TWI686666B - Substrate container - Google Patents

Abstract

A reticle container for containing a reticle. The reticle container may include a pod including a base plate and a cover. The cover may be adapted to engage the base plate to define an enclosure for containing the reticle. The base plate may have an upwardly facing first surface and a downwardly facing second surface. The base plate may additionally include a plurality of support structures positioned on and extending upwardly from the upwardly facing surface to support the reticle on the base plate. The base plate may additionally include a pellicle mounting recess in the upwardly facing surface. The pellicle mounting recess may be defined by a recess sidewall and a bottom sidewall which defines a shape for receiving a pellicle at least partially within the recess.

Description

Substrate container

The present invention relates generally to a container for storing, transporting, transporting, and processing fragile devices such as photomasks, reticles, printed circuit boards, and substrates. More specifically, the present invention relates to a transportable and transportable reticle carrier including a pellicle mounting groove and a plurality of window mounting grooves.

One of the process steps often encountered in the manufacture of integrated circuits and other semiconductor devices is photolithography. In summary, photolithography involves using a patterned template to selectively expose a specially prepared wafer surface to a radiation source to form an etched surface layer. Typically, the patterned template is a photomask, which is a very flat glass plate containing the pattern to be reproduced on the wafer. A typical photomask substrate material is optically transparent quartz. Due to the small size of the key components of modern integrated circuits, the operating surface of the reticle (ie, the patterned surface) should be kept free of contaminants, which may damage the surface or cause projection to during processing The image on the photoresist layer is distorted. Both of these situations will result in a final product with unacceptable quality. In some examples, the patterned surface of the photomask is covered by a protective film that includes an optically transparent film, which is usually formed of nitrocellulose, is attached to a frame, and is The frame is supported and attached to the reticle. The protective film helps to isolate contaminants and reduce printing defects that may be caused by such contaminants migrating to the image plane.

Generally, the photomask is stored and/or transported in a small clean room type environment, which is formed in a SMIF container or box having a base and a lid. The cover cooperates with the base to form a hermetically sealed housing for holding the photomask. In some examples, the hermetically sealed housing includes one or more windows, which are disposed on the outer surface of the housing. During processing, the internal mask can be monitored from the outside of the housing through the window to verify the processing and function of the mask, determine whether the mask is properly aligned, and take other quality control measures.

Since photomasks are susceptible to damage to the precision features on the patterned surface due to sliding friction and abrasion, it is highly undesirable to cause non-contact between the photomask and other surfaces during manufacturing, processing, transportation, handling, transportation, or storage. Necessary and unintentional contact. In addition, any contamination of the surface of the photomask by the particles may harm the photomask to a certain extent, which is sufficient to seriously affect any final product obtained by using this photomask during processing. Particles may be generated in a controlled environment containing a photomask during processing, transportation and transportation. The sliding friction between the reticle and the container and the components of the container can also become a source of contaminating particles. In addition, it is now known that gas and trace moisture may escape from the polymer material used in the photomask container, which may cause haze and crystal growth on the photomask and damage the photomask.

Lithography is moving towards the use of extreme ultraviolet (EUV) light sources, which have shorter wavelengths to allow the production of smaller integrated circuits (often in a vacuum environment), so It is designed to store, transport and ship a container or box designed to impose significant functional requirements for a photomask used in extreme ultraviolet lithography. For example, small particles that are not large enough to cause a problem in conventional lithography may become a significant problem in extreme ultraviolet lithography. In addition, extreme ultraviolet lithography can be performed under a vacuum, which may make degassing and/or water decomposition and absorption from the container components become a problem, especially when these components are polymer Compound.

The box used for extreme ultraviolet lithography usually uses an inner box and an outer box. Examples can be found in Kolbow et al. U.S. Patent No. 8,231,005 (``Kolbow''), Gregerson et al. U.S. Patent No. 7,607,543 (``Gregerson''), and Lystad et al. U.S. Patent Publication No. 2015/0266660 (``Lystad "), each of these patents is owned by the owner of the application, and its disclosure content is incorporated by reference in its entirety except for all the patent claims and clear definitions.

One or more embodiments of the invention relate to a bottom plate for an inner box assembly in a reticle container. In various embodiments, the bottom plate includes one or more windows and a protective film mounting groove. The protective film mounting groove is used to receive a protective film in the bottom plate. The protective film mounting groove may be located in one of the upward facing surfaces of the bottom plate, and in one or more embodiments, the protective film mounting groove is defined by a groove side wall and a bottom side wall, the groove side wall And the bottom side wall defines a shape for tightly accommodating the protective film.

Each of the one or more windows includes an opening through the bottom plate and a transparent substrate. The transparent substrate can be installed into a window installation groove of the bottom plate in a downward-facing surface of the bottom plate. The window mounting groove may include a first groove and a second groove, the first groove is defined by a first groove side wall and a first bottom side wall, and the second groove is located at the first The bottom side wall is defined by a second groove side wall and a second bottom side wall. In various embodiments, the second groove side wall and the second bottom side wall define a shape in the window mounting groove for tightly accommodating the transparent substrate. In one or more embodiments, each opening of the one or more windows extends from the second bottom side wall of the window mounting groove through the bottom plate to the upwardly facing surface.

In various embodiments, the bottom plate includes a window holding member for holding the transparent substrate in the window mounting groove. The window holding member may include a pair of longitudinal arched portions and a pair of widthwise portions. In various embodiments, the window holding member is by positioning at least one of the pair of widthwise portions in an undercut portion of the first groove and fixing the other of the pair of widthwise portions to the The window installation groove is installed in the first groove, so that the longitudinal arch portion contacts the transparent substrate to hold the transparent substrate in the second groove.

Various embodiments benefit from a protective film mounting groove that enables the use of a protective film in an inner box assembly of a reticle container. Therefore, embodiments of the present invention benefit from improved particle protection in the inner box assembly, thereby extending the life of the reticle. For example, during the reproduction of an integrated circuit by photolithography, the protective film will help prevent dust particles on the surface of the photomask from being imaged into the photomask.

In addition, one or more embodiments provide many advantages by compensating for the reduction in material thickness caused by the addition of a protective film mounting groove in the bottom plate. The reduction in material thickness will reduce the window retention options in the inner box assembly. Therefore, one or more embodiments provide other window holding options that are compatible with the protective film groove, thereby enabling the inner box assembly to continue to incorporate windows in the bottom plate for quality control, process monitoring, and other effect. In addition, one or more embodiments provide the advantage of making a window holding mechanism easier to install and/or disassemble and clean than current screw holding methods.

The above summary is not intended to illustrate each illustrated embodiment or every implementation of the present invention.

100: photomask container

104: Outer box assembly

108: inner box assembly

112: Central axis

116: Mask

120: upper part

124: lower part

128: cover

132: Base

136: Alignment pin

140: Guide groove

144: Edge

148: top surface

152: Lateral surface

156: protrusion

160: through hole

164: Surface

165: Face up

168: Lateral surface

170: Mask support member

172: Windows

204: base/floor

208: Face down

216: Protective film installation groove

220: groove side wall

224: bottom side wall

225: Protective film

226: Clamping area

228: Windows

229: Windows

232: opening

233: opening

236: Transparent substrate

240: Windows installation groove

241: Lips

242: lips

244: first groove

248: sidewall of the first groove

252: Width edge

256: lengthwise edge

260: First bottom side wall

264: Undercut part

268: Overhang

272: Second groove

276: second groove side wall

280: second bottom side wall

284: Window holding member

288: Lengthwise arched part

292: Width part

304: Window holding member

404: Window holding member

408: screw

412: thinner area

416: thicker area

The drawings included in this application are incorporated into this specification and form part of this specification. The drawings illustrate embodiments of the present invention, and the description is used together to explain the principle of the present invention. The drawings are only illustrative of certain embodiments and do not limit the present invention.

Figure 1 shows a photomask container of the prior art; Figure 2 shows a top perspective view of a base of an inner box assembly of a photomask container according to one or more embodiments of the present invention; Figure 3 shows a According to one or more embodiments of the present invention, an exploded perspective view of a base of an inner box assembly including a protective film and a reticle; FIG. 4 illustrates one or more embodiments according to the present invention , A bottom perspective view of a base of an inner box assembly of a reticle container; FIG. 5 illustrates a cross-sectional view of a window mounting groove according to one or more embodiments of the present invention, the window mounting groove including a transparent substrate And a window holding member; FIG. 6 shows a cross-sectional view of a window mounting groove according to one or more embodiments of the present invention, the window mounting groove includes a transparent substrate and a window holding member; FIG. 7 shows according to One or more embodiments of the present invention, a cross-sectional view of a window mounting groove including a transparent substrate and a window holding member; and FIG. 8 illustrates a window according to one or more embodiments of the present invention A cross-sectional view of the installation groove. The window installation groove includes a transparent substrate and a window holding member.

Although the embodiments of the present invention are suitable for making various retouching and alternative forms, they have been shown by way of example in the drawings and the details of these embodiments will be explained in detail. However, it should be understood that the intention is not to limit the invention to the particular embodiments described. On the contrary, intent covers attribution All retouching, equivalent forms and alternatives within the spirit and scope of the present invention.

FIG. 1 shows a reticle container 100 according to the prior art. The photomask container 100 includes an outer box assembly 104 and an inner box assembly 108, the outer box assembly 104 and the inner box assembly 108 are aligned with a central axis 112, and the inner box assembly 108 accommodates a photomask 116. As used herein, the term reticle 116 refers to a thin planar substrate, reticle, or printed circuit board. The outer box assembly 104 includes an upper portion 120 and a lower portion 124. The upper portion 120 and the lower portion 124 cooperate to define a housing. The inner box assembly 108 includes a cover 128 and a base 132, and can be disposed in the outer box assembly 104. The cover 128 and the base 132 can be aligned by a plurality of alignment pins 136 extending from the cover 128. Each of the alignment pins 136 may be located in a respective guide groove 140, and the guide groove 140 is formed on an edge 144 of the base 132. Although the reticle box shown herein has a generally square outline, it should be understood that other boxes may have other shapes, for example, a polygon, a circle, or other suitable shapes.

The cover 128 of the inner box assembly may have a one-piece structure machined from a single block (eg, a metal, such as stainless steel). The cover 128 defines a top surface 148 opposite a bottom surface or inward-facing surface that is spaced from the top surface 148 by a lateral surface 152, the lateral surface 152 substantially along a plane extend. In an embodiment, the cover 128 may be provided with at least one protrusion 156 that extends outward from the lateral surface 152 and extends from the top surface 148 to the bottom surface. A through hole 160 is formed at a position in the protrusion 156 for accommodating the alignment pin 136. One axis of the through hole 160 is substantially perpendicular to the top surface 148. The present invention further covers that the cover 128 may not have the protrusion 156, and the through hole 160 may be drilled substantially adjacent to the lateral surface 152. The size of the alignment pin 136 may be determined to achieve an interference fit with the through hole 160.

The base 132 of the inner box assembly may also have an integral metal structure and include an upward-facing surface or inward-facing surface 164, and an upward-facing surface or inward-facing surface 164 and a The downward facing surface or bottom surface is opposed with a lateral surface 168 extending therebetween, the lateral surface 168 extending substantially along a plane. The base 132 includes a plurality of reticle support members 170 to support the reticle 116 within the inner box assembly 108 near each of the corners of the reticle 116. The reticle support member 170 extends from the inward-facing surface 164 . The base 132 may be provided with at least one guide groove 140 that is inwardly indented from the plane of the lateral surface 168 and extends through the surface 164 and the bottom surface. In one embodiment, the guide groove 140 is positioned on the base 132 such that when the cover 128 engages the base 132, the alignment pin 136 is located at a precise position within the guide groove 140, and thus the alignment pin 136 A tight fit engagement is formed with the guide groove 140. The base 132 further includes a plurality of windows 172, and the windows 172 each include a transparent substrate disposed in the base 132 to monitor the photomask from the outside of the inner box assembly 108 via the window 172.

Functionally, the cover 128 and the base 132 sealingly cooperate with each other to define a hermetically sealed housing without significant axial movement between the cover 128 and the base 132. The configuration of the one-piece structure of the cover 128 and the base 132 eliminates or reduces the presence of surfaces that are in clamping contact, thereby reducing or eliminating particles trapped between these clamped surfaces and the ensuing particles Scattering problems that may occur over time. The one-piece construction can also eliminate multiple manufacturing steps and reduce the accumulation of tolerances associated with the cover 128 and the base 132.

Referring to FIGS. 2 to 4, it illustrates a base 204 of an inner box assembly of a reticle container according to one or more embodiments of the present invention. In one or more embodiments, the substrate 204 has an integral metal structure and includes an upwardly facing surface 165 that is opposite to a downwardly facing surface 208 with a lateral surface 168 extending therebetween. The base 204 further includes a plurality of reticle support members 170 for supporting a reticle 116, and the reticle support members 170 extend from the upward surface 165. In some embodiments, the base 204 includes one or more guide grooves 140 to align the base 204 with a cover, and the guide grooves 140 retract inwardly from the lateral surface 168.

In one or more embodiments, the substrate 204 includes a protective film mounting groove 216 defined in the upwardly facing surface 165. The film mounting groove 216 includes a groove side wall 220 and a bottom side wall 224, and the groove side wall 220 and the bottom side wall 224 define one of at least partially accommodating and supporting a film in the film mounting groove 216 shape. In one or more embodiments, the substrate 204 additionally includes a plurality of clamping regions 226 at various points around the periphery of the protective film mounting groove 216 to facilitate insertion of a protective film into the groove 216 and/or self-protective film The mounting groove 216 is removed. In various embodiments, the groove side wall 220 and the bottom side wall 224 define a shape that conforms to the shape of a protective film to position the protective film in the protective film mounting groove 216.

FIG. 3 is an exploded view of the base plate 204, a protective film 225, and a photomask 116 according to one or more embodiments. The protective film 225 is located below the reticle 116 and can be lowered down into the protective film mounting groove 216. In various embodiments, the depth of the protective film mounting groove 216 is substantially the same as the height of the protective film 225 so that the protective film is substantially flush with the upward-facing surface 165 when lowered into the protective film mounting groove 216 , And the reticle 116 contacts the reticle support member 170 to support the reticle on the positioning of the bottom plate 204 and the protective film 225 in combination. In some embodiments, the depth of the protective film mounting groove 216 may vary, so that the depth of the protective film mounting groove 216 is greater than or less than the height of the protective film 225.

Referring to FIGS. 2 to 6, in various embodiments, the substrate 204 additionally includes a plurality of windows 228 and 229. Each of the windows 228 and 229 includes an opening 232 and 233 through the base 204 and a transparent substrate 236. In various embodiments, each of the openings 232, 233 extends through the bottom plate 204 to the upwardly facing surface 165. In one or more embodiments, the transparent substrate 236 is made of transparent glass, plastic, or other materials suitable for processing in an extreme ultraviolet environment.

In various embodiments, the transparent substrates 236 are respectively disposed in the plurality of window mounting grooves 240 of the base 204 on the downward surface 208. In some of the examples shown in Figure 5 and Figure 6 In an embodiment, the window mounting groove 240 includes a first groove 244 respectively. The first groove 244 is defined by a first groove side wall 248 and a first bottom side wall 260. The first groove side wall 248 has a pair of A widthwise edge 252 and a pair of lengthwise edges 256. In some embodiments, one or more of the widthwise edges 252 includes an undercut portion 264 formed by a lateral groove in the first groove sidewall 248, the lateral groove An overhang 268 is defined.

In some embodiments, the window mounting grooves 240 each include a second groove 272 in the first bottom sidewall 260. The second groove 272 is defined by a second groove side wall 276 and a second bottom side wall 280. In one or more embodiments, the second groove side wall 276 and the second bottom side wall 280 define a shape for at least partially closely accommodating the transparent substrate 236 within the second groove 272.

In one or more embodiments, openings 232, 233 having various sizes may be formed according to the sizes/types of the windows 228, 229. For example, as shown in Figures 2 to 6, the window 228 is an alignment window used to check the positioning of the reticle during processing. Therefore, the opening 232 is larger than the opening 233 to better observe through the bottom plate 204 into the inner box assembly. However, the area of each of the openings 232, 233 is at least smaller than the area of the second bottom side wall 280, so that the openings 232, 233 and the second bottom side wall 280 define a lip 241 in the window mounting groove 240 242, the lips 241, 242 are sufficient to support the transparent substrate 236. For example, as shown in FIGS. 5-6, the transparent substrate 236 in each window mounting groove 240 is supported by a lip having an edge that supports the corresponding edge of the transparent substrate 236.

In one or more embodiments, the base 204 includes a plurality of window holding members 284. The shape and size of the window holding member 284 is suitable to be firmly positioned in the first groove 244 by a snap fit, a spring fit, a spiral fit, or other ways to hold the transparent substrate 236 in the second groove 272 Positioning. For example, referring to Figures 5 to 6, each of these windows is fixed The holding member 284 has a pair of longitudinal arched portions 288 and a pair of widthwise portions 292. The pair of width direction portions 292 are located in the undercut portions 264 of the window installation grooves 240, whereby the window holding member 284 is fixed to the positioning by the overhanging portion 268. Once in positioning, the longitudinal arch portion 288 bends to contact the transparent substrate 236, thereby holding the transparent substrate 236 in positioning in the second groove 272.

In one or more embodiments, the window holding member 284 may be installed into the first groove by appropriately bending one or more of the width direction portions 292 of the member into the undercut portion 264. In one or more embodiments, the window holding member 284 is constructed using a material with spring properties so that once the window holding member 284 is no longer bent into the undercut portion 264, the window holding member 284 springs back to it The original shape, whereby the longitudinal arch portion 288 contacts the transparent substrate 236. Therefore, in various embodiments, the window holding member 284 is constructed of spring steel (eg, medium carbon steel or high carbon steel). In some embodiments, the window holding member is constructed of a polymer, such as perfluoroalkoxy alkane, polytetrafluoroethylene, or rigid enough to bend And maintain a suitable form of other suitable polymers.

The window holding member can be constructed to have various shapes or designs. For example, referring to FIG. 7, a cross-sectional view of a window holding member 304 is shown. The window holding member 304 is constructed of a spring wire elastic material. Referring to FIG. 8, it shows a window holding member 404. In one or more embodiments, the window holding member 404 is partially held by screws, one of its widthwise edges is located in an undercut portion 264 of the first groove 244 and the other of its widthwise edges is It is fixed in position in the bottom plate 204 by a screw 408.

In one or more embodiments, due to the film mounting groove 216, the window mounting groove 240 is positioned such that a portion is located on one of the thinner areas 412 of the bottom plate 204 and another portion is located On a thicker area 416 of the bottom plate 204. Due to the lack of floor material, the thinner area 412 prevents the use of conventional holding methods such as screws 408. Therefore, in various embodiments, the undercut portion 264 is located in the sidewall of the groove corresponding to the thinner region 412. In some embodiments, the window holding member 404 has a first widthwise edge and has a second widthwise edge, the first widthwise edge is located in the undercut portion 264 corresponding to the thinner area 412, the second The widthwise edge is fixed in position in the base plate 204 by a screw 408, which is located in the thicker area 416 of the base plate 204.

The description of various embodiments of the present invention is provided for illustrative purposes, and is not intended to be exhaustive or limited to the disclosed embodiments. Those of ordinary skill in the art will understand many retouches and variations, without departing from the scope and spirit of the described embodiments. The terminology used in this article was chosen to explain the principles, practical applications, or technical improvements to the technologies present on the market, or to enable others with ordinary knowledge in this technology to understand this article The disclosed embodiment.

116‧‧‧ Mask

140‧‧‧Guide groove

165‧‧‧ facing up

168‧‧‧Lateral surface

170‧‧‧Mask support member

204‧‧‧Base/Bottom plate

216‧‧‧membrane installation groove

224‧‧‧Bottom side wall

225‧‧‧Film

226‧‧‧ clamping area

228‧‧‧window

229‧‧‧window

232‧‧‧opening

233‧‧‧opening

Claims (22)

A substrate container for accommodating a substrate. The substrate container includes: a box including a bottom plate and a cover adapted to engage the bottom plate to define a housing for accommodating a substrate. The bottom plate has an upward direction And a downward-facing surface, the bottom plate includes: a plurality of windows located in the bottom plate, each of the windows includes: a window mounting groove located in the downward-facing surface, the window mounting groove is formed by a recess The groove side wall and a bottom side wall are defined. The groove side wall has a pair of widthwise edges and a pair of lengthwise edges. At least one of the widthwise edges defines an undercut portion in the groove sidewall; an opening, Located in the bottom side wall of the window mounting groove and extending through the upwardly facing surface, the opening and the bottom side wall define a lip in the window mounting groove, the lip supporting a transparent substrate; and a The window holding member has a pair of lengthwise arched portions and a pair of widthwise portions, at least one of the pair of widthwise portions is located in the undercut portion, thereby forming between the transparent substrate and the lengthwise arched portions Contact to hold the transparent substrate in position in the window installation groove. The substrate container according to claim 1, further comprising: a protective film mounting groove located in the upward-facing surface, the protective film mounting groove is defined by a protective film groove side wall and a protective film bottom side wall, The side wall of the protective film groove and the bottom side wall of the protective film define a shape for accommodating a protective film at least partially in the protective film mounting groove. The substrate container according to claim 1, wherein the window mounting groove includes: a first groove defined by a first groove side wall and a first bottom side wall, the first groove The groove side wall has the pair of widthwise edges and the pair of lengthwise edges; and a second groove located in the first bottom side wall of the first groove, the second groove is composed of a second groove side wall and A second bottom side wall defining, the second groove side wall and the second bottom side wall defining a shape for at least partially housing the transparent substrate in the second groove; and wherein the opening is located in the first In the two bottom side walls, the opening and the second bottom side wall define the lip in the window mounting groove, and the lip supports the transparent substrate. The substrate container according to claim 1, further comprising a plurality of supporting structures to support the substrate on the bottom plate, the supporting structures are located on the upward surface and extend upward from the upward surface. The substrate container according to claim 1, wherein the window holding member is constructed of spring steel. The substrate container according to claim 1, wherein one of the pair of widthwise portions of the window holding member is located in the undercut portion of the window mounting groove, and the other one of the pair of widthwise portions is fixed To the bottom plate. The substrate container according to claim 6, wherein the other one of the pair of widthwise portions is fixed to the bottom plate by a screw. The substrate container according to claim 1, wherein the pair of widthwise edges of the side wall of the groove respectively include an undercut portion. The substrate container according to claim 8, wherein the undercut portions are defined by a plurality of grooves in the side wall of the first groove, and the grooves further define an overhang in each of the widthwise edges ( overhang). The substrate container according to claim 9, wherein the pair of widthwise portions of the window holding member Each of them is located in the undercut portions of the side wall of the first groove and is held in position by the overhangs. The substrate container according to claim 1, wherein the substrate is a flat mask. A substrate container for accommodating a substrate, the substrate container includes: an outer box assembly including an upper portion and a lower portion, the upper portion and the lower portion collectively define a first housing; and an inner box assembly It is used for accommodating a substrate therein. The inner box assembly is adapted to be accommodated in the first housing of the outer box assembly. The inner box assembly includes a bottom plate and a cover. The cover is adapted to engage the bottom plate A second casing is defined to accommodate the substrate. The bottom plate has an upward surface and a downward surface. The bottom plate includes: a plurality of windows located in the bottom plate, each of the windows includes: a window mounting groove , Located in the downward-facing surface, the window mounting groove is defined by a groove side wall and a bottom side wall, the groove side wall has a pair of widthwise edges and a pair of lengthwise edges, at least one of the pair of widthwise edges One defines an undercut portion in the side wall of the groove; an opening located in the bottom side wall of the window mounting groove and extending through the upward-facing surface, the opening and the bottom side wall are installed in the window A lip is defined in the groove, the lip supports a transparent substrate; and a window holding member having a pair of lengthwise arched portions and a pair of widthwise portions, at least one of the pair of widthwise portions is located in the undercut In part, the contact between the transparent substrate and the arched portions in the longitudinal direction is formed to hold the transparent substrate in position in the window installation groove. The substrate container according to claim 12, further comprising: a protective film mounting groove located in the upward-facing surface, the protective film mounting groove is defined by a protective film groove side wall and a protective film bottom side wall, The side wall of the protective film groove and the bottom side wall of the protective film define a shape for accommodating a protective film at least partially within the protective film mounting groove. The substrate container according to claim 12, wherein the window mounting groove includes: a first groove defined by a first groove side wall and a first bottom side wall, the first groove side wall having the pair of width directions An edge and the pair of lengthwise edges; and a second groove located in the first bottom side wall of the first groove, the second groove is defined by a second groove side wall and a second bottom side wall, The second groove side wall and the second bottom side wall define a shape for at least partially housing the transparent substrate in the second groove; and wherein the opening is located in the second bottom side wall, the opening The hole and the second bottom side wall define the lip in the window mounting groove, and the lip supports the transparent substrate. The substrate container according to claim 12, further comprising a plurality of support structures to support the substrate on the bottom plate, the support structures being located on the upward surface and extending upward from the upward surface. The substrate container according to claim 12, wherein the window holding member is constructed of spring steel. The substrate container according to claim 12, wherein one of the pair of widthwise portions of the window holding member is located in the undercut portion of the window mounting groove, and the other one of the pair of widthwise portions is fixed To the bottom plate. The substrate container according to claim 17, wherein the other of the pair of widthwise portions is provided by A screw is fixed to the bottom plate. The substrate container according to claim 12, wherein the pair of widthwise edges of the side wall of the groove respectively include an undercut portion. The substrate container according to claim 19, wherein the undercut portions are defined by a plurality of grooves in the side wall of the first groove, and the grooves further define an overhang in each widthwise edge. The substrate container according to claim 20, wherein each of the pair of widthwise portions of the window holding member is located in the undercut portions of the side wall of the first groove and held by the overhangs On positioning. The substrate container according to claim 12, wherein the substrate is a flat mask.

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