (much like a ball bearing may have inner and outer races, each of which interfaces with a different one of the two parts between which the ball bearing is installed). In other instances, the two portions may be physically disconnected from one another, e.g., one portion may be installed on one rotatable component with the other portion installed on the other rotatable component-then the two rotatable components are mated together, the two portions of the rotational encoder may align with one another to permit rotational position measurement, but the two portions may actually never come into contact with one another during operation. In <FIG>, the first rotational encoder <NUM> may have a first portion 682a that is fixedly connected with the first movable link <NUM> and a second portion 682b that is fixedly connected with the base <NUM>. Similarly, the second rotational encoder <NUM> may have a first portion 684a that is fixedly connected with the second movable link <NUM> and a second portion 684b that is fixedly connected with the first movable link <NUM>, and the third rotational encoder <NUM> may have a first portion 686a that is fixedly connected with the third movable link <NUM> and a second portion 686b that is fixedly connected with the second movable link <NUM>.

Encoders suitable for use in the wafer handling robot arms discussed herein may generally be of the optically based variety, e.g., encoders in which one portion includes a set of high-precision fiducial marks that are optically readable by a sensor located in the second portion. Other types of encoders, e.g., mechanical, magnetic, or capacitive encoders, are generally unsuitable for use in such robot arms due to poor accuracy, friction, or other factors. Examples of rotational encoders that may be used in the implementations discussed herein include, for example, the RESOLUTE™ encoder series offered by Renishaw Plc. of New Mills, Wotton-under-Edge, Gloucestershire, UK. Such rotational encoders are capable of <NUM>-bit resolution and can provide rotational angle measurement accuracies of up to ±<NUM> arc second (±<NUM>°). Optical rotational encoders are generally more expensive than other types of rotational encoders and more prone to experiencing performance degradation when dirty, e.g., when dust accumulates on the optical sensors or light emitters of such rotational encoders. Nonetheless, the present inventor determined that the precision provided by such optical rotational encoders outweighed such potential disadvantages.

The rotational encoders in the robot arm <NUM> may be connected with a controller <NUM>, which may include one or more processors <NUM> and a memory <NUM> by way of one or more cables that are fed through the various rotational joints of the robot arm that separate each rotational encoder from the base <NUM>. The memory <NUM> may, for example, store instructions for executing a PID (proportional-integral-derivative) control loop that utilizes data from the rotational encoders in order to determine rotational speeds for the motors (the controller <NUM> may also be communicatively connected with the motors and to provide control signals for controlling the motors to the motors).

The robot arm <NUM> that is shown in <FIG> is suitable for use in atmospheric conditions and does not, as shown, include seals or other features that would render it suitable for use in a vacuum environment. However, it is to be understood that such a robot arm could easily be modified to operate in a vacuum by replacing or augmenting some or all of the existing rotational bearings with vacuum-rated/sealed bearings, as will be discussed in more detail with reference to the following implementation. Furthermore, while the rotational encoders are shown mounted externally to the robot arm, other implementations may feature such rotational encoders at located within the movable links and/or the base <NUM> so as to better protect the rotational encoders from damage and dirt.

<FIG> depicts another example robot arm that is more complex than that shown in <FIG>; the depicted example not only includes two end effectors, but each end effector is also capable of independent rotation relative to the movable link that supports them. The depicted example also includes z-axis motion capability (which, it will be understood, may also be implemented in implementations similar to that shown in <FIG>) and is configured to operate in a vacuum environment.

In <FIG>, an example robot arm <NUM> is depicted. The robot arm <NUM>, in this example, has a base <NUM>, a first movable link <NUM>, a second movable link <NUM>, a third movable link <NUM>, and a fourth movable link <NUM>. The third movable link <NUM> and the fourth movable link <NUM> terminate in a first end effector <NUM> and a second end effector <NUM>, respectively, which may be blade-type end effectors that may be placed underneath semiconductor wafers, like a spatula, in order to lift them from below. A first end 706A of the first movable link <NUM> may be rotatably connected with the base <NUM> via a first rotational joint <NUM>, which may include one or more sets of rotational bearings <NUM>. Similarly, a first end 708A of the second movable link <NUM> may be rotatably connected with a second end 706B of the first movable link <NUM> by a second rotational joint <NUM> and a first end 710A of the third movable link <NUM> may be rotatably connected with a second end 708B of the second movable link <NUM> by a third rotational joint <NUM>. The first rotational joint <NUM> may be configured to allow the first movable link <NUM> to rotate about a first rotational axis <NUM> relative to the base <NUM> responsive to a rotational input received from a first motor <NUM> located in the base <NUM>. Similarly, the second rotational joint <NUM> may be configured to allow the second movable link <NUM> to rotate about a second rotational axis <NUM> relative to the first movable link <NUM>, and the third rotational joint <NUM> may be configured to allow the third movable link <NUM> and the fourth movable link <NUM> to independently rotate about a third rotational axis <NUM> relative to the second movable link <NUM>.

Unlike the robot arm <NUM>, the depicted example robot arm <NUM> has five degrees of freedom. In order to provide such degrees of freedom, the robot arm <NUM> includes a total of four motors and a linear actuator <NUM>. The first motor <NUM> and a second motor <NUM>, as well as the linear actuator <NUM>, are housed within the base, whereas a third motor <NUM> and a fourth motor <NUM> are located in the first movable link <NUM>. It is to be understood that the third motor <NUM> and/or the fourth motor <NUM> could, alternatively, be housed in the base <NUM> as well, and their rotational output communicated through the first rotational joint <NUM> using concentric drive shafts (like is already done for the output of the second motor <NUM>). The linear actuator <NUM> may be used to drive a sub-portion of the base that houses the first motor <NUM> and the second motor <NUM>, as well as supports the first rotational joint <NUM> and the movable links, up and down in the vertical dimension to facilitate z-axis movement. A guide rail <NUM> may guide such motion and provide for stable movement along the z-axis. A bellows <NUM> may be provided to seal the movable sub-portion of the base <NUM> to the remainder of the base <NUM>, thereby allowing for vertical movement of the sub-portion relative to the remainder of the base <NUM> without providing a leak path for gas into the base <NUM>. In practice, the upper surface of the base <NUM> may, for example, be connected to an interface to a transfer module in an air-tight fashion to prevent leakage past the upper surface of the base <NUM>, thereby allowing a vacuum environment around the movable links of the robot arm <NUM> to be maintained.

In this example robot arm, the first motor <NUM> directly drives the first movable link <NUM>, as is shown by the tubular shaft that extends down into the first motor <NUM>. The second motor <NUM>, however, indirectly drives the second movable link <NUM> through a first rotational drive transfer mechanism <NUM>, which includes a first pulley <NUM>, a second pulley <NUM>, and a first belt <NUM>. The first belt <NUM> is, in this example, a timing belt or other continuous-loop belt. The first pulley <NUM> is directly driven by the second motor <NUM>. Unlike the second pulley <NUM>, however, the second pulley <NUM> is fixedly connected with the second movable link <NUM> such that the second movable link <NUM> and the second pulley <NUM> move in unison. When the first pulley <NUM> is rotated about the first rotational axis <NUM> relative to the first movable link <NUM>, e.g., by actuating the second motor <NUM> without actuating the first motor <NUM> (or by actuating both motors at different speeds and/or directions), the relative rotational motion between them may be transferred to the second pulley <NUM> by way of the first belt <NUM>, thereby causing the second pulley <NUM>, and the second movable link <NUM> connected therewith, to rotate relative to the first movable link <NUM>.

In addition to the first rotational drive transfer mechanism <NUM> located in the first movable link <NUM>, the robot arm <NUM> may also have a second rotational drive transfer mechanism <NUM> that is located in the second movable link <NUM>. The second rotational drive transfer mechanism <NUM> may include a third pulley <NUM>, a fourth pulley <NUM>, and a second belt <NUM>. In contrast to the third pulley <NUM>, which was fixedly connected with the first movable link <NUM>, the third pulley <NUM> is, in this example, rotatably connected with the first movable link <NUM> so that the first movable link <NUM> and the third pulley <NUM> may be rotated independently about the second rotational axis <NUM>. In this example, the third pulley <NUM> is driven by a third rotational drive transfer mechanism <NUM>, which may include a fifth pulley <NUM>, a sixth pulley <NUM>, and a third belt <NUM>. The output of the third motor <NUM> may drive the fifth pulley <NUM>, which, in turn, drives the third belt <NUM>, thereby causing the sixth pulley <NUM>, as well as the third pulley <NUM> that is fixedly connected therewith, to rotate-this causes the fourth pulley <NUM>, and the third movable link <NUM> fixedly connected therewith, to rotate relative to the second movable link <NUM>. It is to be understood that other implementations may have a third motor <NUM> that directly drives the sixth pulley <NUM>/third pulley <NUM> or may locate the third motor <NUM> in the base, with additional drive transfer mechanisms used to convey the motive power from the third motor <NUM> to the sixth pulley <NUM> (and thus the third pulley <NUM>). It is to be understood that the third pulley <NUM> and the sixth pulley <NUM> may, in some instances, be the same diameter and even simply be different portions of the same cylindrical exterior surface of a tube (the same can be said for the seventh pulley <NUM> and the tenth pulley <NUM>, which are discussed below). Since each rotational joint in this example robot arm is independently driven by a separate motor, the sizes of the various pulleys used may be varied, if desired, and any variations accommodated through control of the motor speeds/displacements.

In a dual end effector implementation, a fourth rotational drive transfer mechanism <NUM> may be provided that includes a seventh pulley <NUM>, an eighth pulley <NUM>, and a fourth belt <NUM>. The eighth pulley <NUM> may be fixedly connected with the fourth movable link <NUM> such that rotation of the eighth pulley <NUM> about the third rotational axis <NUM> relative to the second movable link <NUM> causes the fourth movable link <NUM> and the second end effector <NUM> to also rotate about the third rotational axis <NUM> relative to the second movable link <NUM>. Similar to the third pulley <NUM>, the seventh pulley <NUM> may be rotatably connected with the first movable link <NUM> and the second movable link <NUM> such that the seventh pulley <NUM> may be rotated independently of the first movable link <NUM> and the second movable link <NUM>. Thus, when the seventh pulley <NUM> is rotated about the second rotational axis <NUM> relative to the second movable link <NUM>, the corresponding movement of the fourth belt <NUM> may cause the eighth pulley <NUM> to rotate as well, thereby causing rotation of the fourth movable link <NUM> about the third rotational axis <NUM> relative to the second movable link <NUM>.

In this example, the seventh pulley <NUM> is driven by a fifth rotational drive transfer mechanism <NUM> which may include a ninth pulley <NUM>, a tenth pulley <NUM>, and a fifth belt <NUM>. The output of the fourth motor <NUM> may drive the ninth pulley <NUM>, which, in turn, drives the fifth belt <NUM>, thereby causing the tenth pulley <NUM>, as well as the seventh pulley <NUM> that is fixedly connected therewith, to rotate-this causes the eighth pulley <NUM>, and the fourth movable link <NUM> fixedly connected therewith, to rotate relative to the second movable link <NUM>. It is to be understood that other implementations may have a fourth motor <NUM> that directly drives the seventh pulley <NUM>/tenth pulley <NUM> or may locate the fourth motor <NUM> in the base <NUM>, with additional drive transfer mechanisms used to convey the motive power from the fourth motor <NUM> to the tenth pulley <NUM> (and thus the seventh pulley <NUM>).

Such configurations allow the second motor <NUM> and the third motor <NUM> to independently control the relative rotational positions of the second movable link <NUM> and the third movable link <NUM>, respectively.

As mentioned above, the robot arm <NUM> also includes rotational encoders located at each rotational joint. For example, a first rotational encoder <NUM> may be located near the first rotational joint <NUM> (in this case, it is located adjacent to the first motor <NUM> and is located within the base <NUM>, but it is still centered on the first rotational axis <NUM> of the first rotational joint <NUM>), a second rotational encoder 784A may be located at the second rotational joint <NUM>, a third rotational encoder <NUM> and a fourth rotational encoder <NUM> may be located at the third rotational joint <NUM>.

In <FIG>, the first rotational encoder <NUM> may have a first portion 782a that is fixedly connected with the first movable link <NUM> and a second portion 782b that is fixedly connected with the base <NUM>. Similarly, the second rotational encoder 784A may have a first portion 784Aa that is fixedly connected with the second movable link <NUM> and a second portion 784Ab that is fixedly connected with the first movable link <NUM>, the third rotational encoder <NUM> may have a first portion 786a that is fixedly connected with the third movable link <NUM> and a second portion 786b that is fixedly connected with the second movable link <NUM>, and the fourth rotational encoder <NUM> may have a first portion 788a that is fixedly connected with the fourth movable link <NUM> and a second portion 788b that is fixedly connected with the second movable link <NUM>. Additionally, in some implementations, additional rotary encoders (also referred to as rotational encoders herein) may be provided at other locations to provide for the possibility of even greater accuracy. For example, an additional second rotational encoder 784B may be provided at the second motor <NUM> (with a first portion 784Ba fixedly connected with the first pulley <NUM> and a second portion 784Bb fixedly connected with a vertically translatable portion of the base <NUM>); in such instances, the output of the second rotational encoder 784A, which is positioned at the second rotational joint <NUM>, may be used to provide positional data to the control loop, whereas the other second rotational encoder 784B, which is positioned at the second motor <NUM>, may be used to provide velocity data to the control loop. This approach may be used to account for any compliance in the first belt <NUM>; similar approaches may be adopted for the other rotational encoders used as well, if desired.

As with the robot arm <NUM>, the robot arm <NUM> also may include a controller <NUM> with a memory <NUM> and one or more processors <NUM>; the memory <NUM> may similarly store computer-executable instructions for controlling the robot arm <NUM>, e.g., instructions for executing a PID routine to use inputs from the rotational encoders in order to control the motors to cause the robot arm to move to a desired position.

Another difference between the robot arm <NUM> and the robot arm <NUM> is that the robot arm <NUM> includes vacuum-tight rotary seals <NUM> at each rotational joint, or at least at each rotational joint that has a pulley with a belt attached to it. Examples of such vacuum-tight seals are ferrofluidic seals, which provide a robust, low-friction vacuum-tight seal that does not produce much, if any, particulate contamination (any metal particles that are abraded off during operation are immediately captured by the magnetic field of the seal, thereby preventing the migration of such particles onto, for example, a wafer being transported by the wafer handling robot). The vacuum tight seals may be integrated into bearing assemblies or used in combination with rotational bearings that allow for smooth rotational motion through the vacuum-tight seal. This allows the interior of the movable links that are sealed with vacuum-tight seals to be kept at atmospheric pressure, while the environment around the movable links is kept at vacuum. Generally speaking, only the outermost seals for each movable link that is held at atmospheric pressure may be provided by vacuum-tight seals; the other rotational bearings may not be equipped with such seals. By sealing the belt-drive systems in atmospheric sections of the movable links, any particulates generated by the belts will be kept isolated from the vacuum environment, thereby preserving its cleanliness.

It is to be understood that the concepts of off-center robot arm mounting, the use of timing belts in place of steel belts, and the use of rotary encoders at each rotational joint of the robot arm may each represent a separate idea and may be implemented separately or as an interdependent combination or subcombination. Thus, for example, a robot arm with timing belts and joint-mounted rotary encoders may be used in non-off-center mounting locations, and so forth.

It is to be understood that the term "set," unless further qualified, refers to a set of one or more items-it does not require that multiple items be present unless there is further language that implies that it does. For example, a "set of two or more items" would be understood to have, at a minimum, two items in it. In contrast, a "set of one or more items" would be understood to potentially only have one item in it. In a similar vein, it is to be understood that the term "each" may be used herein to refer to each member of a set, even if the set only includes one member. The term "each" may also be used in the same manner with implied sets, e.g., situations in which the term set is not used but other language implies that there is a set. For example, "each item of the one or more items" is to be understood to be equivalent to "each item in the set of one or more items.

As discussed above, in some implementations, a controller may be part of the wafer handling systems discussed herein. The wafer handling system may also be viewed as being a semiconductor processing tool, e.g., it may also include semiconductor processing equipment, including a processing chamber or chambers, a platform or platforms for processing, and/or specific processing components (a wafer pedestal, a gas flow system, etc.). These systems (including the robot arm) may be integrated with electronics for controlling their operation before, during, and after processing of a semiconductor wafer or substrate. The electronics may be referred to as the "controller," which may control various components or subparts of the system or systems. The controller, depending on the processing requirements and/or the type of system, may be programmed to control any of the processes disclosed herein, such as processes for controlling the wafer handling robot, as well as other processes or parameters not discussed herein, such as the delivery of processing gases, temperature settings (e.g., heating and/or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, positional and operation settings, wafer transfers into and out of a chamber and other transfer tools and/or load locks connected to or interfaced with a specific system.

Broadly speaking, the controller may be defined as electronics having various integrated circuits, logic, memory, and/or software that receive instructions, issue instructions, control operation, enable cleaning operations, enable endpoint measurements, and the like. The integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and/or one or more microprocessors, or microcontrollers that execute program instructions (e.g., software). Program instructions may be instructions communicated to the controller in the form of various individual settings (or program files), defining operational parameters for carrying out a particular process on or for a semiconductor wafer or to a system. The operational parameters may, in some embodiments, be part of a recipe defined by process engineers to accomplish one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and/or dies of a wafer.

The controller, in some implementations, may be a part of or coupled to a computer that is integrated with, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the controller may be in the "cloud" or all or a part of a fab host computer system, which can allow for remote access of the wafer processing. The computer may enable remote access to the system to monitor current progress of fabrication operations, examine a history of past fabrication operations, examine trends or performance metrics from a plurality of fabrication operations, to change parameters of current processing, to set processing steps to follow a current processing, or to start a new process. In some examples, a remote computer (e.g. a server) can provide process recipes to a system over a network, which may include a local network or the Internet. The remote computer may include a user interface that enables entry or programming of parameters and/or settings, which are then communicated to the system from the remote computer. In some examples, the controller receives instructions in the form of data, which specify parameters for each of the processing steps to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process to be performed and the type of tool that the controller is configured to interface with or control. Thus as described above, the controller may be distributed, such as by comprising one or more discrete controllers that are networked together and working towards a common purpose, such as the processes and controls described herein. An example of a distributed controller for such purposes would be one or more integrated circuits on a chamber in communication with one or more integrated circuits located remotely (such as at the platform level or as part of a remote computer) that combine to control a process on the chamber.

Without limitation, example wafer handling systems may include or have attached to them a plasma etch chamber or module, a deposition chamber or module, a spin-rinse chamber or module, a metal plating chamber or module, a clean chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an atomic layer deposition (ALD) chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, and any other semiconductor processing systems that may be associated or used in the fabrication and/or manufacturing of semiconductor wafers.

As noted above, depending on the process step or steps to be performed by the tool, the controller might communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout a factory, a main computer, another controller, or tools used in material transport that bring containers of wafers to and from tool locations and/or load ports in a semiconductor manufacturing factory.

Claim 1:
A wafer handling system comprising:
a robot arm (<NUM>) including:
a base (<NUM>);
a first movable link (<NUM>), a first end (706A) of the first movable link rotatably connected to the base via a first rotational joint (<NUM>);
a second movable link (<NUM>), a first end (708A) of the second movable link rotatably connected to a second end (706B) of the first movable link via a second rotational joint (<NUM>);
a first rotational drive transfer mechanism (<NUM>) including a first pulley (<NUM>), a second pulley (<NUM>), and one or more first belts (<NUM>) spanning between the first pulley and the second pulley, wherein:
the second pulley is fixedly connected with the second movable link, and
the first rotational drive transfer mechanism is configured such that rotation of the first pulley relative to the first movable link causes the second pulley and the second movable link to rotate relative to the first movable link about a center axis of the second rotational joint;
a first motor (<NUM>), the first motor located in the base and having a rotational output connected to the first movable link and configured to drive the first movable link;
a second motor (<NUM>), the second motor located in the base and having a rotational output connected to the first pulley and configured to drive the first pulley;
a first rotational encoder (<NUM>) with a first portion fixedly connected with the base and a second portion fixedly connected with the first movable link; and
a second rotational encoder (784A) with a first portion fixedly connected with the first movable link and a second portion fixedly connected with the second movable link,
wherein:
interior spaces of the base, the first movable link, and the second movable link are in fluidic communication with one another within the robot arm,
the first rotational joint and the second rotational joint are both equipped with vacuum-tight seals (<NUM>),
the first rotational joint is hollow along its centerline and a portion of a wiring connected to the second encoder is disposed in the hollow of the first rotational joint,
each of the one or more first belts is a v-belt, a flat belt, a toothed belt, or a round belt, and
each of the one or more first belts is made from a material that includes a polymeric material or a polymeric material in combination with a textile.