WO2018157179A2

WO2018157179A2 - Atmospheric robotic end effector

Info

Publication number: WO2018157179A2
Application number: PCT/US2018/024226
Authority: WO
Inventors: Thomas Walton; Michael Dailey; Manon LEMOINE; Joe Garcia
Original assignee: Fabworx Solutions, Inc.
Priority date: 2017-02-24
Filing date: 2018-03-24
Publication date: 2018-08-30
Also published as: WO2018157179A3

Abstract

A robotic end effector is provided which includes a housing, an end effector blade, and an actuator disposed within the housing. The actuator has a protrusion which advances and retracts along an axis. The protrusion is equipped, on a terminal end thereof, with a resilient mass. The end effector is further equipped with a control unit, and a flag. The flag has a first end which is attached to the actuator, and a second end which is magnetically coupled to the control unit. The flag has a profile which reduces particle generation.

Description

ATMOSPHERIC ROBOTIC END EFFECTOR

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to U.S. Provisional Application No. 62/462,934, filed on February 24, 2017, which has the same title and the same inventors, and which is incorporated herein by reference in its entirety.

FIELD OF THE DISCLOSURE

[0002] The present application relates generally to robotic end effectors, and more particularly to methodologies for reducing the level of particle contaminants originating from such end effectors, and to end effectors produced in accordance with those methodologies.

BACKGROUND OF THE DISCLOSURE

[0003] In a typical semiconductor manufacturing process, a single wafer may be exposed to a number of sequential processing steps including, but not limited to, chemical vapor deposition (CVD), physical vapor deposition (PVD), etching, planarization, and ion implantation. These processing steps are typically performed by robots, due in part to the ability of robots to perform repetitive tasks quickly and accurately and to work in environments that are dangerous to humans.

[0004] Many modern semiconductor processing systems are centered around robotic cluster tools that integrate a number of process chambers. This arrangement allows multiple sequential processing steps to be performed on the wafer within a highly controlled processing environment, and thus minimizes exposure of the wafer to external contaminants. The combination of chambers in a cluster tool, as well as the operating conditions and parameters under which those chambers are utilized, may be selected to fabricate specific structures using a specific process recipe and process flow. Some commonly used process chambers include degas chambers, substrate pre-conditioning chambers, cool-down chambers, transfer chambers, chemical vapor deposition chambers, physical vapor deposition chambers and etch chambers.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] FIG. 1 is an illustration of a 300mm Yaskawa robot with its robotic arm shown in an extended position.

[0006] FIG. 2 is an image of a 300mm Yaskawa robot with its robotic arm shown in a retracted position.

[0007] FIG. 3 is an image of the end effector blade of the robot of FIG. 1.

[0008] FIG. 4 is an image of a portion of the end effector of FIG. 3 with the housing removed to show the various components thereof.

[0009] FIG. 5 is a magnified view of the actuator utilized in the end effector of the robot of FIG. 4.

[0010] FIG. 6 is a view of the pneumatic tube utilized in the end effector of the robot of FIG. 2.

[0011] FIGs. 7(a), 7(b) and 7(c) are images of a test chamber designed to simulate an Equipment Front End Module (EFEM). The EFEM-like test chamber is equipped with a Fan Filter Unit (FFU) to provide laminar flow, and was used for the particle counter measurements described herein.

[0012] FIG. 8 is a graph of particle count as a function of particle size obtained during validation testing conducted with the test chamber of FIG. 7.

[0013] FIGS. 9(a) and 9(b) are graphs of particle count as a function of particle size obtained during validation testing conducted with the test chamber of FIG. 7. The graph in FIG. 9(a) was obtained during an ATM blade pressure change, while that in FIG. 9(b) was obtained during changes in CDA pressure. [0014] FIG. 10 is a series of illustrations indicating the effect of pad wear on the pads of the end effector blade of FIG. 3. FIG. 10(a) shows the profile of a pad that has undergone wafer abrasion. FIG. 10(b) shows the profile of a new pad for comparison.

[0015] FIG. 11 is an image of a wafer mounted on the end effector blade of FIG. 3.

[0016] FIG. 12 is an image of various components of the end effector of the robot of FIG. 2. Thus, FIG. 12(a) depicts a pneumatic pump, FIG. 12(b) depicts a portion of a metal flag showing the installation thereof, and FIG. 12(c) depicts a pneumatic flag.

[0017] FIG. 13 is a first embodiment of a particle guard in accordance with the teachings herein in which the particle barrier is mounted to the front of the actuator in the end effector of a robot of the type depicted in FIG. 2.

[0018] FIG. 14 is a second embodiment of a particle guard in accordance with the teachings herein in which the particle barrier is mounted to the front of the actuator in the end effector of a robot of the type depicted in FIG. 2.

[0019] FIG. 15 is a set of images showing the original equipment manufacturer (OEM) flag (FIG. 15(a)) for the actuator in the end effector of a robot of the type depicted in FIG. 2, and a modified flag (FIG. 15(b)) in accordance with the teachings herein. The modified flag may be used as a replacement form the OEM flag.

[0020] FIG. 16 is an image of a pressure regulator valve (FIG. 16(a)) and speed controllers (FIG. 16(b)) which may be utilized in the end effectors disclosed herein.

[0021] FIG. 17 is a set of images illustrating some differences between the OEM fang and a preferred embodiment of the fangs disclosed herein. Thus, FIG. 17(b) shows an embodiment of a fang in accordance with the present disclosure, and FIG. 17(a) shows a side-by-side comparison of an OEM fang and the Fang of FIG. 17(b).

[0022] FIG. 18 is a set of images comparing an embodiment of an end effector in accordance with the teachings herein (FIG. 18(b)) to the original OEM version (FIG. 18(a)). The end effectors in both images are shown with the housing removed to reveal the inner components of the actuators. [0023] FIG. 19 is a set of graphs illustrating the difference in particle contaminant levels between an OEM end effector for the robot of FIG. 2 (FIG. 19(a)) and an end effector made in accordance with the teachings herein (FIG. 19(b)).

[0024] FIG. 20 is a set of images showing top (FIG. 20(a)) and bottom (FIG. 20(b)) views of a particle barrier and actuator in accordance with the teachings herein, with the parts separated.

[0025] FIG. 21 is a set of images showing top (FIG. 21 (a)) and bottom (FIG. 21 (b)) views of a particle barrier and actuator in accordance with the teachings herein, with the parts joined.

[0026] FIG. 22 is a set of illustrations of an actuator used in an embodiment of an end effector made in accordance with the teachings herein. FIG. 22(a) is a side view of the actuator, and FIG. 22(b) is a front view of the actuator.

[0027] FIG. 23 is a set of illustration of an OEM actuator corresponding to the actuator of FIG. 22. FIG. 23(a) is a side view of the actuator, and FIG. 23(b) is a front view of the actuator, and FIG. 23(c) is a rear view of the actuator.

[0028] FIGs. 24-27 are illustrations of a particular, non-limiting embodiment of a flag in accordance with the teachings herein.

[0029] FIGs. 28-42 are perspective illustrations of a particular, non-limiting embodiment of a tab (or fang) in accordance with the teachings herein.

SUMMARY OF THE DISCLOSURE

[0030] In one aspect, a robotic end effector is provided which comprises (a) an end effector blade; (b) a housing disposed on a first end of said end effector blade; (c) an actuator disposed within said housing; and (d) a plurality of tabs disposed on said blade adjacent to said housing; wherein each of said plurality of tabs includes a first portion adapted to receive a semiconductor wafer thereon, and a second portion which is raised with respect to said first portion, and wherein said each of said plurality of tabs comprises a polyaryletherketone. The polyaryletherketone is preferably polyether ether ketone (PEEK). [0031] In another aspect, a robotic end effector is provided which comprises (a) an end effector blade; (b) a housing disposed on a first end of said end effector blade; (c) an actuator disposed within said housing; and (d) a plurality of tabs disposed on said blade adjacent to said housing; wherein each of said plurality of tabs includes a first portion adapted to receive a semiconductor wafer thereon, and a second portion which is raised with respect to said first portion and which is separated therefrom by way of a vertical wall, wherein the first portion of each tab is equipped with a front edge which is parallel to said wall and first and second lateral edges, and wherein said front edge adjoins said first lateral edge by way of a first beveled edge.

[0032] In a further aspect, a robotic end effector is provided which comprises (a) an end effector blade; (b) a housing which is equipped with a front wall and which is releasably attached to a first end of said end effector blade; (c) an actuator disposed within said housing, said actuator having a protrusion which extends through an aperture in said front wall; and (d) a closed-cell foam barrier disposed within said housing and adjacent to said front wall.

[0033] In still another aspect, a robotic end effector is provided which comprises (a) an end effector blade; (b) an actuator disposed within said housing, said actuator having a protrusion which advances and retracts along a first axis, said protrusion being equipped on a terminal end thereof with a resilient mass, and wherein said resilient mass traces out a three-dimensional space as said protrusion advances and retracts along said first axis; (c) a control unit; and (d) a flag having a first end which is attached to said actuator, and having a second end which is magnetically coupled to said control unit; wherein said flag has first and second segments that are adjoined at an angle, wherein said first end of said flag is disposed on said first segment, and wherein said second end of said flag is disposed on said second segment; and wherein said first segment is equipped with a first portion having a first major surface which is essentially parallel to said first axis, and wherein said first segment is further equipped with a second major surface which is essentially perpendicular to said first major surface and which is wholly disposed within said three-dimensional space. [0034] In a further aspect, a robotic end effector is provided which comprises (a) a housing; (b) an end effector blade; (c) an actuator disposed within said housing, said actuator having a protrusion which advances and retracts along a first axis, said protrusion being equipped on a terminal end thereof with a resilient mass, and wherein said resilient mass traces out a three-dimensional space as said protrusion advances and retracts along said first axis; (d) a control unit; and (e) a flag having a first end which is attached to said actuator, and having a second end which is magnetically coupled to said control unit; wherein said flag has first and second segments that are adjoined at an angle, wherein said first end of said flag is disposed on said first segment, and wherein said second end of said flag is disposed on said second segment; and wherein said first segment is equipped with a first portion having a first major surface which is essentially parallel to said first axis, and wherein said first segment is further equipped with a second major surface which is essentially perpendicular to said first major surface and which is wholly disposed within said three-dimensional space.

[0035] In yet another aspect, a robotic end effector is provided which comprises (a) a housing; (b) an end effector blade; (c) an actuator disposed within said housing, said actuator having a protrusion which advances and retracts from said housing along a first axis; and (d) a rigid, polymeric particle barrier disposed between said housing and said end effector blade, said particle barrier having an aperture therein through which said protrusion expands and retracts.

DETAILED DESCRIPTION

[0036] Robotic end effectors are a crucial component of cluster tools. These devices are tasked with the actual handling and placement of semiconductor wafers within the tool. Ideally, robotic end effectors operate in a repeatable, high speed manner to provide high tool throughput and high product yields.

[0037] Particle contamination is a serious issue which must be dealt with during semiconductor manufacturing, and which can adversely affect product yield. Typically, great care is taken in these processes to avoid the introduction of external particle contaminants, and to reduce or eliminate particle contaminants arising from the semiconductor processes themselves. For example, various processes have been introduced in the art to reduce or eliminate particle contamination arising from the use of abrasive particles or the generation of abraded materials during chemical mechanical polishing (CMP). Unfortunately, significant levels of particle contamination still persist, despite the use of the foregoing measures to eliminate them.

[0038] It has now been found that the robotic end effectors utilized in semiconductor processing are themselves significant sources of particle contamination. Careful analysis has traced the source of these contaminants back to various features on the robotic end effector. Methodologies and devices, including modifications to robotic end effectors, are disclosed herein for reducing or eliminating these contaminants. These methodologies and devices may also reduce or eliminate damage to wafer edges and tab (or fang) wear, while increasing actuator lifetime. While these methodologies and devices disclosed herein are specifically illustrated with respect to the 300mm Yaskawa atmospheric robot depicted in FIGs. 1-6, one skilled in the art will appreciate that these methodologies and devices may be readily extended to various other robots, end effectors, cluster tools, and other such devices.

[0039] Careful studies of robotic actuators and their components were undertaken to understand the source of various issues reported in the field, including the presence of particles, damage to wafer edges, tab (or fang) wear, and lower than expected actuator lifetimes. The studies focused on the 300mm Yaskawa atmospheric robot 101 depicted in FIGs. 1-6, since this is a common robotic actuator and is similar in many respects to other actuators used in the semiconductor arts.

[0040] As seen in FIG. 1, the 300mm Yaskawa atmospheric robot 101 includes a hub 103 having a first arm 105 rotatably attached thereto, and a second arm 107 is rotatably attached to the first arm 105. A third arm 109 is rotatably attached on one end thereof to the second arm 107, and is attached on the opposing end thereof to an end effector 111. The robot is further equipped with a connector panel 113. During operation, the robot commonly moves between an extended configuration such as that depicted in FIG. 1, and a retracted position such as that depicted in FIG. 2.

[0041] As best seen in FIG. 3, the end effector 111 includes a blade 121 with a housing 123 disposed on one end thereof which houses an actuator 125 (see FIG. 4; note that the actuator 125 is removed in FIG. 3). The end effector blade 121 is equipped with a plurality of pads 126 that support a wafer 122 on the end effector blade 121 as shown in FIG. 11.

[0042] As seen in FIG. 4 (which shows the end effector 111 with the housing 123 removed), the actuator 125 comprises a resilient wheel 127 (shown up close in FIG. 5) disposed on the end of a metal rod 129. The rod 129 is driven by a pneumatic piston 131 (shown in greater detail in FIG. 6) which is controlled by a controller 133. A seal 135 is provided around the rod 129 to prevent air flow from the pneumatic pump 131 from reaching the wafer. A metal flag 137 is disposed on the rod 129 adjacent to the wheel 127 to help control the motion of the rod 129, and to serve as a barrier to particulate contaminants generated within the housing 123. In operation, the actuator 125 operates to extend and retract the wheel 127 so that it respectively engages and disengages a wafer disposed on the end effector blade 121 (see FIG. 3).

[0043] Initial studies have implicated the shaft seals 135 in these robots as one suspected source of particles (see FIG. 5). In particular, as the shaft seal 135 in the actuator 125 becomes worn, air and particles are allowed to blow past it. It was suspected that these particles could be "pushed" by the flat surface 139 of the flag 137 (see FIG. 15(a)) and propelled out of the actuator housing 123. Other suspected sources were air leakage at tubing connections (see FIG. 6), and the wearing of tabs 126 or fangs on the end effector blade 121 (see FIG. 2).

[0044] In order to test the foregoing, a test chamber 201 was created (see FIG. 7) to simulate an equipment front end module (EFEM) chamber. The test chamber 201 was equipped with a fan filter unit (FFU) (not shown) to provide a laminar flow through the chamber. A CyberOptics APS particle wafer 203 (see FIG. 7(b)) was utilized in these tests (with particle size up to 0.5u). The findings of these studies were verified with a PMS Abacus 301 particle counter 205 (available commercially from Artisan Technology Group, Champaign, IL). Measurements were taken at various positions on the end effector 111 and at various compressed dry air (CD A) pressures.

[0045] In one test, each on and off sequence was roughly 3 minutes long. The piston cycled 25 times during each "Piston On" sequence. The CDA set point was 25 psi (it being noted that the Best Known Method (BKM) of the Original Equipment Manufacturer (OEM) 45 psi). The results of the particle count measurements are depicted in the graphs of FIGs. 8-9. These results suggest a relationship between particle count and CDA pressure. These results also suggest that CDA blowing past the actuator seal is a particle source.

[0046] It has been found that wafer damage (and in particular, wafer film damage) sometimes occurs to wafer edges in the vicinity of the end effector pads 126. These areas may be appreciated from FIG. 11, which depicts a wafer 122 disposed on the pads 126 of an end effector blade. Without wishing to be bound by theory, this is believed to be due to undercut wear on the end effector pads 126 (especially the front set of pads). Such undercut wear may be appreciated by comparing the profile of a worn pad 126b to that of a new pad 126a in FIG. 10. It has been observed that wafers occasionally catch on front pads during lift motion, due to such undercut wear. Pad (or fang) wear is found to occur, in part, as a result of excessive impact and lateral sliding during clamping.

[0047] In summary, the foregoing study suggested that particle generation may occur due to actuator leaks. It also suggested that the flag may act as a "particle pusher" due to its shape. The study further suggested that end-effector pads may become worn due to lateral wafer sliding, and found that high air pressures and fast piston action in the pneumatic actuators may lead to hard wafer impacts. The study further revealed that damage to the edge of a wafer may occur due to a high regulator set point of BKM. It was also determined that the OEM end-effector pad shape results in a large wafer contact area, which may contribute to particle generation. The study also found that the lifetime of piston actuators and fangs may be adversely affected as a result of increased piston pressure due to faulty pressure regulators, fast actuation of the plunger, and pad shape and material selection. [0048] FIG. 12 depicts in greater detail some of the components of the robotic end effector of FIG. 3, namely, the flag 137 and the piston 131. Among these components, the actuator piston 131 is preferably reduced in size compared to the OEM component. The smaller form factor of this component provides additional room for a particle barrier (see below). The particular actuator chose in one particular, non-limiting embodiment of this configuration is rated to 10 million cycles, and achieved good results in both low and high pressure tests.

[0049] FIG. 13 depicts an end effector 401 equipped with a first particular, non- limiting embodiment of particle barrier 403 in accordance with the teachings herein. This particle barrier 403 is mounted to the front of the actuator 405. The particle barrier 403 preferably comprises polytetrafluoroethylene (PTFE), such as that sold under the trademark Teflon^®. The particle barrier 403 may be threaded onto the actuator 405 and is preferably self-aligning to insure that the piston 407 does not rub on the particle barrier 403. The particle barrier 403 is preferably designed with a double wall that provides high probability particle containment in the event of a leaking valve seal. Aside from the particle barrier 401, the remaining components of the end effector 401 are similar to those depicted in FIG. 4. FIGs. 20-23 show a preferred embodiment of the particle barrier 403 and piston 407 in greater detail.

[0050] FIG. 14 depicts an end effector 501 equipped with a second particular, non- limiting embodiment of a particle barrier 503 that may be utilized in the devices and methodologies disclosed herein. This particle barrier 503 may be utilized to create a separation between the wafer and the various end effector particle sources. The black areas in the figure depict where "Closed Cell Foam" is inserted. This foam creates a second line of defense for possible polyline or actuator leakages and also from various other robot induced particles streaming to the wafer side of the blade. The material used for this particle barrier is preferably semiconductor-grade, closed cell foam, and is not a particle source. Aside from the particle barrier 501, the remaining components of the end effector 401 are similar to those depicted in FIG. 4. [0051] FIG. 15 provides a comparison between an OEM position flag 137 (FIG. 15(a)) and a particular, nonlimiting embodiment of a modified position flag 537 in accordance with the teachings herein (FIG. 15(b)). The modified position flag 537 has been redesigned in comparison to the OEM position flag 137 to reduce the surface area of the front wall 139 seen on the OEM flag. Without wishing to be bound by theory, this is believed to reduce the surface area of the front wall 139, thus reducing the air turbulence that may be created when it is actuated. In particular, as the actuator is extended, it will push air forward across the wafer. The surface area of the front wall may add to the mass of air being pushed forward and may thus increase turbulence. This may agitate nearby particles, pushing them onto the wafer.

[0052] FIGs. 24-27 show the modified flag 537 in greater detail. This flag may be utilized as a component of a robotic end effector comprising a control unit and an end effector blade, and an actuator having a protrusion which advances and retracts along a first axis. The protrusion is equipped on a terminal end thereof with a resilient mass, which is preferably in the form of a wheel. The resilient mass traces out a three-dimensional space as said protrusion advances and retracts along said first axis. The flag has a first terminal portion which is attached to the actuator, and a second terminal portion which is magnetically coupled to the control unit. The flag has first and second segments that are adj oined at an angle (preferably about 90°). The first terminal portion of the flag is disposed on the first segment, and the second terminal portion of the flag is disposed on the second segment.

[0053] Preferably, the first segment is equipped with a first portion having a first maj or surface which is essentially parallel to the first axis, and a second major surface which is essentially perpendicular to the first major surface. The second major surface of the first segment is preferably essentially rectangular in shape. The second major surface of said first segment is preferably essentially rectangular in shape. Even more preferably, the resilient mass is a wheel having a diameter d_w, the second major surface has a diameter d₂, and d_w > d₂. The first segment is equipped with a first portion having a first major surface which is essentially parallel to said first axis, and is further equipped with a second major surface which is essentially perpendicular to said first major surface and which is wholly disposed within said three-dimensional space. This configuration may be utilized to minimize the air turbulence created as the actuator extends and retracts, since the surface area of the flag does not appreciably add to the mass of air being pushed forward (because the second major surface of the first section is hidden behind then resilient mass). This may thus reduce or eliminate the agitation of any nearby particles, thus helping to reduce or eliminate these particles as a source of wafer contamination.

[0054] FIG. 18 depicts another particular, non-limiting embodiment of an end effector 601 in accordance with the teachings herein. In this embodiment, the OEM pressure regulator 651 (see FIG. 16(a)) is preferably replaced with a robust SMC valve 653 (see FIG. 16(b)) that is tamperproof. The valve 653 may be set to specified pressure and locked. This will help to ensure no changes can be made without proper investigation. The valve 653 may be mounted in current location of OEM valve 651. A tamperproof speed controller is also preferably installed in the robot arms to allow speed control for both extension and retraction of the piston and to prevent impact with the wafer and with internal actuator seals. The controller is tamperproof to prevent unauthorized adjustment.

[0055] The particular embodiment of the end effector 601 depicted also includes particle barriers 651, 653 which are similar or identical in design and functionality to the particle barriers 403 and 503 in FIGs. 13 and 14, respectively. This end effector 601 further includes a flag 655 which is similar or identical to the enhanced flag 537 depicted in FIG. 15.

[0056] The devices and methodologies disclosed herein preferably utilize a pad, fang or tab that has been modified compared to the OEM component. Particular, non-limiting embodiments of the modified pad 701 are depicted in FIGs. 17-18, and in greater detail in FIGs. 30-44. FIG. 17(a) depicts a prior art pad 703 side by side with the modified pad 701.

[0057] Preferably, the modified pad 701 comprises a polyaryletherketone, and more preferably, the modified pad 701 comprises a polyether ether ketone (PEEK), such as that sold under the tradename Ketron^®. The PEEK is preferably not carbon filled. This material provides excellent chemical resistance, very low moisture absorption and inherently good wear and abrasion resistance, and is unaffected by continuous exposure to environments.

[0058] The modified pad 701 is preferably modified in comparison to the OEM pad 703 to provide a smaller contact area, and no corner contact. The modified pad 701 preferably dimensionally matches the OEM. It has been found that the modified pad 701 exhibits a longer lifetime than the OEM pad 703, and lower wear properties (e.g., over 3 million cycles with no discernible wear). By contrast, the OEM pad 703 is a carbon-filled polymer with a large wafer contact area. The OEM pad 703 exhibits high wear properties, showing signs of wear after 800K cycles and severe wear at 1 million cycles.

[0059] As seen in FIGs. 28-42, the modified pad 701 or tab includes a first portion 703 which is adapted to receive a semiconductor wafer thereon, and a second portion 705 which is raised with respect to said first portion and which is separated therefrom by way of a vertical wall 707. The first portion 703 of each pad 701 is equipped with a front edge 709 which is parallel to the wall 707, and first 711 and second 713 lateral edges. The front edge 709 adjoins the first lateral edge by way of a first beveled edge 715.

[0060] The above description of the present invention is illustrative, and is not intended to be limiting. It will thus be appreciated that various additions, substitutions and modifications may be made to the above described embodiments without departing from the scope of the present invention. Accordingly, the scope of the present invention should be construed in reference to the appended claims. It will also be appreciated that the various features set forth in the claims may be presented in various combinations and sub-combinations in future claims without departing from the scope of the invention. In particular, the present disclosure expressly contemplates any such combination or subcombination that is not known to the prior art, as if such combinations or subcombinations were expressly written out.

Claims

WHAT IS CLAIMED IS:

1. A robotic end effector, comprising:

an end effector blade;

a housing disposed on a first end of said end effector blade;

an actuator disposed within said housing; and

a plurality of tabs disposed on said blade adjacent to said housing;

wherein each of said plurality of tabs includes a first portion adapted to receive a semiconductor wafer thereon, and a second portion which is raised with respect to said first portion, and wherein said each of said plurality of tabs comprises a

polyaryletherketone.

2. The robotic end effector of claim 1, wherein said polyaryletherketone is poly ether ether ketone (PEEK).

3. The robotic end effector of claim 1, wherein said PEEK is unfilled.

4. The robotic end effector of claim 1, wherein said second portion has an aperture therein, and wherein each of said plurality of tabs is secured to said wafer blade by way of a threaded fastener which extends through said aperture.

5. The robotic end effector of claim 1, wherein said blade has a base portion which is attached to said housing, and first and second protruding portions which extend from said base portion in first and second directions, respectively, away from said housing.

6. The robotic end effector of claim 1, wherein said actuator has a rotatable wheel disposed on a first end thereof, and wherein said wheel comprises a polyaryletherketone.

7. The robotic end effector of claim 6, wherein said polyaryletherketone is polyether ether ketone (PEEK).

8. A robotic end effector, comprising:

an end effector blade;

a housing disposed on a first end of said end effector blade;

an actuator disposed within said housing; and

a plurality of tabs disposed on said blade adjacent to said housing;

wherein each of said plurality of tabs includes a first portion adapted to receive a semiconductor wafer thereon, and a second portion which is raised with respect to said first portion and which is separated therefrom by way of a vertical wall, wherein the first portion of each tab is equipped with a front edge which is parallel to said wall and first and second lateral edges, and wherein said front edge adjoins said first lateral edge by way of a first beveled edge.

9. The robotic end effector of claim 8, wherein said first and second lateral edges are opposing edges.

10. The robotic end effector of claim 8, wherein said front edge adjoins said second lateral edge by way of a second beveled edge.

11. The robotic end effector of claim 8, wherein said actuator extends and retracts along an axis which lies between a first and second tab selected from the group consisting of said plurality of tabs.

12. The robotic end effector of claim 8, wherein said actuator has a rotatable wheel disposed on a first end thereof.

13. A robotic end effector, comprising:

an end effector blade; a housing which is equipped with a front wall and which is releasably attached to a first end of said end effector blade;

an actuator disposed within said housing, said actuator having a protrusion which extends through an aperture in said front wall; and

a closed-cell foam barrier disposed within said housing and adjacent to said front wall.

14. The robotic end effector of claim 13, wherein said end effector blade has a base portion having first and second opposing sides, and wherein said housing is disposed on said base portion.

15. The robotic end effector of claim 14, wherein said closed-cell foam barrier extends from said first side of said base to said second side of said base.

16. The robotic end effector of claim 14, wherein said base portion has first and second finger portions protruding therefrom.

17. The robotic end effector of claim 13, wherein said closed-cell foam barrier comprises a resilient polymeric material.

18. The robotic end effector of claim 13, further comprising:

a control unit; and

a flag having a first end which is attached to said actuator, and having a second end which is magnetically coupled to said control unit.

19. The robotic end effector of claim 18, wherein said flag has first and second segments that are adjoined at an angle, wherein said first end of said flag is disposed on said first segment, and wherein said second end of said flag is disposed on said second segment.

20. The robotic end effector of claim 19, wherein said first and second segments are essentially orthogonal to each other.

21. The robotic end effector of claim 19, wherein said flag is disposed between said closed-cell foam barrier and said end effector blade.

22. The robotic end effector of claim 13, wherein said closed-cell foam barrier is essentially Z-shaped.

23. A robotic end effector, comprising:

an end effector blade;

an actuator disposed within said housing, said actuator having a protrusion which advances and retracts along a first axis, said protrusion being equipped on a terminal end thereof with a resilient mass, and wherein said resilient mass traces out a three- dimensional space as said protrusion advances and retracts along said first axis;

a control unit; and

a flag having a first terminal portion which is attached to said actuator, and having a second terminal portion which is magnetically coupled to said control unit;

wherein said flag has first and second segments that are adjoined at an angle, wherein said first terminal portion of said flag is disposed on said first segment, and wherein said second terminal portion of said flag is disposed on said second segment; and wherein said first segment is equipped with a first portion having a first major surface which is essentially parallel to said first axis, and wherein said first segment is further equipped with a second major surface which is essentially perpendicular to said first major surface and which is wholly disposed within said three-dimensional space.

24. The robotic end effector of claim 23, further comprising: a housing which is equipped with a front wall and which is releasably attached to a first end of said end effector blade, wherein said protrusion on said actuator extends through an aperture in said front wall.

25. The robotic end effector of claim 23, wherein said resilient mass is a wheel.

26. The robotic end effector of claim 25, wherein said wheel is rotatable about a second axis which is orthogonal to said first axis.

27. The robotic end effector of claim 23, wherein said protrusion is mounted on a pneumatically driven rod.

28. The robotic end effector of claim 27, wherein said flag is releasably attached to said rod.

29. The robotic end effector of claim 27, wherein said second terminal portion of said flag is attached to said rod.

30. The robotic end effector of claim 27, wherein said second major surface of said first segment is essentially rectangular in shape.

31. The robotic end effector of claim 27, wherein said resilient mass is a wheel, and wherein said second major surface of said first segment is essentially rectangular in shape.

32. The robotic end effector of claim 31, wherein said wheel has a diameter d_w, wherein said second major surface has a diameter d₂, and wherein d_w > d₂.

33. The robotic end effector of claim 23, wherein said wherein said flag has first and second segments that are perpendicular to each other.

34. A robotic end effector, comprising:

a housing;

an end effector blade;

a control unit; and

a flag having a first end which is attached to said actuator, and having a second end which is magnetically coupled to said control unit;

wherein said flag has first and second segments that are adjoined at an angle, wherein said first end of said flag is disposed on said first segment, and wherein said second end of said flag is disposed on said second segment; and

wherein said first segment is equipped with a first portion having a first major surface which is essentially parallel to said first axis, and wherein said first segment is further equipped with a second major surface which is essentially perpendicular to said first major surface and which is wholly disposed within said three-dimensional space.

35. A robotic end effector, comprising:

a housing;

an end effector blade;

an actuator disposed within said housing, said actuator having a protrusion which advances and retracts from said housing along a first axis; and

a rigid, polymeric particle barrier disposed between said housing and said end effector blade, said particle barrier having an aperture therein through which said protrusion expands and retracts.

36. The robotic end effector of claim 35, wherein said particle barrier comprises polytetrafluoroethylene (PTFE).

37. The robotic end effector of claim 35, wherein said particle barrier comprises a rectangular face, the edges of which form an airtight seal with the housing.

38. The robotic end effector of claim 35, wherein said particle barrier is equipped with a first set of threads which rotatingly engage a second set of threads disposed on said actuator.

39. The robotic end effector of claim 35, wherein said particle barrier is equipped with alignment features which register the aperture with the protrusion to prevent contact between them.