Composite end effector and method of making a composite end effector

A composite end effector including a lower sandwich panel having a first side and a second side opposite the first side, an upper sandwich panel having a first side and a second side opposite the first side, wherein the first side of the upper sandwich panel is bonded to the first side of the lower sandwich panel, and an intermediate element disposed between the second side of the lower sandwich panel and the second side of the upper sandwich panel. The intermediate element may include an electrical conductor, wherein an electrostatic chuck is electrically coupled to the electrical conductor through an aperture in the upper sandwich panel. Alternatively or additionally, the intermediate element may include a pair of optical fibers disposed within a pair of channels formed in at least one of the first side of the upper sandwich panel and the first side of the lower sandwich panel.

FIELD OF THE DISCLOSURE

Embodiments of the present disclosure generally relate to the field of substrate processing, and more particularly to a composite robotic end effector having an intermediate element and a method of making thereof.

BACKGROUND OF THE DISCLOSURE

Silicon substrates are used in the fabrication of semiconductors and solar cells. During such fabrication, the substrates are subjected to a multi-step manufacturing process that may involve a plurality of machines and a plurality of stations. Thus, the substrates need to be transported from one machine/station to another machine/station one or more times.

The transport of the substrates typically employs apparatuses called end effectors. A typical end effector may be a flat platform having a hand-like or claw-like appearance defined by a base unit with a plurality of flat fingers or tines extending therefrom. The fingers may be adapted to support a substrate in a horizontal orientation. During operation, the end effector may typically be moved linearly (e.g., forward and backward) as well as rotationally all in the same plane (e.g., x-y axis). The end effector may also be moved in a third direction along a z-axis to provide a full range of motion. It is generally desirable for end effectors to be formed of materials that are lightweight, that are stiff, and that do not produce contaminants (i.e., particulate matter) during use. It is also generally desirable for end effectors to have working surfaces (i.e., surfaces that engage substrates) that are very flat, hard, and easy to clean. Still further, it is generally desirable for end effectors to be very thin to facilitate insertion between silicon substrates that are stored in a stacked arrangement in close vertical proximity to one another, such as in a front opening unified pod (FOUP) or other storage medium.

It is common for end effectors to be provided with sensors and/or other components that facilitate the loading, unloading, positioning, and/or secure transport of silicon substrates. For example, an end effector may be provided with a photoelectric sensor, such as a through beam sensor, for detecting the presence or absence of substrates in a FOUP or other storage medium from which substrates can be collected for subsequent transport and processing. It is also common for end effectors to be provided with electrostatic chucks (“e-chucks”) that are capable of producing electrostatic forces for securely clamping substrates to an end effector during transport and/or processing.

Although sensors and components such as those described above may confer numerous advantages and benefits, they are also associated with a number of drawbacks. For example, the provision of such sensors and components, which are typically mounted on the top and/or bottom surfaces of an end effector, can increase the overall profile and thickness of an end effector. Furthermore, such sensors and components, including associated wiring, connectors, fasteners, etc., create irregularities on the otherwise flat surfaces of an end effector. Such surface irregularities can complicate, and therefore prolong, the cleaning of an end effector, thereby creating undesirable delays during manufacturing processes.

In view of the foregoing, it would be advantageous to provide an end effector having sensors and/or other components that aid in the loading, unloading, positioning, and/or secure transport of substrates, wherein such end effector has substantially flat, easy-to-clean surfaces. It would further be advantageous to provide such an end effector having a very thin profile.

SUMMARY

In general, various embodiments of the present disclosure provide a method and an apparatus for making a planar end effector. A first exemplary embodiment of a composite end effector accordance with the present disclosure may include a lower sandwich panel having a first side and a second side opposite the first side, an upper sandwich panel having a first side and a second side opposite the first side, wherein the first side of the upper sandwich panel is bonded to the first side of the lower sandwich panel, and an intermediate element disposed between the second side of the lower sandwich panel and the second side of the upper sandwich panel. The intermediate element may include an electrical conductor, wherein an electrostatic chuck is electrically coupled to the electrical conductor through an aperture in the upper sandwich panel. Alternatively or additionally, the intermediate element may include a pair of optical fibers disposed within a pair of channels formed in at least one of the first side of the upper sandwich panel and the first side of the lower sandwich panel.

An exemplary method of making a composite end effector in accordance with the present disclosure may include forming a lower sandwich panel from a first sheet of material, the lower sandwich panel having a first side and a second side opposite the first side, forming an upper sandwich panel from a second sheet of material, the upper sandwich panel having a first side and a second side opposite the first side, disposing an intermediate element between the first side of the lower sandwich panel and the first side of the upper sandwich panel, and bonding the first side of the lower sandwich panel to the first side of the upper sandwich panel. The method may further include forming an aperture in the upper sandwich panel, mounting an electrostatic chuck in the aperture, and coupling the electrostatic chuck to the intermediate element through the aperture, wherein the intermediate element is an electrical conductor. Additionally or alternatively, the method may include forming a first channel in at least one of the first side of the lower sandwich panel and the first side of the upper sandwich panel, and disposing the intermediate element within the channel, wherein the intermediate element is an optical fiber.

DETAILED DESCRIPTION

A low profile end effector having one or more embedded, intermediate elements in accordance with the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the end effector are shown. The end effector may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the end effector to those skilled in the art. In the drawings, like numbers refer to like elements throughout unless otherwise noted.

In accordance with a first exemplary embodiment of the present disclosure,FIG. 1illustrates a perspective view of a low profile end effector10having integrated e-chucks12a,12b,12c. For the sake of convenience and clarity, terms such as “top,” “bottom,” “upper,” “lower,” “vertical,” “horizontal,” “lateral,” “longitudinal,” “inner,” and “outer” may be used herein to describe the relative placement and orientation of the features and components of the end effector10, each with respect to the geometry and orientation of the end effector10as it appears inFIG. 1. Said terminology will include the words specifically mentioned, derivatives thereof, and words of similar import.

The end effector10may include a base portion14having two fingers16,18extending therefrom, and a wrist portion20having a mounting hub22and a plurality of mounting apertures24that may facilitate attachment of the end effector10to a robot or other manipulation device. The end effector10may further include e-chucks12a,12b,12cthat may be partially integrated into the fingers16,18and in the base portion14, respectively, as further described below. It will be understood that the particular configuration of the end effector10shown inFIG. 1is provided by way of example only, and that many other configurations may be similarly implemented without departing from the present disclosure. For example, alternative end effector designs may include only one finger or more than two fingers with corresponding integrated e-chucks.

Referring toFIG. 2, the end effector may be formed of a lower sandwich panel26, an upper sandwich panel28, and a ridigizing panel30that may be bonded together in a stacked, flatly-abutting arrangement as further described below. The lower sandwich panel26and the upper sandwich panel28may, in some embodiments, be substantially identical and may define the full footprint of the end effector10(i.e., the base portion14, the fingers16,18, and the wrist portion20shown inFIG. 1). The rigidizing panel30may only include the wrist portion20and a rear part of the base portion14of the end effector10footprint. Thus, a forward portion of the end effector10, including the fingers16,18and a forward part of the base portion14, may be relatively thin for facilitating insertion between substrates (not shown) stored in a stacked arrangement in close vertical proximity to one another, such as in a front opening unified pod (FOUP) or other storage medium. The rear portion of the end effector10, including the wrist portion20and a rear part of the base portion14, may be relatively thick for providing the end effector10with rigidity and support. A front edge31of the rigidizing panel30, which in the illustrated embodiment includes a concave contour, may be contoured so as not to interfere with substrates that are supported on the forward portion of the end effector10. Alternative embodiments of the end effector10are contemplated in which the rigidizing panel30is entirely omitted.

The lower sandwich panel26, upper sandwich panel28, and ridigizing panel30may be formed of any suitably rigid, lightweight, non-contaminating material. For example, the lower sandwich panel26, upper sandwich panel28, and ridigizing panel30may be formed of a carbon fiber composite (CFC). Other materials that may additionally or alternatively be used in the construction of the end effector10include, but are not limited to, aluminum, quartz, and ceramic.

The mounting hub22may include a base portion38that flatly engages a lower surface of the lower sandwich panel26, and may further include a mounting pin40that extends through vertically-aligned through holes41in the lower sandwich panel26, upper sandwich panel28, and ridigizing panel30. The mounting apertures24in the wrist portion20of the end effector10may extend through each of the lower sandwich panel26, the upper sandwich panel28, the ridigizing panel30, and the mounting hub22. It will be appreciated by those of ordinary skill in the art that the arrangement and configuration of the mounting hub22and/or the mounting apertures24can be varied without departing from the present disclosure.

The e-chucks12a,12b,12cof the of the end effector10may be operatively connected to an electrical conductor42(best shown in ghost dashed lines inFIG. 1) that may be sandwiched between the lower sandwich panel26and the upper sandwich panel28as further described below. In the illustrated embodiment, the electrical conductor may be a substantially planar, ribbon-like flex circuit. However, it is contemplated that the electrical conductor42may be any type of conductor capable of being disposed intermediate the lower sandwich panel26and the upper sandwich panel28without interfering with a substantially flat bond therebetween and without interfering with the planarity of the overall end effector10. In an alternative embodiment, it is contemplated the electrical conductor42may be partially or entirely disposed within a complimentary channel (not shown) formed in the lower sandwich panel26and/or in the upper sandwich panel28. Since the electrical conductor42is disposed intermediate or within the lower sandwich panel26and upper sandwich panel28, the electrical conductor42may be referred to generically as an “intermediate element” in the context of the present disclosure.

The e-chucks12a,12b,12cmay be connected to the electrical conductor42via electrical connectors44a,44b,44cthat may be disposed within respective apertures46a,46b,46cformed in the upper sandwich panel28(aperture46cis visible inFIG. 5). In one non-limiting example, the electrical connectors44a,44b,44cmay be elastomeric electrical connectors sold by Fujipoly Corporation under the trade name ZEBRA. In a contemplated alternative embodiment of the end effector10, the electrical connectors44a,44b,44cmay be omitted and the e-chucks12a,12b,12cmay be connected directly to the electrical conductor42.

The electrical connectors44a,44b,44cmay be seated on respective portions of the electrical conductor42. The electrical conductor42may be connected to an electrical power source (not shown) and may deliver electrical power to the e-chucks12a,12b,12cvia the electrical connectors44a,44b,44c, such as during operation of the e-chucks12a,12b,12c. The e-chucks12a,12b,12cmay thereby produce respective electromagnetic fields that may “clamp” a substrate to the end effector10in a manner that will be familiar to those of ordinary skill in the art. While the e-chucks12a,12b,12c, electrical connectors44a,44b,44c, and apertures46a,46b,46care shown as being circular in shape, it is contemplated that shapes of one or more of the e-chucks12a,12b,12c, electrical connectors44a,44b,44c, and apertures46a,46b,46ccan be varied without departing from the present disclosure. Moreover, while three e-chucks12a,12b,12care shown, it is contemplated that greater or fewer numbers of e-chucks can be used.

Referring toFIG. 3, a detailed cross section view illustrating the e-chuck12a, the electrical connector44a, and the associated portions of the electrical conductor42, lower sandwich panel26, and upper sandwich panel28is shown. The features and arrangement of e-chucks12b,12c, electrical connectors44b,44c, and associated portions of the electrical conductor42, lower sandwich panel26, and upper sandwich panel28are substantially identical to the configuration and features of the e-chuck12a, electrical connector44a, and associated portions of the electrical conductor42, lower sandwich panel26, and upper sandwich panel28. It will therefore be understood that the following description of the features and arrangement of the e-chuck12a, electrical connector44a, and associated portions of the electrical conductor42, lower sandwich panel26, and upper sandwich panel28shall also apply to the features and arrangement of the e-chucks12b,12c, electrical connectors44b,44c, and associated portions of the electrical conductor42, lower sandwich panel26, and upper sandwich panel28.

The e-chuck12amay include a disc-shaped support portion48and a cylindrical neck portion50of smaller diameter extending from the bottom of the support portion48. The lower surface52of the support portion48may be seated atop the upper surface54of the upper sandwich panel26in flat engagement therewith, and the neck portion50may extend into the aperture46a. The neck portion50may be disposed in a radially close-clearance relationship with the circular inner edge58of the upper sandwich panel28that defines that aperture46a. The e-chuck12amay be fastened to the upper sandwich panel28and, optionally, to the lower sandwich panel26, such as with removable mechanical fasteners60(e.g., screws). The fasteners60may be countersunk as shown inFIG. 3so as not to protrude from the upper surface62of the e-chuck12a, thereby preserving the planarity of the upper surface62. The removable fasteners60may facilitate convenient removal and replacement of the e-chuck12a, such as for repair, cleaning, or replacement. Alternatively, it is contemplated that the e-chuck12amay be adhered to the upper sandwich panel28.

The electrical conductor42may be sandwiched between the lower sandwich panel26and the upper sandwich panel28and may extend below the aperture46a. The electrical connector44amay be sandwiched between, and may be in intimate contact with, the electrical conductor42and the neck portion50of the e-chuck12a. The electrical connector44amay thereby provide an electrical connection between the electrical conductor42and the e-chuck12aas described above.

Referring toFIG. 4, a flow diagram illustrating an exemplary method for constructing the end effector10in accordance with the present disclosure is shown. The method will now be described in detail in conjunction with the end effector10shown inFIGS. 1-3.

At step100of the exemplary method, the lower sandwich panel26, upper sandwich panel28, and rigidizing panel30may be cut or otherwise formed from one or more sheets of suitable material, including, but not limited to, CFC, aluminum, quartz, and ceramic. In one embodiment of the method, the sheets from which the lower sandwich panel26, upper sandwich panel28, and rigidizing panel30are cut may be formed of CFC sheets that are produced using a “vacuum-bagging” technique that may provide each of the lower sandwich panel26, upper sandwich panel28, and rigidizing panel30with a first, relatively rough side, and an second, relatively smooth side. The term “rough” is defined herein to mean one or more of uneven, irregular, not smooth, not flat, textured, pitted, etc. In other embodiments of the method, one or more of the lower sandwich panel26, upper sandwich panel28, and rigidizing panel30may be produced using processes which provide them with first and second sides that are both smooth.

At step110of the exemplary method, the apertures46a,46b,46cmay be cut, drilled, milled, or otherwise formed in the upper sandwich panel28. Apertures for accepting the fasteners60may also be similarly formed in the upper sandwich panel28and, optionally, in the lower sandwich panel26.

At step120of the exemplary method, the lower sandwich panel26may be laid on a flat surface, such as a table top, floor, or other flat work surface. In one embodiment of the method, the flat surface may be a bottom mold half70of a vacuum jig72as shown inFIG. 5. If the lower sandwich panel26has a rough first side and a smooth second side as described above, the lower sandwich panel26may be disposed on the flat surface with the smooth second side facing down and the rough first side facing up. The lower sandwich panel26may optionally be temporarily secured to the flat surface in a desired orientation, such as with tape and/or other fasteners or adhesives which, if using the vacuum jig72, may seal the lower sandwich panel26to the bottom mold half70so that a vacuum can effectively be established therebetween. If a vacuum jig is not used, the sandwich panel26may be flatly secured to a flat surface using a temporary, secondary adhesive, such as any low-strength bonding agent, including, but not limited to, fugitive adhesive or pressure sensitive adhesive. Alternatively, it is contemplated that the lower sandwich panel26may be flatly secured to a flat surface using a film that is treated with a low-tack, pressure sensitive adhesive. Still further, it is contemplated that the lower sandwich panel26may be flatly secured to a flat surface using a primary adhesive of a reactive nature, such as a high-density, high-strength polyurethane foam consisting of two precursors. During curing, these precursors may react and increase in volume, thereby forcibly “sandwiching” the flatly-abutting lower sandwich panel26and upper sandwich panel28together and keeping them flat while they are bonded together as further described below.

At step130of the exemplary method, the electrical conductor42may be disposed atop the lower sandwich panel26in a desired position and orientation, such as with portions of the electrical conductor42extending along areas on the lower sandwich panel26that correspond to portions of the upper sandwich panel28in which the apertures46a,46b,46care formed. At step140of the method, an amount of adhesive74may be applied to the lower sandwich panel26. The adhesive74may be any appropriate adhesive, a non-limiting example of which is a flow-modified epoxy. In an alternative embodiment of the method, the adhesive74may be applied to the lower sandwich panel26before the electrical conductor42is disposed atop the lower sandwich panel26.

At step150of the exemplary method, the upper sandwich panel28may be flatly placed on top of the adhesive-covered lower sandwich panel26and electrical conductor42. In one exemplary embodiment of the method, mold-release plugs may be placed in the apertures46a,46b,46cof the upper sandwich panel28before the upper sandwich panel is placed on top of the lower sandwich panel26to prevent the adhesive74from flowing into the apertures46a,46b,46cwhen the adhesive74is compressed between the lower sandwich panel26and the upper sandwich panel28. Such mold-release plugs can be removed from the apertures46a,46b,46cafter the adhesive74has cured.

If the lower sandwich panel26and the upper sandwich panel28each have a rough first side and a smooth second side as described above, the upper sandwich panel28may be placed on top of the lower sandwich panel26with the rough first side of the upper sandwich panel28facing down and with the smooth second side of the upper sandwich panel28facing up. The rough first sides of the lower sandwich panel26and upper sandwich panel28may thereby be disposed in a confronting relationship and separated by the adhesive74.

In one embodiment of the method, the lower sandwich panel26and upper sandwich panel28may be stacked and adhered in the above-described manner using the vacuum jig72shown inFIG. 5. For example, the smooth second side of the lower sandwich panel26may be vacuum sealed flatly against the bottom mold half70of the vacuum jig72and the smooth second side of the upper sandwich panel28may be vacuum sealed flatly against the top mold half76of the vacuum jig72. The top mold half76may then be inverted and lowered onto the bottom mold half70.

At step160of the exemplary method, the adhesive74between the lower sandwich panel26and the upper sandwich panel28may be allowed to cure while the lower sandwich panel26and the upper sandwich panel28are held a short, fixed distance apart from one another, forming a so-called “bond-gap” therebetween that is mostly filled with adhesive, and with the outwardly-facing, non-confronting sides (e.g., the smooth second sides) of the lower sandwich panel26and the upper sandwich panel28held in a substantially parallel relationship with one another. In one embodiment, the lower sandwich panel26and the upper sandwich panel28may be held in this manner using the above-described jig72. For example, with the lower sandwich panel26and the upper sandwich panel28vacuum sealed to the bottom and top mold halves70,76and stacked so that the rough first sides of the lower sandwich panel26and the upper sandwich panel28are disposed in a confronting relationship as described above, one or more spacers or “gap blocks” of substantially identical height may be interposed between the bottom and top mold halves70,76. Such gap blocks may have a height that maintains the mold halves70,76a specified, uniform distance apart so that the resulting end effector10has a desired predetermined thickness.

Since the smooth second sides of the lower sandwich panel26and the upper sandwich panel28were held in a parallel relationship and the rough first sides of the lower sandwich panel26and the upper sandwich panel28were held apart from one another during curing of the adhesive74, the end effector10may be highly planar (i.e., having parallel top and bottom surfaces), with any surface irregularities of the rough first sides of the lower sandwich panel26and the upper sandwich panel28having been “absorbed” by the adhesive74during curing. That is, the surface irregularities of the confronting, rough first sides may not affect the planarity of the end effector10as they otherwise might if the rough first sides were placed in direct contact with one another (i.e., with no bond-gap therebetween), with their respective surface irregularities engaging each other.

At step170of the exemplary method, the rigidizing layer30may be adhered to the top of the upper sandwich panel28in the arrangement shown inFIG. 1, such as with a flow-modified epoxy. Alternatively, the rigidizing panel30may be secured to the upper sandwich panel28with mechanical fasteners. At step180of the method, the mounting apertures24may be cut, drilled, milled, or otherwise formed in the assembled lower sandwich panel26, upper sandwich panel28, and rigidizing panel30and the mounting hub22may be installed in the arrangement shown inFIGS. 1 and 2.

At step180of the exemplary method, the electrical connectors44a,44b,44cmay be seated in the respective apertures46a,46b,46cin the upper sandwich panel28in flat, operative engagement with respective portions of the electrical conductor42. At step190of the method, the neck portions50of the e-chucks12a,12b,12cmay be mounted in the apertures46a,46b,46cin engagement with the electrical connectors44a,44b,44c, and the support portions48of the e-chucks12a,12b,12cmay be fastened to the upper sandwich panel28and, optionally, to the lower sandwich panel26as best illustrated inFIG. 3with respect to the e-chuck12a.

Owing to the high-planarity of the assembled lower sandwich panel26and upper sandwich panel28, the completed end effector10may also be highly planar. Moreover, since the top and bottom surfaces of the end effector10may be formed of the smooth second sides of the upper sandwich panel28and lower sandwich panel26, the major surfaces of the end effector10may be smooth and ultra-flat (e.g. less than about 0.005 inches of variation over about 24 inches of surface). Thus, the end effector10may be very light, very stiff, and not prone to generating, trapping, or distributing contaminants (i.e., particulate matter) during substrate handling processes. Moreover, since the electrical conductor42and the electrical connectors44a,44b,44care embedded within the end effector10, the end effector10may have a slim profile and an exterior of the end effector10may be relatively smooth and regular, thus facilitating convenient and expeditious cleaning thereof.

Referring now toFIG. 6, another exemplary end effector210in accordance with an embodiment of the present disclosure is shown. For the sake of convenience and clarity, terms such as “top,” “bottom,” “upper,” “lower,” “vertical,” “horizontal,” “lateral,” “longitudinal,” “inner,” and “outer” may be used herein to describe the relative placement and orientation of the features and components of the end effector10, each with respect to the geometry and orientation of the end effector10as it appears inFIG. 6. Said terminology will include the words specifically mentioned, derivatives thereof, and words of similar import.

The end effector210may be similar to the end effector210described above and may include a base portion214having two fingers216,218extending therefrom, and a wrist portion220having a plurality of mounting apertures224that may facilitate attachment of the end effector210to a robot or other device. A plurality of pockets or recesses225may be formed in a top surface of the end effector210for holding effector pads (not shown) that may engage and support substrates. The end effector10may further include embedded optical fibers212a,212b(seeFIG. 7) that may be connected to a photo emitter213and a photo sensor215, respectively, of a through beam sensor217(schematically shown inFIG. 6), as described in greater detail below. It will be understood that the particular configuration of the end effector210shown inFIG. 6is provided by way of example only, and that many other configurations may be similarly implemented without departing from the present disclosure. For example, alternative end effector designs may include only one finger or more than two fingers with positions of the optical fibers212a,212badjusted accordingly.

Referring to the exploded view of the end effector210shown inFIG. 7, the end effector210may be formed of a lower sandwich panel226and an upper sandwich panel228that may be bonded together in a stacked, flatly-abutting arrangement as further described below. The lower sandwich panel226and upper sandwich panel228may be formed of any suitably rigid, lightweight, non-contaminating material. For example, the lower sandwich panel226and upper sandwich panel228may be formed of a carbon fiber composite (CFC). Other materials that may additionally or alternatively be used in the construction of the end effector210include, but are not limited to, aluminum, quartz, and ceramic.

A pair of tubular conduits230a,230bmay be sandwiched between the lower sandwich panel226and the upper sandwich panel228in a substantially longitudinally-extending orientation and may be disposed within respective channels232a,232band234a,234b(channels232band234bare shown inFIG. 9) that may be formed in the confronting surfaces of the lower sandwich panel226and the upper sandwich panel228. The conduits230a,230bmay be formed of any suitably durable material, including, but not limited to, stainless steel, polyethylene, or various other metals, plastic, or composites. The channels232a,232band234a,234bmay each have a size and shape that are adapted to hold the conduits230a,230bin a closely conforming relationship therein, thereby restricting radial movement of the conduits within the channels232a,232band234a,234b. In an alternative embodiment of the end effector210, it is contemplated that only one of the lower sandwich panel226and the upper sandwich panel228may have channels formed in the confronting surface thereof, wherein such channels may have a size and a shape that are adapted to hold the entirety of the conduits230a,230b, and that the other of the lower sandwich panel226and the upper sandwich panel228may have no channels formed in the confronting surface thereof. Owing to the recessing of the conduits230a,230bwithin the channels232a,232band234a,234b, the lower sandwich panel226and the upper sandwich panel228may be flatly bonded together (as shown inFIG. 6) with the conduits230a,230bunobtrusively embedded therebetween, thereby providing the end effector210with a slim profile.

The optical fibers212a,212bmay be disposed within the conduits230a,230b, respectively (the optical fibers212a,212bare shown outside of the conduits230a,230binFIG. 7for clarity), with the front tips of the optical fibers212a,212bexposed adjacent the front edges of the respective fingers216,218and directed forward. As described above, the optical fibers212amay be connected to a photo emitter213and the optical fibers212bmay be connected to a photo sensor215(shown inFIG. 6), such as via a harness or other appropriate connection (not shown) at the rear of the end effector. The optical fibers212amay therefore project light produced by the light emitter213toward the optical fibers212bat the tip of the finger218. The received light may be conveyed to the photo sensor215and may be used, in combination with a known position and orientation of the end effector210, to determine the presence or absence of the object in front of the end effector210. For example, the projected and received light may be used to determine the presence or absence of substrates at various vertical positions within a FOUP. Since the electrical conductor42is disposed intermediate or within the lower sandwich panel226and/or the upper sandwich panel228, the optical fibers212a,212bmay be referred to generically as an “intermediate elements” in the context of the present disclosure.

If one or both of the optical fibers212a,212bneeds to be replaced, they may simply be disconnected from the photo emitter213and/or the photo sensor215and may be withdrawn from one of the longitudinal ends of the conduits230a,230b, respectively. New optical fibers may then be inserted into the conduit230aand/or the conduit230b. The optical fibers212a,212bmay therefore be quickly and conveniently replaced without disassembling the end effector210. In an alternative embodiment of the end effector210, it is contemplated that the conduits230a,230bmay be omitted and that the optical fibers212a,212bmay be disposed directly within the respective channels232a,232band234a,234b.

Referring toFIG. 8, a flow diagram illustrating an exemplary method for constructing the end effector210in accordance with the present disclosure is shown. The method will now be described in detail in conjunction with the end effector210shown inFIGS. 6 and 7.

At step300of the exemplary method, the lower sandwich panel226and upper sandwich panel228may be cut or otherwise formed from one or more sheets of suitable material, such as CFC or aluminum. In one embodiment of the method, the sheets from which the lower sandwich panel26and upper sandwich panel28are cut may be formed of CFC sheets that are produced using a “vacuum-bagging” technique that may provide each of the lower sandwich panel26and upper sandwich panel28with a first, relatively rough side, and an second, relatively smooth side. The term “rough” is defined herein to mean one or more of uneven, irregular, not smooth, not flat, textured, pitted, etc. In other embodiments of the method, one or both of the lower sandwich panel26and upper sandwich panel28may be produced using processes which provide them with first and second sides that are both smooth.

At step310of the exemplary method, the channels232a,232band234a,234bmay be cut, milled, or otherwise formed in the confronting surfaces of the lower sandwich panel226and upper sandwich panel228. The recesses225for holding effector pads may also be similarly formed in the top surface of the upper sandwich panel228.

At step320of the exemplary method, the lower sandwich panel226may be laid on a flat surface, such as a table top, floor, or other flat work surface. In one embodiment of the method, the flat surface may be a bottom mold half270of a vacuum jig272as shown inFIG. 9. If the lower sandwich panel226has a rough first side and a smooth second side as described above, the lower sandwich panel226may be disposed on the flat surface with the smooth second side facing down and the rough first side facing up. The lower sandwich panel226may optionally be temporarily secured to the flat surface in a desired orientation, such as with tape and/or other fasteners or adhesives which, if using the vacuum jig272, may seal the lower sandwich panel226to the bottom mold half270so that a vacuum can effectively be established therebetween. If a vacuum jig is not used, the sandwich panel226may be flatly secured to a flat surface using a temporary, secondary adhesive, such as any low-strength bonding agent, including, but not limited to, fugitive adhesive or pressure sensitive adhesive. Alternatively, it is contemplated that the lower sandwich panel226may be flatly secured to a flat surface using a film that is treated with a low-tack, pressure sensitive adhesive. Still further, it is contemplated that the lower sandwich panel226may be flatly secured to a flat surface using a primary adhesive of a reactive nature, such as a high-density, high-strength polyurethane foam consisting of two precursors. During curing, these precursors may react and increase in volume, thereby forcibly “sandwiching” the flatly-abutting lower sandwich panel226and upper sandwich panel228together and keeping them flat while they are bonded together as further described below.

At step330of the exemplary method, an amount of adhesive274may be applied to the lower sandwich panel226. The adhesive274may be any appropriate adhesive, a non-limiting example of which is a flow-modified epoxy. At step340of the method, the conduits230a,230bmay be seated within the respective channels232a,234ain the lower sandwich panel226. In an alternative embodiment of the method, the adhesive274may be applied to the lower sandwich panel226after the conduits230a,230bare seated within the channels232a,234a.

At step350of the exemplary method, the upper sandwich panel228may be flatly placed on top of the adhesive-covered lower sandwich panel226with the channels232b,234bin the upper sandwich panel228fitting over and receiving the conduits230a,230b. Mold release plugs may be placed in the open ends of the conduits230a,230bto prevent the entry of adhesive during placement of the upper sandwich panel228and subsequent curing of the adhesive274. Such plugs may be removed after the adhesive274has cured. If the lower sandwich panel226and the upper sandwich panel228each have a rough first side and a smooth second side as described above, the upper sandwich panel228may be placed on top of the lower sandwich panel226with the rough first side of the upper sandwich panel228facing down and with the smooth second side of the upper sandwich panel228facing up. The rough first sides of the lower sandwich panel226and upper sandwich panel228may thereby be disposed in a confronting relationship and separated by the adhesive274.

In one embodiment of the method, the lower sandwich panel226and upper sandwich panel228may be stacked and adhered in the above-described manner using the vacuum jig272shown inFIG. 9. For example, the smooth second side of the lower sandwich panel226may be vacuum sealed flatly against the bottom mold half270of the vacuum jig272and the smooth second side of the upper sandwich panel228may be vacuum sealed flatly against the top mold half276of the vacuum jig272. The top mold half276may then be inverted and lowered onto the bottom mold half270.

At step260of the exemplary method, the adhesive274between the lower sandwich panel226and the upper sandwich panel228may be allowed to cure while the lower sandwich panel226and the upper sandwich panel228are held a short, fixed distance apart from one another, forming a so-called “bond-gap” therebetween that is mostly filled with adhesive, and with the outwardly-facing, non-confronting sides (e.g., the smooth second sides) of the lower sandwich panel226and the upper sandwich panel228held in a substantially parallel relationship with one another. In one embodiment, the lower sandwich panel226and the upper sandwich panel228may be held in this manner using the above-described jig272. For example, with the lower sandwich panel226and the upper sandwich panel228vacuum sealed to the bottom and top mold halves270,276and stacked so that the rough first sides of the lower sandwich panel226and the upper sandwich panel228are disposed in a confronting relationship as described above, one or more spacers or “gap blocks” of substantially identical height may be interposed between the bottom and top mold halves270,276. Such gap blocks may have a height that maintains the mold halves270,276a specified, uniform distance apart so that the resulting end effector210has a desired predetermined thickness. Once the adhesive has cured, the conduits230a,230bmay be securely fixed with the channels232a,232b,234a,234b.

Since the smooth second sides of the lower sandwich panel226and the upper sandwich panel228were held in a parallel relationship and the rough first sides of the lower sandwich panel226and the upper sandwich panel228were held apart from one another during curing of the adhesive274, the end effector210may be highly planar (i.e., having parallel top and bottom surfaces), with any surface irregularities of the rough first sides of the lower sandwich panel226and the upper sandwich panel228having been “absorbed” by the adhesive274during curing. That is, the surface irregularities of the confronting, rough first sides may not affect the planarity of the end effector210as they otherwise might if the rough first sides were placed in direct contact with one another (i.e., with no bond-gap therebetween), with their respective surface irregularities engaging each other.

At step370of the method, the mounting apertures224may be cut, drilled, milled, or otherwise formed in the assembled lower sandwich panel226and upper sandwich panel228. At step380of the exemplary method, the optical fibers212a,212bmay be inserted into the conduits230a,230b, respectively.

At step390of the exemplary method, the optical fiber212amay be connected to the photo emitter213and the optical fiber212bmay be connected to the photo sensor215.

Owing to the high-planarity of the assembled lower sandwich panel226and upper sandwich panel228, the completed end effector210may also be highly planar. Moreover, since the top and bottom surfaces of the end effector210may be formed of the smooth second sides of the upper sandwich panel228and lower sandwich panel226, the major surfaces of the end effector210may be smooth and ultra-flat (e.g. less than about 0.005 inches of variation over about 24 inches of surface). Thus, the end effector210may be very light, very stiff, and not prone to generating, trapping, or distributing contaminants (i.e., particulate matter) during substrate handling processes. Moreover, since the optical fibers212a,212band the conduits230a,230bare embedded within the end effector210, the end effector210may have a slim profile and an exterior of the end effector210may be relatively smooth and regular, thus facilitating convenient and expeditious cleaning thereof.