Patent Description:
Some semiconductor processing tools process multiple wafers within a common chamber simultaneously and use a rotational indexer to move wafers from processing station to processing station within the chamber. In such semiconductor processing tools, the processing stations may generally be laid out such that the wafer center points are equidistantly spaced along a circular path. A rotational indexer that includes a central hub and multiple arms that radiate outwards from that central hub may be used to move the wafers from station to station; the end of the arms may have some form of wafer support that may be used to support wafers being moved by the indexer. Moving the wafers from station to station using such a device is referred to as "indexing" the wafers. Generally, the number and angular spacing of the arms on the indexer will correspond with the number and angular spacing of the processing stations about the circular path's center point. For example, in a four-station chamber, there may be four arms on the indexer, each oriented at <NUM>° from the adjacent arms. Wafers may be placed on the arms and the central hub and the arms connected thereto may be rotated as a unit about the center point of the circular path, thereby moving the wafers from station to station.

<CIT> discloses an apparatus for polishing substrates; comprising: at least two substrates to be polished; at least two second polishing surfaces; a rotatable carousel; at least two first substrate head assemblies suspended from said carousel and holding thereon respective ones of said substrates; a positioning member coupled to said carousel to move said carousel and thereby position a selected one of said substrate heads over a selected one of said polishing surfaces.

<CIT> and <CIT> disclose two robot arms comprising end effectors which can be adjusted independently using several motors for translating and rotating substrates between cells in a cluster tool.

The invention is defined in the appended independent claims.

In some implementations, an apparatus may be provided that includes a base, a first motor, a second motor, and a first hub. The first motor may be configured to rotate the first hub about a center axis of the first hub and relative to the base, and the apparatus may further include N indexer arm assemblies, each indexer arm assembly including a) a wafer support and b) an indexer arm having a proximal end connected with the first hub and a distal end rotatably connected with the wafer support. Each wafer support may be configured to rotate relative to the indexer arm that supports it about a rotational axis of that wafer support. N may be selected such that there are two or more indexer arm assemblies. The apparatus may further include an actuation mechanism that may be configured to actuated by the second motor and that may be further configured to cause the wafer supports of the indexer arms to simultaneously rotate about the corresponding rotational axes of the wafer supports and relative to the indexer arms responsive to rotation of the first motor, the second motor, or the first motor and the second motor.

In some implementations of the apparatus, the actuation mechanism may include a second hub that is configured to rotate about the center axis of the first hub responsive to actuation by the second motor, and each indexer arm assembly may further include a tie-rod with a proximal end that is rotatably connected with the second hub by a first rotatable interface and a distal end that is rotatably connected with the wafer support of that indexer arm assembly by a second rotatable interface. In such implementations, the actuation mechanism and indexer arm assemblies may be configured such that relative rotation between the first hub and the second hub about the first center axis causes the tie-rods to translate in a generally radial manner relative to the first center axis, thereby causing each tie-rod to rotate the wafer support to which that tie-rod is rotatably connected to rotate relative to the indexer arms and about the rotational axis of that wafer support.

In some implementations of the apparatus, the first hub and the second hub may be configured to be rotatable relative to each other from a first relative rotational position to a second relative rotational position.

In some implementations of the apparatus, the indexer arms, the tie-rods, and the wafer supports may be made of a ceramic material.

In some implementations of the apparatus, each indexer arm assembly may include a third rotatable interface that rotatably connects the wafer support for that indexer arm assembly with the indexer arm for that indexer arm assembly, and the first rotatable interfaces, the second rotatable interfaces, and the third rotatable interfaces may all be ceramic ball bearings.

In some implementations of the apparatus, there may be four indexer arm assemblies. Moreover, each of the wafer supports may be in a third relative rotational position with respect to the first hub when the first hub and the second hub are in the first relative rotational position and in a fourth relative rotational position with respect to the first hub when the first hub and the second hub are in the second relative rotational position; the third relative rotational positions and the fourth relative rotational positions may be <NUM>° out of phase with one another in such an implementation.

In some implementations of the apparatus, the apparatus may include a stop mechanism that is configured to limit relative rotational motion between the first hub and the second hub to between <NUM>° and <NUM>°.

In some implementations of the apparatus, the proximal end of each tie-rod may have an uppermost surface directly above the first rotatable interface for that tie-rod, each first rotatable interface may be horizontally spaced apart from the nearest other first rotatable interface by a first distance, each tie-rod may include an offset region extending between a first longitudinal distance from a rotational center of the first rotatable interface for that tie-rod and a second longitudinal distance from the rotational center of the first rotatable interface for that tie-rod, the first longitudinal distances may be less than the first distances and the second longitudinal distances are greater than the first distances, and the offset region of each tie-rod may have a lowermost surface that is higher than the uppermost surface of the distal end of the tie-rod from an adjacent indexer arm assembly, thereby allowing the distal end of the tie-rod from the adjacent indexer arm assembly to pass underneath that tie-rod when the first hub and the second hub are in the first relative rotational position.

In some implementations of the apparatus, each of the wafer supports may be in a third relative rotational position with respect to the first hub when the first hub and the second hub are in the first relative rotational position and in a fourth relative rotational position with respect to the first hub when the first hub and the second hub are in the second relative rotational position; in such implementations, the third relative rotational positions and the fourth relative rotational positions may be <NUM>°/N out of phase with one another.

In some implementations of the apparatus, the hub may include a separate mounting interface for each indexer arm assembly, each mounting interface may include a tensionable interface and three conical recesses arranged around the tensionable interface. A sphere may be nestled in each conical recess and each indexer arm may include an aperture through which the tensionable interface protrudes and three grooves radiating outward relative to the aperture. Each sphere of the corresponding mounting interface may also be nestled in a corresponding groove of that indexer arm, and the tensionable interfaces may each be configured to compress the spheres between a corresponding one of the indexer arms and a corresponding one of the mounting interfaces.

In some implementations of the apparatus, the tensionable interface associated with each indexer arm may include a threaded component and a spring that is configured to compress that indexer arm against the spheres interposed between that indexer arm and the mounting interface that connects that indexer arm with the first hub when the threaded component is tightened and placed in tension.

In some implementations of the apparatus, the apparatus may further include a motor housing containing the first motor and the second motor and supporting the first hub via a first hub rotational interface, and may also include a z-axis drive system configured to translate the motor housing along a vertical axis responsive to actuation of the z-axis drive system.

In some implementations of the apparatus, the apparatus may further include a semiconductor processing chamber housing, the semiconductor processing chamber housing having N processing stations, each processing station including a pedestal configured to support a semiconductor wafer.

In some implementations of the apparatus, the processing stations may be configured for performing a semiconductor processing operation selected from the group consisting of: deposition operations, etch operations, curing operations, and heat treatment operations.

In some implementations of the apparatus, the apparatus may further include a controller having a memory and one or more processors. The memory and the one or more processors may be communicatively connected, the one or more processors may be configured to control the first motor and the second motor, and the memory may store computer-executable instructions for controlling the one or more processors to cause one or more of the first motor, the second motor, and the first motor and the second motor to be selectively actuated to cause: the first hub and the indexer arm assemblies to rotate such that each wafer support moves from a corresponding one of the processing stations to a neighboring processing station of the processing stations, first relative rotational motion between the first hub and the second hub such that each wafer support rotates about the rotational axis of that wafer support and relative to the first hub by a first amount in a first direction during movement from processing station to processing station, while the wafer supports are resident at each processing station, or during both movement from processing station to processing station and while the wafer supports are resident at each processing station, and second relative rotational motion between the first hub and the second hub such that each wafer support rotates about the rotational axis of that wafer support and relative to the first hub by a first amount in a second direction opposite the first direction during movement from processing station to processing station, while the wafer supports are resident at each processing station, or during both movement from processing station to processing station and while the wafer supports are resident at each processing station.

In some implementations of the apparatus, N may equal <NUM> and the memory may store further computer-executable instructions for controlling the one or more processors to cause the first motor to rotate the first hub by <NUM>° in the first direction while the second hub is kept stationary.

In some implementations, a method may be provided that includes a) picking a plurality of wafers up off of a corresponding plurality of pedestals using an indexer having a corresponding plurality of wafer supports, each wafer support rotatably mounted to a distal end of an indexer arm of the indexer and each indexer arm mounted to a hub of the indexer, wherein the wafers are supported by the wafer supports; b) rotating the hub and the indexer arms about a first rotational axis to move each wafer support from a position above each of the pedestals to a position above an adjacent one of the pedestals; c) placing the wafers onto the pedestals after (b); and d) rotating the wafer supports relative to the indexer arms and about rotational axes of wafer supports in between (a) and (c).

In some implementations of such a method, the indexer may have four indexer arms and (b) may include rotating the hub and the indexer arms by <NUM>° and (d) may include rotating the wafer supports relative to the indexer arms by <NUM>°.

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. For the sake of brevity, many of those permutations and combinations will not be discussed and/or illustrated separately herein.

The rotational indexers with additional rotational axes disclosed herein differ from conventional rotational indexers in that they possess additional degrees of rotational freedom at the distal ends of the indexer arms. For example, in a conventional indexer, the only rotation that is provided is of the entire hub/arm structure about the center axis of the indexer-as a result, when the hub/arm structure is rotated, the items carried at the end of each arm rotate in the same manner about the same rotational axis. This causes the items, e.g., semiconductor wafers, to maintain the same orientation with respect that that rotational axis-for example, the same portion of each item will always be closest to the rotational center axis.

This may be seen in <FIG>, which is a schematic diagram showing wafer rotation in a conventional rotational indexer. Three indexer positions are shown-the starting position is at top, an intermediate position in the middle, and a terminal position at the bottom (this is for a single set of wafer movements from the positions shown at top to the positions shown at bottom). Each wafer <NUM> has a short line/mark at the outermost edge; then the indexer <NUM> is rotated, all four wafers <NUM> rotate about the rotational axis of the indexer <NUM>. As a result, the edges of the wafers <NUM> with the lines/marks remain the edges of the wafers furthest from the rotational axis of the indexer <NUM> throughout the rotational movement. Put another way, the orientation of each wafer relative to the arm that supports it remains unchanged.

Indexers according to the present disclosure, however, are able to provide for additional degrees of rotational motion such that the orientation of the wafers relative to the arms can be altered during, before, and/or after rotational movement of the indexer. As a result, the edges or portions of the edges of the wafers closest to the indexer rotational axis may be changed so that different sides of the wafers may be located closest to the rotational center of the indexer at each station. Thus, such indexers may not only "index" the wafer between different positions, but may also "spin" the wafers during, before, or after such "indexing" movement.

This may be seen in <FIG>, which is a schematic diagram showing wafer rotation supported by a rotational indexer with additional rotational axes, as discussed above and elsewhere herein. <FIG> has a similar layout to <FIG>, with three positions of a rotational indexer <NUM> shown, along with wafers <NUM>. As can be seen in the topmost position, the short lines/marks along the outer edges of the wafers <NUM> are all furthest from the rotational center of the indexer <NUM> and are generally aligned with the arms of the indexer <NUM>. In the middle position, the indexer <NUM> has rotated <NUM>° clockwise, but the wafers <NUM> have also been rotated by the same amount in a counterclockwise direction. As a result, the orientation of each wafer <NUM> relative to the arm that supports it changes, with the wafers <NUM> being rotated by <NUM>° relative to the arms in the lower position. This causes different edges of the wafers <NUM> to be furthest from the rotational center of the indexer <NUM> than in the top position in <FIG>.

<FIG> depicts a top view of part of an example semiconductor processing tool having a rotational indexer that is an example of the rotational indexers discussed herein. In <FIG>, a semiconductor processing tool <NUM> is shown that has a processing chamber <NUM> that includes four semiconductor processing stations <NUM>, each of which has a pedestal <NUM>. The semiconductor processing stations <NUM> are arranged in a radial or circular array about a center axis, and a rotational indexer <NUM> is provided that is configured to rotate about that center axis. The rotational indexer <NUM> may have a plurality of indexer arms <NUM>, e.g., four indexer arms in this example, that are attached to a first hub <NUM> at a proximal end <NUM> such that when the first hub <NUM> is rotated about the center axis (see center axis <NUM> in <FIG>), the arms <NUM> rotate with it. Distal ends <NUM> of the indexer arms <NUM> may be provided with wafer supports <NUM>, each of which may be configured to be rotatable relative to the indexer arm <NUM> that supports it and about a rotational axis that is located at that distal end <NUM> (such rotational axes are depicted in <FIG> as rotational axes <NUM>). Each wafer support <NUM> may be configured to support a wafer <NUM> (wafers <NUM> are shown in dotted outline to allow components of the indexer arms to be more easily seen) during movement of the wafers <NUM> between processing stations <NUM>.

<FIG> depicts a perspective, partially-exploded view of the example rotational indexer of <FIG>. As can be seen in <FIG>, one of the indexer arm assemblies <NUM> is shown in an exploded fashion; the other indexer arm assemblies <NUM> are shown in their assembled states as they would be arranged when fastened to a first hub <NUM> (only one indexer arm assembly <NUM> is numbered). For reference, one of the indexer arm assemblies s is shown supporting a wafer <NUM>, which is shown as partially transparent and with a dotted edge so as to not obscure features of the indexer arm assembly <NUM>. Each indexer arm assembly <NUM> may include an indexer arm <NUM> that has a proximal end <NUM> that is connected, either directly or indirectly, with the first hub <NUM>. Each indexer arm assembly <NUM> may also include a wafer support <NUM> that is rotatably mounted to the distal end <NUM> of the indexer arm <NUM>. The wafer support, may, for example, be a small plate or platform that is configured to support a semiconductor wafer. The wafer support <NUM> may be able to rotate about a rotational axis of the wafer support, e.g., an axis that passes through the center of a semiconductor wafer that the wafer support <NUM> is designed to support, relative to the indexer arm <NUM> that supports it.

Generally speaking, the first hub <NUM>, and the indexer arm assemblies <NUM> attached thereto, may be rotatable about a rotational axis of the first hub <NUM> to move wafers <NUM> from station to station. In addition to such rotation, the indexer <NUM> may also include an actuation mechanism that may be configured to cause all of the wafer supports <NUM> to simultaneously rotate relative to the indexer arms <NUM> and about respective rotational axes located in the distal ends <NUM> of the indexer arms <NUM>. The actuation mechanism may be further configured to cause all of the wafer supports <NUM> to rotate simultaneously responsive to a single mechanical input. For example, a common rotational drive shaft located in the center of the rotational indexer <NUM> may be connected with drive shafts extending along each indexer arm <NUM> through bevel or other types of gearing; each drive shaft may, in turn cause the wafer supports <NUM> to rotate responsive to rotation of the drive shaft. In an alternative implementation, flexible belts, e.g., thin stainless steel belts, may be looped between pulleys attached to each wafer support <NUM> and a common rotational drive shaft so that rotation of the drive shaft relative to the indexer arms <NUM> causes the wafer supports <NUM> to also rotate relative to the indexer arms <NUM>.

In some implementations, the actuation mechanism may utilize an array of movable linkages to cause the wafer supports <NUM> to rotate relative to the indexer arms <NUM>. The example rotational indexer <NUM> in <FIG> and <FIG> includes such a mechanism. As can be seen in <FIG>, the actuation mechanism of the rotational indexer <NUM> includes a second hub <NUM>. The second hub <NUM> may be configured to rotate about the same rotational axis that the first hub <NUM> is configured to rotate about. The first hub <NUM> and the second hub <NUM> may be independently rotatable such that the first hub <NUM> and the second hub <NUM> may be placed in a variety of different angular orientations relative to one another.

In such an actuation mechanism, each indexer arm assembly <NUM> may further include a tie-rod <NUM> that extends along the length of the corresponding indexer arm <NUM>. Each tie-rod <NUM> may have a proximal end <NUM> that is rotatably connected with the second hub <NUM> via a first rotatable interface <NUM> and a distal end <NUM> (see <FIG>) that is rotatably connected with a corresponding wafer support <NUM> via a second rotatable interface <NUM>. The first rotatable interface <NUM> and the second rotatable interfaces <NUM> may be located some distance from the center axis <NUM> and the rotational axes <NUM>, respectively, so as to define a moment arm about each axis. The rotational axes <NUM> may, for example, be rotational axes for third rotatable interfaces <NUM>, which may rotatably couple the wafer supports <NUM> to their respective indexer arms <NUM>.

When relative rotational motion between the first hub <NUM> and the second hub <NUM> about the center axis <NUM> is induced, the tie-rods <NUM> are moved in a generally radial manner (there is some tangential motion as well as the tie-rods <NUM> move away from and then closer to the adjacent indexer arms <NUM>) that causes the wafer supports <NUM> to which they are rotatably connected to rotate about the rotational axes <NUM> relative to the indexer arms <NUM> to which the wafer supports <NUM> are attached. When the relative rotational motion between the first hub <NUM> and the second hub <NUM> is non-existent, then the wafer supports <NUM> will remain fixed in position relative to the indexer arms <NUM>.

Such a rotational indexer may thus be driven so as to provide rotation of the wafer supports <NUM> relative to the indexer arms <NUM> without any corresponding rotation of the indexer arms <NUM> (by rotating the second hub <NUM> while keeping the first hub <NUM> stationary), rotation of the indexer arms <NUM> about the center axis <NUM> without any corresponding rotation of the wafer supports <NUM> relative to the indexer arms <NUM> (by rotating the first hub <NUM> and the second hub <NUM> in synchrony (and by the same amount), and rotation of the indexer arms <NUM> about the center axis <NUM> with simultaneous rotation of the wafer supports <NUM> relative to the indexer arms <NUM> (by rotating the first hub <NUM> not in synchrony with the second hub <NUM>, e.g., by rotating the first hub <NUM> about the center axis <NUM> while keeping the second hub <NUM> stationary or by rotating the first hub <NUM> and the second hub <NUM> about the center axis <NUM> at different rates).

In some implementations, such as in the depicted example, the distances between each of the first rotatable interfaces <NUM> and the center axis <NUM> may be equal to the distances between each of the second rotatable interfaces <NUM> and the corresponding rotational axes <NUM> may be equal such that the moment arms defined by the tie-rods <NUM> are the same. In such an implementation, the relative rotation between the wafer supports <NUM> and the indexer arms <NUM> may be the same as the relative rotation between the first hub <NUM> and the second hub <NUM>. Such an implementation may be particularly efficient since this may cause each wafer to be kept in the same absolute orientation (relative to the semiconductor processing tool, for example) regardless of which processing station that wafer is moved to by the rotational indexer <NUM> when each wafer transfer from one station to the next is accomplished by rotating only the first hub <NUM> while keeping the second hub <NUM> stationary.

<FIG> depicts a side section view of the example rotational indexer of <FIG>. As shown in <FIG>, the rotational indexer <NUM> may include a base <NUM> that may be mounted in the semiconductor processing tool <NUM>. The base <NUM> may house various systems that may be used to actuate the rotational indexer <NUM>. For example, the base <NUM> may have a motor housing <NUM> that may house a first motor <NUM> and a second motor <NUM>. The first motor <NUM> may be connected with the first hub <NUM> by a first shaft <NUM>, and the second motor <NUM> may be connected with the second hub <NUM> by a second shaft <NUM>. Thus, the first motor <NUM> may be actuated to rotate the first hub <NUM>, and the second motor may be actuated to rotate the second hub <NUM>.

In some implementations, the rotational indexer <NUM> may also be configured for vertical movement as well. For example, a z-axis drive system <NUM> may be provided to drive the motor housing <NUM>, the first motor <NUM>, the second motor <NUM>, the first hub <NUM>, and the second hub <NUM> up and down vertically, thereby causing the indexer arms <NUM> to move vertically. The z-axis drive system <NUM> may include, in some implementations, a third motor <NUM> configured to rotate a threaded shaft <NUM> that passes through a ball-screw <NUM> attached to the motor housing <NUM>, thereby causing vertical movement when the third motor <NUM> is actuated.

In implementations having an actuation mechanism such as that discussed above in which the wafer supports <NUM> rotate relative to the indexer arms <NUM> about the axes <NUM> by the same amount that the first hub <NUM> and the second hub <NUM> rotate relative to one another, the first rotatable interfaces <NUM> that link the tie-rods <NUM> to the second hub <NUM> may, during such relative rotation between the first hub <NUM> and the second hub <NUM>, be moved so as to be in the same position as an adjacent first rotatable interface <NUM> was in prior to such rotation. <FIG> depicts a detail view of the center of the example rotational indexer of <FIG>, which is an example of such a rotational indexer, with some additional components removed, e.g., with an indexer arm assembly <NUM>, the first hub <NUM> removed, and various other components omitted.

As shown in <FIG>, the tie-rods <NUM> may further include an offset region <NUM>. The offset regions <NUM> may extend along the length of the tie-rods <NUM>, i.e., in a longitudinal direction, for some distance. Each offset region <NUM> may be considered to start at location that is a first longitudinal distance <NUM> from the rotational center axis of the first rotatable interface <NUM> for that offset region's tie-rod <NUM> and may considered to end at a location that is a second longitudinal distance <NUM> from the rotational center axis of the first rotatable interface <NUM> for that offset region's tie-rod <NUM>. Generally speaking, the first longitudinal distance <NUM> and the second longitudinal distance <NUM> may be selected so as to be less than and greater than, respectively, a first distance <NUM> between the rotational center axes of adjacent first rotatable interfaces <NUM>. As shown in <FIG>, the first rotatable interfaces <NUM> are represented by dotted outlines, and a post <NUM> that interfaces with the missing first rotatable interface <NUM> is depicted (the first rotatable interfaces <NUM> in this example are rotational bearing assemblies, e.g., ball bearings, roller bearings, or other similar devices).

Each offset region <NUM> may be configured such that the tie-rod <NUM> of which it is part does not contact or collide with the proximal end <NUM> of an adjacent tie-rod <NUM> during rotational motion as described above, i.e., when each first rotatable interface <NUM> is advanced in position to the location last occupied by an adjacent first rotatable interface <NUM>. Thus, the tie-rod <NUM> may, in the offset region <NUM>, include a jog or other deviation from the general shape of the tie-rod <NUM>.

In the implementation shown in <FIG>, for example, the offset region <NUM> includes a lowermost surface <NUM> (not shown in <FIG>, but see <FIG>) that is positioned at an elevation that is, when the rotational indexer is positioned with the center axis <NUM> in a vertical orientation and with the base <NUM> below the indexer arms <NUM>, higher than an uppermost surface <NUM> of the proximal end <NUM> of the adjacent tie-rod <NUM> directly above the first rotatable interface <NUM> of that adjacent tie-rod <NUM>. This allows the proximal ends <NUM> of the tie-rods <NUM> to pass underneath the offset regions <NUM> (without any of the tie-rods <NUM> contacting each other) of the adjacent tie-rods <NUM> when each first rotatable interface <NUM> is advanced in position to the location last occupied by an adjacent first rotatable interface <NUM>. <FIG> is a detail view showing how the proximal end <NUM> of a tie-rod <NUM> may pass underneath the offset region <NUM> of another tie-rod <NUM>.

The offset region concept may also be employed in a manner that is "horizontal" instead of "vertical. " For example, <FIG> depicts such an implementation. As can be seen, the offset region <NUM> is offset from a nominal centerline (dash-dot-dot line in this Figure) of the tie-rod <NUM> by a distance D, which may be selected such that a proximal end <NUM> of an adjacent tie-rod <NUM> may be moved into the position shown without contacting the tie-rod <NUM> shown in <FIG> as having the offset region <NUM>.

The rotational indexers with additional rotational axes disclosed herein may be particularly advantageous when used in certain types of semiconductor processing equipment. For example, in multi-station deposition or etch processing tools, there may be process non-uniformities in the wafers that are biased towards the center of the array of processing stations, e.g., towards the center axis <NUM>.

If a conventional rotational indexer is used to move wafers from station to station in such a semiconductor processing tool, then the wafers may be subjected to such non-uniformities at each processing station and in the same manner, as the same edges of the wafers may be closest to the center axis <NUM> at every station. However, if a rotational indexer with additional rotational axes, as disclosed herein, is used to move wafers from station to station in such a semiconductor processing tool, then the wafers may be rotated from station to station such that a different edge or portion of the edge of the wafers may be closest to the center axis <NUM> at each station. This may help average out or mitigate the non-uniformities, thereby enhancing wafer processing quality.

If the rotational indexers with additional rotational axes discussed herein are used in certain contexts, e.g., in deposition or etch processing semiconductor processing tools, it may be advantageous in some such circumstances to include further features beyond those described above. For example, in some implementations, the indexer arms <NUM>, the tie-rods <NUM>, and/or the wafer supports <NUM> may be manufactured from a ceramic material, such as aluminum oxide, that has a low coefficient of thermal expansion, e.g., on the order of <NUM>/m/C, and that is generally resistant to corrosion or chemical attack. Deposition and etching operations may involve elevated temperatures or large temperature swings that cause the rotational indexer to heat up and experience thermal expansion. Due to the length of the indexer arms <NUM>, such thermal expansion (or contraction, if there is cooling) may cause the wafers being supported by the indexer arms to be slightly misaligned with the rotational axes <NUM> of the wafer supports <NUM>, which may, in turn, cause the wafers to further misalign when rotated about those rotational axes <NUM>. While some degree of misalignment may be acceptable, the use of a ceramic or other material with a low coefficient of thermal expansion may allow such misalignment to be reduced, minimized, or otherwise kept to an acceptable level. In some cases, additional components in the indexer arm assemblies <NUM> may also be made from similar materials. For example, the first, second, and third rotatable interfaces <NUM>, <NUM>, and <NUM> may be ceramic ball bearings, ceramic roller bearings, or ceramic thrust bearings, e.g., bearings with inner and outer races, as well as rolling elements, that are made from a ceramic material. Other elements of the indexer arm assemblies <NUM> may also be made of ceramic material, e.g., screws, bearing caps, retainer cups, and so forth. The first hub <NUM> and the second hub <NUM> may also be made of ceramic material, but may, in many implementations, be made of a more robust and easier to manufacture material, e.g., stainless steel or aluminum. Such metal-based materials may be more susceptible to chemical attack, but may also be more isolated from active species used in semiconductor processing due to the fact that the first hub <NUM> and the second hub <NUM> may remain in the center of the processing chamber housing <NUM> and do not pass through the processing stations <NUM> at any time, regardless of the rotational movement undergone.

In such implementations, the indexer arm assemblies <NUM> may be connected with the first hub <NUM> via a corresponding number of mounting interfaces. Such mounting interfaces may allow for the indexer arm assemblies <NUM> to be easily installed, aligned with the center axis <NUM>, and secured in place relative to the first hub <NUM>.

<FIG> depicts another perspective, partially-exploded view of the example rotational indexer of <FIG>. <FIG> depicts a perspective, partially-exploded view of the example rotational indexer of <FIG> showing the underside of the example rotational indexer. In <FIG> and <FIG>, details of one example mounting interface are depicted (such features are also visible in <FIG>).

In <FIG> and <FIG>, a mounting plate <NUM> may be provided that includes a plurality, e.g., three, conical recesses <NUM> that are arrayed about a central mounting location, e.g., a threaded hole. In the depicted example, the three conical recesses <NUM> that are depicted are arranged in an evenly spaced circular pattern about the central mounting location.

Each conical recess <NUM> may have a spherical bearing <NUM> nestled within it; the spherical bearings may be made of the same material as either the indexer arms <NUM> or the mounting plate <NUM>, or may be made of a different material, if desired.

The indexer arms <NUM> may include an aperture <NUM> (see <FIG>) that may be configured to receive a tensionable interface <NUM> that may be connected with the mounting plate <NUM>. The tensionable interface <NUM> may be tightened to draw the indexer arms <NUM> closer to the mounting plate <NUM>, thereby compressing the spheres <NUM> in between the two components. The tensionable interface <NUM> may, for example, include a threaded component <NUM>, e.g., a screw or bolt, and a spring <NUM>, e.g., a Belleville washer, and potentially an adapter, such as that pictured, to transfer the compressive force generated by the threaded component <NUM> to the spring <NUM>. Thus, when the threaded component <NUM> is screwed into the mounting plate <NUM>, the spring <NUM> may be compressed, thereby exerting compressing force on the indexer arm <NUM>. Of course, the spring <NUM> may not be used in some implementations, although its presence may reduce the risk of overtightening and may also act to help spread the compressive load onto the indexer arm. For a ceramic indexer arm <NUM>, this may be particularly advantageous since it may reduce the risk of initiating cracks in the ceramic components.

To aid in properly aligning the indexer arm assemblies <NUM> relative to the mounting plate, the undersides of the indexer arms <NUM> that contact the spheres <NUM> may include a plurality of grooves <NUM> that may be configured to receive the spheres <NUM> when the assembly is bolted together. Each groove <NUM> for a particular indexer arm <NUM> may, for example, follow a radial path extending outwards from the center of the aperture <NUM> so that during thermal expansion or contraction of the mounting plate <NUM> relative to the indexer arm <NUM>, the spheres <NUM> may slide radially inward or outward along the grooves from a common point (the center of the aperture <NUM>) without binding and without causing the indexer arm <NUM> to move off-center from, for example, the center of the tensionable interface. Since the mounting plate <NUM> may be made of aluminum or stainless steel in some implementations, for example, and the indexer arms <NUM> may be made of a ceramic material in such implementations, interfaces such as the above groove/sphere/conical recess interfaces may allow for such components to experience different thermal expansion behavior (due to the different coefficients of thermal expansion in play) without causing misalignment or undue stress. Such a kinematic mount may be constructed using ceramic spheres such that if there is sliding motion between the spheres <NUM> and the grooves <NUM>, but little or no motion between the spheres <NUM> and the conical recesses <NUM> (the conical recesses <NUM> having a greater contact area with the spheres <NUM> than the grooves <NUM>, thereby seeing a generally higher friction loading (assuming that the coefficients of friction are generally equivalent) relative to the conical recesses <NUM> than to the grooves <NUM>), thereby preventing sliding/abrasive movement between ceramic and non-ceramic, e.g., metal, parts.

In the depicted example, the indexer arm assemblies <NUM> may be mounted to the mounting plates <NUM>, and the resulting assemblies may then be mounted to the first hub <NUM>. Before bolts that secure the mounting plates <NUM> to the first hub <NUM> are tightened, a fixture may be mounted to the rotational indexer <NUM>. The fixture, for example, may have a centering feature that allows it to be centered on the first hub <NUM> or the second hub <NUM>, as well as arms or other structure that extends out at least some distance along the indexer arms <NUM>. The fixture may be secured to the rotational indexer <NUM> in a centered position, and then each indexer arm assembly <NUM> may be adjusted so that alignment features, e.g., holes, on the indexer arm assemblies <NUM> interface with corresponding alignment features on the fixture. After each indexer arm assembly <NUM> has been aligned with the fixture, the mounting plate <NUM> for that indexer arm assembly may be clamped in place by tightening the fasteners that secure it to the first hub <NUM>. Once all of the indexer arm assemblies <NUM> are installed and secured in place, the fixture may be removed before using the rotational indexer <NUM>. In other implementations, other types of mounting interfaces may be used to secure the indexer arm assemblies <NUM> to the first hub <NUM>.

Also visible in <FIG> and <FIG> are a stop mechanism that may include, for example, a stop <NUM> and an arc-shaped groove or recess <NUM>. The stop mechanism may allow the first hub <NUM> and the second hub <NUM> to only rotate relative to one another by a predefined amount, e.g., <NUM>° to <NUM>° in the case of a four-arm indexer, to prevent over-rotation that might cause the actuation mechanism to bind or be damaged.

<FIG> depict the example rotational indexer of <FIG> through various states of actuation of the rotatable wafer supports located at the distal ends of the indexer arms. In this example, the first hub <NUM> is kept stationary and the second hub <NUM> is rotated in a clockwise manner (by <NUM>° between each consecutive pair of Figures). The outlines of the positions of the moving parts in each previous Figure are depicted in dashed or broken lines. It will be understood that if the first hub <NUM> is rotated while the second hub <NUM> is held stationary, the wafer supports <NUM> will rotate in exactly the same manner relative to the indexer arms <NUM> at the same time that all of the indexer arms <NUM> rotate about the center axis <NUM>. Thus, wafers supported by the wafer supports <NUM> may be simultaneously moved from station to station and rotated during each such movement so that the absolute angular orientation of the wafers relative to the word coordinate system remains the same.

In some implementations, particularly for rotational indexers used in semiconductor processing equipment that performs deposition operations, additional features may be provided to route a purge gas, e.g., argon, helium, or nitrogen, to the various rotatable interfaces. By allowing purge gas to flow through each rotatable interface, processing gases that might otherwise cause deposition to occur on the bearings may be flushed out of or away from the rotatable interfaces, thereby preventing deposition on the surfaces of such components and prolonging the lifespan of the rotatable interfaces.

<FIG> depicts part of a rotational indexer with various portions of some components cut away. In <FIG>, the second shaft (not numbered, but see <FIG>) may be hollow and may be used as a conduit to route purge gas to the second hub <NUM> at location <NUM>. The second hub <NUM> may have one or more conduits or gas pathways <NUM>, <NUM> that may fluidically connect with (or otherwise bias purge gas to flow towards) various ports or gas flow passages. For example, the posts <NUM> that may connect the second hub <NUM> with the first rotational interfaces <NUM> may have holes in them that fluidically connect with the purge gas flow paths. This may allow purge gas to be flowed up through the posts <NUM> and into the proximal ends <NUM> of the tie-rods <NUM>, where some of the purge gas may flow through the first rotational interface <NUM> (such as between the balls or rollers of the bearing) and the remainder of the purge gas flowing through the posts <NUM> may flow into passages <NUM> internal to the tie-rods <NUM>. The passages <NUM> that are within the tie-rods <NUM> may extend along the entire length of the tie-rods <NUM> until they exit into the distal ends <NUM> of the tie-rods <NUM>, thereby allowing the purge gas to also be flowed through the second rotatable interface <NUM>. In <FIG>, heavy black lines and arrows are used to show representative flow paths for the purge gas; dotted lines may be used in some locations to show general flow path directions in situations where the flow path itself has departed from the cutaway planes.

The indexer arms <NUM> may also have internal gas flow passages <NUM>' that may be provided with purge gas via passages or channels in the first hub <NUM> and the second hub <NUM>. Such purge gas may be flowed to the third rotatable interfaces <NUM> located at the distal ends <NUM> of the indexer arms <NUM> in order to protect the third rotatable interfaces <NUM> from unwanted deposition as well.

It is to be understood that other arrangements of gas flow passages and conduits may be used as well, and are considered to be within the scope of this disclosure.

<FIG> depicts an example flow diagram for one technique for controlling a rotational indexer with additional rotational axes; the rotational indexer in question includes N equally-spaced indexer arms, where N is an integer greater than <NUM>. The technique in <FIG> represents movements taken to sequentially advance a set of wafers from one station to the next in a semiconductor processing tool using such a rotational indexer. The technique may be repeated to perform further wafer advancement.

In block <NUM>, the wafers that are on each pedestal may be lifted off their respective pedestals, e.g., by activating a lift-pin system (in which pins located within each pedestal move upwards, or the pedestal moves downwards, in order to cause the wafer to be lifted off the pedestal upper surface to allow the wafer supports of the rotational indexer to be moved underneath the wafers.

In block <NUM>, the first motor and the second motor may be actuated so as to both rotate for +<NUM>°/N (or to cause the first hub to rotate for this amount); this assumes that each indexer arm is stowed midway between each station so as to not interfere with wafer processing operations when the rotational indexer is not in use. Such a rotation may cause the indexer arms and their wafer supports to move to locations where the wafer supports are underneath the wafers.

In block <NUM>, the lift pins may be lowered (or the rotational indexer elevated) to cause the wafers to be lifted off the lift pins by the wafer supports of the rotation indexer.

In block <NUM>, the first motor may be actuated so as to cause the first hub to rotate for <NUM>°/N while the second motor is inactive or otherwise unactuated. As a result, the indexer arms may be rotated to move the wafers from their stations to the next adjacent stations while at the same time, the wafer supports may rotate relative to the indexer arms by the same amount in the same direction so as to maintain the wafers in the same absolute angular orientation.

In block <NUM>, the lift pins may be used to lift the wafers off of the wafer supports (or the rotational indexer may be lowered to cause the wafer to rest on the lift pins and be lifted off the wafer supports).

In block <NUM>, the first motor may be actuated to cause the first hub to rotate for <NUM>°/N in the opposite direction as previous rotations while, at the same time, the second motor may be actuated to cause the second hub to rotate for <NUM>°/N in the same direction as previous rotations. Thus, the relative rotational movement between the first and second hubs will be -<NUM>°/N, which may cause the wafer supports to rotate into the same angular position relative to indexer arms that they were in in between blocks <NUM> and <NUM>, effectively resetting their positioning. At the same time, the indexer arms may be moved into their "stowed" positions midway between each pair of processing stations.

Once the indexer arms have cleared the processing stations, block <NUM> may be performed to lower the wafers onto the pedestals for a further semiconductor processing operation. As noted above, this process may be repeated as desired to continue to advance the wafers through the array of processing stations.

It will be understood, as discussed earlier, that there are many ways to control the rotational indexer to perform wafer transfers between stations. The first hub and the second hub may be driven so as to move simultaneously, move sequentially, move at different rates and/or in different directions, and so forth. It will be appreciated that all such different combinations of actuating the motors for operating the rotational indexers described herein are considered to be within the scope of this application.

As discussed above, in some implementations, a controller may be part of the rotational indexer systems discussed herein. <FIG> depicts a schematic of an example controller <NUM> with one or more processors <NUM> and a memory <NUM>, which may be integrated with electronics for controlling the operation of the first motor <NUM>, the second motor <NUM>, and, if present, the third motor <NUM> during wafer transfer operations. 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 rotational indexer, 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 rotational indexers according to the present disclosure may be mounted in or part of semiconductor processing tools with 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.

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.

Claim 1:
An apparatus for transferring wafers from station to station in a multi-station semiconductor processing chamber (<NUM>), the apparatus comprising:
a rotational indexer (<NUM>) for simultaneously moving multiple wafers between equidistantly-spaced locations along a circular path when the wafers are placed upon the rotational indexer (<NUM>) and the rotational indexer (<NUM>) is activated, the rotational indexer (<NUM>) including:
a base (<NUM>);
a first motor (<NUM>);
a first hub (<NUM>); and
N indexer arm assemblies (<NUM>), each indexer arm assembly (<NUM>) including a wafer support (<NUM>), wherein:
the first motor (<NUM>) is configured to rotate the first hub (<NUM>) about a center axis of the first hub (<NUM>) and relative to the base (<NUM>), and
N is an integer greater than or equal to two, the apparatus characterized in that:
the rotational indexer (<NUM>) further includes a second motor (<NUM>);
each indexer arm assembly (<NUM>) further includes an indexer arm (<NUM>) having a proximal end (<NUM>) fixedly connected with the first hub (<NUM>) and a distal end (<NUM>) rotatably connected with the wafer support (<NUM>) of that indexer arm assembly (<NUM>); and
the rotational indexer (<NUM>) further includes an actuation mechanism, wherein:
the second motor (<NUM>) is configured to provide rotational input to the actuation mechanism,
each wafer support (<NUM>) is configured to rotate relative to the indexer arm (<NUM>) of the corresponding indexer arm assembly (<NUM>) and about a rotational axis of that wafer support (<NUM>),
the rotational axis of each wafer support (<NUM>) is located so as to pass through a center of a corresponding one of the wafers when the wafer supports (<NUM>) are supporting the wafers, and
the actuation mechanism is configured to cause the wafer supports (<NUM>) of the indexer arms (<NUM>) to simultaneously rotate by the same amounts, in the same rotational directions, and about the corresponding rotational axes of the wafer supports (<NUM>) relative to the indexer arms (<NUM>) responsive to rotation of: the first motor (<NUM>) without rotation of the second motor (<NUM>), the second motor (<NUM>) without rotation of the first motor (<NUM>), or the first motor (<NUM>) and the second motor (<NUM>) such that the actuation mechanism actuates.