Extreme UV Inner Pod Seal Gap

Abstract

The apparatus includes a reticle pod. The reticle pod includes a base plate having a first surface, a cover having a second surface, and a standoff mechanism on at least one of the cover and the base plate. The first surface includes a first sealing surface about a periphery of the base plate. The second surface includes a second sealing surface about a periphery of the cover. The standoff mechanism is configured to create a linear gap between the first sealing surface and the second sealing surface when the cover is attached to the base plate.

Description

[Technical Field]

[0001] This disclosure claims priority to U.S. Provisional Patent Application No. 63 / 271,617, filed October 25, 2021, which priority document is incorporated herein by reference for all purposes.

[0002] The present disclosure relates generally to reticle pods for use with reticles, and more particularly to an apparatus and method for creating a linear gap between sealing surfaces of a cover and a base plate when the cover is attached to the base plate of a reticle pod, such as an extreme ultraviolet (EUV) reticle pod. [Background technology]

[0003] Reticle pods are used to house reticles, such as photolithography masks used during semiconductor processing, such as EUV processing. Reticle pods can be used for storing and transporting reticles. Reticle pods can include inner pods that are handled and manipulated by one or more tools during processing. The inner pod of a reticle pod includes a base plate and a cover that house the reticle and protect it from contamination or physical damage during transportation, storage, and processing. Reticle pods include, for example, EUV pods for use with EUV photolithography tools. Reticle pods can include an outer pod with a pod door and a pod dome that houses the inner pod. Summary of the Invention

[0004] The present disclosure relates generally to reticle pods for use with reticles, and more particularly to an apparatus and method for creating a linear gap between sealing surfaces of a cover and a base plate when the cover is attached to the base plate of a reticle pod, such as an extreme ultraviolet (EUV) reticle pod.

[0005] The reticle pod can include an inner pod (e.g., a metal inner pod, etc.). The inner pod of the reticle pod includes a cover and a base plate. Over time, wear occurs on the sealing surfaces of the cover and base plate during use. While maintaining a minimum distance between the sealing surfaces of the cover and base plate, a linear gap can be created to eliminate contact or to move the contact (between the sealing surfaces) and the associated wear away from the sealing surfaces.

[0006] In one embodiment, the apparatus includes a reticle pod. The reticle pod includes a base plate having a first surface, a cover having a second surface, and a standoff mechanism on at least one of the cover and the base plate. The first surface includes a first sealing surface around the periphery of the base plate. The second surface includes a second sealing surface around the periphery of the cover. The standoff mechanism is configured to create a seal between the first sealing surface and the second sealing surface via a linear gap when the cover is attached to the base plate.

[0007] In one embodiment, the linear gap extends from the periphery of the cover and the periphery of the base plate to an interior space within the reticle pod.

[0008] In one embodiment, the reticle pod is an EUV reticle pod. The base plate and cover are configured to house the reticle when the cover is attached to the base plate.

[0009] In one embodiment, the apparatus further comprises an outer pod dome and an outer pod door configured to enclose the base plate and the cover within the outer pod dome when the outer pod door is attached to the outer pod dome.

[0010] In one embodiment, the minimum size of the linear gap is at or about 2 microns.

[0011] In one embodiment, the maximum size of the linear gap is at or about 40 microns.

[0012] In one embodiment, the standoff feature includes a plurality of standoff pads. One of the first and second sealing surfaces includes a plurality of retention openings. The other of the first and second sealing surfaces includes a plurality of recesses. Each pad of the plurality of pads extends into one of the plurality of retention openings and is partially received within one of the plurality of recesses.

[0013] In one embodiment, the plurality of pads includes at least three pads.

[0014] In one embodiment, the plurality of pads includes eight pads.

[0015] In one embodiment, the pads are made of a polymer.

[0016] In one embodiment, the pads are made of metal.

[0017] In one embodiment, the plurality of retention openings are a plurality of through holes.

[0018] In one embodiment, the pads are pressed into the retention openings, respectively, and extend a fixed height from one of the first sealing surface and the second sealing surface to create a linear gap.

[0019] In one embodiment, the plurality of pads are molded or machined within the plurality of retention openings, respectively, and extend a fixed height from one of the first sealing surface and the second sealing surface to create a linear gap.

[0020] In one embodiment, the top surface of each pad of the plurality of pads is flush with or slightly below the top surface of the cover or the bottom surface of the base plate.

[0021] In one embodiment, the reticle pod further comprises a filter, and the seal is configured such that the reticle pod has a conductance of at least 90%. In one embodiment, the conductance is at least 94%.

[0022] In one embodiment, a method for assembling a reticle pod is provided. The reticle pod includes a base plate having a first surface, a cover having a second surface, and a standoff mechanism on at least one of the cover and the base plate. The first surface includes a first sealing surface around the periphery of the base plate. The second surface includes a second sealing surface around the periphery of the cover. The standoff mechanism is configured to create a seal between the first sealing surface and the second sealing surface via a linear gap when the cover is attached to the base plate. The method includes providing the standoff mechanism on at least one of the cover and the base plate.

[0023] In one embodiment, the method further includes inserting a plurality of standoff pads of the standoff mechanism into the plurality of retention openings, respectively, and adjusting the height of each pad of the plurality of pads to a constant height. The plurality of retention openings are on one of the first sealing surface and the second sealing surface. In one embodiment, the plurality of recesses are on the other of the first sealing surface and the second sealing surface. In one embodiment, adjusting the height of each pad of the plurality of pads to a constant height includes machining the plurality of pads so that the height of each pad of the plurality of pads is a constant height.

[0024] In one embodiment, adjusting the height of each of the plurality of pads to a constant height includes pressing the plurality of pads so that the height of each of the plurality of pads is a constant height.

[0025] In one embodiment, the minimum distance between each pad of the plurality of pads and the interior boundary of the first sealing surface or the second sealing surface is 4 mm or about 4 mm. [Brief explanation of the drawings]

[0026] Reference is made to the accompanying drawings which form a part of this disclosure and which show by way of illustration embodiments in which the systems and methods described herein may be practiced. The accompanying drawings illustrate various embodiments of systems, methods, and embodiments of various other aspects of the present disclosure. Those skilled in the art will recognize that illustrated element boundaries in the figures (e.g., boxes, collections of boxes, or other shapes) represent examples of such boundaries. In some examples, one element may be designed as multiple elements, or multiple elements may be designed as one element. In some examples, an element shown as an internal component of one element may be implemented as an external component of another element, and vice versa. Furthermore, elements may not be drawn to scale. A non-limiting and non-exhaustive description is set forth with reference to the following drawings. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating principles. [Figure 1A] 1 is a cross-sectional view of an inner pod of a reticle pod when closed, according to one embodiment. [Figure 1B] 1B is a cross-sectional view of the inner pod of FIG. 1A when open, according to one embodiment. [Figure 2] FIG. 1B is a plan view of a base plate in a reticle pod according to one embodiment. [Figure 3] FIG. 10 is a bottom view of a cover for a reticle pod according to one embodiment. [Figure 4] FIG. 1 is an exploded view of an inner pod of a reticle pod including a cover and a base plate, according to one embodiment. [Figure 5] FIG. 5 is a top view of the cover of FIG. 4 according to one embodiment. [Figure 6] FIG. 5 is a cross-sectional view of the inner pod taken along line A1-A2 of FIG. 4, according to one embodiment. [Figure 7] FIG. 10 is a schematic diagram of a gap created between a cover and a base plate, according to one embodiment. [Figure 8] FIG. 2 is a perspective view of a reticle pod according to one embodiment. [Figure 9]1 is a flowchart diagram of a method for assembling a reticle pod, according to one embodiment.Like reference characters refer to like parts throughout. DETAILED DESCRIPTION OF THE INVENTION

[0027] The present disclosure relates generally to reticle pods for use with reticles, and more particularly to an apparatus and method for creating a linear gap between sealing surfaces of a cover and a base plate when the cover is attached to the base plate of a reticle pod, such as an extreme ultraviolet (EUV) reticle pod.

[0028] Photolithography tools can utilize EUV light to enable finer linewidths. Due to the use of EUV light, lithography can be performed under vacuum to reduce energy loss of the EUV light. Considering the vacuum requirements, pods used to transport and store reticles used in EUV can be designed as dual-pods, consisting of an outer pod (typically made of polymeric materials, etc.) to protect the reticle when it is outside the lithography tool, and an inner pod (mainly made of metal and low-outgassing materials, etc.) to transport the reticle into the vacuum region of the EUV lithography tool. The EUV inner pod utilizes two flat mating surfaces (typically constructed of metal, etc.) to create a particle barrier and protect the reticle. These mating surfaces wear during use due to the cycling of the outer pod and the opening and closing of the inner pod. This wear can be considered a particle concern and defect that reduces the quality of the pod. The embodiments disclosed herein can reduce wear at this interface, for example by creating a linear gap between the sealing / mating surfaces, as well as reduce particles generated during reticle transfer.

[0029] The following definitions are applicable throughout this disclosure. As defined herein, the term "linear" can refer to, for example, being arranged in or extending along a straight or approximately straight line. The term "linear gap" can refer to, for example, a gap formed between a first edge and a second edge, where each of the first edge and the second edge is arranged in or extends along a straight or approximately straight line, and the size of the gap is the distance between the first edge and the second edge. For example, a linear gap can be created between the sealing surfaces of a cover and a base plate, and the size of the gap is the distance between the sealing surfaces of the cover and the base plate.

[0030] Some embodiments of the present application will be described in detail with reference to the accompanying drawings so that those skilled in the art can more easily understand the advantages and features of the present application. Terms such as "near," "far," "top," "bottom," "left," and "right" used in the present application are defined for the convenience of explanation according to a typical observation angle of a person skilled in the art. These terms are not limited to a specific direction.

[0031] Those skilled in the art will recognize that, for this and other processes and methods disclosed herein, the functions performed in the processes and methods may be performed in differing order. Furthermore, the outlined steps and operations are provided merely as examples, and some of the steps and operations may be optional, combined into fewer steps and operations, or expanded into additional steps and operations without detracting from the essence of the embodiments of the present disclosure.

[0032] Specific embodiments of the present disclosure are described herein with reference to the accompanying drawings. However, it should be understood that the embodiments of the present disclosure are merely examples of the present disclosure, which can be embodied in various forms. To avoid unnecessarily obscuring the present disclosure in detail, well-known functions or structures are not described in detail. Therefore, specific structural and functional details disclosed herein should not be construed as limiting, but merely as a basis for the claims and, in fact, as a representative basis for teaching those skilled in the art how to variously utilize the present disclosure in any appropriately detailed structure. In this specification and in the drawings, like reference numerals represent elements that can perform the same, similar, or equivalent functions.

[0033] Furthermore, the present disclosure may be described herein in terms of functional block components and various processing steps. It should be appreciated that such functional blocks may be realized by any number of hardware and / or software components configured to perform the specified functions. For example, the present disclosure may employ various processing elements, logic elements, etc., that can perform various functions under the control of one or more microprocessors or other control devices.

[0034] The scope of the present disclosure should be determined by the appended claims and their legal equivalents, rather than by the examples provided herein. For example, unless otherwise specified, the steps recited in any method claim can be performed in any order and are not limited to the order presented in the claims. Further, unless specifically described herein as "critical" or "essential," no element is essential to the practice of the present disclosure.

[0035] 1A and 1B show cross-sectional views of an inner pod 1 of a reticle pod according to one embodiment. FIG. 1A shows the inner pod 1 when closed. FIG. 1B shows the inner pod 1 when open. The inner pod 1 has an interior space with a reticle receiving portion 3 for receiving a reticle 5. The pod 1 can include reticle supports 7A, 7B within the reticle receiving portion 3 for supporting the reticle 5 within the inner pod 1.

[0036] The internal pod 1 includes a base plate 10 and a cover 40. In one embodiment, the base plate 10 and the cover 40 are configured to be joined together to provide a seal between the base plate 10 and the cover 40. As shown in FIG. 1A , the internal space of the internal pod 1 is enclosed (e.g., closed) by placing the cover 40 on the base plate 10. In one embodiment, the cover 40 directly contacts the base plate 10. Specifically, the lower portion 42 of the cover 40 contacts the upper portion 12 of the base plate 10. In another embodiment, a gap (e.g., a linear gap, see FIG. 7 ) can be created between the sealing surfaces of the cover 40 and the base plate 10. The internal pod 1 is opened by moving the cover 40 away from the base plate 10 (e.g., by moving the cover upward in direction D1). For example, an external tool (e.g., an automated arm, etc.) opens the internal pod 1 to access the reticle housing 3 and remove the reticle 5.

[0037] The base plate 10 and the cover 40 include one or more sealing surfaces configured to provide a seal between the base plate 10 and the cover 40. For example, the seal can be configured to reduce or prevent external contents (e.g., air, dust, etc.) from entering the pod 1 by passing between the base plate 10 and the cover 40. In one embodiment, the base plate 10 includes one or more sealing surfaces that directly contact the cover 40 when the cover 40 is disposed on the base plate 10. In another embodiment, a gap (e.g., a linear gap, see FIG. 7 ) can be created between the one or more sealing surfaces of the base plate 10 and the cover 40 when the cover 40 is disposed on the base plate 10. In one embodiment, the cover 40 includes one or more sealing surfaces configured to directly contact the base plate 10 when the cover 40 is disposed on the base plate 10. In another embodiment, a gap (e.g., a linear gap, see FIG. 7 ) can be created between the one or more sealing surfaces of the cover 40 and the base plate 10 when the cover 40 is disposed on the base plate 10. For example, base plate 10 can include a first sealing surface (eg, sealing surface 14) and cover 40 can include a second sealing surface (eg, sealing surface 44).

[0038] Sealing at sealing surface 40 can be achieved by providing a linear gap having a predetermined size, which is selected so that sealing always occurs even when the sealing surfaces do not contact each other. Sealing can occur when a pressure differential is created between the interior of inner pod 1 and the ambient environment for a predetermined period of time after a change in conditions occurs in the ambient environment, such as pumping down to a vacuum in the ambient environment or releasing a previously achieved vacuum, as may occur in a load lock in which inner pod 1 may be placed. The pressure differential indicates that the seal significantly resists airflow into and out of the interior space of inner pod 1, even when a gap exists between the sealing surfaces.

[0039] In one embodiment where the inner pod 1 includes a filter, the sealing effectiveness of the sealing surface can be measured by determining the conductance. Conductance can be the ratio of the amount of flow through the filter to the total flow through the filter and sealing surface to the inner pod 1. Conductance can be calculated using the following formula: This can be determined by TIFF0007791321000001.tif14170. During the ceremony, V = Volume inside the inner pod P EIP = pressure inside the inner pod P chamber = pressure in the test chamber t = time.

[0040] In one embodiment, the size of the linear gap between the sealing surfaces can be selected to provide a conductance of 90% or greater. In one embodiment, the size of the linear gap between the sealing surfaces can be selected to provide a conductance of 92% or greater. In one embodiment, the size of the linear gap between the sealing surfaces can be selected to provide a conductance of 94% or greater. In one embodiment, the size of the linear gap between the sealing surfaces can be selected to provide a conductance of 95% or greater. In one embodiment, the size of the linear gap between the sealing surfaces of pod 1 that provides a suitable seal is approximately 13 microns, or approximately 0.0005 inches. It is understood that the linear gap size is an average value, and surface variations, manufacturing tolerances, and the like may result in some variation in the linear gap size across the sealing surfaces. The sealing surfaces can be spaced sufficiently apart to reduce or eliminate contact at the sealing surfaces, thereby providing these conductance values ​​while reducing friction or other mechanical contact that may cause wear and particle generation at the sealing surfaces.

[0041] Figure 2 is a plan view of a base plate 10 for a reticle pod according to one embodiment. Figure 2 shows a top portion 12 of the base plate 10. A cover 40 is configured to be placed on the top portion 12 of the base plate 10. The base plate 10 can also include a reticle support 7A.

[0042] The base plate 10 includes a sealing surface 14 and a base plate body 16. The sealing surface 14 is formed on the base plate body 16. The base plate 10 of FIG. 2 includes a single, continuous sealing surface 14. The sealing surface 14 extends along the entire circumference of the base plate 10. However, in one embodiment, the base plate 10 can include multiple sealing surfaces. For example, separate sealing surfaces 14 can be provided in locations where a greater amount of wear occurs between the base plate 10 and the cover 40. In one embodiment, the sealing surface 14 of the base plate 10 can extend along only a portion of the circumference of the base plate 10.

[0043] 2, the one or more sealing surfaces 14 are provided to cover less than 75% of the base plate 10. In one embodiment, the one or more sealing surfaces 14 are provided to cover less than 50% of the base plate 10. The embodiments described and listed herein are not limited to the quantities described; that is, the quantities described and listed herein are provided for illustrative purposes only and are not intended to be limiting.

[0044] Figure 3 is a bottom view of a cover 40 for an inner pod according to one embodiment. Figure 3 shows a lower portion 42 of the cover 40. The lower portion 42 of the cover 40 is configured to be disposed on the upper portion 12 of the base plate 40. The cover 40 may also include a reticle receiving portion 3 and a reticle support 7B that supports a reticle 5 within the inner pod.

[0045] The cover 40 includes a sealing surface 44 and a cover body 46. The sealing surface 44 is formed on the cover body 46. The cover 40 of FIG. 3 includes a single, continuous sealing surface 44. However, in one embodiment, the cover 40 can include multiple sealing surfaces. For example, each of the sealing surfaces 44 extends only along a portion of the circumference of the base plate 40. For example, separate sealing surfaces 44 can be provided in locations where a greater amount of wear occurs between the base plate 10 and the cover 40.

[0046] The sealing surface 44 extends along the entire periphery of the cover 40. Thus, when the cover 40 is placed on the base plate 10, the sealing surface 44 is provided to extend along the entire periphery of the base plate 10. In some embodiments, the one or more sealing surfaces 14 of the base plate 10 and the one or more sealing surfaces 44 of the cover 40 can be provided to extend along the entire periphery of the base plate 10 in combination. For example, the sealing surface 14 of the base plate 10 may not extend along the entire periphery of the base plate 10, but the sealing surface 44 of the cover 40 may extend along a portion of the outer periphery of the base plate 10 without the sealing surface 14. When considered in combination, the sealing surface 14 of the base plate 10 and the sealing surface 44 of the cover 40 extend along the entire periphery of the base plate 10.

[0047] The sealing surface 44 is provided to cover less than 75% of the cover 40. In one embodiment, the sealing surface 44 covers less than 50% of the cover 40. The sealing surfaces 14, 44 of the inner pod 1 are formed to cover less than 75% of the base plate 10 and cover 40. In one embodiment, the sealing surfaces 14, 44 are formed to cover less than 50% of the base plate 10 and cover 40. The embodiments described and listed herein are not limited to the quantities listed. That is, the quantities described and listed herein are provided for illustrative purposes only and are not intended to be limiting.

[0048] 4 is an exploded view of an inner pod 400 of a reticle pod, including a cover 410 and a base plate 420, according to one embodiment. It will be appreciated that inner pod 400 can be inner pod 1 of FIGS. 1A and 1B. Cover 410 can be cover 40 of FIGS. 1A, 1B, and 3. Base plate 420 can be base plate 10 of FIGS. 1A, 1B, and 2.

[0049] The cover 410 has an upper surface 410A and a lower surface facing the base plate 420. The cover 410 also has a sealing surface (412, see FIG. 5). The sealing surface 412 may be the sealing surface 44 in FIGS. 1A, 1B, and 3. The base plate 420 has an upper surface 420A facing the cover 410 and a lower surface. The base plate 420 also has a sealing surface 422. The sealing surface 422 may be the sealing surface 14 in FIGS. 1A, 1B, and 2.

[0050] In one embodiment, the inner pod 400 includes standoff features (430, 440, 450). It will be appreciated that the standoff features can be on the cover 410 or the base plate 420, or that a portion of the standoff feature can be on the cover 410 and another portion of the standoff feature can be on the base plate. The standoff features (430, 440, 450) are configured to minimize wear on the sealing surfaces (412, 422) or between the sealing surface 412 of the cover 410 and the sealing surface 422 of the base plate 420. The standoff features (430, 440, 450) are configured to create a gap (e.g., a linear gap, see FIG. 7 ) and maintain a minimum space between the sealing surfaces (412, 422) when the cover 410 is attached (or placed) on the base plate 420. In one embodiment, the standoff features (430, 440, 450) are configured to reduce or eliminate physical contact and associated wear from the sealing area surfaces (412, 422). In another embodiment, the standoff features (430, 440, 450) are configured to eliminate physical contact or move physical contact and associated wear away from the sealing area surfaces (412, 422). In one embodiment, the standoff features 430, 440, 450 comprise protrusions from one of the cover 410 or the base plate 420. In one embodiment, the protrusions can be a soft, ductile material, such as gold. In one embodiment, the protrusions can be formed by material deposition. In one embodiment, the protrusions can be integrally formed during machining of the cover 410 or the base plate 420. In one embodiment, the protrusions can be coated with a material. The coating material can be selected to reduce particle generation due to contact between the protrusion and the cover 410 or base plate 420 opposite the protrusion.

[0051] In one embodiment, the standoff features (430, 440, 450) comprise a plurality of retention openings 430, a plurality of standoff pads 440, and a plurality of recesses 450. In one embodiment, as shown in FIG. 4 , the openings 430 and pads 440 may be on the cover 410 within the area defined by the sealing surface 412, and the recesses 450 may be on the base plate 420 within the area defined by the sealing surface 422. In another embodiment, the openings 430 and pads 440 may be on the base plate 420 within the area defined by the sealing surface 422, and the recesses 450 may be on the cover 410 within the area defined by the sealing surface 412. It will be appreciated that the standoff features may have any suitable configuration so long as they are capable of creating a gap (e.g., a linear gap, see FIG. 7 ) and maintaining a minimal space between the sealing surfaces (412, 422) when the cover 410 is attached to the base plate 420.

[0052] It will be appreciated that each pad 440 of the pads corresponds to one opening 430 and one recess 450. That is, the number of openings 430, the number of pads 440, and the number of recesses 450 can be the same. Each pad 440, its corresponding opening 430, and its corresponding recess 450 are aligned with one another along the Z direction (the height direction of the inner pod 400). The number and spacing of the pads can be determined based on the characteristics of the cover 410 and / or base plate 420, such as flatness and surface variations, such that the pads 440 collectively are sufficient to provide and maintain the appropriate spacing between the cover 410 and base plate 420. In one embodiment, the minimum number of pads 440 can be three. In one embodiment, the number of pads 440 can be four. In one embodiment, a pad 440 can be provided at each corner of the cover 410 or base plate 420. In one embodiment, the number of pads 440 can be eight (see FIG. 4 ), or any suitable number. It will be appreciated that the number of pads 440 may depend on the flatness of the sealing surfaces of the cover 410 and / or base plate 420, as well as the pressure and load applied to the sealing surfaces. In one embodiment, the pads 440 may be made of a polymer (e.g., a wear-resistant polymer, etc.) such as a filled PEEK material, including, by way of non-limiting example, polytetrafluoroethylene (PTFE)-filled (polyetheretherketone) PEEK or fiber-filled PEEK. The material of the pads 440 may be selected to reduce wear resulting from contact between the pads 440 and the cover 410 or base plate 420. In one embodiment, the material of the pads 440 is selected to have a hardness that differs from the hardness of the cover 410 or base plate 420. In one embodiment, the pads 440 may be made of a metal, such as a wear-resistant metal or a soft metal, by way of non-limiting example, tungsten carbide, steel, gold, etc.

[0053] In one embodiment, the standoff features (430, 440, 450) are provided within the area defined by the sealing surfaces 412 and / or 422. That is, the standoff features (430, 440, 450) are provided within the boundaries of the sealing surfaces 412 and / or 422. The sealing surface 422 extends along the periphery of the base plate 420 from an outer edge 422A of the base plate to an outer edge 422B of the interior space within the internal pod 400 (see FIG. 1A , the interior space with the reticle receiving portion 3). Similarly, the sealing surface 412 (see FIG. 5 ) extends along the periphery of the cover 410 from an outer edge 412A of the cover to an outer edge 412B of the interior space within the internal pod 400 (see FIG. 1A , the interior space with the reticle receiving portion 3).

[0054] In one embodiment, each pad 440 extends into a corresponding retention opening 430 and is partially received in a corresponding recess 450, extending or protruding a certain height between seal 412 and seal 422 to create a gap (e.g., a linear gap, see FIG. 7 ) when cover 410 is attached to base plate 420. In one embodiment, recess 450 is larger in size than pad 440. In one embodiment, recess 450 has a cross-sectional shape that is at least generally similar to the cross-sectional shape of pad 440, such as each having a circular cross-section. In one embodiment, recess 450 has a cross-sectional shape that is different from the cross-sectional shape of pad 440. In one embodiment, recess 450 has a depth ranging from 0.5 millimeters (mm) to 3 mm.

[0055] In one embodiment, each retention opening 430 may be a through-hole. In one embodiment, the top surface of each pad 440 may be flush with the top surface 410A of the cover 410. In another embodiment, the top surface of each pad 440 may be slightly below the top surface 410A of the cover 410. In an embodiment in which the pads 440 and retention openings 430 are on the base plate 420 and the recess 450 is on the cover 410, the bottom surface of each pad 440 may be flush with the bottom surface 420B of the base plate 420 or slightly above the top surface 420B of the base plate 420.

[0056] In one embodiment, each pad 440 can be pressed into a corresponding retention opening 430 to create a press fit (or interference fit, friction fit, etc.). In other embodiments, each pad 440 can be molded (e.g., injection molded, etc.) or machined into a corresponding retention opening 430. In one embodiment, each pad 440 can be pressed into a corresponding recess 450 to create a press fit (or interference fit, friction fit, etc.). In one embodiment, each retention opening 430 can pass completely through the cover 410 or base plate 420. In one embodiment, each retention opening 430 has a depth of between 0.5 mm and 3 mm.

[0057] 5 is a plan view of the cover 410 of FIG. 4 according to one embodiment. The cover 410 includes an upper surface 410A. It will be appreciated that the sealing surface 412 (see the area indicated by the dotted arrow) is located on the lower surface (410B, see FIG. 6). Similarly, the outer edge 412B (see the dotted line) of the internal space (see the internal space with the reticle receiving portion 3 in FIG. 1A) is also located on the lower surface (410B, see FIG. 6).

[0058] FIG. 6 is a cross-sectional view of inner pod 400 along line A1-A2 of FIG. 4, according to one embodiment.

[0059] In one embodiment, when the inner pod 400 is assembled, the standoff features (430, 440, 450) can separate the cover 410 and the base plate 420. In one embodiment, the size or height of the gap (e.g., linear gap) between the cover 410 and the base plate 420 (when the cover 410 is attached to the base plate 420) can be controlled during assembly of the standoff features (430, 440, 450), such as during insertion of the pad 440 into the recess 450. In such an embodiment, the pad 440 is inserted into the recess 450 and serves as a standoff to separate the cover 410 and the base plate 420. The surface of the recess 450 that contacts the pad 440 (which is in a different plane than the plane of the sealing surface) can create a wear surface that does not come into contact with the actual flow of air or gas passing through the gap (e.g., linear gap, see 470 in FIG. 7 ) between the cover 410 and the base plate 420.

[0060] FIG. 7 is a schematic diagram 700 of a gap 470 created between a cover 410 and a base plate 420, according to one embodiment.

[0061] Gap 470 may be a linear gap having a size or height of H2. In one embodiment, the minimum size of linear gap 470 is at or about 2 microns. It will be appreciated that the minimum size may assist in preventing / reducing wear on the sealing surfaces of cover 410 and base plate 420. In one embodiment, the maximum size of linear gap 470 is at or about 40 microns. In one embodiment, the maximum size of linear gap 470 is at or about 30 microns. It will be appreciated that up to the maximum size, little air and / or particles may pass through small sized linear gap 470, and therefore, a seal may be created via linear gap 470 to achieve a desired seal between cover 410 and base plate 420 when cover 410 is attached to the base plate (without contacting base plate 420). Tests on the conductance of the pod (i.e., the amount of air that moves through the sealing surface to the inside of the inner pod versus the air that passes through the filter on the pod) have shown that the flatness of the sealing surface allows for a gap of up to or about 40 microns to achieve the desired sealing results.

[0062] In one embodiment, the linear gap 470 can extend from the perimeter 412A of the cover 410 and the perimeter 422A of the base plate 420 to the boundaries (412B, 422B) of the interior space within the inner pod 400. That is, the linear gap 470 extends along the entire perimeter (or sealing surface) of the cover 410 and the base plate 420 when the cover 410 is attached to the base plate 420, spacing the cover 410 from the base plate 420. In one embodiment, when standoff features (430, 440, 450) are used to create the linear gap 470, the minimum distance between each pad 440 and the interior boundaries (412B, 422B) of the sealing surface of the cover 410 and / or the sealing surface of the base plate 420 is 4 mm or approximately 4 mm.

[0063] It will be recognized that a pumping effect may occur if the gap is a nonlinear gap. It will also be recognized that a pumping effect may occur if a tortuous path (e.g., one with pockets, protrusions, depressions, etc. along the path) exists between the perimeter 412A of the cover 410 (and / or the perimeter 422A of the base plate 420) and the boundaries (412B, 422B) of the interior space within the interior pod 400. As defined herein, the term “pumping effect” may refer to, for example, the compression of an air pocket, thereby causing air movement. A nonlinear gap or tortuous path may cause a sudden increase in air pressure differential when separating the cover 410 from the base plate 420, which may carry / push / pull particles into the interior space of the interior pod 400. In contrast, a linear gap may open quickly to avoid or reduce the pumping effect, thereby preventing such an undesirable situation from occurring.

[0064] 8 is a perspective view of a reticle pod 200 according to one embodiment. Reticle pod 200 includes an inner pod 210 and an outer pod 220. For example, reticle pod 200 may be, but is not limited to, a reticle pod for EUV processing of photolithography masks. In one embodiment, inner pod 210 may have a length of, for example, 8 inches or approximately 8 inches and a width of, for example, 8 inches or approximately 8 inches.

[0065] Inner pod 210 comprises a cover 212 and a base plate 214. In one embodiment, cover 212 and base plate 214 are configured to be joined together to provide a seal between base plate 214 and cover 212. When joined together, cover 212 and base plate 214 define an interior space sized and shaped to accommodate reticle 230 for use. For example, but not limited to, reticle 230 may be a photolithography mask used in EUV processing, etc. In some embodiments, at least one of cover 212 and base plate 214 comprises one or more standoff features 216, similar to those discussed above for base plate 10 and cover 40 in FIGS. 1A-7. In some embodiments, cover 212 and base plate 214 each comprise at least one standoff feature 216 (those of cover 212 are not visible in FIG. 8). Cover 212 can be, for example, cover 40 described above and shown in Figures 1A, 1B, and 3. Base plate 214 can be, for example, base plate 10 described above and shown in Figures 1A, 1B, and 2.

[0066] The external pod 220 includes an external pod dome 222 and an external pod door 224. The external pod 220 is configured to house the internal pod 210 within an interior space defined by the external pod dome 222 and the external pod door 224. The external pod dome 222 can be secured to the external pod door 224 to enclose the interior space and house the internal pod 210, for example, during shipping and handling of the reticle pod 200. The external pod dome 222 and the external pod door 224 can each include or be made entirely of one or more polymeric materials or any other suitable material.

[0067] 9 is a flowchart diagram of a method 900 for assembling an internal pod of a reticle pod, according to one embodiment. While various blocks are shown as separate blocks, they may be divided into additional blocks, combined into fewer blocks, or eliminated depending on the desired implementation. The internal pod may be an internal pod (1, 210, 400) described in FIGS. 1A-8.

[0068] In one embodiment, method 900 may begin at 910. Block 910 may refer to providing a plurality of standoffs that create a linear gap, such as linear gap 470. In one embodiment, creating linear gap 470 may include assembling standoff mechanisms (430, 440, 450). In another embodiment, creating linear gap 470 may include utilizing any other suitable mechanism to create linear gap 470. In one embodiment, assembling standoff mechanisms (430, 440, 450) may include inserting pads 440 into retention openings 430, respectively. Block 910 may be followed by block 920.

[0069] Block 920 may refer to fixing or controlling the size of the linear gap 470. In one embodiment, fixing the size of the linear gap 470 may include adjusting the height of each pad 440 to a constant height. Adjusting the height of each pad 440 to a constant height may include machining the pads 440 to have a constant height and / or pressing the pads 440 into the recesses 450 to have a constant height. For example, the pads 440 may be pressed to a constant depth to create and control the size of the linear gap 470.

[0070] The embodiments disclosed herein can minimize wear on the contact surfaces or barriers between the mating cover and base plate by using a suitable mechanism to create a controlled linear gap to prevent particles from being generated from wear on the sealing surfaces and drawn / pushed / transferred into the interior space of the inner pod without compromising the sealing requirements.

[0071] Aspects:

[0072] It is understood that any of the embodiments 1-18 can be combined with any of the embodiments 19-23.

[0073] Aspect 1. An apparatus comprising a reticle pod, the reticle pod comprising: a base plate having a first surface, the first surface comprising a first sealing surface around a periphery of the base plate; a cover having a second surface, the second surface comprising a second sealing surface around a periphery of the cover; standoff mechanisms on at least one of the cover and the base plate; and The apparatus, wherein the standoff mechanism is configured to create a seal via a linear gap between the first sealing surface and the second sealing surface when the cover is attached to the base plate.

[0074] Embodiment 2. The apparatus according to embodiment 1, wherein the linear gap extends from the periphery of the cover and the periphery of the base plate to an interior space within the reticle pod.

[0075] Aspect 3. The reticle pod is an extreme ultraviolet (EUV) reticle pod; The apparatus according to any of aspects 1-2, wherein the base plate and the cover are configured to house the reticle when the cover is attached to the base plate.

[0076] Embodiment 4. The apparatus according to any of embodiments 1-3, further comprising an external pod dome and an external pod door configured to house the base plate and cover within the external pod dome when the external pod door is attached to the external pod dome.

[0077] Embodiment 5. A device according to any of embodiments 1-4, wherein the minimum size of the linear gap is at or about 2 microns.

[0078] Embodiment 6. An apparatus according to any of embodiments 1-5, wherein the maximum size of the linear gap is at or about 40 microns.

[0079] Embodiment 7. The device according to any of embodiments 1-6, wherein the standoff mechanism comprises a plurality of protrusions from one of the cover or the base plate, and the other of the cover or the base plate comprises a surface configured to contact the plurality of protrusions.

[0080] Aspect 8. The standoff mechanism comprises a plurality of standoff pads; one of the first sealing surface and the second sealing surface includes a plurality of retention openings; the other of the first sealing surface and the second sealing surface comprises a plurality of recesses; The device according to any of aspects 1-7, wherein each pad of the plurality of pads extends into one of the plurality of retaining openings and is partially received within one of the plurality of recesses.

[0081] Embodiment 9. The device according to embodiment 8, wherein the plurality of pads comprises at least three pads.

[0082] Embodiment 10. The device according to embodiment 8, wherein the plurality of pads includes eight pads.

[0083] Embodiment 11. The device according to any of embodiments 8-9, wherein the plurality of pads are made of a polymer.

[0084] Embodiment 12. The device according to any of embodiments 8-9, wherein the plurality of pads are made of metal.

[0085] Embodiment 13. The device according to any of embodiments 8-12, wherein the plurality of retention openings are a plurality of through holes.

[0086] Embodiment 14. A device according to any of embodiments 8-13, wherein a plurality of pads are pressed within a plurality of retention openings, respectively, and extend a fixed height from one of the first sealing surface and the second sealing surface to create a linear gap.

[0087] Embodiment 15. An apparatus according to any of embodiments 8-14, wherein the plurality of pads are molded or machined within the plurality of retention openings, respectively, and extend a fixed height from one of the first sealing surface and the second sealing surface to create a linear gap.

[0088] Embodiment 16. The device according to any of embodiments 8-15, wherein an upper surface of each pad of the plurality of pads is flush with or slightly below the flush with an upper surface of the cover or a lower surface of the base plate.

[0089] Embodiment 17. The apparatus according to any of embodiments 1-16, wherein the reticle pod further comprises a filter, and the seal is configured such that the reticle pod has a conductance of at least 90%.

[0090] Embodiment 18. The device according to any of embodiments 1-17, wherein the conductance is at least 94%.

[0091] Aspect 19. A method of assembling a reticle pod, the reticle pod comprising: a base plate having a first surface; a cover having a second surface; and a standoff mechanism on at least one of the cover and the base plate, the first surface comprising a first sealing surface around the periphery of the base plate and the second surface comprising a second sealing surface around the periphery of the cover, the standoff mechanism configured to create a seal between the first sealing surface and the second sealing surface via a linear gap when the cover is attached to the base plate, the method comprising providing the standoff mechanism on at least one of the cover and the base plate.

[0092] Aspect 20. Inserting a plurality of standoff pads of a standoff mechanism into a plurality of retention openings, respectively; and Adjusting the height of each pad to a uniform height further comprising a plurality of retention openings on one of the first sealing surface and the second sealing surface; a plurality of recesses on the other of the first sealing surface and the second sealing surface; 20. The method of claim 19.

[0093] Embodiment 21. The method according to embodiment 20, wherein adjusting the height of each pad of the plurality of pads to a constant height includes machining the plurality of pads such that the height of each pad of the plurality of pads is a constant height.

[0094] Embodiment 22. The method according to embodiment 20, wherein adjusting the height of each pad of the plurality of pads to a constant height includes pressing the plurality of pads so that the height of each pad of the plurality of pads is a constant height.

[0095] Embodiment 23. The method of claim 20, wherein the minimum distance between each pad of the plurality of pads and the interior boundary of the first sealing surface or the second sealing surface is 4 mm or about 4 mm.

[0096] The examples disclosed in this application should be considered in all respects as illustrative and not restrictive. The scope of the invention is indicated by the appended claims, rather than the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein.

[0097] The terms used herein are intended to describe particular embodiments and are not intended to be limiting. The terms "a," "an," and "the" include the plural as well, unless otherwise specified. The terms "comprises" and / or "comprising," as used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, and / or components.

[0098] With respect to the foregoing description, it should be understood that changes in detail, particularly to the materials of construction employed, and to the shape, size, and arrangement of parts, may be made without departing from the scope of the present disclosure. The specification and described embodiments are exemplary only, the true scope and spirit of the present disclosure being indicated by the following claims.

Claims

1. 1. An apparatus comprising a reticle pod, the reticle pod comprising: a base plate having a first surface, the first surface comprising a first sealing surface around a periphery of the base plate; a cover having a second surface, the second surface comprising a second sealing surface around a periphery of the cover; a standoff mechanism on at least one of the cover and the base plate; and the standoff mechanism is configured to create a seal between the first sealing surface and the second sealing surface via a linear gap when the cover is attached to the base plate; the linear gap has a predetermined size; the reticle pod comprises a filter; the seal is configured so that the reticle pod has a conductance of at least 90%; The conductance is the amount of air moving through the sealing surface to the inside of the inner pod of the reticle pod relative to the air passing through the filter on the inner pod, and is calculated using the following formula: (In the formula, V = volume inside the inner pod PEIP = Pressure inside the inner pod Pchamber = pressure in the test chamber t = time) The apparatus is required by:

2. the standoff mechanism comprises a plurality of standoff pads; one of the first sealing surface and the second sealing surface includes a plurality of retention openings; the other of the first sealing surface and the second sealing surface includes a plurality of recesses; 2. The apparatus of claim 1, wherein each of the plurality of standoff pads extends into one of the plurality of retention openings and is partially received within one of the plurality of recesses.

3. A method of assembling a reticle pod, the reticle pod comprising: a base plate having a first surface; a cover having a second surface; and standoff mechanisms on at least one of the cover and the base plate, the first surface comprising a first sealing surface around a periphery of the base plate and the second surface comprising a second sealing surface around a periphery of the cover, the standoff mechanisms configured to create a seal between the first sealing surface and the second sealing surface via a linear gap when the cover is attached to the base plate, the method comprising: providing the standoff mechanisms on at least one of the cover and the base plate; the linear gap has a predetermined size; the reticle pod comprises a filter; the seal is configured so that the reticle pod has a conductance of at least 90%; The conductance is the amount of air moving through the sealing surface to the inside of the inner pod of the reticle pod relative to the air passing through the filter on the inner pod, and is calculated using the following formula: During the ceremony, V = volume inside the inner pod PEIP = Pressure inside the inner pod Pchamber = pressure in the test chamber t = time) The method is determined by:

4. Inserting a plurality of standoff pads of the standoff mechanism into a plurality of retention openings, respectively; and adjusting the height of each of the plurality of standoff pads to a constant height; further comprising the plurality of retention openings are on one of the first sealing surface and the second sealing surface; a plurality of recesses on the other of the first sealing surface and the second sealing surface; The method of claim 3.

5. 4. The method of claim 3, wherein a minimum distance between each of a plurality of standoff pads of the standoff mechanism and an internal boundary of the first sealing surface or the second sealing surface is at or about 4 mm.

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