Patent Publication Number: US-2023148165-A1

Title: Reticle pod including motion limiting features and method of assembling same

Description:
PRIORITY 
     This disclosure claims priority to U.S. provisional patent No. 63/277,188 with a filing date of Nov. 9, 2021. The priority document is incorporated by reference herein. 
     FIELD 
     This disclosure is directed to reticle pods, particularly reticle pods including fine as well as gross alignment features. 
     BACKGROUND 
     Reticle pods can be used to hold reticles, for example to secure the reticles during processing such as photolithography, including extreme ultraviolet (EUV) processes. The reticle pods can include outer pods and an inner pod, with the inner pod including a cover and a baseplate. The cover and baseplate can be made of hard materials, such as metal. Relative movement of the cover and baseplate can result in rubbing of the hard materials, in turn resulting in the generation of particles from wearing where the surfaces of the cover and baseplate rub against one another. 
     SUMMARY 
     This disclosure is directed to reticle pods, particularly reticle pods including fine as well as gross alignment features. 
     Reticle pods according to embodiments can be used in processes such as, for example, extreme ultraviolet (EUV) processes. Motion limiting features can be provided to improve the relative positioning of the cover and baseplate of the reticle pod. The motion limiting features can restrict smaller relative movements of the cover and the baseplate, reducing rubbing of the cover and baseplate to in turn reduce particle generation during use of the reticle pods. This can improve the purity of processes conducted using the reticle pods, increasing yields and reducing loss from particle contamination, misalignment of pod components, and the like. 
     In an embodiment, a reticle pod includes an inner pod including a baseplate and a cover. The inner pod includes at least one gross alignment feature and a plurality of motion limiting features. Each of the plurality of motion limiting features includes an alignment retention cutout formed in one of the cover or the baseplate and an elastic bodies disposed in the alignment retention cutout. The elastic body is configured to contact both of the baseplate and the cover when the inner pod is assembled. The plurality of motion limiting features are configured such that when a force having a component parallel to a plane of the baseplate or the cover is applied to the inner pod, at least one of the plurality of motion limiting features provides resistance to the force prior to the at least one gross alignment feature providing resistance to the force. 
     In an embodiment, a reticle pod includes an inner pod including a baseplate and a cover. The inner pod includes at least one gross alignment feature and a plurality of motion limiting features. Each of the plurality of motion limiting features includes a mating pin extending from one of the cover or the baseplate, and an elastic contact surface provided on the other of the cover or the baseplate. The mating pin is configured to contact the elastic contact surfaces when the inner pod is assembled. The plurality of motion limiting features are configured such that when a force having a component parallel to a plane of the baseplate or the cover is applied to the inner pod, at least one of the plurality of motion limiting features provides resistance to the force prior to the at least one gross alignment feature providing resistance to the force. 
     In an embodiment, the elastic contact surface is provided on an elastic body, the elastic body including a hollow portion opposite a surface where the mating pin is configured to contact said elastic contact surface. 
     In an embodiment, each of the mating pins is disposed in a mating pin channel, each mating pin channel formed in the one of the cover or the baseplate. 
     In an embodiment, a reticle pod includes an inner pod including a baseplate and a cover. The inner pod includes at least one gross alignment feature and a plurality of motion limiting features. Each of the plurality of motion limiting features includes a diaphragm disposed in one of the cover or the baseplate and a pin extending from the other of the cover or the baseplate, the pin configured to contact the diaphragm when the inner pod is assembled. The diaphragm has a resistance to deformation in a direction in plane with the cover or the baseplate that is greater than a resistance to deformation in a direction perpendicular to a plane of the cover or the baseplate. Each of the pins have a taper at an end configured to contact one of the plurality of diaphragms. The plurality of motion limiting features are configured such that when a force having a component parallel to a plane of the baseplate or the cover is applied to the inner pod, at least one of the plurality of motion limiting features provides resistance to the force prior to the at least one gross alignment feature providing resistance to the force. 
     In an embodiment, each of the motion limiting features includes an alignment retention cutout configured to accommodate the diaphragm and a retention ring configured to retain the diaphragm in the alignment retention cutout. 
     In an embodiment, the pin is disposed in a pin channel formed in the one of the cover or the baseplate. 
     In an embodiment, a reticle pod includes an inner pod including a baseplate and a cover. The inner pod includes at least one gross alignment feature and a plurality of motion limiting features. Each of the plurality of motion limiting features includes a motion limiting pin extending from one of the cover or the baseplate and a motion limiting cup provided in the other of the cover or the baseplate. The motion limiting pin is configured to be contacted by a plurality of distinct surfaces of the motion limiting cup when the inner pod is assembled. The plurality of motion limiting features are configured such that when a force having a component parallel to a plane of the baseplate or the cover is applied to the inner pod, at least one of the plurality of motion limiting features provides resistance to the force prior to the at least one gross alignment feature providing resistance to the force. 
     In an embodiment, the motion limiting cup is formed directly in one of the cover or the baseplate. 
     In an embodiment, the motion limiting cup is formed in an insert, the insert configured to be received in a recess formed in one of the cover or the baseplate. 
     In an embodiment, a method of securing an inner pod of a reticle pod includes engaging one or more gross alignment features included on one of a cover and a baseplate with the other of the cover and the baseplate, and engaging each of a plurality of motion limiting features provided on one of the cover or the baseplate with the other of the cover or the baseplate. The plurality of motion limiting features includes a plurality of alignment retention cutouts and a plurality of elastic bodies. Each elastic body is disposed in one of the alignment retention cutouts, and each of the plurality of elastic bodies is configured to contact both of the baseplate and the cover when the inner pod is assembled. When a force having a component in plane with the cover or the baseplate acts on the inner pod, the engagement of the motion limiting features provides resistance to the component of the force before the engagement of the cover gross alignment features with the baseplate gross alignment features provide resistance to the component of the force. In an embodiment, a reticle is located within the inner pod, and the method further includes placing the inner pod within an outer pod of the reticle pod and securing the outer pod to enclose the reticle pod and subjecting the inner pod to an extreme ultraviolet process. 
     In an embodiment, a method of securing an inner pod of a reticle pod includes engaging one or more gross alignment features included on one of a cover and a baseplate with the other of the cover and the baseplate and engaging each of a plurality of motion limiting features provided on one of the cover or the baseplate with the other of the cover or the baseplate. The plurality of motion limiting features includes a plurality of mating pins extending from one of the cover or the baseplate and a plurality of elastic contact surfaces on the other of the cover or the baseplate. Each of the plurality of mating pins is configured to contact one of the elastic contact surfaces. When a force having a component in plane with the cover or the baseplate acts on the inner pod, the engagement of the motion limiting features provides resistance to the component of the force before the engagement of the cover gross alignment features with the baseplate gross alignment features provide resistance to the component of the force. In an embodiment, a reticle is located within the inner pod, and the method further includes placing the inner pod within an outer pod of the reticle pod and securing the outer pod to enclose the reticle pod and subjecting the inner pod to an extreme ultraviolet process. 
     In an embodiment, a method of securing an inner pod of a reticle pod includes engaging one or more gross alignment features included on one of a cover and a baseplate with the other of the cover and the baseplate and engaging each of a plurality of motion limiting features provided on one of the cover or the baseplate with the other of the cover or the baseplate. The plurality of motion limiting features includes a plurality of diaphragms, each of the plurality of diaphragms disposed in one of the cover or the baseplate and a plurality of pins extending from the other of the cover or the baseplate. Each of the plurality of pins is configured to contact one of the plurality of diaphragms when the inner pod is assembled. Each of the plurality of diaphragms has a resistance to deformation in a direction in plane with the cover or the baseplate that is greater than a resistance to deformation in a direction perpendicular to a plane of the cover or the baseplate. Each of the pins have a taper at an end configured to contact one of the plurality of diaphragms. When a force having a component in plane with the cover or the baseplate acts on the inner pod, the engagement of the motion limiting features provides resistance to the component of the force before the engagement of the cover gross alignment features with the baseplate gross alignment features provide resistance to the component of the force. In an embodiment, a reticle is located within the inner pod, and the method further includes placing the inner pod within an outer pod of the reticle pod and securing the outer pod to enclose the reticle pod and subjecting the inner pod to an extreme ultraviolet process. 
     In an embodiment, a method of securing an inner pod of a reticle pod includes engaging one or more gross alignment features included on one of a cover and a baseplate with the other of the cover and the baseplate and engaging each of a plurality of motion limiting features provided on one of the cover or the baseplate with the other of the cover or the baseplate. The plurality of motion limiting features includes a plurality of motion limiting pins extending from one of the cover or the baseplate and a plurality of motion limiting cups provided in the other of the cover or the baseplate. Each of the plurality of motion limiting pins is configured to be contacted by a plurality of distinct surfaces of one of the plurality of motion limiting cups when the inner pod is assembled. When a force having a component in plane with the cover or the baseplate acts on the inner pod, the engagement of the motion limiting features provides resistance to the component of the force before the engagement of the cover gross alignment features with the baseplate gross alignment features provide resistance to the component of the force. In an embodiment, a reticle is located within the inner pod, and the method further includes placing the inner pod within an outer pod of the reticle pod and securing the outer pod to enclose the reticle pod and subjecting the inner pod to an extreme ultraviolet process. 
     In an embodiment, a reticle pod includes an inner pod including a baseplate and a cover. The inner pod includes at least one gross alignment feature and a plurality of motion limiting features. Each of the plurality of motion limiting features includes a pin extending from the cover on a side of the cover configured to face the baseplate when the inner pod is assembled, a slot formed in the baseplate, the slot configured to receive the pin, and a flexible member configured to cover the slot on a side of the baseplate opposite the cover when the inner pod is assembled. The flexible member includes a contact surface configured to be contacted by an end of the pin, the flexible member configured such that the contact surface can be deflected by contact with the pin. 
     In an embodiment, the inner pod includes at least three of the motion limiting features. In an embodiment, a major axis of each slot extends in a different direction from the major axes of all other slots. 
     In an embodiment, the reticle pod further includes a baseplate retention feature formed in the baseplate, and the flexible member includes a flexible member retention feature configured to engage with the baseplate retention feature. 
    
    
     
       DRAWINGS 
         FIG.  1    shows a reticle pod according to an embodiment. 
         FIG.  2    shows a sectional view of an inner pod of a reticle pod according to an embodiment. 
         FIG.  3    shows a sectional view of an inner pod of a reticle pod according to an embodiment. 
         FIG.  4    shows a sectional view of an inner pod of a reticle pod according to an embodiment. 
         FIG.  5    shows a plan view of a diaphragm in a baseplate of a reticle pod according to an embodiment. 
         FIG.  6    shows a sectional view of an inner pod of a reticle pod according to an embodiment. 
         FIG.  7    shows a baseplate of an inner pod of a reticle pod according to an embodiment. 
         FIG.  8    shows a sectional view of an inner pod of a reticle pod according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     This disclosure is directed to reticle pods, particularly reticle pods including fine as well as gross alignment features. 
       FIG.  1    shows a reticle pod according to an embodiment. Reticle pod  100  is configured to accommodate a reticle  102 . The reticle pod  100  includes an outer pod  104 , which includes pod dome  106  and pod door  108 . The reticle pod  100  further includes inner pod  110 , including baseplate  112  and cover  114 . Inner pod  110  further includes gross alignment features  116 . 
     Reticle pod  100  is a pod configured to store a reticle during transportation, handling, and processing, particularly for processing such as photolithography including, for example, Extreme Ultraviolet (EUV). The reticle is, for example, a photolithography mask for a semiconductor wafer. Reticle  102  is a reticle that can be contained within the reticle pod  100 , for example for transportation, handling, or processing such as processing by photolithography such as EUV. 
     The reticle pod  100  includes an outer pod  104 . The outer pod  104  is configured to accommodate inner pod  110 . The outer pod  104  can include pod dome  106  and pod door  108 . Outer pod  104  can be made of, for example, polymer materials. Pod dome  106  and pod door  108  can be configured such that they can be secured together to define an enclosed space, for example by way of a latching mechanism (not shown). 
     The inner pod  110  is configured to accommodate reticle  102 . Inner pod  110  can be sized such that it can be placed into outer pod  104 . Inner pod  110  can include a metal material, for example, being made of metal, made of metal having a coating, including one or more metal components, or the like. Inner pod  110  includes baseplate  112  and cover  114 . Baseplate  112  and cover  114  are configured to be placed together to enclose the reticle  102  within the inner pod  110 . The baseplate  112  and cover  114  can include features for alignment of the baseplate  112  and cover  114 , as discussed below and shown in  FIGS.  2 - 6   . The features for alignment can be configured to reduce relative movement of the baseplate  112  and cover  114  with respect to one another to reduce rubbing at contact surfaces where baseplate  112  and cover  114  meet one another. The features for alignment can be in addition to gross alignment features  116  used to guide assembly of the inner pod  110 . In an embodiment, the features for alignment can be provided on the gross alignment features  116 , such as providing a shoulder, ledge, or other such feature on at least a portion of the gross alignment features  116 . 
     Gross alignment features  116  can be provided on one or both of baseplate  112  and cover  114  to facilitate proper assembly of inner pod  110 . The gross alignment features can be any suitable feature for guiding or governing the relative alignment of baseplate  112  and cover  114  when inner pod  110  is being assembled. In the embodiment shown in  FIG.  1   , the gross alignment features  116  are extensions of the cover  114  at portions of the perimeter of the cover  114 , projecting outwards with respect to a surface of the cover  114  facing the baseplate  112  when inner pod  110  is assembled. In the embodiment shown in  FIG.  1   , the gross alignment features  116  define an area in which baseplate  112  is received when inner pod  110  is assembled. In an embodiment, the gross alignment features  116  can be provided at corners of the baseplate  112  or cover  114 . In an embodiment, the gross alignment features  116  can be provided at portions of the perimeter of baseplate  112  or cover  114  other than corners of the baseplate  112  or cover  114 . In an embodiment, the gross alignment features  116  can include first and second gross alignment features that engage with one another when the inner pod  110  is assembled. Other gross alignment features  116  that can be used include, as a non-limiting example, pins and corresponding channels, for example as shown in  FIG.  6    and described below. 
       FIG.  2    shows a sectional view of an inner pod of a reticle pod according to an embodiment. Inner pod  200  includes cover  202 . Cover  202  includes contact surface  204 . Reticle pod  200  further includes baseplate  206 . Baseplate  206  includes an alignment retention cutout  208 . An elastic body  210  can be disposed in the alignment retention cutout  208 . 
     Inner pod  200  is an inner pod of a reticle pod, such as an inner pod of reticle pod  100  shown in  FIG.  1    and described above. Inner pod  200  can be sized to fit within an outer pod of the reticle pod. Inner pod  200  can further be configured to define an internal space capable of containing a reticle, such as reticle  102  described above and shown in  FIG.  1   . 
     Cover  202  is a cover of a reticle pod, such as cover  114  of reticle pod  100  as described above and shown in  FIG.  1   . The cover  202  includes a contact surface  204  where the cover  202  is configured to contact at least a portion of baseplate  206  and/or elastic body  210  when cover  202  and baseplate  206  are assembled to form inner pod  200 . In an embodiment, contact surface  204  is the bare material of the cover  202 . In an embodiment, contact surface  204  can include a coating on the material of the cover  202 . In an embodiment, contact surface  204  is a flat surface of the cover  202 . In an embodiment, the contact surface  204  is a substantially smooth surface. In an embodiment, the contact surface  204  can include texturing, with non-limiting examples of the texturing including grooves, roughened sections, relatively raised bumps, combinations thereof, or the like. 
     Baseplate  206  is a baseplate of inner pod  200 . Baseplate  206  is configured to be joined with cover  202  to form inner pod  200 , with inner pod  200  providing an internal space capable of containing a reticle such as reticle  102  described above and shown in  FIG.  1   . Baseplate  206  includes a plurality of alignment retention cutouts  208 . While one representative alignment retention cutout  208  is shown in  FIG.  2   , a baseplate  206  can have a plurality of such retention cutouts  208 . In an embodiment, the baseplate  206  includes at least three alignment retention cutouts  208 . In an embodiment, the baseplate  206  includes four alignment retention cutouts  208 . In an embodiment, the alignment retention cutouts can be distributed around a perimeter of baseplate  206 . In an embodiment, the alignment retention cutouts can be located proximate to corners of the baseplate  206 . The alignment retention cutouts  208  are each an opening formed in a surface of the baseplate  206  that faces cover  202  when the inner pod  200  is assembled. The alignment retention cutouts  208  can each have any suitable shape for accommodating the elastic body  210  such that elastic body  210  can be retained in the alignment retention cutout  208  with a portion of the elastic body  210  protruding from the surface of the baseplate  206 . In an embodiment, all of the alignment retention cutouts  208  provided on baseplate  206  have the same shape. In an embodiment, at least some of the alignment retention cutouts  208  provided on the baseplate  206  can have shapes that differ from one another. 
     The elastic body  210  is a body made of elastic material and configured to be placed into one of the alignment retention cutouts  208  such that a portion of the elastic body  210  extends above the surface of the baseplate  206  such that it can contact cover  202  at contact surface  204  when the inner pod is assembled. The elastic body  210  can have any suitable shape based on the shape of the alignment retention cutouts  208 . In an embodiment, the elastic body  210  can be a spherical shape. In embodiments, elastic bodies  210  used in an inner pod  200  can each have the same shape. In embodiments, elastic bodies  210  having differing shapes can be used in one inner pod  200 . The elastic bodies  210  can include any suitable elastic or compressible material. The elastic or compressible material can be a material capable of withstanding conditions during processing of reticles contained within inner pod  200 . The elastic or compressible material can be, as a non-limiting example, an elastomer such as a fluoroelastomer. 
     While  FIG.  2    shows the contact surface  204  being provided on cover  202  and the alignment retention cutout  208  being provided on the baseplate  206 , it is understood that the contact surface and the alignment retention cutout can be reversed, such that the contact surface  204  is included in baseplate  206  and alignment retention cutout  208  is provided in cover  202  with the elastic body  210  placed in alignment retention cutout  208  extending outwards from a surface of cover  202  facing baseplate  206  when the inner pod  200  is assembled. 
     When inner pod  200  is assembled, contact surface  204  contacts and compresses elastic bodies  210 . Friction between the contact surface  204  and elastic bodies  210  can provide force resisting relative movement of the cover  202  and baseplate  206  with respect to one another where the relative movement includes a component in plane with the cover  202  or the baseplate  206 . This can reduce rubbing between the cover  202  and baseplate  206  and corresponding particle generation. 
     The contact surface  204  and the alignment retention cutouts  208  and elastic bodies  210  can form motion limiting features that retain the cover  202  and baseplate  206 . The motion limiting features can be separate and distinct from first and second gross alignment features also included in inner pod  200 , such as the first and second gross alignment features shown in  FIG.  6    and discussed below, such as gross alignment pins provided on one of cover  202  or baseplate  206  and corresponding gross alignment channels on the other of the cover  202  or baseplate  206 , where the gross alignment channels receive the gross alignment pins. 
       FIG.  3    shows a sectional view of an inner pod of a reticle pod according to an embodiment. Inner pod  300  includes cover  302 . Cover  302  includes a mating pin  304 . In the embodiment shown in  FIG.  3   , the mating pin  304  is disposed in a mating pin channel  306 . Inner pod  300  further includes baseplate  308 . Baseplate  308  includes an elastic contact surface  310 . In the embodiment shown in  FIG.  3   , the elastic contact surface  310  is included in an elastic body  312 . The elastic body  312  can be disposed in an alignment retention cutout  314  formed in the baseplate  308 . 
     Inner pod  300  is an inner pod of a reticle pod, such as an inner pod of reticle pod  100  shown in  FIG.  1    and described above. Inner pod  300  can be sized to fit within an outer pod of the reticle pod. Inner pod  300  can further be configured to define an internal space capable of containing a reticle, such as reticle  102  described above and shown in  FIG.  1   . 
     Cover  302  is a cover of a reticle pod, such as cover  114  of reticle pod  100  as described above and shown in  FIG.  1   . Cover  302  includes a plurality of mating pins  304 . Each mating pin  304  is a pin extending from cover  302  on a side of cover  302  that faces baseplate  308  when the inner pod  300  is assembled. Each of the mating pins  304  is configured to contact an elastic contact surface  310  provided on baseplate  308 . In an embodiment, mating pin  304  is formed integrally with the cover  302 . In an embodiment, mating pin  304  is a separate component from cover  302  that is disposed in a mating pin channel  306  formed in the cover  302 . In an embodiment, some or all of the mating pins  304  are the mating pins formed separately from the cover  302  and inserted into mating pin channels  306 . In an embodiment, the mating pins  304  disposed in mating pin channels  306  can be secured by a mechanical connection between the mating pin  304  and the mating pin channel  306 . In an embodiment, the mechanical connection can be a press-fit. In an embodiment, the mating pin channels  306  are through holes extending through an entire thickness of the cover  302 . In an embodiment, the mating pin channels are formed to a predetermined depth from a surface of cover  302  that faces baseplate  308  when the inner pod  300  is assembled. 
     Baseplate  308  is a baseplate of the reticle pod. Baseplate  308  is configured such that elastic contact surfaces  310  can be provided to contact each of the mating pins  304  of cover  302  when the inner pod  300  is assembled. The elastic contact surfaces  310  can be surfaces provided on baseplate  308  that are made of an elastic material that face the cover  302  when the inner pod  300  is assembled, such that the elastic contact surfaces  310  are contacted by the mating pins  304  provided on cover  302 . The elastic contact surfaces  310  can be surfaces that are raised above, flush with, or depressed with respect to a surface of baseplate  308  facing the cover  302  when the inner pod  300  is assembled. In an embodiment, at least three elastic contact surfaces  310  can be provided on baseplate  308 . In an embodiment, four elastic contact surfaces  310  can be provided on baseplate  308 . In an embodiment, the elastic contact surfaces  310  can be provided proximate to corners of the baseplate  308 . 
     The elastic contact surface  310  can be provided using an elastic body  312  disposed in an alignment retention cutout  314  formed in the baseplate  308 . Elastic body  312  can be a body having any suitable shape including the elastic contact surface and configured to be retained in the alignment retention cutout  314 . The alignment retention cutout  314  can have any suitable shape to accept at least a portion of the elastic body  312 . The elastic body  312  can be made of any suitable elastic or compressible material, such as, as a non-limiting example an elastomer such as a fluoroelastomer. The elastic body  312  is a body made of an elastic material. In an embodiment, elastic body  312  is a plug that is insertable into the alignment retention cutout  314 . In an embodiment, the elastic body  312  includes a lip that has a perimeter greater than a perimeter of the alignment retention cutout  314 . In an embodiment, the elastic body  312  includes an insertion portion having a shape corresponding to the alignment retention cutout  314 , such that a press-fit can be formed between the elastic body  312  and baseplate  308 . In an embodiment, elastic body is solid. In an embodiment, elastic body  312  includes a hollow section opposite the portion of the elastic body  312  that is contacted by the mating pin  304 . 
     When inner pod  300  is assembled, the mating pins  304  each contact a corresponding one of the elastic contact surfaces  310 . The mating pins  304  press into the elastic contact surfaces  310 , with this contact restricting relative motion of cover  302  and baseplate  308  where there is a component in plane with the cover  302  or the baseplate  308 . The mating pins  304  and elastic contact surfaces  310  can form motion limiting features additional to and distinct from gross alignment features included in cover  302  and/or baseplate  308 , such as motion limiting pins and channels. The motion limiting features can limit lateral motion or translational motion of the baseplate  308  and cover  302  relative to one another. Examples of such gross alignment features are, for example, discussed below and shown in  FIG.  6   . When inner pod  300  is assembled, the cover  302  and baseplate  308  can be contact with one another. In embodiments, variance in the surfaces such as manufacturing tolerances can cause some areas to be out of contact in the regions of cover  302  and baseplate  308  that correspond to one another. 
     While the embodiment shown in  FIG.  3    provides the elastic contact surfaces  310  on the baseplate  308  and the mating pins  304  on the cover  302 , it is understood that these features can be reversed such that the mating pins  304  are provided on baseplate  308  and the elastic contact surfaces are provided on cover  302 , with corresponding changes in the positions of the mating pin channels  306 , elastic bodies  312 , and alignment retention cutouts  314 . 
       FIG.  4    shows a sectional view of an inner pod of a reticle pod according to an embodiment. Inner pod  400  includes cover  402 . Cover  402  includes a pin  404 . In the embodiment shown in  FIG.  4   , pin  404  can be disposed in a pin channel  406  formed in cover  402 . Inner pod  400  further includes baseplate  408 . The baseplate  408  can include diaphragm openings  410 . A diaphragm  412  can be provided in each of the diaphragm openings  410 . A retention ring  414  can be provided to secure each diaphragm  412  in its respective diaphragm opening  410 . 
     Inner pod  400  is an inner pod of a reticle pod, such as an inner pod of reticle pod  100  shown in  FIG.  1    and described above. Inner pod  400  can be sized to fit within an outer pod of the reticle pod. Inner pod  400  can further be configured to define an internal space capable of containing a reticle, such as reticle  102  described above and shown in  FIG.  1   . 
     Cover  402  is a cover included in inner pod  400 . Cover  402  includes a plurality of pins  404  extending from a surface of cover  402  that faces baseplate  408  when the inner pod  400  is assembled. The pins  404  can have a tip having a taper or curve, such that the pins can be inserted to a predetermined depth when received in an opening provided in diaphragm  412 . In an embodiment, the pins  404  can be formed integrally with the cover  402 . In an embodiment, the pins  404  are each disposed in a pin channel  406  formed in the cover  402 . The pins  404  can be secured in pin channel  406  by any suitable connection, such as, as a non-limiting example, press-fit between each pin  404  and its respective pin channel  406 . In an embodiment, three or more pins  404  can be provided on cover  402 . In an embodiment, four pins  404  can be provided on cover  402 . In an embodiment, the pins  404  can be disposed proximate to corners of the cover  402 . In an embodiment, the pin channels  406  are openings recessed to a predetermined depth from the surface of cover  402  that faces the baseplate  408  when inner pod  400  is assembled. In an embodiment, the pin channels  406  can be through holes extending through an entire thickness of cover  402 . 
     Baseplate  408  is the baseplate included in inner pod  400 . Baseplate  408  includes a plurality of diaphragm openings  410  formed in positions corresponding to the positions of the pins  404  on cover  402 , such that the pins  404  can be received in diaphragms  412  when the cover  402  and baseplate  408  are assembled to form inner pod  400 . The diaphragm openings  410  are openings in the baseplate  408  that are each configured to contain a diaphragm  412 . In an embodiment, diaphragm openings  410  include a step, shoulder, or ledge that is recessed from the surface of baseplate  408  that faces the cover  402  when the inner pod is assembled. In an embodiment, a portion of the diaphragm opening  410  is a through hole extending through an entire thickness of baseplate  408 . In an embodiment, the diaphragm opening  410  does not extent completely through the thickness of baseplate  408 . 
     A diaphragm  412  is disposed in each of the diaphragm openings  410 . Diaphragm  412  is configured to receive an end of one of the pins  404  when the cover  402  is assembled to the baseplate  408 . The diaphragm  412  is configured such that the portion receiving the end of the pin  404  can be displaced in a direction substantially perpendicular to the plane of diaphragm  412 . The diaphragm  412  can provide substantially greater resistance to movement of the portion receiving the end of the pin  404  in directions parallel to the plane of diaphragm  412 . The diaphragm  412  can be made of any suitable material such as, for example, steel materials. An example of a diaphragm  412  is shown in  FIG.  5    and described in further detail below. 
     Retention ring  414  is configured to retain the diaphragm  412  in diaphragm opening  410 . The retention ring  414  can be, for example, a snap ring. Retention ring  414  can be made of any suitable materials including polymer or metal materials. The retention ring  414  can hold diaphragm  412  against steps, shoulders, or ledges provided in the diaphragm opening  410 . Retention ring  414  can have any suitable shape for engaging with the diaphragm opening  410  and retaining diaphragm  412  in position within the diaphragm opening  410 . In an embodiment, retention ring  414  can have a shape corresponding to the shape of the diaphragm opening  410 . 
     When inner pod  400  is assembled by placing cover  402  and baseplate  408  together, the tapered ends of the pins  404  each engage with one of the diaphragms  412 . The portion of the diaphragm  412  receiving the end of a pin  404  can move in a direction perpendicular to the diaphragm  412  such that the inner pod  400  can be assembled with little resistance. The engagement of diaphragm  412  and pin  404  can restrict relative movement of cover  402  and baseplate  408  that is in plane with the cover  402  or baseplate  408  due to the properties of the diaphragm  412  and differences in its resistance to deformation in plane versus deformation perpendicular to the plane of the diaphragm  412 . Accordingly, relative movement of cover  402  and baseplate  408  having a component in plane with the cover  402  or baseplate  408  is restricted, limiting rubbing of cover  402  against baseplate  408  when the inner pod  400  is assembled. The pins  404  and diaphragms  412  can form motion limiting features that are separate and distinct from first and second gross alignment features formed in the cover  402  and baseplate  408 , such as the gross alignment features shown in  FIG.  6    and described below. 
     While  FIG.  4    shows the pins  404  extending from the cover  402  and the diaphragm  412  disposed in a diaphragm opening  410  formed in the baseplate  408 , it is understood that these features can be reversed such that the pins  404  instead extend from baseplate  408  and the diaphragm  412  is disposed in a diaphragm opening  410  that is instead formed in cover  402 , with corresponding changes to the positions of other features such as the pin channels  406  and the retention rings  414 . 
       FIG.  5    shows a plan view of a diaphragm in a baseplate of a reticle pod according to an embodiment. Diaphragm  500  includes a central opening ring  502 , a plurality of spring beams  504 , which can include spring beam opening  506 . The diaphragm  500  is installed into diaphragm opening  508  formed in baseplate  510 . The diaphragm  500  can be secured in diaphragm opening  508  by a retention ring  512 . 
     Diaphragm  500  is an embodiment of diaphragm  412  as discussed above. Diaphragm  500  is configured to be deformable in a direction perpendicular to the plane of the diaphragm  500 , and to provide substantially greater resistance to deformation in directions parallel to the plane of the diaphragm  500 . The diaphragm  500  includes a central opening ring  502  configured to receive a tip of a pin, such as pin  404  described above and shown in  FIG.  4   . The central opening ring  502  can be configured to engage the tip of the pin along a tapered or curved portion. The central opening ring  502  can have any suitable shape for receiving and engaging with the pin, such as the circular opening shown in  FIG.  5   . Central opening ring  502  is supported by spring beams  504 . The spring beams  504  can be radially distributed about the central opening ring  502 . The spring beams  504  can have any suitable shape for allowing deformation that moves central opening ring  502  perpendicular to the plane of diaphragm  500 . In an embodiment, spring beams  504  each include their own respective spring beam opening  506 . The spring beams can each connect to a perimeter of the diaphragm  500  (not shown; covered by the retention ring  512 ). 
     Diaphragm opening  508  is an opening formed in baseplate  510 . The diaphragm opening  508  can be any suitable shape for accommodating diaphragm  500 . In an embodiment, diaphragm opening  508  includes a step, shoulder, or ledge recessed from a surface of the reticle pod  510  and sized such that the diaphragm  500  can rest on the step or ledge. In an embodiment, the diaphragm opening  508  is a recess from the surface of reticle pod  510  having a predetermined depth. In an embodiment, the diaphragm opening  508  includes at least a portion drilled through an entire thickness of the baseplate  510 . 
     Retention ring  512  is configured to retain the diaphragm  500  within the diaphragm opening  508 . Retention ring  512  can have any suitable shape to correspond to the perimeter of diaphragm  500  and fit within at least a portion of the diaphragm opening  508 . In an embodiment, the retention ring  512  is a snap ring. In an embodiment, retention ring  512  can press the diaphragm against a step, shoulder, or ledge formed in diaphragm opening  508  to secured the position of diaphragm  500  in place. 
       FIG.  6    shows a sectional view of an inner pod of a reticle pod according to an embodiment. Reticle pod  600  includes cover  602 . Cover  602  includes motion limiting pin  604 . The motion limiting pin  604  can be disposed in a motion limiting channel  606  provided in cover  602 . Reticle pod  604  further includes a baseplate  608 . Baseplate  608  includes a motion limiting cup  610 . In the embodiment shown in  FIG.  6   , the motion limiting cup  610  is provided on an insert  612 , with the insert provided in recess  614  formed in the baseplate  608 . A supplemental contact surface  616  can also be provided. In the embodiment shown in  FIG.  6   , a first gross alignment feature  618  and a second gross alignment feature  620  can also be seen. 
     Inner pod  600  is an inner pod of a reticle pod, such as an inner pod of reticle pod  100  shown in  FIG.  1    and described above. Inner pod  600  can be sized to fit within an outer pod of the reticle pod. Inner pod  600  can further be configured to define an internal space capable of containing a reticle, such as reticle  102  described above and shown in  FIG.  1   . 
     Cover  602  is a cover included in inner pod  600 . Cover  602  includes motion limiting pins  604 . In an embodiment, cover  602  includes at least 3 motion limiting pins  604 . In an embodiment, cover  602  includes 4 motion limiting pins  604 . In an embodiment, cover  602  includes a motion limiting pin  604  proximate to each corner of the cover  602 . Motion limiting pins  604  project from a surface of cover  602  that faces baseplate  608  when inner pod  600  is assembled. Motion limiting pins  604  can each have a tapered or curved tip. In an embodiment, motion limiting pin  604  can be formed integrally with cover  602 . In an embodiment, motion limiting pin  604  can be disposed in motion limiting channel  606 . The motion limiting pin  604  can be retained in motion limiting channel  606  by any suitable method. In an embodiment, motion limiting pin  604  is press-fit within motion limiting channel  606 . In an embodiment, motion limiting channel  606  is a recessed from the surface of cover  602 . In an embodiment, motion limiting channel  606  is a through hole extending through an entire thickness of the cover  602 . 
     Baseplate  608  is a baseplate of inner pod  600 . Baseplate  608  includes motion limiting cups  610  each configured to receive one of the motion limiting pins  604  provided on the cover  602 . The motion limiting cups  610  can be positioned such that their relative positions correspond to the positions of the motion limiting pins. In an embodiment, the motion limiting cups are featured formed in the baseplate  608  itself, for example being shaped cutouts from the baseplate  608 . In an embodiment, motion limiting cups  610  are each configured to provide a plurality of discrete points of contact with the motion limiting pin  604  when the motion limiting pin  604  is received in the motion limiting cup  610  when the inner pod  600  is assembled. In an embodiment, the motion limiting cups  610  can include a plurality of sloping portions configured to provide the points of contact with the corresponding motion limiting pin  604 . In an embodiment, the motion limiting cups  610  can each have a rectangular shape at the surface of baseplate  608 . In an embodiment, the motion limiting cups  610  are formed in inserts  612  that are configured to be placed into recesses  614  formed in baseplate  608 . The recesses  614  are configured to receive and retain the inserts  612 . In an embodiment, the recesses  614  retain the inserts by way of a press-fit. The inserts  612  can be made of any suitable material, including metals, coated metals, polymer materials, and the like, so long as the inserts  612  can restrict movement of the motion limiting pins and withstand any processing that inner pod  600  will be used in. The recesses  614  and inserts  612  can have generally rectangular shapes. In an embodiment, the major axis of these rectangular shapes can be angled with respect to the sides of the cover  602  or baseplate  608  such that the major axes of the recesses  614  and inserts  612  are not parallel with any of the sides of the cover  602  or baseplate  608 . 
     Supplemental contact surface  616  can be provided on baseplate  608  to provide further contact with the motion limiting pins  604 . In an embodiment, supplemental contact surface  616  extends above a surface of baseplate  608 . In an embodiment, supplemental contact surface  616  can be integral with baseplate  608 . In an embodiment, supplemental contact surfaces  616  are included in the insert  612 . Supplemental contact surface  616  can each be configured to contact a side of one of the motion limiting pins  604 . 
       FIG.  6    further shows gross alignment features included in inner pod  600 . While not visible in the particular views of  FIGS.  1 - 4   , it is understood that inner pods  110 ,  200 ,  300 , and  400  also include first and second gross alignment features such as the first and second gross alignment features  618 ,  620  visible in  FIG.  6   . First and second gross alignment features  618  and  620  are configured to interface with one another to guide the assembly of the inner pod  600  and to assist in securing the cover  602  to the baseplate  608 . In an embodiment, the first and second gross alignment features  618 ,  620  engage with one another prior to the engagement of motion limiting features such as the motion limiting pins  604  and the motion limiting cup  610 . In an embodiment, the first and second gross alignment features  618 ,  620  engage with one another subsequent to the engagement of motion limiting features such as the motion limiting pins  604  and the motion limiting cup  610 . In an embodiment, the first and second gross alignment features  618 ,  620  engage with one another at the same time as the engagement of motion limiting features such as the motion limiting pins  604  and the motion limiting cup  610 . 
     First gross alignment feature  618  can be a projection, for example a projection extending from cover  602 . The first gross alignment feature  618  can be formed integrally with cover  602 , or as shown in  FIG.  6   , can be a pin disposed in and extending from a channel formed in the cover  602 . 
     Second gross alignment feature  620  can be a channel configured to receive the first gross alignment feature  618 . The second gross alignment feature can be configured such that there is more space than necessary to receive first gross alignment feature  618  such that the engagement of first and second gross alignment features  620  allows for relative movement of cover  602  and baseplate  608  that is in plane with the cover  602  or the baseplate  608 . First and second gross alignment features  618 ,  620  can optionally be reversed such that the first gross alignment feature  618  projects from the baseplate  608  and the second gross alignment feature  620  is formed in the cover  602 . The interface of the first gross alignment features  618  and the corresponding second gross alignment features  620  can be such that up to 0.2 millimeters (mm) of relative movement in plane with the cover or baseplate may be allowed before the interface of the first and second gross alignment features  618 , 620  prohibits further movement. 
     When inner pod  600  is assembled by joining cover  602  to baseplate  608 , each of the motion limiting pins  604  interfaces with each of multiple contact surfaces provided by motion limiting cup  610  and supplemental contact surface  616 . The engagement of each of the motion limiting pins  604  with those multiple contact surfaces can restrict movement of the cover  602  relative to baseplate  608  such that relative movement in plane with cover  602  or baseplate  608  is restricted. 
     While the inner pod  600  shown in  FIG.  6    includes the motion limiting pin  604  in the cover  602  and the motion limiting cup  610  is provided on baseplate  608 , it is understood that these features can be reversed such that the motion limiting pin  604  instead projects from baseplate  608  and the motion limiting cup is provided on cover  602 , with any corresponding features such as motion limiting channel  606 , recess  614 , and supplemental contact surface  616  being correspondingly reversed from the cover  602  to the baseplate  608  and vice versa. 
     While the motion limiting features are shown individually in inner pods  200 ,  300 ,  400 , and  600  in  FIGS.  2 ,  3 ,  4 , and  6   , respectively, it is understood that the individual motion limiting features shown in those Figures can be combined, for example including the corresponding motion limiting features from two or more of inner pods  200 ,  300 ,  400 , and/or  600  in the cover and baseplate of another inner pod. 
       FIG.  7    shows a baseplate of an inner pod of a reticle pod according to an embodiment. Baseplate  700  includes a plurality of slots  702  formed on surface  704  facing a cover of the inner pod. The slots  702  are each backed by a flexible member  706  provided on an opposite side of the baseplate  700  and having a contact surface  708 . 
     Slots  702  are formed in the baseplate  700 . Slots  702  extend through the body of baseplate  700 . Slots  702  are sized to receive pins provided on a cover used with the baseplate  700  to form an inner pod, such as cover  802  having pins  804  as described below and shown in  FIG.  8   . Slots  702  are positioned such that at least a portion of each slot extends out of an area where a reticle is positioned when the reticle is stored in the inner pod including baseplate  700 . Each of the slots  702  has a major axis. In an embodiment, the baseplate  700  includes three slots  702 . Slots  702  can have any suitable two-dimension shape, for example a circular hole, a rectangle, an oval, a stadium or capsule shape, or the like. In an embodiment, slots  702  include straight sides perpendicular to a plane of the baseplate  700 . In an embodiment, slots  702  have sides angled with respect to the plane of the baseplate such that the slots  702  taper as they extend through baseplate  700 . The slots  702  can include a lead-in to facilitate insertion of pins into each of the slots  702 . In an embodiment, the slots  702  include a bevel and/or radiusing on a side of slots  702  facing the cover used with baseplate  702 . In an embodiment, the major axis of each of the slots  702  extends in a different direction. In an embodiment, the slots  702  are positioned such that the slots  702  are arranged mirrored to kinematic coupling grooves formed in a side of the baseplate  700  opposing surface  700 . In an embodiment, the baseplate  700  includes four or more slots  702 . In an embodiment, the major axes of at least two of the slots  702  are collinear or parallel. In an embodiment, the major axes of the slots  702  provided on baseplate  700  intersect at a center of the baseplate  700 . 
     Flexible members  706  are provided such that pins inserted into the slots  702  each contact a flexible member  706  after passing through the body of baseplate  700  through which slots  702  extend. The flexible members  706  can include a resilient polymer material, a metal spring arm, or any other suitable flexible material allowing a contact surface  708  of the flexible member to be deflected when a pin contacts the contact surface  708 . The contact surface  708  is a portion of flexible member  706  configured to engage with a pin of a cover to restrict movement of the pin along the extending direction of the slot  702  that the flexible member backs, thus limiting movement of the cover including said pin. The flexible member  706  can deflect such that the contact surface  708  engages with the pin at a taper, an angled end, or any other such other suitable surface formed on the pin. The flexible member  706  can have a flexibility selected such that the deflection of contact surface  708  is controlled to match a depth to which the pin protrudes through slot  702  when the inner pod including baseplate  700  is assembled. 
       FIG.  8    shows a sectional view of an inner pod of a reticle pod according to an embodiment. Inner pod  800  includes cover  802  including pins  804 . The pins  804  include an end  806 . Inner pod  800  further includes baseplate  808  including slots  810 . A flexible member  812  is provided at each of the slots  810 . Each flexible member includes a contact surface  814  and a flexible member retention feature  816 . The flexible member retention feature  816  is configured to engage with a baseplate retention feature  818  formed in the baseplate  808 . 
     Cover  802  is a cover of a reticle pod, configured to, when combined with baseplate  808 , form inner pod  800  including an internal space configured to accommodate a reticle. The cover  802  includes pins  804 . Pins  804  can be positioned such that the pins  804  do not extend through the inner pod at positions where the reticle may be present when the reticle is stored within inner pod  800 . The pins  804  extend a length such that the pins  804  can extend through the slots  810  to contact the contact surfaces  814  when the inner pod  800  is assembled. One or more pins  804  can be provided for each of the slots  810  included in the corresponding baseplate  808 , such as three pins  804  being provided in a cover  802  to be used with baseplate  700  having three slots  702  as described above and shown in  FIG.  7   . 
     Each of pins  804  includes end  806 . End  806  can be shaped to engage with the contact surface  814  provided by flexible member  812  at the respective slot  810 . In an embodiment, end  806  is tapered. In an embodiment, end  806  includes an angled surface that is not parallel or perpendicular to a direction of extension of the pin  804 . In an embodiment, end  806  comes to a point. When end  806  engages with contact surface  814 , movement of the pin  804  along slot  810  can be restricted by the contact of end  806  or a portion thereof with the contact surface  814 . 
     Baseplate  808  is a baseplate of the inner pod  800 . Baseplate  808  includes slots  810  formed in the baseplate  808 . Slots  810  extend through the thickness of baseplate  808 . Each slot  810  is configured to receive a corresponding pin  804  provided on the cover  802 . The slots can be included in any suitable number and arrangement, as described above for slots  702  shown in  FIG.  7   . A flexible member  812  is provided on a side of baseplate  808  opposite the cover  802  when the inner pod  800  is assembled. The flexible member  812  can be shaped to cover at least a portion of the opening formed by the slot  810 . Flexible member  812  covers an opening formed by slot  810  on the side opposite cover  802 . Flexible member  812  provides a contact surface  814  configured to engage with pin  804  so as to restrict movement of the cover  802  along a direction in which slot  810  extends. The flexible member  812  is configured such that contact surface  814  can be delfected by contact with the pin  804 . The contact surface  814  and deflection thereof can be configured such that the contact surface engages with features of end  806  of the pin  804 , such as an angled surface, a taper, or the like to restrict translational movement of the pin  804  along slot  810  and thus retain cover  802  at a particular position. The retention of cover  802  by way of the engagement of pin  804  with slot  810  and contact surface  814  can thus restrict translational motion of cover  802  relative to baseplate  808  such that alignment is maintained and sliding and particle generation at contacting surfaces of cover  802  and baseplate  808  are reduced. 
     Flexible member  812  includes flexible member retention feature  816  and baseplate  808  includes baseplate retention feature  818 . Flexible member retention feature  816  and baseplate retention feature  818  can be any suitable corresponding features for securing the flexible member  812  to baseplate  808 . In an embodiment, the baseplate retention feature  818  can be a groove or hole configured to receive a projection provided on flexible member  812  as the flexible member retention feature  816 . In an embodiment, the flexible member retention feature can be press-fit into the baseplate retention feature  818 . In an embodiment, the groove or hole can receive an undercut configured to receive a flange, tab, or other such projection from the flexible member retention feature  816 . In an embodiment, an adhesive can be provided to secure the flexible member retention feature  816  to baseplate retention feature  818 . 
     Aspects 
     It is understood that any of the following aspects may be combined with any other of the following aspects. 
     Aspect 1. A reticle pod, comprising: 
     an inner pod including a baseplate and a cover, wherein: 
     the inner pod includes at least one gross alignment feature and a plurality of motion limiting features, each of the plurality of motion limiting features including: 
     an alignment retention cutout formed in one of the cover or the baseplate and an elastic bodies disposed in the alignment retention cutout, wherein the elastic body is configured to contact both of the baseplate and the cover when the inner pod is assembled, and 
     wherein the plurality of motion limiting features are configured such that when a force having a component parallel to a plane of the baseplate or the cover is applied to the inner pod, at least one of the plurality of motion limiting features provides resistance to the force prior to the at least one gross alignment feature providing resistance to the force. 
     Aspect 2. A reticle pod, comprising: 
     an inner pod including a baseplate and a cover, wherein: 
     the inner pod includes at least one gross alignment feature and a plurality of motion limiting features, each of the plurality of motion limiting features including: 
     a mating pin extending from one of the cover or the baseplate, and an elastic contact surface provided on the other of the cover or the baseplate, wherein the mating pin is configured to contact the elastic contact surfaces when the inner pod is assembled, and 
     wherein the plurality of motion limiting features are configured such that when a force having a component parallel to a plane of the baseplate or the cover is applied to the inner pod, at least one of the plurality of motion limiting features provides resistance to the force prior to the at least one gross alignment feature providing resistance to the force. 
     Aspect 3. The reticle pod according to aspect 2, wherein the elastic contact surface is provided on an elastic body, the elastic body including a hollow portion opposite a surface where the mating pin is configured to contact said elastic contact surface. 
     Aspect 4. The reticle pod according to any of aspects 2-3, wherein each of the mating pins is disposed in a mating pin channel, each mating pin channel formed in the one of the cover or the baseplate. 
     Aspect 5. A reticle pod, comprising: 
     an inner pod including a baseplate and a cover, wherein: 
     the inner pod includes at least one gross alignment feature and a plurality of motion limiting features, each of the plurality of motion limiting features including: 
     a diaphragm disposed in one of the cover or the baseplate; 
     a pin extending from the other of the cover or the baseplate, the pin configured to contact the diaphragm when the inner pod is assembled; 
     wherein the diaphragm has a resistance to deformation in a direction in plane with the cover or the baseplate that is greater than a resistance to deformation in a direction perpendicular to a plane of the cover or the baseplate, and 
     each of the pins have a taper at an end configured to contact one of the plurality of diaphragms, 
     wherein the plurality of motion limiting features are configured such that when a force having a component parallel to a plane of the baseplate or the cover is applied to the inner pod, at least one of the plurality of motion limiting features provides resistance to the force prior to the at least one gross alignment feature providing resistance to the force. 
     Aspect 6. The reticle pod according to aspect 5, wherein each of the motion limiting features includes an alignment retention cutout configured to accommodate the diaphragm and a retention ring configured to retain the diaphragm in the alignment retention cutout. 
     Aspect 7. The reticle pod according to any of aspects 5-6, wherein the pin is disposed in a pin channel formed in the one of the cover or the baseplate. 
     Aspect 8. A reticle pod, comprising: 
     an inner pod including a baseplate and a cover, wherein: 
     the inner pod includes at least one gross alignment feature and a plurality of motion limiting features, each of the plurality of motion limiting features including: 
     a motion limiting pin extending from one of the cover or the baseplate; and a motion limiting cup provided in the other of the cover or the baseplate, 
     wherein the motion limiting pin is configured to be contacted by a plurality of distinct surfaces of the motion limiting cup when the inner pod is assembled,
 
wherein the plurality of motion limiting features are configured such that when a force having a component parallel to a plane of the baseplate or the cover is applied to the inner pod, at least one of the plurality of motion limiting features provides resistance to the force prior to the at least one gross alignment feature providing resistance to the force.
 
     Aspect 9. The reticle pod according to aspect 8, wherein the motion limiting cup is formed directly in one of the cover or the baseplate. 
     Aspect 10. The reticle pod according to any of aspects 8-9, wherein the motion limiting cup is formed in an insert, the insert configured to be received in a recess formed in one of the cover or the baseplate. 
     Aspect 11. A method of securing an inner pod of a reticle pod, comprising: 
     engaging one or more gross alignment features included on one of a cover and a baseplate with the other of the cover and the baseplate; 
     engaging each of a plurality of motion limiting features provided on one of the cover or the baseplate with the other of the cover or the baseplate, wherein the plurality of motion limiting features includes a plurality of alignment retention cutouts and a plurality of elastic bodies, wherein each elastic body disposed in one of the alignment retention cutouts, and each of the plurality of elastic bodies is configured to contact both of the baseplate and the cover when the inner pod is assembled, 
     wherein when a force having a component in plane with the cover or the baseplate acts on the inner pod, the engagement of the motion limiting features provides resistance to the component of the force before the engagement of the cover gross alignment features with the baseplate gross alignment features provide resistance to the component of the force. 
     Aspect 12. The method according to aspect 11, wherein a reticle is located within the inner pod, the method further comprising: placing the inner pod within an outer pod of the reticle pod and securing the outer pod to enclose the reticle pod, and 
     subjecting the inner pod to an extreme ultraviolet process. 
     Aspect 13. A method of securing an inner pod of a reticle pod, comprising: 
     engaging one or more gross alignment features included on one of a cover and a baseplate with the other of the cover and the baseplate; 
     engaging each of a plurality of motion limiting features provided on one of the cover or the baseplate with the other of the cover or the baseplate, wherein the plurality of motion limiting features includes a plurality of mating pins extending from one of the cover or the baseplate, and a plurality of elastic contact surfaces on the other of the cover or the baseplate, wherein each of the plurality of mating pins is configured to contact one of the elastic contact surfaces, 
     wherein when a force having a component in plane with the cover or the baseplate acts on the inner pod, the engagement of the motion limiting features provides resistance to the component of the force before the engagement of the cover gross alignment features with the baseplate gross alignment features provide resistance to the component of the force. 
     Aspect 14. The method according to aspect 13, wherein a reticle is located within the inner pod, the method further comprising: 
     placing the inner pod within an outer pod of the reticle pod and securing the outer pod to enclose the reticle pod, and
 
subjecting the inner pod to an extreme ultraviolet process.
 
     Aspect 15. A method of securing an inner pod of a reticle pod, comprising: 
     engaging one or more gross alignment features included on one of a cover and a baseplate with the other of the cover and the baseplate; 
     engaging each of a plurality of motion limiting features provided on one of the cover or the baseplate with the other of the cover or the baseplate, wherein the plurality of motion limiting features includes 
     a plurality of diaphragms, each of the plurality of diaphragms disposed in one of the cover or the baseplate; 
     a plurality of pins extending from the other of the cover or the baseplate, each of the plurality of pins configured to contact one of the plurality of diaphragms when the inner pod is assembled; 
     wherein each of the plurality of diaphragms has a resistance to deformation in a direction in plane with the cover or the baseplate that is greater than a resistance to deformation in a direction perpendicular to a plane of the cover or the baseplate; 
     each of the pins have a taper at an end configured to contact one of the plurality of diaphragms, 
     wherein when a force having a component in plane with the cover or the baseplate acts on the inner pod, the engagement of the motion limiting features provides resistance to the component of the force before the engagement of the cover gross alignment features with the baseplate gross alignment features provide resistance to the component of the force. 
     Aspect 16. The method of according to aspect 15, wherein a reticle is located within the inner pod, the method further comprising: 
     placing the inner pod within an outer pod of the reticle pod and securing the outer pod to enclose the reticle pod, and
 
subjecting the inner pod to an extreme ultraviolet process.
 
     Aspect 17. A method of securing an inner pod of a reticle pod, comprising: 
     engaging one or more gross alignment features included on one of a cover and a baseplate with the other of the cover and the baseplate; 
     engaging each of a plurality of motion limiting features provided on one of the cover or the baseplate with the other of the cover or the baseplate, wherein the plurality of motion limiting features includes: 
     a plurality of motion limiting pins extending from one of the cover or the baseplate; and
 
a plurality of motion limiting cups provided in the other of the cover or the baseplate,
 
wherein each of the plurality of motion limiting pins is configured to be contacted by a plurality of distinct surfaces of one of the plurality of motion limiting cups when the inner pod is assembled,
 
     wherein when a force having a component in plane with the cover or the baseplate acts on the inner pod, the engagement of the motion limiting features provides resistance to the component of the force before the engagement of the cover gross alignment features with the baseplate gross alignment features provide resistance to the component of the force. 
     Aspect 18. The method according to aspect 17, wherein a reticle is located within the inner pod, the method further comprising: 
     placing the inner pod within an outer pod of the reticle pod and securing the outer pod to enclose the reticle pod, and
 
subjecting the inner pod to an extreme ultraviolet process.
 
     Aspect 19. A reticle pod, comprising: 
     an inner pod including a baseplate and a cover, wherein: 
     the inner pod includes at least one gross alignment feature and a plurality of motion limiting features, each of the plurality of motion limiting features including: 
     a pin extending from the cover on a side of the cover configured to face the baseplate when the inner pod is assembled; 
     a slot formed in the baseplate, the slot configured to receive the pin; and 
     a flexible member configured to cover the slot on a side of the baseplate opposite the cover when the inner pod is assembled, the flexible member including a contact surface configured to be contacted by an end of the pin, the flexible member configured such that the contact surface can be deflected by contact with the pin. 
     Aspect 20. The reticle pod according to aspect 19, wherein the inner pod includes at least three of the motion limiting features. 
     Aspect 21. The reticle pod according to aspect 20, wherein a major axis of each slot extends in a different direction from the major axes of all other slots. 
     Aspect 22. The reticle pod according to aspect 19, further comprising a baseplate retention feature formed in the baseplate, wherein the flexible member includes a flexible member retention feature configured to engage with the baseplate retention feature. 
     The examples disclosed in this application are to be considered in all respects as illustrative and not limitative. The scope of the invention is indicated by the appended claims rather than by the foregoing description; and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.