Substrate container with door gasket

Abstract

A substrate container is described that includes an opening, a door for closing the opening, and a gasket for sealing the opening when the door is placed across the opening. The gasket includes a gasket body that contacts a flat portion, and a sealing segment attached to the gasket body, the sealing segment having a heel and a tip, and when the door is positioned to cover the opening and press the sealing segment between an outer peripheral surface of the opening and an outer peripheral surface of the door, the heel contacts a surface of a recess.

Description

Technical Field

[0001] The present disclosure relates to a substrate container that includes an opening, a door for closing the opening, and a gasket for sealing the opening when the door is placed across the opening.

Background Art

[0002] Semiconductor wafers, and the ultra-small electronic devices formed on their surfaces, are prepared by a series of precise processing steps that are carried out under extremely clean conditions. Between those processing steps, the wafers may be moved from one processing location to a different processing location using still extremely clean conditions.

[0003] Semiconductor wafers are fragile and can be easily damaged by physical contact or electrostatic shock, and are extremely sensitive to particle contamination.

[0004] Special containers are used to hold and transfer multiple wafers being processed so as to prevent damage to the wafers during movement between processing steps and to avoid introducing particle contamination to the wafer surfaces. These special containers, sometimes called "wafer carriers", are designed to safely move semiconductor wafers under conditions that prevent physical damage to the wafers and do not introduce contamination to the wafer surfaces. In the latter regard, the materials and design of the wafer carrier structure are selected so as not to be a source of particle contamination.

[0005] Containers generally include a multi-sided container body (e.g., a "shell") that defines the interior of the container, an opening into the interior on one side of the container body, a removable door adapted to cover the opening, and a gasket that creates a seal between the door and the container body.

[0006] As ultra-small electronic devices become smaller and the number of features per wafer area increases, those devices become more sensitive to contaminants. The size of the contaminants affecting ultra-small electronic circuits continues to decrease and approaches the molecular scale. Accordingly, throughout all stages of semiconductor wafer manufacturing, processing, transfer, and storage, continuously improving contamination control is required.

[0007] Exemplary wafer containers may be referred to as "SMIF pods" (Standard Mechanical Interface pods), "FOUPs" (Front Opening Unified Pods), or "FOSBs" (Front Opening Shipping Boxes). The sealing mechanism for the carrier included a relatively basic elastomeric gasket between the surface of the door and the surface of the container body surrounding the opening in the container. Generally, a portion of the gasket fits into a groove in the door (sometimes referred to as a "gland") around the outer periphery of the door. The surface and the gasket face the opening and contact the container body at the surface surrounding the opening. When the door is placed across the opening to cover the opening, the gasket is pressed between the surface of the door and the surface of the container surrounding the opening. SUMMARY OF THE INVENTION

[0008] Gaskets for wafer carriers have identifiable defects. Some of these are due to the special use of the gasket as a component of the wafer carrier. Others are the result of degradation and wear that occur during the use of the gasket in any context or application.

[0009] Most or all forms of the sealing gasket have the drawback of gradually deteriorating physical properties that occur over the gasket's service life. Some gaskets undergo a progressive reduction in elasticity or bending strength (resistance) over many cycles of bending the gasket to form a seal. The reduction in the gasket's elasticity or bending strength causes a reduction in the effectiveness of the gasket in forming a seal between the door and the container surface and preventing gas or particle contamination between the interior and exterior of the container.

[0010] For gaskets designed for the special use of sealing a wafer container, the goal is to avoid generating particle contamination during use. In particular, small particles of the gasket material can be generated by sloughing or shedding from the surface of the gasket when elastic tension is applied to the gasket or during mechanical contact or movement between the surface of the gasket and the surface of the door or container.

[0011] A typical gasket for a wafer container generally includes one flexible portion fixed to the surface of the door by being inserted into a channel or "groove" and a second flexible portion that contacts the surface of the container surrounding the container opening. The second portion, the "sealing segment," is pressed between the door and the container surface to form a seal that prevents gas from passing between the container and the door. Examples are shown in U.S. Patent No. 9,520,310 and Taiwan Patent Document TW M 552185 U.

[0012] According to the present invention, a gasket for sealing a wafer container includes a sealing segment that forms a seal between a first surface of the container and a second surface of the container. One surface is the surface of the door, and one surface is the surface surrounding an opening in the wafer container. (It can be the surface of the door or the surface of the container body surrounding the opening) The first surface contains a recess. The sealing segment includes a surface that contacts the recess. The sealing segment includes a second surface that contacts the second surface. When the door is placed to cover the opening, the sealing segment contacts the first surface and the second surface and is pressed between the first surface and the second surface to form a seal between the first surface and the second surface. In an exemplary gasket and container, the sealing segment can undergo a reduction in length between the location where the sealing segment contacts the first surface and the location where the sealing segment contacts the second surface when compressed.

[0013] In one aspect, the present invention relates to a wafer container comprising a container body having an opening and an opening-perimeter surface extending around the opening, a door having a door-perimeter surface adapted to cover the opening and adapted to face the opening-perimeter surface, flat portions and recesses both extending around the opening-perimeter surface or the door-perimeter surface, and a gasket. The gasket includes a gasket body that contacts the flat portion and a sealing segment attached to the gasket body. The sealing segment includes a heel and a tip. When the door is positioned to cover the opening and press the sealing segment between the opening-perimeter surface and the door-perimeter surface, the heel contacts the surface of the recess.

[0014] In another aspect, the present invention relates to a method for closing a door of a wafer container. The wafer container includes an opening, an outer peripheral surface of the opening extending around the opening, a door adapted to cover the opening and having a door outer peripheral surface adapted to face the outer peripheral surface of the opening, both a flat portion and a recess extending around the outer peripheral surface of the opening or the door outer peripheral surface, and a gasket. The gasket includes a gasket body contacting the flat portion and a sealing segment attached to the gasket body. The sealing segment includes a heel and a tip. The method includes placing the door across the opening to press the gasket between the heel and the tip to seal the opening, wherein the heel contacts the surface of the recess.

Brief Description of the Drawings

[0015]

Figure 1A

Figure 1B

Figure 2A

Figure 2B

Figure 2C

Figure 3A

Figure 3B

Figure 4

Figure 5

Figure 6

Best Mode for Carrying Out the Invention

[0016] All figures are schematic and not to scale.

[0017] The following describes a wafer container including a container body having an interior and an opening for accessing the interior, a door for covering the opening, and a gasket for forming a seal between the surface of the container body and the surface of the door when the door covers the opening.

[0018] The wafer container includes a multi-sided container body (sometimes referred to as a "shell") that defines a container interior adapted to contain and support one or more semiconductor wafers. The body includes an opening ("container opening") that enables access to the container interior on one face of the container body. The container includes a door adapted to cover the opening.

[0019] In use, the door is used to cover the container body opening and to seal and close the interior from the outside at the opening. To form the seal, a gasket is included between the surface of the door at the outer periphery of the door and the surface of the container body surrounding the opening. When the door is placed to cover the opening, the surface at the outer periphery of the door ("door outer peripheral surface") contacts the gasket on one face of the gasket. The opposite face of the gasket contacts the surface of the container body surrounding the container opening along the outer periphery of the opening ("opening outer peripheral surface"). When the door covers the opening, the gasket is pressed between the door outer peripheral surface and the opening outer peripheral surface to form a seal between the door and the container at the opening.

[0020] Generally, the seal is formed between two surfaces of the container, which may be referred to herein as the "first surface" and the "second surface". One of these two surfaces of the door outer peripheral opening. The other of these two surfaces is the opening outer peripheral surface. The gasket is fixed to one of these two surfaces, which can be either the door outer peripheral surface or the opening outer peripheral surface. The surface to which the gasket is attached may be referred to as the "first surface". The "second" surface is either the door outer peripheral surface or the opening outer peripheral surface that is not the "first" surface, whichever it may be.

[0021] The surface to which the gasket is attached, i.e., the "first surface", contains a recess. The recess is a depression in the first surface that extends along the entire length of the outer periphery of the surface, i.e., the outer periphery of the door on the outside, or the outer periphery of the surface of the container body surrounding the opening. The recess is sized to allow a portion of the sealing segment of the gasket to be placed within the recess during use of the gasket to seal the opening of the container and to allow the surface of the sealing segment of the gasket to contact the surface of the recess, and is a small depression or channel formed along the outer periphery of the first surface.

[0022] Exemplary recesses are shown in FIGS. 2A and 2B. As shown, the exemplary first surface includes a "flat" portion 208 that is parallel to the "x" direction, i.e., parallel to the plane of the opening of the container and parallel to the plane of the door when the door is arranged to cover the opening. The gasket includes a body 212 having a portion arranged at (with respect to) the flat portion 208 of the first surface. The gasket also includes a sealing segment 220 arranged near (adjacent to) the recess 208.

[0023] The recess can be of any shape. The exemplary recess 208 (shown in FIGS. 2A and 2B) starts at a flat portion 208 and has a form in which the depth gradually increases along the x - direction as the distance in the x - direction from the flat portion 208 increases. The exemplary recess can be in the form of an asymmetric “well” or “channel” (in cross - section) formed in the first surface that has a variable depth with the depth gradually increasing. The angle of the surface of the recess with respect to the flat portion (the angle “z” shown in FIG. 2A, which is a function of the rate of change of the depth of the recess measured from the start of the channel to the maximum depth) can be any useful angle, such as an angle in the range from 10 to 80 degrees, for example, from 20 to 70 degrees or from 30 to 60 degrees. The recess can have any maximum depth and minimum effective depth with respect to the flat portion of the first surface such that the sealing segment of the gasket is effective as described. The depth of the recess is at least 0.3 millimeters, for example, at least 0.5, and can be, for example, from 0.5 to 5 millimeters, or from 1 to 3 millimeters.

[0024] The gasket includes a gasket body attached to the first surface and a sealing segment attached to the gasket body. The body includes a flat portion that contacts the flat portion of the first surface. The body can be attached to the first surface by any useful structure or mechanism. In an exemplary gasket, the gasket body includes a flat portion and is attached to a mounting segment connected to the flat portion of the gasket body. The mounting segment of the gasket fits snugly into a mounting channel (or “groove”) formed in the first surface to frictionally secure the gasket to the first surface.

[0025] When viewed in cross-section along the length of the gasket, the mounting segment of the gasket is separated from the sealing segment of the gasket by a flat segment of the gasket body, and the flat segment can generally be any flat segment that effectively connects the mounting segment and the sealing segment. When viewed in cross-section along the length of the gasket attached to the first surface, the mounting channel of the first surface is separated from the recess of the first surface by a flat portion of the first surface. The mounting channel is different from the recess, but also extends around the entire outer circumference of the first surface adjacent to the recess, for example, along the entire outer circumference of the surface of the door facing the container or along the entire outer circumference of the surface of the container body surrounding the container opening.

[0026] The sealing segment of the gasket includes two surfaces adapted to bring the first surface and the second surface of the container into contact, i.e., to form a seal between the outer peripheral surface of the door and the outer peripheral surface of the opening. One surface of the gasket is the "heel" of the sealing segment that contacts the first surface of the container, and the second surface of the gasket is the tip of the sealing segment that contacts the second surface of the container. The sealing segment of the gasket connects to the gasket body near the "heel" portion of the sealing segment. From the heel, the sealing segment extends away from the gasket body and away from the first surface of the container in a direction along a length that ends at the "tip" of the sealing segment of the gasket.

[0027] During use of a gasket to form a seal between a first surface and a second surface of a container, a surface of a heel portion of the gasket contacts a surface of a recess of the first surface of the container. Also, a surface at a tip of a seal segment contacts the second surface of the container. The seal segment is pressed between the first surface and the second surface of the container and then held, and the seal segment or a portion of the seal segment is subjected to a series of forces that cause compression, movement, tension, or expansion, or a combination thereof, against one or both of the first and second surfaces. For example, in a preferred example of a gasket, the seal segment is compressed along a line extending between a heel of the seal segment at a contact point with the surface of the recess and a tip of the seal segment at a contact point with the second surface of the container.

[0028] Also, during use, when a door covers the container opening and the tip of the seal segment contacts the second surface, the tip slides along the second surface. The tip is moved along two direction components, namely, in a direction toward the first surface and in a direction away from the body of the gasket.

[0029] At least some previous gasket designs include a sealing segment that operates primarily by the sealing segment being bent and tensioned (as opposed to compressed) when the door is placed across an opening in a container so as to cover the opening, and the sealing segment is pressed between a first surface and a second surface of the wafer container. FIGS. 1A and 1B show an example of a previous gasket that includes an elongated “wiper” type sealing segment. As shown, the wafer container 100 includes a container body 102 adjacent to the opening 104 and a door 106. The door 106 is adapted to cover the opening 104 by pressing the gasket 110 between the surface 122 of the door 106 and the surface 124 of the container body 102, and in particular, by pressing the sealing segment 120 of the gasket 110 between these two surfaces. The sealing segment 120 of the gasket 110 includes a surface at the tip 130 that contacts the surface 124 and a surface at the heel 132 that contacts the surface 122. The attachment segment 118 is disposed within a channel (“ground”) 116 so as to secure the gasket 110 to the door 106.

[0030] As shown in FIG. 1A, the gasket 110 includes a body 112 secured to the door 106 that includes a portion adjacent to the flat portion 108. The gasket 110 also includes a sealing segment 120 connected to an end of the body 112 that is positioned to contact both the surface 122 of the door 106 (by the heel surface 132) and the surface 124 of the wafer container body 102 (by the tip 130). When the door 106 is spaced apart from the container body 102, the sealing segment 120 is un-flexed. See FIG. 1A. No force acts on the sealing segment 120.

[0031] Referring to FIG. 1B, when door 106 is placed across opening 104 to seal the interior of container 100, door 106 is moved in the direction of container body 102. Surface 130 contacts surface 124, and tip 130 moves in the lateral direction in the “x” direction, in direction and distance d1, in contact with surface 124. Tip 130 also moves in the depth direction (in the “y” direction) along the direction of movement of door 106, in distance and direction d2, towards body 102. The contact and movement between tip 130 and surface 124 creates the potential for particulate debris to be generated at tip 130 that can be dispersed within the interior of wafer container 100 and exposed to the wafers within its interior.

[0032] When sealing segment 120 is held between first surface 132 and second surface 124, sealing segment 120 receives a series of forces applied from the first and second surfaces. For example, surface 140 of sealing segment 120 can be subject to tensile stress due to expansion, and a portion of surface 142 can be subject to compression. The tensile stress along surface 140 stretches the surface of the length of sealing segment 120 along surface 140, creating the potential for particulate debris to be generated at surface 140 that can be dispersed within the interior of wafer container 100. The interior of sealing segment 120 between tip 130 and heel 132 along line L does not receive a significant amount of compression, although some amount of compression can exist near heel 132, particularly in the contact with flat portion 108. The cycling of the door to seal and unseal the container by bending gasket sealing segment 120 creates a certain amount of strain on sealing segment 120, which, when repeatedly applied and released, causes a relaxation of the force required to bend gasket sealing segment 120. The sealing force of sealing segment 120 decreases over the cycle of opening and closing door 106.

[0033] In contrast, during use of the gasket's sealing segment in this specification, the force applied to the sealing segment includes a significant amount of compression along the length of the sealing segment between the tip and the heel in the inner portion of the sealing segment, which includes a greater amount of compression than exists along line L of the sealing segment 120 in FIG. 1B. The preferred sealing segment is compressed at a location along a line extending between the heel of the sealing segment at the point of contact with the surface of the recess and the tip of the sealing segment at the point of contact with the second surface of the container.

[0034] Exemplary gasket designs are shown in cross-section in FIGS. 2A, 2B, and 2C. Each gasket 210 includes a body 212, a sealing segment 220, and an attachment segment 218. As will be explained, the attachment segment 218 is adapted to fit within a channel (a "ground") on the surface of the wafer container, such as a channel in a door, and the channel is also adjacent to a recess on its surface. The sealing segment 220 is connected to an end of the body 212 that is opposite the attachment segment 218. The body 212 includes an elongated portion 214 between the attachment segment 218 and the sealing segment 220, and the length of the elongated portion 214 is sufficient to position a portion of the sealing segment 218 within the recess while the attachment segment 218 is held in the channel. When the gasket 210 is installed with the attachment segment 218 held within the channel on its surface, the sealing segment 220 is positioned at a location for contacting the surface of the recess.

[0035] The sealing segment 220 of each gasket 210 includes a heel 232, a tip 230, and a length L between the heel 232 and the tip 230. The cross-sectional shape of the sealing segment 220 can be any shape that will allow the sealing segment to function as described herein. The exemplary sealing segment 220 of the gasket 210 of FIG. 2A is substantially circular or bulbous and includes a heel 232 adapted to contact a recess in the first surface of the wafer container and a tip 230 at a location for contacting the second surface of the wafer container. The exemplary sealing segments 220 of each gasket 210 of FIGS. 2B and 2C are elongated and also include a heel 232 adapted to contact a recess in the first surface of the wafer container and a tip 230 at a location for contacting the second surface of the wafer container.

[0036] FIGS. 3A and 3B show an example of a gasket being described. The wafer container 200 includes a container body 202 adjacent to an opening 204 and a door 206. The door 206 is adapted to cover the opening 204 by pressing the gasket 210 between the surface 222 of the recess 238 of the door 206 and the surface 224 of the container body 202, and in particular by pressing the sealing segment 220 of the gasket 210 between these surfaces of the body 202 and the door 206. The sealing segment 220 includes a surface at the tip 230 that contacts the surface 224 and a surface at the heel 232 that contacts the surface 222 of the recess 238. The attachment segment 218 is disposed within a channel (“ground”) 216 to secure the gasket 210 to the door 206.

[0037] As shown in FIG. 3A, the gasket 210 includes a body 212 secured to the door 206 (the door is the “first surface” of the container in this example) that includes an elongated portion 214 adjacent to a flat portion 208. The gasket 210 also includes a sealing segment 220 connected to an end of the body 212 and positioned to contact both the surface 222 within the recess 238 of the door 206 and the surface 224 of the wafer container body 202.

[0038] When the door 206 is separated and spaced apart from the container body 202, the sealing segment 220 is not bent. No force is acting on the sealing segment 220. An example of the length L’ between the tip 230 and the heel 232, measured with the sealing segment 220 not bent as in the case of Fig. 3A, can be in the range from 2 to 5 centimeters, for example, in the range from 3 to 4 centimeters.

[0039] Referring to Fig. 3B, when the door 206 is placed across the opening 204 to seal the interior of the container 200, the door 206 is moved in the direction of the container body 202. The surface of the tip 230 contacts the surface 224, and the tip 230 moves horizontally in the “x” direction, in the direction and by the distance d1’. The tip 230 also moves in the depth direction (in the “y” direction) along the direction of movement of the door 206, by the distance and in the direction d2’, towards the door 206.

[0040] Compared with the sealing segment 120 of the gasket 110 (Figs. 1A and 1B), the sealing segment 220 of the gasket 210 is of a shorter length (L’) between the associated heel surfaces 132, 232 at the location of contact with the surfaces 122, 222 and the surfaces of the tips 130, 230 at the location of contact with the surfaces 124, 224. As shown, the distance d1’ can be less than the distance d1, and the distance d2’ can be less than the distance d2’. If the distance d1’ is less than the distance d1 and the distance d2’ is less than the distance d2, a shorter distance of contact movement between the tip 230 and the surface 224 results in a reduction in the likelihood of particulate debris generated by friction at the tip 230, compared with the tip 130 of the gasket 110.

[0041] According to a useful or preferred exemplary sealing segment of the present invention, when the sealing segment is pressed between the door and the surface of the container body to form a useful seal, the distance d1' (the moving distance of the tip 230 in the x direction) can be less than 1 millimeter, for example, less than 0.8 millimeter. Also, according to a useful or preferred exemplary sealing segment, when the sealing segment is pressed between the door and the surface of the container body to form a useful seal, the distance d2' (the moving distance of the tip 230 in the y direction) can be less than 3 millimeters, for example, less than 2 millimeters.

[0042] As a further comparison, the sealing segment 220 of the gasket 210 undergoes a greater degree of compression along the length L' compared to the level of compressive force present along the length L of the sealing segment 120 when pressed between the surfaces 230 and 232. When the sealing segment 220 is pressed and held between the first surface 222 and the second surface 224, the sealing segment 220 receives a series of forces applied from the first and second surfaces. The surface 240 of the sealing segment 220 can be subjected to tension due to expansion, and the surface 242 can be subjected to compression. The interior of the sealing segment 220 between the tip 230 and the heel 232 along the line L' is compressed along a substantial portion of the length of L'. The angle Z between the flat portion 208 and the line L' is at least 30 degrees, for example, at least 40 degrees, which indicates the compressive force along the line L'.

[0043] Therefore, the length L’ between the tip 230 and the heel 232, measured with the sealed segment 220, is that in the uncompressed (relaxed) condition in FIG. 3A, and is greater than the length L’ between the tip 230 and the heel 232, measured with the sealed segment 220 pressed between the surface 222 and the surface 224 as in the case of FIG. 2B. The difference in length between the compressed state (FIG. 3B) and the uncompressed state (FIG. 3A) is at least 0.1, 0.2, or 0.3 mm (millimeters), and can be, for example, a difference within the range from 0.1 to 0.5 millimeters. In contrast, the length of the sealed segment 120 in FIGS. 1A and 1B is not equivalently reduced compared to the length of the relaxed segment 120 (shown in FIG. 1A) when the sealed segment 120 is pressed between the first surface and the second surface (as shown in FIG. 1B).

[0044] The design of the sealed segment 220 can result in an improvement in the performance of the sealed segment 220 compared to the sealed segment 120. The sealed segment 220 can exhibit a more consistent closing force over many door opening and closing cycles, can exhibit a reduction in dimensional change over many door closing and opening cycles, or both.

[0045] FIG. 4 shows an additional example of a gasket 210 that includes a body 212 fixed to a door 206 (in this example, the door is the “first surface” of the container), the body 212 including an elongated portion 214 adjacent to a flat portion 208. Other features and functions of the gasket 210 in FIG. 4 are similar to those of the gasket 210 in FIGS. 3A and 3B with similar numerical designations. The gasket 210 also includes a (cross-sectionally) bulbous sealed segment 220 that is connected to an end of the body 212 and is positioned to contact both the surface 222 within the recess 238 of the door 206 and the surface 224 of the wafer container body 202.

[0046] When the door 206 is separated and spaced apart from the container body 202, the sealing segment 220 is not bent. When the door 206 is placed across the opening 204, as in the case of FIG. 4, to seal the interior of the container 200, the surface of the tip 230 contacts the surface 224, and the tip 230 moves in the direction and distance d1' in the "x" direction, laterally, relative to the non-bent position upon contact with the surface 224. The tip 230 also moves in the distance and direction d2' in the depth direction (in the "y" direction) along the direction of movement of the door 206, toward the door 206, relative to the non-bent position. When the sealing segment 220 is pressed and held between the first surface 222 and the second surface 224, the sealing segment 220 receives a series of forces applied from the first and second surfaces. The surface 240 of the sealing segment 220 may be subjected to tensile stress due to expansion, and the surface 242 may be subjected to compression. The interior of the sealing segment 220 between the tip 230 and the heel 232 along the line L' is compressed along a substantial portion of the length of L'.

[0047] FIG. 5 has data comparing a gasket design having a sealing segment that is substantially deflected and substantially not compressed along the interior of the sealing segment (as shown, for example, in FIGS. 1A and 1B) and labeled "POR" with the sealing segment of the present invention that is less deflected and subjected to a greater amount of compression, length reduction, or both along the interior of the sealing segment (as shown, for example, in FIGS. 3A and 3B).

[0048] The table in Figure 5 shows data on the dimensional degradation of the gasket's sealing segment over time when the sealing segment of the gasket was continuously compressed for two weeks at the door of the container. For the control (POR) seal and the seal of the present invention, the height of the sealing segment relative to the outer peripheral surface of the door was measured using a height gauge for the gasket initially installed at the door. The door was placed across the opening of the container, and the sealing segment was pressed between the outer peripheral surface of the door and the outer peripheral surface of the opening of the container. After two weeks of being pressed between those surfaces, the height of the sealing segment was measured again. As shown in Figure 5, the sealing segment of the present invention underwent a reduction in height of approximately 10 percent over two weeks, and the POR sealing segment underwent a reduction in height of approximately 16 percent over the same period.

[0049] Figure 6 is an exploded view of the wafer container being described. The wafer container 1 includes a container body (e.g., a "shell") 2, an interior 18, an opening 4, and an outer peripheral surface 14 of the opening. The wafer container 1 also includes a door 6 having an outer peripheral surface 16 extending along the outer periphery of the door 6, a recess 16 extending along the outer periphery of the door 6, and a channel 10 extending along the outer periphery of the door 6. A gasket 8 is held in place by a mounting segment (not specifically shown) of the gasket 8, which fits into the channel 10.

[0050] The gasket 8 can be used to seal the opening of the container body 2 when the door 6 is placed across the opening 4. Although the gasket 8 is shown as being attached to the outer periphery of the door 6, the gasket 8 can alternatively be attached to the surface of the body 2 surrounding the opening 4.

[0051] The wafer container 1 can be used to transfer, contain, or store semiconductor wafers (i.e., wafers that are "being processed") that are being processed by a series of processing steps between steps of a series of steps. The wafer container 1 is, as shown, a front-opening container, e.g., a front-opening unified pod (FOUP).

[0052] The container body 2 defines an interior 18 within the wafer container 1, and an open end 4 is provided on one face of the container body 2 to enable access to the interior. The open end 4 enables a plurality of wafers to be placed inside and removed from the interior of the container body 2.

[0053] The door 6 can be used to cover the opening 4. When the opening 4 is covered by the door 6, a seal can be formed between the door and the container using the gasket 8. The sealed interior of the wafer container 1 is a microenvironment that is protected from contaminants outside the wafer container 1.

[0054] The gasket 8 is the gasket described herein, for example, the gasket 210 shown in FIGS. 3A and 3B. When the door 6 covers the opening 4, the gasket 8 forms a seal between the surface of the container body 2 surrounding the opening 4 (the opening outer peripheral surface 16) and the surface of the door 6 (the door outer peripheral surface 14). One surface of a sealing segment of the gasket 8, i.e., the heel, contacts the surface of the recess 12 of the door outer peripheral surface 16. The surface at the tip of the sealing segment contacts the opening outer peripheral surface 14. When held between the door outer peripheral surface 16 and the opening outer peripheral surface 14, the sealing segment is compressed along the length between the tip and the heel, and the length of the sealing segment between the tip and the heel is reduced.

[0055] The gasket 8 can be made of any suitable material for forming a seal, such as a polymeric material. Exemplary materials for the gasket 8 include natural and synthetic elastomeric materials, including polymers, particularly thermoplastic elastomers having a Shore A hardness of 50 to 80 durometers.

[0056] As shown in FIG. 6, door 6 includes a channel (or “ground” 10) formed in the door outer peripheral surface 16, which faces the container body 2 and the opening outer peripheral surface 14 when the door 6 and the container 2 are assembled to close the opening 4. Channel 10 is configured to hold gasket 8. Channel 10 is a groove configured to receive the protrusion or “attachment segment” of gasket 8. Although channel 10 is shown as being disposed on door 6, it should be understood that the channel can be in any suitable position for holding gasket 8 such that gasket 8 can form a seal between door 6 and container body 2, for example at the outer periphery of opening 4.

[0057] The exemplary gaskets herein are useful for forming a seal between the door and the opening of a wafer container that is effective for commercial use of the wafer container. The effectiveness of this type of seal formed by an elastomeric gasket is sometimes referred to as “vacuum conductance” and has units of flow rate / pressure, such as volume / time / pressure difference, for example, liter per second per atmosphere. The exemplary gaskets herein can be effective for forming a seal having a conductance of 0.2 liters per second per atmosphere (L / s / atm) or less or 0.1 liters per second per atmosphere or less.

[0058] The gasket will create a force when, during use, the gasket is pressed between the door and the container body. This force is sometimes referred to as the "sealing force". Equipment and methods useful for measuring the sealing force are commercially known. Useful equipment includes a device known as a "load port", which is an analytical device that removes the door and replaces it while measuring the relevant force. The door can be closed to different positions relative to the container body. At different positions, different forces are applied to the gasket, resulting in different "sealing forces". The gasket described by the method of closing the door to a location 165.5 millimeters from the facial datum plane (center of the 300 mm wafer) contained in the wafer container can create a sealing force in the range of 15 to 20 pounds (force).

Claims

1. A wafer container comprising: a container body having an opening and an outer peripheral surface of the opening extending around the opening; a door having a door outer peripheral surface adapted to cover the opening and adapted to face the outer peripheral surface of the opening; both a flat portion and a recess extending around the outer peripheral surface of the opening or the outer peripheral surface of the door; a gasket comprising: a gasket body contacting the flat portion; a sealing segment attached to the gasket body, the sealing segment having a heel and a tip; a gasket; wherein when the door covers the opening and is positioned to press the sealing segment between the outer peripheral surface of the opening and the outer peripheral surface of the door, the heel contacts the surface of the recess. A wafer container.

2. When the outer peripheral surface of the door has the recess and the door is positioned to seal the opening, the heel contacts the surface of the recess in a heel contact region, the tip contacts the outer peripheral surface of the opening in a tip contact region, and the sealing segment is compressed between the heel contact region and the tip contact region. The wafer container according to claim 1.

3. The outer peripheral surface of the door has a channel adjacent to the recess, the gasket has an insertion segment connected to a body segment, and the insertion segment is disposed in the channel to fix the gasket to the outer peripheral surface of the door. The wafer container according to claim 1.

4. When the door seals the opening, the conductance through the joint of the door is less than 0.2 liter / s / atm. The wafer container according to claim 1.

5. The gasket comprises a thermoplastic elastomer having a Shore A hardness ranging from 50 to 80 durometer. The wafer container according to claim 1.

6. The gasket has a sealing force within a range of 15 to 20 pound force. The wafer container according to claim 1.

7. The sealing segment has a length between the heel and the tip within a range of 3 to 4 cm. The wafer container according to claim 1.

8. The sealing segment is bulbous. The wafer container according to claim 1.

9. The sealing segment is elongated. The wafer container according to claim 1.

10. ​ A method for closing a door of a wafer container, wherein the wafer container has an opening, an outer peripheral surface of the opening extending around the opening, a door adapted to cover the opening and having an outer peripheral surface of the door adapted to face the outer peripheral surface of the opening, both a flat portion and a recess extending around the outer peripheral surface of the opening or the outer peripheral surface of the door, a gasket, a gasket body contacting the flat portion, a sealing segment attached to the gasket body, the sealing segment having a heel and a tip, the gasket comprising comprising, The method includes placing the door across the opening to press the gasket between the heel and the tip to seal the opening, the heel contacting the surface of the recess.

11. The method according to claim 10, wherein the sealing segment has a length between the heel and the tip in the range of 3 to 4 cm.

12. The method according to claim 10, wherein the gasket is pressed between the heel and the tip, and the length from the heel to the tip is reduced.

13. The method according to claim 10, wherein the sealing segment is bulbous.

14. The method according to claim 10, wherein the sealing segment is elongated.

15. The outer peripheral surface of the door has the recess, the tip contacts the outer peripheral surface of the opening, when the door is in a position to cover and seal the opening, the sealing segment is compressed between the heel and the tip. The method according to claim 10.

16. Pressing the tip against the outer peripheral surface of the opening to compress the sealing segment including, the tip contacting the outer peripheral surface of the opening and moving along the outer peripheral surface of the opening by a distance of less than 1 mm. The method according to claim 15.

17. The method according to claim 10, wherein the sealed opening has a conductance of less than 0.2 liter / s / atm.

18. The method according to claim 10, wherein the gasket comprises a thermoplastic elastomer having a Shore A hardness in the range of 50 to 80 durometers.

19. The method according to claim 10, wherein the gasket has a sealing force in the range of 15 to 20 pound force.

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