EP2563689A1

EP2563689A1 - Opener for extreme ultra violet lithography reticle pods

Info

Publication number: EP2563689A1
Application number: EP11775403A
Authority: EP
Inventors: Kung Chris Wu
Original assignee: Fortrend Engineering Corp
Current assignee: Fortrend Engineering Corp
Priority date: 2010-04-30
Filing date: 2011-05-02
Publication date: 2013-03-06
Also published as: CN102753454B; CN102753454A; TW201206787A; US20130043776A1; WO2011136856A1

Abstract

A two stage opener (50) for an EUV RSP (32, 34) includes an outer RSP pod opener (42, 44) having: 1. a RSP latch mechanism (42rlm) for latching a sealed outer RSP pod (32, 34) in place on the RSP pod opener (42, 44); and 2. a RSP lock/unlock mechanism (42lulm) for unlocking the RSP pod (32, 34) so the RSP pod opener (42, 44) can separate a RSP pod cover (32c, 343c) from a RSP pod door (32d, 34d). After the RSP lock/unlock mechanism (42lulm) unlocks the RSP pod (32,34), the RSP pod opener (42, 44) separates the RSP pod door (32d, 34d) from the RSP pod cover (32c, 34c) thereby exposing a metal case (20). The pod opener (50) also includes a metal case opener (52) having at least two (2) arms (56) for receiving and supporting the metal case cover (22) while the two stage pod opener (50) separates the metal case base (24) from the metal case cover (22) thereby exposing the bare reticle (26) carried om the metal case base (24).

Description

OPENER FOR EXTREME ULTRA VIOLET LITHOGRAPHY RETICLE PODS

Technical Field

The present disclosure relates generally to the technical field of photolithographic manufacturing equipment and, more particularly, to openers for pods that enclose a photolithographic reticle.

Background Art

As semiconductor line width continue shrinking below 22nm circuit printing lithography tools can no longer use a conventional photo mask (also known as the reticle) that is covered by a pellicle film. When using an extra deep UV ("EUV") light source, that is necessary for printing a litho- graphic pattern having line widths below 22nm on a product, the pellicle's film distorts and/or absorbs the light thereby diminishing image quality. To avoid pattern distortion, exposing a lithography pattern having line widths below 22nm requires using both:

1. the EUV light source; and

2. a bare glass photo mask.

Historically, a protective pellicle film has been a critical for preventing particles from landing directly on the photo mask patterned glass surface. Contamination of a reticle's patterned glass surface by particles has an immediate impact on the yield of printed products, i.e. the yield of integrated circuit ("IC") die on a wafer. Removing the pellicle film from the reticle to accommodate 22nm or narrower line width lithographic printing creates a problem for storing and carrying bare glass reticles while concurrently avoiding particle contamination when using the photo mask.

The Semiconductor Equipment and Materials International's ("SEMI's") solution for storing and carrying bare glass reticles in a typical clean room environment is:

1. a metal case, identified by the general reference number 20 in FIG. 1A, for carrying the bare glass reticle; that is enclosed within

2. a conventional plastic case. The illustration of FIG 1A depicts the metal case 20 when open with its cover 22 above its base 24 with a photo mask 26 (reticle 26) resting on the base 24. The conventional plastic cases used for storing and carrying a bare glass reticle 26 enclosed in the metal case 20 is known as the reticle Standard Mechanical InterFace ("SMIF") Pod or RSP. FIG. IB depicts a 200mm RSP, referred to by the general reference number 32, that may enclose the metal case 20, and FIG. 1C depicts a 150mm RSP, referred to by the general reference number 34, that may also enclose the metal case 20. The primary differences between the two different RSPs 32, 34 are their respective:

1. mechanical dimensions; and

2. locking mechanism and location.

SEMI standards^' specify configurations for the two different RSPs 32, 34 and the metal case 20. The SEMI standard envisions keeping the metal case 20 closed whenever it is outside an ultra-clean environment that is free of contaminating particles such as when the metal case 20 is outside a vacuum chamber.

In accordance with the SEMI standard, the cover 22 of a closed metal case 20 does not lock onto the base.24. That is, the cover 22 of a closed metal case 20 lifts easily off the base 24 to expose the reticle 26 stored inside. The SEMI standard also provides a detailed specification for handles located on the cover 22 so the cover 22 can be lifted from the base 24 either manually by a human operator or automatically by a mechanical mechanism.

Similar to the metal case 20, both RSPs 32, 34 include a cover that may be separated from their base. The upper half of the RSPs 32, 34 is commonly known as or called respectively the pod cover 32c, 34c, and the lower half of the RSPs 32, 34 is commonly known as or called the pod door 32d, 34d. As illustrated respectively in FIGs . 2A and 2B, the SEMI standard specifies that the metal case 20 rests on the pod door 32d, 34d and is constrained by internal fixtures that prevent the metal case 20 from moving freely on the pod door 32d, 34d. After the pod cover 32c, 34c closes and mates with to the pod door 32d, 34d sealing the RSPs 32, 34, constraining fixtures attached to the pod cover 32c, 34c lock the metal case 20 from moving inside the RSPs 32, 34 while transporting the RSPs 32, 34 within an IC manufacturing facility either by automated equipments or human operators. The RSPs 32, 34 includes a locking mechanism that secures the pod cover 32c, 34c to the pod door 32d, 34d as specified in SEMI Standard E-19.4 for the 200 mm RSP 32, and SEMI Standard E-100 for the 150 mm RSP 34.

Everyone designing and manufacturing the EUV RSPs 32, 34 must comply with SEMI standards so EUV pod opener manufacturers can design proprietary opening/closing mechanisms that comply with the appropriate SEMI standard. Consequently, the design of the metal case 20 and the RSPs 32, 34 is not a subject of this disclosure.

Disclosure

An object of the present disclosure is to provide an opener for a pod that encloses and carries a bare photolithographic reticle.

Yet another object of the present disclosure is to provide an opener for a pod that encloses and carries a bare photolithographic reticle which is simple.

Yet another object of the present disclosure is to provide an opener for a pod that encloses and carries a bare photolithographic reticle which is durable.

Yet another object of the present disclosure is to provide an opener for a pod that encloses and carries a bare photolithographic reticle that is cost effective.

Yet another object of the present disclosure is to provide an opener for a pod that encloses and carries a bare photolithographic reticle that is easy to manufacture.

Yet another object of the present disclosure is to provide an opener for a pod that encloses and carries a bare photolithographic reticle that is easy to maintain.

Yet another object of the present disclosure is to provide an opener for a pod that encloses and carries a bare photolithographic reticle that is economical to manufacture.

Yet another object of the present disclosure is to provide an opener for a pod that encloses and carries a bare photolithographic reticle that forestalls reticle contamination .

Briefly, disclosed herein is a two stage pod opener for a pod that encloses and carries a bare photolithographic reticle. The reticle enclosing pod includes an outer RSP pod having :

1. a RSP pod door that is adapted for receiving a metal case, the metal case being adapted.for receiving and enclosing the bare reticle; and

2. a RSP pod cover that mates with and locks to the RSP pod door thereby enclosing the metal case within the sealed outer RSP pod.

The metal case includes:

1. a metal case base that is adapted for receiving the bare reticle; and

2. a metal case cover that mates with the metal case base having the bare reticle received thereon thereby enclosing the bare reticle within the metal case within the sealed outer RSP pod.

The two stage pod opener includes an outer RSP pod opener that includes :

1. a RSP latch mechanism for latching the sealed outer RSP pod in place on the outer RSP pod opener; and

2. a RSP lock/unlock mechanism for unlocking the outer RSP pod so the outer RSP pod opener can separate the

RSP pod cover from the RSP pod door.

After the RSP lock/unlock mechanism unlocks the outer RSP pod, the outer RSP pod opener separates the RSP pod door from the RSP pod cover thereby exposing the metal case. The two stage pod opener also includes a metal case opener having at least two (2) arms for receiving and supporting the metal case cover while the two stage pod opener separates the metal case base from the metal case cover thereby exposing the bare reticle carried on the metal case base .

These and other features, objects and advantages will be understood or apparent to those of ordinary skill in the art from the following detailed description of the preferred embodiment as illustrated in the various drawing figures. Brief Description of Drawings

FIG. 1A is a perspective view depicting an open metal case specified by the SEMI standard having a bare photo mask (reticle) resting on a base of the metal case ;

FIG. IB is a perspective view depicting a 200 mm RSP specified by the SEMI standard that may enclose the metal case depicted in FIG. 1A;

FIG. 1C is a perspective view depicting a 150 mm RSP specified by the SEMI standard that may enclose the metal case depicted in FIG. 1A;

FIG. 2A is a perspective view depicting the 200 mm RSP illustrated in FIG. IB when open with the RSP's cover raised above the RSP's door, and with the metal case depicted in FIG. 1A adjacent to the RSP's door;

FIG. 2B is a perspective view depicting the 150 mm RSP illustrated in FIG. 1C when open with the RSP's cover raised off of the RSP's door, and with the metal case depicted in FIG. 1A resting on the RSP's door;

FIG. 3A is a perspective view depicting an opener for opening and closing the 200 mm RSP depicted in FIGs . IB and 2A;

FIG. 3B is a perspective view depicting an opener for opening and closing the 150 mm RSP depicted in FIGs. 1C and 2B;

FIG. 4A is a plan view of the 200 mm RSP pod opener taken along the line 4A-4A in FIG. 3A with a 200 mm RSP resting thereon and with a latch mechanism adjacent thereto;

FIG. 4B is a perspective view depicting a pod table for receiving the 200 mm RSP that appears in FIGs 3A and 4A together with the RSP latch mechanism located at the top of the RSP pod opener depicted in FIG. 3A;

FIG. 4C is a perspective view depicting a lock/unlock mechanism located below the pod table depicted in FIGs. 4B for rotating latch pins depicted in FIG. 4B;

FIG. 4D is a partially cut-away perspective view depicting the 200 mm RSP pod opener illustrated in FIGs. 3A and 4A depicting a pod table elevator for lowering and raising the pod table including the elevator's linear bearings along which an arm moves vertically, a lead screw coupled to the arm, and an elevator drive motor for rotating the lead screw; FIG. 4E is another partially cut-away perspective view depicting the 200 mm RSP pod opener illustrated in FIG. 3A, 4A and 4D depicting the pod table elevator including the elevator's linear bearings along which the arm moves vertical- ly, the lead screw coupled to the arm, and the elevator drive motor;

FIG. 4F is an elevational view depicting the 200 mm RSP pod opener illustrated in FIG. 3A, 4A, 4D and 4E taken along the line 4F-4F in FIG. 4E depicting the pod table elevator including the arm to which the pod table attaches, and the pod table carrying the 200 mm RSP ' s door upon which the metal case rests when located at an inner metal case open/close position;

FIG. 4G is a perspective view depicting the 200 mm RSP pod opener depicted in FIGs . 3A, 4A, 4D, 4E and 4F included in the two stage EUV reticle pod opener with the RSP's cover removed and the pod table carrying the pod door and the metal case carried thereon located at the inner metal case open/close position;

FIG. 5 is a perspective view depicting a two stage EUV reticle pod opener in accordance with the present disclosure;

FIG. 6A is a plan view depicting a pair of inner metal case openers included in the two stage EUV reticle pod opener depicted in FIG. 5 with each inner metal case opener's pair of swing arms retracted and therefor disengaged from any metal case that may be located between the pair of inner metal case openers ;

FIG. 6B is a plan view depicting the pair of inner metal case openers illustrated in FIG. 6A with each inner metal case opener's pair of swing arms extended for engaging the cover of the metal case as the RSP pod opener may position between the pair of inner metal case openers,-

FIG. 7, is a perspective view depicting the two stage EUV reticle pod opener including the 200 mm RSP pod opener depicted in FIGs. 3A, 4A, 4D, 4E and 4F with the RSP's cover removed and the pod table carrying the pod door and the metal case carried thereon at the inner metal case open/close position; FIG. 8, is a plan view of the underside of the pod table depicted in FIG. 4C illustrating a sealed cover that encloses the lock/unlock mechanism; and

FIG. 9, is a plan view depicting the pair of inner metal case openers depicted in FIGs . 6A and 6B each of which is enclosed within a sealed cover, and with each inner metal case opener's pair of swing arms extended for engaging any metal case that may be between the pair of inner metal case openers. Best Mode for Carrying Out the Disclosure

The two stage EUV pod openers disclosed herein are adaptations of existing opener mechanisms marketed commercially by Fortrend Engineering Corporation respectively:

1. identified by the general reference number 42 in FIG. 3A for opening and closing the SEMI standard

E-19.4 200 mm RSP 32; or

2. identified by the general reference number 44 in FIG. 3B for opening and closing the SEMI standard E-100 150 mm RSP 34.

The adaptation of the standard Fortrend Engineering Corporation RSP pod openers 42, 44 adds a second mechanism for opening the inner metal case 20 the after opening the RSPs 32, 34. In other words, the EUV pod opener disclosed herein has two sub-assemblies. The first assembly (the existing RSP pod openers 42, 44) is the mechanism that opens the RSPs 32, 34; and the second assembly, an inner casing opener, is a mechanism that opens the metal case 20. Since the metal case 20 cannot be accessed until the RSPs 32, 34 has been opened, the following section describes the 200 mm RSP pod opener 42 illustrated in FIG. 3A to describe its structure and exemplify the complete opening sequence for the 200 mm RSP 32. The 150 mm RSP pod opener 44 operates similarly to the following description except that the pod locking mechanism differs from that of the 200 mm RSP pod opener 42. The lock/unlock mechanism included in either of the RSP pod openers 42, 44 is not a subject of this disclosure. The 200 mm RSP Pod Opener 42

The 200 mm RSP pod opener 42 opener is a "3-axis" motorized system that includes:

1. a RSP latch mechanism 42rlm illustrated in FIGs . 4A and 4B that is located at the top of the 200 mm RSP pod opener 42;

2. a RSP lock/unlock mechanism 42lulm illustrated in FIG. 4C that is located beneath a pod table 42pt that is depicted in FIG. 4B; and

3. a pod table elevator 42pte illustrated in FIG.

4D-4G.

The RSP latch mechanism 42rlm uses a dual-motor, dual-latch mechanism. When the 200 mm RSP 32 rests on the pod table 42pt of the 200 mm RSP pod opener 42 depicted in FIG. 4, the RSP latch mechanism 42rlm latches the 200 mm RSP 32 in place. The RSP latch mechanism 42rlm includes two (2) latch assemblies 421a depicted in FIGs. 4A and 4B that are respectively located along opposite sides of the 200 mm RSP pod opener 42. Each latch assembly 421a includes a linear motor 421m driving a friction rod 42fr linearly. A 90-degree angled arm 42aa is located atop a rotation shaft 42rs that is encircled by an 0-ring 42or that also presses against the friction rod 42fr. Moving the friction rod 42fr linearly rotates the O-ring 42or together with the rotation shaft 42rs thereby latching the 200 mm RSP 32 onto the pod table 42pt. The latch assemblies 421a are positioned symmetrically on opposite sides of the 200 mm RSP 32 preferably for locking the 200 mm RSP 32 along its front and rear edges. Alternatively, if required the latch assembly 421a can also be located for locking the 200 mm RSP 32 along the left and right edges.

As depicted in FIG. 4B, three (3) registration pins 42rp project upward above the pod table 42pt upon which the pod door 32d of the 200 mm RSP 32 rests. When the pod door 32d rests on the RSP latch mechanism 42rlm, the registration pins 42rp engage mating apertures formed into the pod door 32d. With the mechanical registration pins 42rp constraining planar motion of the 200 mm RSP 32 on the pod table 42pt, operators can not remove the 200 mm RSP 32 unless the latch assemblies 421a release the 200 mm RSP 32.

As also depicted in FIG.4B, two (2) RSP lock pins 421p project upward through arcuate slots 42as that pierce the pod table 42pt that receives the pod door 32d of the 200 mm RSP 32. With the pod door 32d of the 200 mm RSP 32 resting on the pod table 42pt, the RSP lock pins 421p engage locking mechanism holes in the pod door 32d. The RSP lock pins 421p extend downward through the arcuate slots 42as to the RSP lock/unlock mechanism 421ulm illustrated in FIG. 4C that is located on the underside of the pod table 42pt. The RSP lock/unlock mechanism 421ulm includes a dc motor 42dcm that drives a worm gear assembly 42wga to which attach one end of the RSP lock pins 421p. Via the worm gear assembly 42wga, the dc motor 42dcm energizes rotation of the RSP lock pins 421p either clockwise or counterclockwise along the arcuate slots 42as. The RSP lock/unlock mechanism 421ulm also includes a pod presence sensor 42pps which indicates when a 200 mm RSP 32 rests on the pod table 42pt, and a pair of pod lock/unlock sensors 42puls for indicating when the RSP lock pins 421p are in a position that unlocks the pod cover 32c from the pod door 32d. Operation of the RSP latch mechanism 42rlm described herein opens and closes the locking mechanism included in a pod door 32d of any 200 mm RSP 32 that complies with SEMI E-19.4 standard.

After the RSP lock/unlock mechanism 42lulm unlocks the 200 mm RSP 32 thereby allowing the pod door 32d to be separated from the pod cover 32c, the pod table elevator 42pte illustrated in FIG. 4D-4G lowers the pod table 42pt carrying the pod door 32d thereby separating the pod cover 32c from the pod door 32d and exposing the metal case 20. The pod table elevator 42pte conventionally includes a pair of vertically-oriented linear bearings 421b. Each linear bearing 421b carries opposite ends of an arm 42ar which, together with the pod table 42pt secured thereto, moves freely up and down the linear bearings 421b. The pod table elevator 42pte also includes a vertically-oriented lead screw 421s that is coupled to the arm 42ar. As is well known to those skilled in the relevant art, depending upon the handedness of the lead screw 421s rotation of the lead screw 421s in one direction, e.g. clockwise, moves the pod table 42pt upward while rotation in the opposite direction, e.g. counter-clockwise, moves the pod table 42pt downward. An elevator drive motor 42edm located near the bottom of the 200 mm RSP pod opener 42 rotates the lead screw 421s either clockwise or counter-clockwise.

Two Stage Pod Opener 50

A two stage pod opener 50 in accordance with the present disclosure depicted in FIG. 5 adds to the existing 200 mm RSP pod opener 42 as described thus far a pair of swing arm inner metal case openers 52. After being separated from the pod cover 32c, the pod door 32d carrying the metal case 20 descends within the two stage pod opener 50 along the pod table elevator 42pte to an inner metal case open/close position depicted in FIG. 4F and 4G. As illustrated in FIGs . 4G and 5, the inner metal case openers 52 are located along opposite sides of the 200 mm RSP pod opener 42 at the inner metal case open/close position. Each inner metal case opener 52 includes a base plate 54 attached to the structure of the 200 mm RSP pod opener 42.

As illustrated in FIGs. 6A and 6B, each inner metal case opener 52 includes a pair of arms 56 that are attached to the base plate 54 at pivot points 58 to be rotatable thereabout. Each arm 56 attaches by a linkage 62 to one end of a single axis linear motor 64 that is also secured to the base plate 54. One end of each linear motor 64 passes through a linear bearing guide 66 before connecting to one of the two (2) linkages 62. Energizing the linear motor 64 pulls on one of the arms 56 included in each inner metal case opener 52 while simultaneously pushing on the other arm 56. Force applied by the linear motor 64 to the pair of arms 56 of each inner metal case opener 52 causes both arms 56 to rotate about their respective pivot points 58 and swing toward the opposite inner metal case opener 52.

With the pod table 42pt located in the inner metal case open/close position, the configuration of the inner metal case openers 52 and their respective attachment to the 200 mm RSP pod opener 42 positions extended ends of the arms 56 as illustrated in FIG. 6B for receiving handles on the cover 22 of the metal case 20. After the arms 56 extend, the pod table elevator 42pte carrying the pod door 32d resumes descending along the linear bearings 421b. As illustrated in FIG. 7, further lowering of the pod table elevator 42pte causes the inner metal case openers 52 to engage and support the cover 22 of the metal case 20. Continued descent of the pod table elevator 42pte separates the cover 22 from the base 24 thereby exposing the bare reticle 26 that previously remained enclosed within the base 24 ,

Industrial Applicability

To ensure the cleanliness of the two stage pod opener 50, all moving parts that might create particles due to surface contact or friction are located in a contamination containing environment. Accordingly, as depicted in FIG. 8 on the underside of the pod table 42pt a sealed cover 72 encloses the RSP lock/unlock mechanism 421ulm. The sealed cover 72 is adequate for retaining any particles generated by moving parts included in the RSP lock/unlock mechanism 42lulm. As illustrated in FIG. 4E, all moving parts of the pod table elevator 42pte are:

1. located on a back side of the two stage pod opener

50 furthest from the pod table 42pt; and 2. separated from the pod table 42pt and the pod door 32d resting thereon by a wall 74.

Similar to the sealed cover 72, a sealed cover 76, depicted partially cut away in FIG. 4F so the elevator drive motor 42edm is visible, closes the back side of the two stage pod opener 50 where the linear bearings 421b, lead screw 421s and elevator drive motor 42edm are located. To ensure that a low pressure environment surrounds pod table elevator 42pte, multiple exhaust ports 78 depicted in FIG 4F are positioned along the lower edge of the two stage pod opener 50. Lastly, as depicted in FIG. 9 a sealed cover 82 encloses the mechanism of each of the two (2) inner metal case openers 52, and exhaust ports 82 located at one end of each base plate 54 ensures that a low pressure environment surrounds each inner metal case openers 52. Including the exhaust ports 78 and the exhaust ports 82 permits vacuum applied thereto to establish a low pressure environment respectively around pod table elevator 42pte and each of the two (2) inner metal case openers 52 for removing particles produced respectively thereby from the two stage pod opener 50.

Although the present invention has been described in terms of the presently preferred embodiment, it is to be understood that such disclosure is purely illustrative and is not to be interpreted as limiting. Consequently, without departing from the spirit and scope of the disclosure, various alterations, modifications, and/or alternative applications of the disclo- sure will, no doubt, be suggested to those skilled in the art after having read the preceding disclosure. Accordingly, it is intended that the following claims be interpreted as encompassing all alterations, modifications, or alternative applications as fall within the true spirit and scope of the disclosure.

Claims

The Claims What is claimed is:

1. A two stage pod opener for opening a pod that encloses and carries a photolithographic reticle therein, the pod including:

a. an outer RSP pod having:

i. a RSP pod door that is adapted for receiving a metal case, the metal case being adapted for receiving and enclosing a bare reticle; and ii. a RSP pod cover that mates with and locks to the RSP pod door thereby enclosing the metal case within the sealed outer RSP pod,

b. the metal case including:

i. a metal case base that is adapted for receiving the bare reticle; and

ii. a metal case cover that mates with the metal case base having the bare reticle received thereon thereby enclosing the bare reticle within the metal case within the sealed outer RSP pod,

the two stage pod opener comprising:

a. an outer RSP pod opener that includes:

i . a RSP latch mechanism for latching the sealed outer RSP pod in place on the outer RSP pod opener; and

ii. a RSP lock/unlock mechanism for unlocking the outer RSP pod so the outer RSP pod opener can separate the RSP pod cover from the RSP pod door ;

after the RSP lock/unlock mechanism unlocks the outer RSP pod, the outer RSP pod opener separating the RSP pod door from the RSP pod cover thereby exposing the metal case;

b. a metal case opener that includes at least two (2) arms for receiving and supporting the metal case cover while the two stage pod opener separates the metal case base from the metal case cover thereby exposing the bare reticle carried on the metal case base .

2. The two stage pod opener of claim 1 wherein the outer RSP pod opener includes an elevator adapted for lowering a pod table that receives the RSP pod door of the outer RSP pod when enclosing the bare reticle, the outer RSP pod opener separating the RSP pod door from the RSP pod cover thereby exposing the metal case by lowering the pod table carrying the RSP pod door downward from the RSP pod cover.

3. The two stage pod opener of claim 2 wherein a sealed cover about the elevator forestalls contaminating the bare reticle with particles produced by the elevator.

4. The two stage pod opener of claim 3 wherein at least one exhaust port coupled to the sealed cover permits establishing a low pressure environment about the elevator.

5. The two stage pod opener of claim 2 wherein the pod table also carries the RSP lock/unlock mechanism.

6. The two stage pod opener of claim 5 wherein a sealed cover about the RSP lock/unlock mechanism forestalls contaminating the bare reticle with particles produced by the RSP lock/unlock mechanism.

7. The two stage pod opener of claim 2 wherein the elevator lowers the RSP pod door to an inner metal case open/close position thereby juxtaposing the metal case carried on the RSP pod door with the metal case opener.

8. The two stage pod opener of claim 7 wherein positioning each of the arms of the metal case opener for receiving and supporting the metal case cover includes rotating the arms about respective pivot points.

9. The two stage pod opener of claim 8 wherein the two stage pod opener separates the metal case base from the metal case cover by lowering the pod table carrying the RSP pod door downward from the metal case cover.

10. The two stage pod opener of claim 1 wherein a sealed cover about the metal case opener forestalls contaminating the bare reticle with particles produced by the metal case opener.

11. The two stage pod opener of claim 10 wherein at least one exhaust port coupled to the metal case opener permits establishing a low pressure environment about the metal case opener .

12. The two stage pod opener of claim 1 wherein positioning each of the arms of the metal case opener for receiving and supporting the metal case cover includes rotating the arms about respective pivot points.

13. The two stage pod opener of claim 12 wherein an elevator included in the two stage pod opener that is adapted for lowering a pod table that receives the RSP pod door of the outer RSP pod that carries the metal case separates the metal case base from the metal case cover by lowering the pod table carrying the RSP pod door downward from the metal case cover.

14. The two stage pod opener of claim 13 wherein a sealed cover about the elevator forestalls contaminating the bare reticle with particles produced by the elevator.

15. The two stage pod opener of claim 14 wherein at least one exhaust port coupled to the elevator permits establishing a low pressure environment about the elevator.