WO2020099126A1

WO2020099126A1 - Multiple-pad reticle bumpers to distribute impact load

Info

Publication number: WO2020099126A1
Application number: PCT/EP2019/079558
Authority: WO
Inventors: Eric Justin MONKMAN; John Robert BURROUGHS
Original assignee: Asml Holding N.V.
Priority date: 2018-11-16
Filing date: 2019-10-29
Publication date: 2020-05-22
Also published as: JP7329047B2; NL2024120A; KR20210090185A; JP2022507522A

Abstract

A bumper apparatus for a reticle includes a first arm and a second arm. The first arm is configured to contact the reticle along a first direction. The second arm is configured to contact the reticle along a second direction. The first arm includes a first bumper disposed toward a distal end of the first arm and a second bumper adjacent the first bumper and disposed toward a proximal end of the first arm. The first bumper includes a first stiffness linkage and the second bumper includes a second stiffness linkage. The first and second bumpers are configured to uniformly distribute an impact force of the reticle.

Description

MULTIPLE-PAD RETICLE BUMPERS TO DISTRIBUTE IMPACT LOAD

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority of U.S. Provisional Patent Application Number

62/768,161, which was filed on November 16, 2018, and which is incorporated herein in its entirety by reference.

FIELD

[0002] The present disclosure relates to safety mechanisms, for example, a bumper apparatus for a reticle in lithography apparatuses and systems.

BACKGROUND

[0003] A lithographic apparatus is a machine constructed to apply a desired pattern onto a substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). A lithographic apparatus may, for example, project a pattern of a patterning device (e.g., a mask, a reticle) onto a layer of radiation-sensitive material (resist) provided on a substrate.

[0004] To project a pattern on a substrate a lithographic apparatus may use electromagnetic radiation. The wavelength of this radiation determines the minimum size of features which can be formed on the substrate. A lithographic apparatus, which uses extreme ultraviolet (EUV) radiation, having a wavelength within the range 4-20 nm, for example 6.7 nm or 13.5 nm, may be used to form smaller features on a substrate than a lithographic apparatus which uses, for example, radiation with a wavelength of 193 nm.

[0005] During loss of a reticle clamping functionality, for example, power loss or vacuum loss, a reticle may crash into other components of a reticle stage, causing damage to the reticle and/or other nearby components. The reticle can crash at a high force (i.e., high acceleration) depending on the pre-crash motion and momentum of the reticle stage. If the components surrounding the reticle are too strong, a crash can result in damage to the reticle (e.g., cracks, scratches, particle contamination, etc.). If the components surrounding the reticle are too weak, a crash can result in damage or destruction of the surrounding components due to an impact force of the reticle. There is a need to reduce damage to the reticle and/or other nearby components during a crash in a reliable, uniform, and efficient manner.

SUMMARY

[0006] In some embodiments, a bumper apparatus for a reticle includes a first arm and a second arm. In some embodiments, the first arm is configured to contact the reticle along a first direction. In some embodiments, the second arm is configured to contact the reticle along a second direction. In some embodiments, the first arm includes a first bumper disposed toward a distal end of the first arm. In some embodiments, the first arm includes a second bumper adjacent the first bumper and disposed toward a proximal end of the first arm. In some embodiments, the first bumper includes a first stiffness linkage. In some embodiments, the second bumper includes a second stiffness linkage. In some embodiments, the first and second bumpers are configured to uniformly distribute an impact force of the reticle.

[0007] In some embodiments, the second arm includes a first bumper disposed toward a distal end of the second arm. In some embodiments, the second arm includes a second bumper adjacent the first bumper and disposed toward a proximal end of the second arm. In some embodiments, the first bumper of the second arm includes a first stiffness linkage. In some embodiments, the second bumper of the second arm includes a second stiffness linkage.

[0008] In some embodiments, a stiffness of the first stiffness linkage is equal to a stiffness of the second stiffness linkage. In some embodiments, a stiffness of the first stiffness linkage is less than a stiffness of the second stiffness linkage. In some embodiments, the first direction is orthogonal to the second direction. In some embodiments, the first and second arms include a tempered martensitic stainless steel alloy.

[0009] In some embodiments, a lithographic apparatus includes a reticle stage, a reticle disposed on the reticle stage, and a reticle cage disposed adjacent to the reticle. In some embodiments, the reticle cage is configured to uniformly distribute an impact force of the reticle. In some embodiments, the reticle cage includes an arm configured to contact the reticle. In some embodiments, the arm includes a first bumper disposed toward a distal end of the arm and a second bumper adjacent the first bumper and disposed toward a proximal end of the arm. In some embodiments, the first bumper includes a first stiffness linkage and the second bumper includes a second stiffness linkage. [0010] In some embodiments, the arm includes a third bumper adjacent the second bumper and disposed toward a proximal end of the arm. In some embodiments, the third bumper includes a third stiffness linkage. In some embodiments, a stiffness of the first stiffness linkage is less than a stiffness of the second stiffness linkage and the stiffness of the second stiffness linkage is less than a stiffness of the third stiffness linkage. In some embodiments, a stiffness of the first stiffness linkage, a stiffness of the second stiffness linkage, and a stiffness of the third stiffness linkage are equal.

[0011] In some embodiments, the arm includes a plurality of additional bumpers. In some embodiments, the plurality of additional bumpers includes a plurality of stiffness linkages. In some embodiments, a stiffness of the plurality of stiffness linkages increases from the distal end to the proximal end of the arm. In some embodiments, the reticle cage is a plurality of reticle cages disposed around a perimeter of the reticle and configured to uniformly distribute an impact force of the reticle over a plurality of impact locations. In some embodiments, the first and second stiffness linkages of the arm have a controlled stiffness distribution, such that the impact force of the reticle is distributed evenly between the first and second bumpers.

[0012] In some embodiments, a method for reducing an impact force of a reticle includes disposing a bumper apparatus adjacent the reticle. In some embodiments, the bumper apparatus contacts the reticle with an arm. In some embodiments, the arm includes a first bumper disposed toward a distal end of the arm and a second bumper adjacent the first bumper and disposed toward a proximal end of the arm. In some embodiments, the first bumper includes a first stiffness linkage and the second bumper includes a second stiffness linkage. In some embodiments, the method for reducing the impact force of the reticle further includes distributing the impact force of the reticle uniformly between the first and second bumpers.

[0013] In some embodiments, the method for reducing the impact force of the reticle further includes flexing the first and second bumpers to redistribute the impact force of the reticle along the first and second stiffness linkages. In some embodiments, the method for reducing the impact force of the reticle further includes positioning the bumper apparatus to a minimum gap distance between the reticle and the bumper apparatus, such that the impact force of the reticle is reduced.

[0014] Further features and advantages of the invention, as well as the structure and operation of various embodiments of the invention, are described in detail below with reference to the accompanying drawings. It is noted that the invention is not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Additional embodiments will be apparent to persons skilled in the relevant art(s) based on the teachings contained herein.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

[0015] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate the present invention and, together with the description, further serve to explain the principles of the invention and to enable a person skilled in the relevant art(s) to make and use the invention. Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings, in which:

[0016] FIG. 1 is a schematic illustration of a lithographic apparatus, according to an exemplary embodiment;

[0017] FIG. 2 is a perspective schematic illustration of a reticle stage, according to an exemplary embodiment;

[0018] FIG. 3 is a top plan view of the reticle stage of Figure 2;

[0019] FIG. 4 is a partial perspective schematic illustration of the reticle stage of Figure

2;

[0020] FIG. 5 is a perspective schematic illustration of a bumper apparatus, according to an exemplary embodiment;

[0021] FIG. 6 is a top plan view of the bumper apparatus of Figure 5;

[0022] FIG. 7 is a top plan schematic illustration of a bumper apparatus, according to an exemplary embodiment;

[0023] FIG. 8 is a top plan schematic illustration of a bumper apparatus, according to an exemplary embodiment;

[0024] FIG. 9 is a top plan schematic illustration of a bumper apparatus, according to an exemplary embodiment; and

[0025] FIG. 10 is a top plan schematic illustration of a bumper apparatus, according to an exemplary embodiment.

[0026] The features and advantages of the present invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. Additionally, generally, the left-most digit(s) of a reference number identifies the drawing in which the reference number first appears. Unless otherwise indicated, the drawings provided throughout the disclosure should not be interpreted as to-scale drawings.

DETAILED DESCRIPTION

[0027] This specification discloses one or more embodiments that incorporate the features of this invention. The disclosed embodiment(s) merely exemplify the invention. The scope of the invention is not limited to the disclosed embodiment(s). The invention is defined by the claims appended hereto.

[0028] The embodiment(s) described, and references in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment(s) described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is understood that it is within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0029] Spatially relative terms, such as“beneath,”“below,”“lower,”“above,”“on,”

“upper” and the like, may be used herein for ease of description to describe one element or feature’s relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

[0030] The term“about” as used herein indicates the value of a given quantity that can vary based on a particular technology. Based on the particular technology, the term“about” can indicate a value of a given quantity that varies within, for example, 10-30% of the value (e.g., ±10%, ±20%, or ±30% of the value). [0031] Embodiments of the disclosure may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the disclosure may also be implemented as instructions stored on a machine-readable medium, which may be read and executed by one or more processors. A machine-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, a machine-readable medium may include read only memory (ROM); random access memory (RAM); magnetic disk storage media; optical storage media; flash memory devices; electrical, optical, acoustical or other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.), and others. Further, firmware, software, routines, and/or instructions may be described herein as performing certain actions. However, it should be appreciated that such descriptions are merely for convenience and that such actions in fact result from computing devices, processors, controllers, or other devices executing the firmware, software, routines, instructions, etc., and in doing that may cause actuators or other devices to interact with the physical world.

[0032] Before describing such embodiments in more detail, however, it is instructive to present an example environment in which embodiments of the present disclosure may be implemented.

[0033] Exemplary Lithographic System

[0034] FIG. 1 shows a lithographic system comprising a radiation source SO and a lithographic apparatus FA. The radiation source SO is configured to generate an EUV radiation beam B and to supply the EUV radiation beam B to the lithographic apparatus FA. The lithographic apparatus FA comprises an illumination system IF, a support structure MT configured to support a patterning device MA (e.g., a mask), a projection system PS, and a substrate table WT configured to support a substrate W.

[0035] The illumination system IF is configured to condition the EUV radiation beam B before the EUV radiation beam B is incident upon the patterning device MA. Thereto, the illumination system IF may include a facetted field mirror device 10 and a facetted pupil mirror device 11. The faceted field mirror device 10 and faceted pupil mirror device 11 together provide the EUV radiation beam B with a desired cross-sectional shape and a desired intensity distribution. The illumination system IF may include other mirrors or devices in addition to, or instead of, the faceted field mirror device 10 and faceted pupil mirror device 11. [0036] After being thus conditioned, the EUV radiation beam B interacts with the patterning device MA. As a result of this interaction, a patterned EUV radiation beam B’ is generated. The projection system PS is configured to project the patterned EUV radiation beam B’ onto the substrate W. For that purpose, the projection system PS may comprise a plurality of mirrors 13, 14 which are configured to project the patterned EUV radiation beam B’ onto the substrate W held by the substrate table WT. The projection system PS may apply a reduction factor to the patterned EUV radiation beam B’, thus forming an image with features that are smaller than corresponding features on the patterning device MA. For example, a reduction factor of 4 or 8 may be applied. Although the projection system PS is illustrated as having only two mirrors 13, 14 in FIG. 1, the projection system PS may include a different number of mirrors (e.g. six or eight mirrors).

[0037] The substrate W may include previously formed patterns. Where this is the case, the lithographic apparatus LA aligns the image, formed by the patterned EUV radiation beam B’, with a pattern previously formed on the substrate W.

[0038] A relative vacuum, i.e. a small amount of gas (e.g. hydrogen) at a pressure well below atmospheric pressure, may be provided in the radiation source SO, in the illumination system IL, and/or in the projection system PS.

[0039] The radiation source SO may be a laser produced plasma (LPP) source, a discharge produced plasma (DPP) source, a free electron laser (FEL), or any other radiation source that is capable of generating EUV radiation.

[0040] Exemplary Reticle Stage and Reticle Cage Systems

[0041] FIGS. 2 through 4 show schematic illustrations of an exemplary reticle stage 200, according to some embodiments of this disclosure. Reticle stage 200 can include top stage surface 202, bottom stage surface 204, side stage surfaces 206, reticle 208, and reticle cage 300. In some embodiments, a part of reticle cage 300 can include a bumper apparatus 400 with shock absorbers that can be used around the reticle 208 to absorb possible forces or shocks occurring from a crash such that damage to the reticle 208 and reticle cage 300 can be reduced or eliminated completely. In some embodiments, reticle stage 200 with reticle 208 can be implemented in lithographic apparatus LA. For example, reticle stage 200 can be support structure MT and reticle 208 can be patterning device MA in lithographic apparatus LA. In some embodiments, reticle 208 and reticle cage 300 can be disposed on top stage surface 202. For example, as shown in FIG. 2, reticle 208 can be disposed at a center of top stage surface 202 with reticle cages 300 disposed adjacent to each corner of reticle 208.

[0042] In some lithographic apparatuses, for example, lithographic apparatus LA, a reticle stage or chuck 200 can be used to hold and position a reticle 208 for scanning or patterning operations. The reticle stage 200 requires powerful drives, large balance masses, and heavy frames to support it. The reticle stage 200 has a large inertia and can weigh over 500 kg to propel and position a reticle 208 weighing about 0.5 kg. To accomplish reciprocating motions of the reticle 208, which are typically found in lithographic scanning or patterning operations, accelerating and decelerating forces can be provided by linear motors that drive the reticle stage 200.

[0043] During a catastrophic failure of the reticle stage 200, for example, by major power loss or serious system failure, the reticle can become detached from the reticle stage while the stage continues to undergo high accelerating and decelerating forces. A reticle 208 can crash into other components of the reticle stage 200, causing damage to the reticle 208 and/or other nearby components. The reticle 208 can crash at a high force (i.e., high acceleration) depending on the pre-crash motion and momentum of the reticle stage 200. If the components surrounding the reticle 208 (e.g., reticle cage 300) are too strong, a crash can result in damage to the reticle 208 (e.g., cracks, scratches, particle contamination, etc.). If the components surrounding the reticle 208 (e.g., reticle cage 300) are too weak, a crash can result in damage or destruction of the surrounding components due to an impact force of the reticle 208. Current methods use some form of a safety mechanism to reduce or decrease the force of a reticle during a crash. However, due to the high impact stress (force) of the reticle in worst case crashes, damage can still occur to the reticle and/or current safety mechanisms.

[0044] One possible solution is to position a safety mechanism, for example, a reticle cage 300 around the reticle 208 to act as a shock absorber to reduce an impact force of the reticle 208 during a crash. For example, a bumper apparatus 400 with shock absorbers, for example, first arm 410 and second arm 430, can be used around the reticle 208 to absorb possible forces or shocks occurring from a crash such that damage to the reticle 208 and reticle cage 300 can be reduced or eliminated completely. Such shock absorbers can be implemented by wholly or partially resilient materials (e.g., high yield strength) and/or by providing active or passive shock absorbing devices, for example, buffers, dampers, springs, etc. For example, the reticle 208 can be restrained by four safety mechanisms, for example, reticle cages 300 with independent bumper apparatuses 400 arranged adjacent to the comers of the reticle 208.

[0045] In some embodiments, as shown in FIGS. 2 and 3, reticle stage 200 can include first encoder 212 and second encoder 214 for positioning operations. For example, first and second encoders 212, 214 can be interferometers. First encoder 212 can be attached along a first direction, for example, a transverse direction (i.e., X-direction) of reticle stage 200 and second encoder 214 can be attached along a second direction, for example, a longitudinal direction (i.e., Y-direction) of reticle stage 200. In some embodiments, as shown in FIGS. 2 and 3, first encoder 212 can be orthogonal to second encoder 214.

[0046] As shown in FIGS. 2 through 4, reticle stage 200 can include one or more reticle cages 300. Reticle cage 300 can be configured to secure and reduce damage to reticle 208 during a crash. Reticle cage 300 can be configured to uniformly distribute an impact force of reticle 208 during a crash. In some embodiments, a plurality of reticle cages 300 can be disposed in top stage surface 202 and arranged around a perimeter of reticle 208. For example, multiple reticle cages 300 can be disposed adjacent each comer of reticle 208 to uniformly distribute an impact force of reticle 208 over a plurality of impact locations.

[0047] As shown, for example in FIG. 4, reticle cage 300 can include body 302, securing mechanism 304, safety latch 306, and bumper apparatus 400. Reticle cage 300 can be a rigid material, for example, a metal or a ceramic. In some embodiments, body 302 of reticle cage 300 can extend through a portion of reticle stage 200. For example, body 302 can be cylindrical and extend through top stage surface 202 for rigid alignment with a comer of reticle 208. In some embodiments, reticle cage 300 can be secured to top stage surface 202 with one or more securing mechanisms 304. For example, securing mechanism 304 can be a bolt. In some embodiments, safety latch 306 can be configured to secure (i.e., catch) and reduce damage to reticle 208 during a crash. For example, safety latch 306 can extend over a top surface of reticle 208 and be configured to prevent movement of reticle 208 in a direction perpendicular to top stage surface 202 (i.e., Z-direction).

[0048] Exemplary Bumper Apparatuses

[0049] Hooke’s law states that the force (F) needed to extend or compress a spring (i.e., an elastic object that stores energy) by some distance d scales linearly with respect to that distance: F = k -d, where k is the stiffness of the spring (e.g., positive constant factor characteristic of the spring). Stiffness is the extent to which an object resists deformation in response to an applied force. When an external force F_ext is applied to the spring, a restoring force is exerted by the spring: F_ext = k- Ad.

[0050] FIGS. 4 through 6 show schematic illustrations of an exemplary bumper apparatus

400, according to some embodiments of this disclosure. Bumper apparatus 400 can be configured to contact reticle 208. Bumper apparatus 400 can be configured to accurately and uniformly (e.g., evenly) distribute an impact stress or impact force of reticle 208 during a crash. Bumper apparatus 400 can be configured to reduce damage to reticle 208 and/or reticle cage 300 during a crash. Various geometries and bumper materials can be used to achieve a reduction in impact stress or impact force to reticle 208. For example, as shown in FIG. 4, bumper apparatus 400 can be arranged in an L-shape or concave hexagon. Bumper apparatus 400 can be a rigid material, for example, a metal or a ceramic. In some embodiments, bumper apparatus 400 can be a high yield strength material. For example, bumper apparatus 400 can be a tempered martensitic stainless steel alloy (e.g., STAVAX®).

[0051] In some embodiments, bumper apparatus 400 can be positioned to a minimum gap distance between reticle 208 and bumper apparatus 400 to reduce an impact force of reticle 208 during a crash. For example, the minimum gap distance between reticle 208 and bumper apparatus 400 can be at least 1.0 mm. In some embodiments, bumper apparatus 400 can be positioned to a minimum gap distance between reticle 208 and bumper apparatus 400 for a majority of scanning or positioning operations. For example, bumper apparatus 400 can be at the minimum gap distance, for example, 1.0 mm, at all times except during a reticle exchange process.

[0052] As shown in FIG. 4, bumper apparatus 400 can include extension 402, first arm

410, and second arm 430. In some embodiments, first and second arms 410, 430 can be connected to body 302 of reticle cage 300 by extension 402. For example, extension 402 can be monolithic with first and second arms 410, 430. First arm 410 can include distal end 406 and proximal end 407 opposite distal end 406. Second arm 430 can include distal end 408 and proximal end 409 opposite distal end 408. In some embodiments, second arm 430 can be omitted from bumper apparatus 400. First and second arms 410, 430 can be any shape or size and any material. In some embodiments, first and second arms 410, 430 can be a high yield strength material. For example, first and second arms 410, 430 can be a tempered martensitic stainless steel alloy (e.g., STAVAX®). In some embodiments, first arm 410 can extend along a first direction of reticle 208 and second arm 430 can extend along a second direction of reticle 208. For example, as shown in FIG. 4, first direction (i.e., X-direction) can be orthogonal to second direction (i.e., Y-direction).

[0053] As shown in FIGS. 5 and 6, first arm 410 of bumper apparatus 400 can include first bumper 412 and second bumper 414. First bumper 412 can be disposed toward distal end 406 and second bumper 414 can be adjacent first bumper 412 and disposed toward proximal end 407. First bumper 412 can include first stiffness linkage 424 with stiffness ki. Second bumper 414 can include second stiffness linkage 426 with stiffness k2. In some embodiments, stiffness ki can be equal to stiffness k2. In some embodiments, stiffness ki can be less than stiffness k2. In some embodiments, as shown in FIG. 6, first and second bumpers 412, 414 can include first and second bumper pads 418, 420, respectively. For example, first and second bumper pads 418, 420 can be configured to directly contact a perimeter of reticle 208 and allow first and second stiffness linkages 424, 426, respectively, to flex while in contact with reticle 208 in order to redistribute or dissipate the impact force of reticle 208 during a crash.

[0054] First and second bumpers 412, 414 can be configured to uniformly redistribute or dissipate an impact force or impact energy of reticle 208 during a crash along first and second stiffness linkages 424, 426, respectively. In some embodiments, first and second stiffness linkages 424, 426 can have a controlled stiffness distribution such that an impact force of reticle 208 during a crash can be distributed uniformly (e.g., evenly) between first and second bumpers 412, 414. For example, the controlled stiffness distribution (e.g., ki and k2) can be engineered such that a first force Fi exerted on first bumper 412 can be equal to a second force F2 exerted on second bumper 414 and, thus, reduce the impact force of reticle 208 (i.e., F_ext) by a factor of two. In some embodiments, the controlled stiffness distribution (e.g., ki and k2) can be engineered from a single piece of high yield strength material, for example, a tempered martensitic stainless steel alloy (e.g., STAVAX®). For example, the controlled stiffness distribution (e.g., ki and k2) can be engineered or machined by wire electrical discharge machining (EDM).

[0055] In some embodiments, as shown in FIGS. 5 and 6, first arm 410 can include a third bumper 416. For example, third bumper 416 can be disposed toward proximal end 407 and adjacent second bumper 414. Third bumper 416 can include third stiffness linkage 428 with stiffness k3. In some embodiments, stiffness ki, stiffness k2, and stiffness k3 can be equal. In some embodiments, stiffness ki can be less than stiffness ]_¾ and stiffness ]_¾ can be less than stiffness !_¾. In some embodiments, as shown in FIG. 6, third bumper 416 can include third bumper pad 422. For example, third bumper pad 422 can be configured to directly contact a perimeter of reticle 208 and allow third stiffness linkage 428 to flex while in contact with reticle 208 in order to redistribute or dissipate the impact force of reticle 208 during a crash.

[0056] In some embodiments, first, second, and third stiffness linkages 424, 426, 428 can have a controlled stiffness distribution, such that an impact force of reticle 208 during a crash can be distributed uniformly (e.g., evenly) between first, second, and third bumpers 412, 414, 416. For example, the controlled stiffness distribution (e.g., ki, k2, and k3) can be engineered, such that a first force Fi exerted on first bumper 412, a second force F2 exerted on second bumper 414, and a third force F3 exerted on third bumper 416 can be equal and, thus, reduce the impact force of reticle 208 (i.e., F_ext) by a factor of three. This principle (e.g., whippletree or whiffletree model) can be extended to reduce the impact force of reticle 208 by a factor of n', where n' is the number of bumpers on first arm 410.

[0057] In some embodiments, first arm 410 can include a plurality of bumpers or an array of bumpers. For example, as shown in FIGS. 5 and 6, the plurality or array of bumpers can include first bumper 412, second bumper 414, and/or third bumper 416. In some embodiments, the plurality of bumpers include a plurality of stiffness linkages. For example, the plurality of bumpers can include first stiffness linkage 424, second stiffness linkage 426, and/or third stiffness linkage 428. In some embodiments, a stiffness of the plurality of stiffness linkages can increase from distal end 406 to proximal end 407 of first arm 410. For example, as shown in FIGS. 5 and 6, stiffness ki of first stiffness linkage 424 can be less than stiffness k2 of second stiffness linkage 426, and/or stiffness k2 of second stiffness linkage 426 can be less than stiffness k3 of third stiffness linkage 428.

[0058] As shown in FIGS. 5 and 6, second arm 430 of bumper apparatus 400 can include first bumper 432 and second bumper 434. First bumper 432 can be disposed toward distal end 408 and second bumper 434 can be adjacent first bumper 432 and disposed toward proximal end 409. First bumper 432 can include first stiffness linkage 444 with stiffness ki. Second bumper 434 can include second stiffness linkage 446 with stiffness k2. In some embodiments, stiffness ki can be equal to stiffness k2. In some embodiments, stiffness ki can be less than stiffness k2. In some embodiments, as shown in FIG. 6, first and second bumpers 432, 434 can include first and second bumper pads 438, 440, respectively. For example, first and second bumper pads 438, 440 can be configured to directly contact a perimeter of reticle 208 and allow first and second stiffness linkages 444, 446, respectively, to flex while in contact with reticle 208 in order to redistribute or dissipate the impact force of reticle 208 during a crash.

[0059] First and second bumpers 432, 434 can be configured to uniformly redistribute or dissipate an impact force or impact energy of reticle 208 during a crash along first and second stiffness linkages 444, 446, respectively. In some embodiments, first and second stiffness linkages 444, 446 can have a controlled stiffness distribution, such that an impact force of reticle 208 during a crash can be distributed uniformly (e.g., evenly) between first and second bumpers 432, 434. For example, the controlled stiffness distribution (e.g., ki and k2) can be engineered, such that a first force Fi exerted on first bumper 432 can be equal to a second force F2 exerted on second bumper 434 and, thus, reduce the impact force of reticle 208 (i.e., F_ext) by a factor of two. In some embodiments, the controlled stiffness distribution (e.g., ki and k2) can be engineered from a single piece of high yield strength material, for example, a tempered martensitic stainless steel alloy (e.g., STAVAX®). For example, the controlled stiffness distribution (e.g., ki and k2) can be engineered or machined by wire electrical discharge machining (EDM).

[0060] In some embodiments, as shown in FIGS. 5 and 6, second arm 430 can include a third bumper 436. For example, third bumper 436 can be disposed toward proximal end 409 and adjacent second bumper 434. Third bumper 436 can include third stiffness linkage 448 with stiffness k3. In some embodiments, stiffness ki, stiffness k2, and stiffness k3 can be equal. In some embodiments, stiffness ki can be less than stiffness k2, and stiffness k2 can be less than stiffness k3. In some embodiments, as shown in FIG. 6, third bumper 436 can include third bumper pad 442. For example, third bumper pad 442 can be configured to directly contact a perimeter of reticle 208 and allow third stiffness linkage 448 to flex while in contact with reticle 208 in order to redistribute or dissipate the impact force of reticle 208 during a crash.

[0061] In some embodiments, first, second, and third stiffness linkages 444, 446, 448 can have a controlled stiffness distribution, such that an impact force of reticle 208 during a crash can be distributed uniformly (e.g., evenly) between first, second, and third bumpers 432, 434, 436. For example, the controlled stiffness distribution (e.g., ki, k2, and k3) can be engineered, such that a first force Fi exerted on first bumper 432, a second force F2 exerted on second bumper 434, and a third force F3 exerted on third bumper 436 can be equal and, thus, reduce the impact force of reticle 208 (i.e., F_ext) by a factor of three. This principle (e.g., whippletree or whiffletree model) can be extended to reduce the impact force of reticle 208 by a factor of n", where n" is the number of bumpers on second arm 430.

[0062] In some embodiments, second arm 430 can include a plurality of bumpers or an array of bumpers. For example, as shown in FIGS. 5 and 6, the plurality or array of bumpers can include first bumper 432, second bumper 434, and/or third bumper 436. In some embodiments, the plurality of bumpers include a plurality of stiffness linkages. For example, the plurality of bumpers can include first stiffness linkage 444, second stiffness linkage 446, and/or third stiffness linkage 448. In some embodiments, a stiffness of the plurality of stiffness linkages can increase from distal end 408 to proximal end 409 of second arm 430. For example, as shown in FIGS. 5 and 6, stiffness ki of first stiffness linkage 444 can be less than stiffness k2 of second stiffness linkage 446, and/or stiffness k2 of second stiffness linkage 446 can be less than stiffness k3 of third stiffness linkage 448.

[0063] FIG. 7 shows a schematic illustration of an exemplary bumper apparatus 400, according to some embodiments of this disclosure. Bumper apparatus 400 can include first arm 410, second arm 430, and extension 402. First arm 410 of bumper apparatus 400 can include second bumper 414. Second arm 430 of bumper apparatus 400 can include first bumper 432. First bumper 432 can include first stiffness linkage 444 with stiffness ki. Second bumper 414 can include second stiffness linkage 426 with stiffness k2. In some embodiments, stiffness ki can be equal to stiffness k2. In some embodiments, stiffness ki can be less than stiffness k2. In some embodiments, as shown in FIG. 7, first and second bumpers 432, 414 can include first and second bumper pads 438, 420, respectively. For example, first and second bumper pads 438, 420 can be configured to directly contact a perimeter of reticle 208 and allow first and second stiffness linkages 444, 426, respectively, to flex while in contact with reticle 208 in order to redistribute or dissipate the impact force of reticle 208 during a crash.

[0064] First and second bumpers 438, 420 can be configured to uniformly redistribute or dissipate an impact force or impact energy of reticle 208 during a crash along first and second stiffness linkages 444, 426, respectively. In some embodiments, first and second stiffness linkages 444, 426 can have a controlled stiffness distribution such that an impact force of reticle 208 during a crash can be distributed uniformly (e.g., evenly) between first and second bumpers 432, 414. For example, the controlled stiffness distribution (e.g., ki and k2) can be engineered such that a first force Fi exerted on first bumper 432 can be equal to a second force F2 exerted on second bumper 414 and, thus, reduce the impact force of reticle 208 (i.e., F_ext) by a factor of two. In some embodiments, the controlled stiffness distribution (e.g., ki and ]_¾) can be engineered from a piece of high yield strength material, for example, a tempered martensitic stainless steel alloy (e.g., STAVAX®). For example, the controlled stiffness distribution (e.g., ki and k2) can be engineered or machined by wire electrical discharge machining (EDM).

[0065] In some embodiments, as shown in FIG. 7, extension 402 can be a third bumper.

For example, extension 402 can connect to body 302 of reticle cage 300 and connect to first and second arms 410, 430, for example, extension 402 can be disposed between first and second bumpers 432, 414. Extension 402 can include extension stiffness linkage 404 with stiffness k3. In some embodiments, stiffness ki, stiffness k2, and stiffness k3 can be equal. In some embodiments, stiffness ki can be less than stiffness k2, and stiffness k2 can be less than stiffness k3. In some embodiments, as shown in FIG. 7, extension 402 can include extension bumper pad 403. For example, extension bumper pad 403 can be configured to directly contact a perimeter of reticle 208 and allow extension stiffness linkage 404 to flex while in contact with reticle 208 in order to redistribute or dissipate the impact force of reticle 208 during a crash.

[0066] In some embodiments, first, second, and extension stiffness linkages 444, 426,

404 can have a controlled stiffness distribution, such that an impact force of reticle 208 during a crash can be distributed uniformly (e.g., evenly) between first, second, and extension bumpers 432, 414, 402. For example, the controlled stiffness distribution (e.g., ki, k2, and k3) can be engineered, such that a first force Fi exerted on first bumper 432, a second force F2 exerted on second bumper 414, and a third force F3 exerted on extension 402 can be equal and, thus, reduce the impact force of reticle 208 (i.e., F_ext) by a factor of three. This principle (e.g., whippletree or whiffletree model) can be extended to reduce the impact force of reticle 208 by a factor of n', where n' is the number of bumpers on bumper apparatus 400. In some embodiments, the controlled stiffness distribution (e.g., k3) can be engineered from a piece of high yield strength material, for example, a tempered martensitic stainless steel alloy (e.g., STAVAX®). For example, the controlled stiffness distribution (e.g., k3) can be engineered or machined by wire electrical discharge machining (EDM).

[0067] FIG. 8 shows a schematic illustration of an exemplary bumper apparatus 400, according to some embodiments of this disclosure. Bumper apparatus 400 can include first arm 410 and extension 402. First arm 410 of bumper apparatus 400 can include first bumper 412 and second bumper 414. First bumper 412 can be disposed toward distal end 406 and second bumper 414 can be adjacent first bumper 412 and disposed toward proximal end 407. First bumper 412 can include first stiffness linkage 424 with stiffness ki. Second bumper 414 can include second stiffness linkage 426 with stiffness k2. In some embodiments, stiffness ki can be equal to stiffness k2. In some embodiments, stiffness ki can be less than stiffness k2. In some embodiments, as shown in FIG. 8, first and second bumpers 412, 414 can include first and second bumper pads 418, 420, respectively. For example, first and second bumper pads 418, 420 can be configured to directly contact a perimeter of reticle 208 and allow first and second stiffness linkages 424, 426, respectively, to flex while in contact with reticle 208 in order to redistribute or dissipate the impact force of reticle 208 during a crash.

[0068] First and second bumpers 412, 414 can be configured to uniformly redistribute or dissipate an impact force or impact energy of reticle 208 during a crash along first and second stiffness linkages 424, 426, respectively. In some embodiments, first and second stiffness linkages 424, 426 can have a controlled stiffness distribution such that an impact force of reticle 208 during a crash can be distributed uniformly (e.g., evenly) between first and second bumpers 412, 414. For example, the controlled stiffness distribution (e.g., ki and k2) can be engineered such that a first force Fi exerted on first bumper 412 can be equal to a second force F2 exerted on second bumper 414 and, thus, reduce the impact force of reticle 208 (i.e., F_ext) by a factor of two. In some embodiments, the controlled stiffness distribution (e.g., ki and k2) can be engineered from a single piece of high yield strength material, for example, a tempered martensitic stainless steel alloy (e.g., STAVAX®). For example, the controlled stiffness distribution (e.g., ki and k2) can be engineered or machined by wire electrical discharge machining (EDM).

[0069] In some embodiments, as shown in FIG. 8, extension 402 can be a third bumper.

For example, extension 402 can connect to body 302 of reticle cage 300 and connect to first arm 410. Extension 402 can include extension stiffness linkage 404 with stiffness k3. In some embodiments, stiffness ki, stiffness k2, and stiffness k3 can be equal. In some embodiments, stiffness ki can be less than stiffness k2, and stiffness k2 can be less than stiffness k3. In some embodiments, as shown in FIG. 8, extension 402 can include extension bumper pad 403. For example, extension bumper pad 403 can be configured to directly contact a perimeter of reticle 208 and allow extension stiffness linkage 404 to flex while in contact with reticle 208 in order to redistribute or dissipate the impact force of reticle 208 during a crash.

[0070] In some embodiments, first, second, and extension stiffness linkages 424, 426,

404 can have a controlled stiffness distribution, such that an impact force of reticle 208 during a crash can be distributed uniformly (e.g., evenly) between first, second, and extension bumpers 412, 414, 402. For example, the controlled stiffness distribution (e.g., ki, k2, and k3) can be engineered, such that a first force Fi exerted on first bumper 412, a second force F2 exerted on second bumper 414, and a third force F3 exerted on extension 402 can be equal and, thus, reduce the impact force of reticle 208 (i.e., F_ext) by a factor of three. This principle (e.g., whippletree or whiffletree model) can be extended to reduce the impact force of reticle 208 by a factor of n', where n' is the number of bumpers on bumper apparatus 400. In some embodiments, the controlled stiffness distribution (e.g., k3) can be engineered from a piece of high yield strength material, for example, a tempered martensitic stainless steel alloy (e.g., STAVAX®). For example, the controlled stiffness distribution (e.g., k3) can be engineered or machined by wire electrical discharge machining (EDM).

[0071] FIG. 9 shows a schematic illustration of an exemplary bumper apparatus 400, according to some embodiments of this disclosure. Bumper apparatus 400 of FIG. 9 is similar to bumper apparatus 400 of FIG. 8. Bumper apparatus 400 can include first arm 410 and first extension 402a. First arm 410 of bumper apparatus 400 can include first bumper 412 and second bumper 414. First bumper 412 can be disposed toward distal end 406 and second bumper 414 can be adjacent first bumper 412 and disposed toward proximal end 407. First bumper 412 can include first stiffness linkage 424 with stiffness ki. Second bumper 414 can include second stiffness linkage 426 with stiffness k2. In some embodiments, stiffness ki can be equal to stiffness k2. In some embodiments, stiffness ki can be less than stiffness k2. In some embodiments, as shown in FIG. 9, first and second bumpers 412, 414 can include first and second bumper pads 418, 420, respectively. For example, first and second bumper pads 418, 420 can be configured to directly contact a perimeter of reticle 208 and allow first and second stiffness linkages 424, 426, respectively, to flex while in contact with reticle 208 in order to redistribute or dissipate the impact force of reticle 208 during a crash.

[0072] First and second bumpers 412, 414 can be configured to uniformly redistribute or dissipate an impact force or impact energy of reticle 208 during a crash along first and second stiffness linkages 424, 426, respectively. In some embodiments, first and second stiffness linkages 424, 426 can have a controlled stiffness distribution such that an impact force of reticle 208 during a crash can be distributed uniformly (e.g., evenly) between first and second bumpers 412, 414. For example, the controlled stiffness distribution (e.g., ki and k2) can be engineered such that a first force Fi exerted on first bumper 412 can be equal to a second force F2 exerted on second bumper 414 and, thus, reduce the impact force of reticle 208 (i.e., F_ext) by a factor of two. In some embodiments, the controlled stiffness distribution (e.g., ki and k2) can be engineered from a single piece of high yield strength material, for example, a tempered martensitic stainless steel alloy (e.g., STAVAX®). For example, the controlled stiffness distribution (e.g., ki and k2) can be engineered or machined by wire electrical discharge machining (EDM).

[0073] In some embodiments, as shown in FIG. 9, first extension 402a can be a third bumper for first arm 410. For example, first extension 402a can connect to body 302 of reticle cage 300 and connect to first arm 410. First extension 402a can include first extension stiffness linkage 404a with stiffness k3. In some embodiments, stiffness ki, stiffness k2, and stiffness k3 can be equal. In some embodiments, stiffness ki can be less than stiffness k2, and stiffness k2 can be less than stiffness k3. In some embodiments, as shown in FIG. 9, first extension 402a can include first extension bumper pad 403a. For example, first extension bumper pad 403a can be configured to directly contact a perimeter of reticle 208 and allow first extension stiffness linkage 404a to flex while in contact with reticle 208 in order to redistribute or dissipate the impact force of reticle 208 during a crash.

[0074] In some embodiments, first, second, and first extension stiffness linkages 424,

426, 404a can have a controlled stiffness distribution, such that an impact force of reticle 208 during a crash can be distributed uniformly (e.g., evenly) between first, second, and first extension bumpers 412, 414, 402a. For example, the controlled stiffness distribution (e.g., ki, k2, and k3) can be engineered, such that a first force Fi exerted on first bumper 412, a second force F2 exerted on second bumper 414, and a third force F3 exerted on first extension 402a can be equal and, thus, reduce the impact force of reticle 208 (i.e., F_ext) by a factor of three. This principle (e.g., whippletree or whiffletree model) can be extended to reduce the impact force of reticle 208 by a factor of n', where n' is the number of bumpers on bumper apparatus 400. In some embodiments, the controlled stiffness distribution (e.g., k3) can be engineered from a piece of high yield strength material, for example, a tempered martensitic stainless steel alloy (e.g., STAVAX®). For example, the controlled stiffness distribution (e.g., !_¾) can be engineered or machined by wire electrical discharge machining (EDM).

[0075] As shown in FIG. 9, bumper apparatus 400 can include second arm 430 and second extension 402b. Second arm 430 of bumper apparatus 400 can include first bumper 432 and second bumper 434. First bumper 432 can be disposed toward distal end 408 and second bumper 434 can be adjacent first bumper 432 and disposed toward proximal end 409. First bumper 432 can include first stiffness linkage 444 with stiffness ki. Second bumper 434 can include second stiffness linkage 446 with stiffness k2. In some embodiments, stiffness ki can be equal to stiffness k2. In some embodiments, stiffness ki can be less than stiffness k2. In some embodiments, as shown in FIG. 9, first and second bumpers 432, 434 can include first and second bumper pads 438, 440, respectively. For example, first and second bumper pads 438, 440 can be configured to directly contact a perimeter of reticle 208 and allow first and second stiffness linkages 444, 446, respectively, to flex while in contact with reticle 208 in order to redistribute or dissipate the impact force of reticle 208 during a crash.

[0076] First and second bumpers 432, 434 can be configured to uniformly redistribute or dissipate an impact force or impact energy of reticle 208 during a crash along first and second stiffness linkages 444, 446, respectively. In some embodiments, first and second stiffness linkages 444, 446 can have a controlled stiffness distribution such that an impact force of reticle 208 during a crash can be distributed uniformly (e.g., evenly) between first and second bumpers 432, 434. For example, the controlled stiffness distribution (e.g., ki and k2) can be engineered such that a first force Fi exerted on first bumper 432 can be equal to a second force F2 exerted on second bumper 434 and, thus, reduce the impact force of reticle 208 (i.e., F_ext) by a factor of two. In some embodiments, the controlled stiffness distribution (e.g., ki and k2) can be engineered from a single piece of high yield strength material, for example, a tempered martensitic stainless steel alloy (e.g., STAVAX®). For example, the controlled stiffness distribution (e.g., ki and k2) can be engineered or machined by wire electrical discharge machining (EDM).

[0077] In some embodiments, as shown in FIG. 9, second extension 402b can be a third bumper for second arm 430. For example, second extension 402b can connect to body 302 of reticle cage 300 and connect to second arm 430. Second extension 402b can include second extension stiffness linkage 404b with stiffness k3. In some embodiments, stiffness ki, stiffness k2, and stiffness k3 can be equal. In some embodiments, stiffness ki can be less than stiffness k2, and stiffness ]_¾ can be less than stiffness k . In some embodiments, as shown in FIG. 9, second extension 402b can include second extension bumper pad 403b. For example, second extension bumper pad 403b can be configured to directly contact a perimeter of reticle 208 and allow second extension stiffness linkage 404b to flex while in contact with reticle 208 in order to redistribute or dissipate the impact force of reticle 208 during a crash.

[0078] In some embodiments, first, second, and second extension stiffness linkages 444,

446, 404b can have a controlled stiffness distribution, such that an impact force of reticle 208 during a crash can be distributed uniformly (e.g., evenly) between first, second, and second extension bumpers 432, 434, 402b. For example, the controlled stiffness distribution (e.g., ki, k2, and k3) can be engineered, such that a first force Fi exerted on first bumper 432, a second force F2 exerted on second bumper 434, and a third force F3 exerted on second extension 402b can be equal and, thus, reduce the impact force of reticle 208 (i.e., F_ext) by a factor of three. This principle (e.g., whippletree or whiffletree model) can be extended to reduce the impact force of reticle 208 by a factor of n', where n' is the number of bumpers on bumper apparatus 400. In some embodiments, the controlled stiffness distribution (e.g., k3) can be engineered from a piece of high yield strength material, for example, a tempered martensitic stainless steel alloy (e.g., STAVAX®). For example, the controlled stiffness distribution (e.g., k3) can be engineered or machined by wire electrical discharge machining (EDM).

[0079] FIG. 10 shows a schematic illustration of an exemplary bumper apparatus 400, according to some embodiments of this disclosure. Bumper apparatus 400 of FIG. 10 is similar to bumper apparatus 400 of FIG. 7. Bumper apparatus 400 can include first bumper section 450, first extension 402a, second bumper section 460, and second extension 402b.

[0080] First bumper section 450 can include first arm 410 and second arm 430. Second bumper section 460 can include first arm 410 and second arm 430. First arm 410 can include second bumper 414. Second arm 430 of bumper apparatus 400 can include first bumper 432. First bumper 432 can include first stiffness linkage 444 with stiffness ki. Second bumper 414 can include second stiffness linkage 426 with stiffness k2. In some embodiments, stiffness ki can be equal to stiffness k2. In some embodiments, stiffness ki can be less than stiffness k2. In some embodiments, as shown in FIG. 10, first and second bumpers 432, 414 can include first and second bumper pads 438, 420, respectively. For example, first and second bumper pads 438, 420 can be configured to directly contact a perimeter of reticle 208 and allow first and second stiffness linkages 444, 426, respectively, to flex while in contact with reticle 208 in order to redistribute or dissipate the impact force of reticle 208 during a crash.

[0081] First and second bumpers 438, 420 can be configured to uniformly redistribute or dissipate an impact force or impact energy of reticle 208 during a crash along first and second stiffness linkages 444, 426, respectively. In some embodiments, first and second stiffness linkages 444, 426 can have a controlled stiffness distribution such that an impact force of reticle 208 during a crash can be distributed uniformly (e.g., evenly) between first and second bumpers 432, 414. For example, the controlled stiffness distribution (e.g., ki and k2) can be engineered such that a first force Fi exerted on first bumper 432 can be equal to a second force F2 exerted on second bumper 414 and, thus, reduce the impact force of reticle 208 (i.e., F_ext) by a factor of two. In some embodiments, the controlled stiffness distribution (e.g., ki and k2) can be engineered from a piece of high yield strength material, for example, a tempered martensitic stainless steel alloy (e.g., STAVAX®). For example, the controlled stiffness distribution (e.g., ki and k2) can be engineered or machined by wire electrical discharge machining (EDM).

[0082] In some embodiments, as shown in FIG. 10, first extension 402a and second extension 402b can each be a third bumper. For example, first and second extensions 402a, 402b can connect to body 302 of reticle cage 300 and connect to first and second arms 410, 430 of first and second bumper sections 450, 460, respectively. For example, first and second extension 402a, 402b can be disposed between first and second bumpers 432, 414. First and second extensions 402a, 402b can include first and second extension stiffness linkages 404a, 404b with stiffness k3, respectively. In some embodiments, stiffness ki, stiffness k2, and stiffness k3 can be equal. In some embodiments, stiffness ki can be less than stiffness k2, and stiffness k2 can be less than stiffness k3. In some embodiments, as shown in FIG. 10, first and second extensions 402a, 402b can include first and second extension bumper pads 403a, 403b, respectively. For example, first and second extension bumper pads 403a, 403b can be configured to directly contact a perimeter of reticle 208 and allow first and second extension stiffness linkages 404a, 404b, respectively, to flex while in contact with reticle 208 in order to redistribute or dissipate the impact force of reticle 208 during a crash.

[0083] In some embodiments, first, second, and first and second extension stiffness linkages 444, 426, 404a, 404b can have a controlled stiffness distribution, such that an impact force of reticle 208 during a crash can be distributed uniformly (e.g., evenly) between first, second, and first and second extension bumpers 432, 414, 402a, 402b, respectively. For example, the controlled stiffness distribution (e.g., ki, k2, and k3) can be engineered, such that a first force Fi exerted on first bumper 432, a second force F2 exerted on second bumper 414, and a third force F3 exerted on first and second extensions 402a, 402b, respectively, can be equal and, thus, reduce the impact force of reticle 208 (i.e., F_ext) by a factor of three. This principle (e.g., whippletree or whiffletree model) can be extended to reduce the impact force of reticle 208 by a factor of n', where n' is the number of bumpers on bumper apparatus 400. In some embodiments, the controlled stiffness distribution (e.g., k3) can be engineered from a piece of high yield strength material, for example, a tempered martensitic stainless steel alloy (e.g., STAVAX®). For example, the controlled stiffness distribution (e.g., k3) can be engineered or machined by wire electrical discharge machining (EDM).

[0084] Methods of operating a bumper apparatus can be accomplished according to the manners of operation disclosed herein. In some embodiments, as shown in FIGS. 5 and 6, bumper apparatus 400 can be arranged in an L-shape or concave hexagon and be configured to contact a comer of reticle 208. In some embodiments, this can be accomplished, for example, by wire EDM of a high yield strength material, for example, a tempered martensitic stainless steel alloy (e.g., STAVAX®), and arranging reticle cages 300 with bumper apparatus 400 adjacent each comer of reticle 208. In some embodiments, an impact force of reticle 208 during a crash can be distributed uniformly (e.g., evenly) between first and second bumpers 412, 414 of first arm 410 and/or first and second bumpers 432, 434 of second arm 430. For example, first and second bumpers 412, 414 and/or first and second bumpers 432, 434 can flex in order to redistribute or dissipate the impact force of reticle 208 along first and second stiffness linkages 424, 426 and/or first and second stiffness linkages 444, 446, respectively. In some embodiments, bumper apparatus 400 can be positioned to a minimum gap distance between reticle 208 and bumper apparatus 400 to reduce the impact force of reticle 208. For example, bumper apparatus 400 can be positioned within 1.0 mm of a perimeter of reticle 208 at all times except during a reticle exchange process.

[0085] The embodiments may further be described using the following clauses:

1. A bumper apparatus for a reticle, comprising:

a first arm configured to contact the reticle along a first direction; and

a second arm configured to contact the reticle along a second direction, wherein the first arm comprises a first bumper disposed toward a distal end of the first arm and a second bumper adjacent the first bumper and disposed toward a proximal end of the first arm,

wherein the first bumper comprises a first stiffness linkage and the second bumper comprises a second stiffness linkage,

wherein the first and second bumpers are configured to uniformly distribute an impact force of the reticle.

2. The bumper apparatus of clause 1, wherein the second arm comprises a first bumper disposed toward a distal end of the second arm and a second bumper adjacent the first bumper and disposed toward a proximal end of the second arm.

3. The bumper apparatus of clause 2, wherein the first bumper of the second arm comprises a first stiffness linkage and the second bumper of the second arm comprises a second stiffness linkage.

4. The bumper apparatus of clause 1, wherein a stiffness of the first stiffness linkage is equal to a stiffness of the second stiffness linkage.

5. The bumper apparatus of clause 1, wherein a stiffness of the first stiffness linkage is less than a stiffness of the second stiffness linkage.

6. The bumper apparatus of clause 1, wherein the first direction is orthogonal to the second direction.

7. The bumper apparatus of clause 1, wherein the first and second arms comprise a tempered martensitic stainless steel alloy.

8. A lithographic apparatus, comprising:

a reticle stage;

a reticle disposed on the reticle stage;

a reticle cage disposed adjacent to the reticle and configured to uniformly distribute an impact force of the reticle, the reticle cage comprising:

an arm configured to contact the reticle,

wherein the arm comprises a first bumper disposed toward a distal end of the arm and a second bumper adjacent the first bumper and disposed toward a proximal end of the arm, wherein the first bumper comprises a first stiffness linkage and the second bumper comprises a second stiffness linkage.

9. The lithographic apparatus of clause 8, wherein the arm comprises a third bumper adjacent the second bumper and disposed toward a proximal end of the arm.

10. The lithographic apparatus of clause 9, wherein the third bumper comprises a third stiffness linkage.

11. The lithographic apparatus of clause 10, wherein a stiffness of the first stiffness linkage is less than a stiffness of the second stiffness linkage and the stiffness of the second stiffness linkage is less than a stiffness of the third stiffness linkage.

12. The lithographic apparatus of clause 10, wherein a stiffness of the first stiffness linkage, a stiffness of the second stiffness linkage, and a stiffness of the third stiffness linkage are equal.

13. The lithographic apparatus of clause 8, wherein the arm comprises a plurality of additional bumpers.

14. The lithographic apparatus of clause 13, wherein the plurality of additional bumpers comprises a plurality of stiffness linkages.

15. The lithographic apparatus of clause 14, wherein a stiffness of the plurality of stiffness linkages increases from the distal end to the proximal end of the arm.

16. The lithographic apparatus of clause 8, wherein the reticle cage is a plurality of reticle cages disposed around a perimeter of the reticle and configured to uniformly distribute an impact force of the reticle over a plurality of impact locations.

17. The lithographic apparatus of clause 8, wherein the first and second stiffness linkages of the arm have a controlled stiffness distribution, such that the impact force of the reticle is distributed evenly between the first and second bumpers.

18. A method for reducing an impact force of a reticle, comprising:

disposing a bumper apparatus adjacent the reticle, wherein the bumper apparatus contacts the reticle with an arm comprising a first bumper disposed toward a distal end of the arm and a second bumper adjacent the first bumper and disposed toward a proximal end of the arm, such that the first bumper comprises a first stiffness linkage and the second bumper comprises a second stiffness linkage; and

distributing the impact force of the reticle uniformly between the first and second bumpers. 19. The method of clause 18, further comprising flexing the first and second bumpers to redistribute the impact force of the reticle along the first and second stiffness linkages.

20. The method of clause 18, further comprising positioning the bumper apparatus to a minimum gap distance between the reticle and the bumper apparatus, such that the impact force of the reticle is reduced.

[0086] Although specific reference may be made in this text to the use of lithographic apparatus in the manufacture of ICs, it should be understood that the lithographic apparatus described herein may have other applications. Possible other applications include the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat-panel displays, liquid-crystal displays (LCDs), thin film magnetic heads, etc.

[0087] Although specific reference may be made in this text to embodiments of the disclosure in the context of a lithographic apparatus, embodiments of the disclosure may be used in other apparatuses. Embodiments of the disclosure may form part of a mask inspection apparatus, a metrology apparatus, or any apparatus that measures or processes an object such as a wafer (or other substrate) or mask (or other patterning device). These apparatuses may be generally referred to as lithographic tools. Such lithographic tools may use vacuum conditions or ambient (non-vacuum) conditions.

[0088] Although specific reference may have been made above to the use of embodiments of the disclosure in the context of optical lithography, it will be appreciated that the disclosure, where the context allows, is not limited to optical lithography and may be used in other applications, for example imprint lithography.

[0089] It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by those skilled in relevant art(s) in light of the teachings herein.

[0090] The above examples are illustrative, but not limiting, of the embodiments of this disclosure. Other suitable modifications and adaptations of the variety of conditions and parameters normally encountered in the field, and which would be apparent to those skilled in the relevant art(s), are within the spirit and scope of the disclosure.

[0091] While specific embodiments of the disclosure have been described above, it will be appreciated that the disclosure may be practiced otherwise than as described. The descriptions above are intended to be illustrative, not limiting. Thus it will be apparent to one skilled in the art that modifications may be made to the disclosure as described without departing from the scope of the claims set out below.

[0092] It is to be appreciated that the Detailed Description section, and not the Summary and Abstract sections, is intended to be used to interpret the claims. The Summary and Abstract sections may set forth one or more but not all exemplary embodiments of the present invention as contemplated by the inventor(s), and thus, are not intended to limit the present invention and the appended claims in any way.

[0093] The present invention has been described above with the aid of functional building blocks illustrating the implementation of specified functions and relationships thereof. The boundaries of these functional building blocks have been arbitrarily defined herein for the convenience of the description. Alternate boundaries can be defined so long as the specified functions and relationships thereof are appropriately performed.

[0094] The foregoing description of the specific embodiments will so fully reveal the general nature of the invention that others can, by applying knowledge within the skill of the art, readily modify and/or adapt for various applications such specific embodiments, without undue experimentation, without departing from the general concept of the present invention. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein.

[0095] The breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

Claims

1. A bumper apparatus for a reticle, comprising:

a first arm configured to contact the reticle along a first direction; and

a second arm configured to contact the reticle along a second direction,

wherein the first arm comprises a first bumper disposed toward a distal end of the first arm and a second bumper adjacent the first bumper and disposed toward a proximal end of the first arm,

2. The bumper apparatus of claim 1, wherein the second arm comprises a first bumper disposed toward a distal end of the second arm and a second bumper adjacent the first bumper and disposed toward a proximal end of the second arm.

3. The bumper apparatus of claim 2, wherein the first bumper of the second arm comprises a first stiffness linkage and the second bumper of the second arm comprises a second stiffness linkage.

4. The bumper apparatus of claim 1, wherein a stiffness of the first stiffness linkage is equal to a stiffness of the second stiffness linkage.

5. The bumper apparatus of claim 1, wherein a stiffness of the first stiffness linkage is less than a stiffness of the second stiffness linkage.

6. The bumper apparatus of claim 1, wherein the first direction is orthogonal to the second direction.

7. The bumper apparatus of claim 1, wherein the first and second arms comprise a tempered martensitic stainless steel alloy.

8. A lithographic apparatus, comprising:

a reticle stage;

a reticle disposed on the reticle stage;

an arm configured to contact the reticle,

wherein the arm comprises a first bumper disposed toward a distal end of the arm and a second bumper adjacent the first bumper and disposed toward a proximal end of the arm,

wherein the first bumper comprises a first stiffness linkage and the second bumper comprises a second stiffness linkage.

9. The lithographic apparatus of claim 8, wherein the arm comprises a third bumper adjacent the second bumper and disposed toward a proximal end of the arm.

10. The lithographic apparatus of claim 9, wherein the third bumper comprises a third stiffness linkage.

11. The lithographic apparatus of claim 10, wherein a stiffness of the first stiffness linkage is less than a stiffness of the second stiffness linkage and the stiffness of the second stiffness linkage is less than a stiffness of the third stiffness linkage.

12. The lithographic apparatus of claim 10, wherein a stiffness of the first stiffness linkage, a stiffness of the second stiffness linkage, and a stiffness of the third stiffness linkage are equal.

13. The lithographic apparatus of claim 8, wherein the arm comprises a plurality of additional bumpers.

14. The lithographic apparatus of claim 13, wherein the plurality of additional bumpers comprises a plurality of stiffness linkages.

15. The lithographic apparatus of claim 14, wherein a stiffness of the plurality of stiffness linkages increases from the distal end to the proximal end of the arm.

16. The lithographic apparatus of claim 8, wherein the reticle cage is a plurality of reticle cages disposed around a perimeter of the reticle and configured to uniformly distribute an impact force of the reticle over a plurality of impact locations.

17. The lithographic apparatus of claim 8, wherein the first and second stiffness linkages of the arm have a controlled stiffness distribution, such that the impact force of the reticle is distributed evenly between the first and second bumpers.

18. A method for reducing an impact force of a reticle, comprising:

distributing the impact force of the reticle uniformly between the first and second bumpers.

19. The method of claim 18, further comprising flexing the first and second bumpers to redistribute the impact force of the reticle along the first and second stiffness linkages.

20. The method of claim 18, further comprising positioning the bumper apparatus to a minimum gap distance between the reticle and the bumper apparatus, such that the impact force of the reticle is reduced.