Substrate container with door gasket

Abstract

Substrate containers are described that include an opening, a door for closing the opening, and a gasket for sealing the opening with the door placed over the opening. The gasket includes: a gasket body contacting the flat portion; and a sealing section attached to the gasket body, the sealing section including a heel and a tip, where the heel contacts a surface of the groove with the door positioned to cover the opening and press the sealing section between an opening peripheral surface and a door peripheral surface.

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 above the opening. Background Art

[0002] Semiconductor wafers and microelectronic devices formed on their surfaces are fabricated by a series of precise processing steps performed under extremely clean conditions. Between those processing steps, the wafers can still be moved from one processing location to different processing locations using extremely clean conditions.

[0003] Semiconductor wafers are fragile, easily damaged by physical contact or vibration due to static electricity, and highly sensitive to particle contamination.

[0004] During wafer movement between processing steps, specialized containers are used to hold and transport wafers in multiple processes in a manner that prevents damage to the wafers and avoids introducing particle contamination onto the wafer surfaces. These specialized containers (sometimes referred to as "wafer carriers") are designed to safely move semiconductor wafers under conditions that prevent physical damage to the wafers and do not introduce contamination onto the wafer surfaces. Regarding the latter, the materials and design of the wafer carrier structure are selected to not be a source of particle contamination.

[0005] Containers typically include a multi-sided container body (e.g., a "housing") that defines the interior of the container, an opening to 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 microelectronic devices become smaller and the number of components per area of the wafers increases, the devices become more sensitive to contaminants. The size of the contaminants that affect microelectronic circuits is continuously decreasing and is approaching molecular dimensions. Therefore, continuous improvement in pollution control is needed during all stages of semiconductor wafer manufacturing, processing, transportation, and storage.

[0007] Example wafer containers can be referred to as "SMIF wafer pods" (Standard Mechanical Interface wafer pods), "FOUPs" (Front Opening Unified Pods), or "FOSBs" (Front Opening Shipping Boxes). The sealing mechanism of the carrier has included a relatively basic elastomeric gasket located between the surface of the door and the surface of the container body that surrounds the opening in the container. Typically, a portion of the gasket fits into a groove (sometimes referred to as a "gland") in the door that surrounds the perimeter of the door. The surfaces and the gasket face the opening and contact the container body at the surface that surrounds the opening. When the door is placed above the opening to cover the opening, the gasket presses between the surface of the door and the surface of the container that surrounds the opening. Summary of the Invention

[0008] The gasket for a wafer carrier has recognizable defects. Some recognizable defects are attributable to the gasket being specifically used as a component of a wafer carrier. Other recognizable defects are the result of deterioration or wear that occurs during the use of the gasket in any context or application.

[0009] Most or all forms of gaskets undergo a gradual deterioration of physical properties that occurs during the period of use of the gasket. Some gaskets experience a gradual reduction in elastic or flexural strength (resistance) over many cycles of flexing the gasket to form a seal. The reduced elastic or flexural strength of the gasket causes a reduction in the effectiveness of the gasket to form a seal between the door and the container surface and prevent gas or particle contamination between the interior and exterior of the container.

[0010] For gaskets designed to be specifically used for sealing wafer containers, the goal is to avoid generating particle contamination during use. Minute particles of the gasket material can be generated by slipping or falling off the surface of the gasket, especially when the gasket is elastically stretched or when there is 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 includes a flexible portion that is usually fixed to the surface of the door by insertion into a channel or "gland", and a second flexible portion that contacts the surface of the container surrounding the opening of the container. The second portion ("sealing section") presses between the door and the surface of the container to form a seal that prevents gas from passing between the container and the door. Examples are shown in US9,520,310 and TWM552185U.

[0012] According to the present invention, a gasket for sealing a wafer container includes a sealing section 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 the opening in the wafer container. The first surface (which can be the surface of the door or the surface of the container body surrounding the opening) contains a groove. The sealing section includes a surface that contacts the groove. The sealing section includes a second surface that contacts the second surface. In the case where the door is placed to cover the opening, the sealing section contacts the first surface, the second surface and presses between the first surface and the second surface to form a seal between the first surface and the second surface. In an example gasket and container, the sealing section is compressed and can experience a reduction in length between the position where the sealing section contacts the first surface and the position where the sealing section contacts the second surface.

[0013] On the one hand, the present invention relates to a wafer container, comprising: a container body including an opening and an opening peripheral surface extending around the opening; a door adapted to cover the opening and including a door peripheral surface adapted to face the opening peripheral surface; a flat portion and a groove both extending around the opening peripheral surface or the door peripheral surface; and a gasket. The gasket comprises: a gasket body contacting the flat portion; and a sealing section attached to the gasket body. The sealing section comprises a heel and a tip. In a case where the door is positioned to cover the opening and presses the sealing section between the opening peripheral surface and the door peripheral surface, the heel contacts a surface of the groove.

[0014] On the other hand, the present invention relates to a method for closing a door of a wafer container. The wafer container comprises: an opening and an opening peripheral surface extending around the opening; a door adapted to cover the opening and including a door peripheral surface adapted to face the opening peripheral surface; a flat surface and a groove both extending around the opening peripheral surface or the door peripheral surface; and a gasket. The gasket comprises: a gasket body contacting the flat portion; and a sealing section attached to the gasket body. The sealing section comprises a heel and a tip. The method comprises placing the door above the opening to press the gasket between the heel and the tip and seal the opening, and the heel contacts a surface of the groove. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIGS. 1A and 1B show cross-sectional views along the length of a prior art gasket and a wafer container door.

[0016] Figure 2A FIGS. 2B and 2C show cross-sectional features of the gasket as described.

[0017] Figure 3A and 3B show cross-sectional views along the length of a gasket and a wafer container door of the present invention.

[0018] Figure 5 show performance data of an exemplary wafer container and gasket.

[0019] Figure 6 show an exploded view of an exemplary wafer container as described.

[0020] All the drawings are schematic and not drawn to scale. DETAILED DESCRIPTION

[0021] A wafer container is described below, which comprises a container body having an interior and an opening for accessing the interior, a door for covering the opening, and a gasket that forms a seal between the surface of the container body and the surface of the door when the door covers the opening.

[0022] The wafer container includes a multi-sided container body (sometimes referred to as a "housing") that defines an interior of the container adapted to receive and support one or more semiconductor wafers. The body includes an opening ("container opening") that permits access to the interior of the container on one side of the container body. The container includes a door adapted to cover the opening.

[0023] During use, the door is used to cover the container body opening and to enclose and seal the interior from the outside at the opening. To form the seal, a gasket is included between the surface of the door at the door perimeter and the surface of the container body surrounding the opening. When the door is placed to cover the opening, the surface at the perimeter of the door ("door perimeter surface") contacts the gasket on one side of the gasket. The opposite side of the gasket contacts the surface of the container body surrounding the container opening along the perimeter of the opening ("opening perimeter surface"). With the door covering the opening, the gasket is pressed between the door perimeter surface and the opening perimeter surface to form a seal between the door and the container at the opening.

[0024] Generally, the seal is formed between two surfaces of the container, which two surfaces may be referred to herein as the "first surface" and the "second surface". One of these two surfaces is the door perimeter surface. The other of these two surfaces is the opening perimeter surface. The gasket is fixed to one of these two surfaces, which may be the door perimeter surface or the opening perimeter surface. The surface to which the gasket is attached may be referred to as the "first surface". The "second" surface is the door perimeter surface or the opening perimeter surface, whichever is not the "first" surface.

[0025] The surface to which the gasket is attached (i.e., the "first surface") also includes a groove. The groove is a recess in the first surface that extends along the entire length of the perimeter of the surface (i.e., the outer perimeter of the door or the perimeter of the surface of the container body surrounding the opening). The groove is a small depression or channel formed along the perimeter of the first surface that is sized to permit a portion of the sealing section of the gasket to be located within the groove during use of the gasket to seal the opening of the container and to permit the surface of the sealing section of the gasket to contact the surface of the groove.

[0026] Example grooves are shown at Figure 2A and 2B. As illustrated, the example 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 positioned to cover the opening). The gasket includes a body 212 that has a portion located (against) the flat portion 208 of the first surface. The gasket also includes a sealing section 220 that is located (adjacent to) near the groove 208.

[0027] The groove can be of any shape, and example groove 208 (as Figure 2Aand as shown at 2B) has a form that begins with a flat portion 208 and the depth of which gradually increases in the x-direction as the distance from the flat portion 208 increases in the x-direction. An example groove can be in the form of an asymmetric (cross-sectional) "well" or "channel" formed in the first surface with a variable depth (depth gradually increasing). The angle of the surface of the groove relative to the flat portion (such as Figure 2A the angle "z" shown at, which varies depending on the rate of change of the depth of the groove measured from the start of the channel to the maximum depth) can be any useful angle, for example, an angle in the range from 10 to 80 degrees, for example, from 20 to 70 degrees or from 30 to 60 degrees. The groove can have any maximum depth relative to the flat portion of the first surface and a minimum depth that allows for an effective sealing section of the gasket, as described. The depth of the groove can be at least 0.3 millimeters, for example, at least 0.5, for example, from 0.5 to 5 millimeters or from 1 to 3 millimeters.

[0028] The gasket includes a gasket body attached to the first surface and a sealing section 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 example gasket, the gasket body includes a flat portion and an attachment section attached to the flat portion of the gasket body that is connected to the gasket body. The attachment section of the gasket fits tightly into an attachment channel (or "gland") formed in the first surface to frictionally secure the gasket to the first surface.

[0029] When viewed in a cross-section along the length of the gasket, the attachment section of the gasket is separated from the sealing section of the gasket by a flat section of the gasket body (which can generally be any flat section that effectively connects the attachment section and the sealing section). When viewed in a cross-section along the length of the gasket attached to the first surface, the attachment channel of the first surface is separated from the groove of the first surface by the flat portion of the first surface. The attachment channel is different from the groove but also extends along the entire length of the perimeter of the first surface adjacent to the groove, for example, along the entire perimeter of the surface facing the door of the container, or along the entire perimeter of the surface of the container body surrounding the container opening.

[0030] The sealing section of the gasket includes two surfaces that are adapted to contact the first and second surfaces of the container to form a seal between the first and second surfaces of the container (i.e., to form a seal between the door perimeter surface and the opening perimeter surface). One surface of the sealing section is referred to as the "heel" of the sealing section and contacts the first surface of the container at the location of the groove. The second surface of the sealing section is referred to as the "tip" of the sealing section and contacts the second surface of the container when forming the seal between the two surfaces. The sealing section of the gasket is connected to the gasket body near the "heel" surface of the sealing section. Starting from the heel, the sealing section includes a body that extends in a direction away from the gasket body and away from the first surface of the container along a length that terminates at the "tip" surface of the sealing section.

[0031] During use of the gasket to form a seal between a first surface and a second surface of a container, the surface of the heel portion of the gasket contacts the surface of a groove in the first surface of the container. Additionally, the surface at the tip of the seal section contacts the second surface of the container. The seal section is pressed and then held between the first surface of the container and the second surface of the container, and is placed under a set of forces that cause the seal section or portions of the seal section to undergo: compression, movement relative to one or both of the first and second surfaces, stretching or elongation, or combinations of these. For example, in a preferred example of the gasket, the seal section is compressed along a line extending between the heel of the seal section at the point of contact with the surface of the groove and the tip of the seal section at the point of contact with the second surface of the container.

[0032] Also during use, when the door covers the container opening and the tip of the seal section contacts the second surface, the tip slides along the second surface. The tip is moved in two direction components: in a direction towards the first surface, and in a direction away from the body of the gasket.

[0033] At least some prior gasket designs included a seal section that, when pressed between a first surface and a second surface of a wafer container, and when a door was placed over an opening in the container to cover the opening, operated largely by the seal section undergoing flexure and stretching (as opposed to compression). FIGS. 1A and 1B show examples of prior gaskets that included an elongated "sliding arm" type seal section. As illustrated, the wafer container 100 includes a container body 102 adjacent to an opening 104, and a door 106. The door 106 is adapted to cover the opening 104 by pressing a gasket 110 between a surface 122 of the door 106 and a surface 124 of the container body 102 (specifically by pressing the seal section 120 of the gasket 110 between these two surfaces). The seal section 120 of the gasket 110 includes a surface at a tip 130 that contacts the surface 124, and a surface at a heel 132 that contacts the surface 122. An attachment section 118 is located within a channel ("capping") 116 to secure the gasket 110 to the door 106.

[0034] As shown in FIG. 1A, the gasket 110 includes a body 112 secured to the door 106, including a portion adjacent to a flat portion 108. The gasket 110 also includes a seal section 120 connected to one end of the body 112, and the seal section 120 is in a position to contact both the surface 122 (and the heel surface 132) of the door 106 and the surface 124 (and the tip 130) of the wafer container body 102. When the door 106 is separated from the container body 102, the seal section 120 is not flexed. See FIG. 1A. No force is acting on the seal section 120.

[0035] Referring to FIG. 1B, when the door 106 is placed above the opening 104 to seal the interior of the container 100, the door 106 moves in the direction of the container body 102. The surface 130 contacts the surface 124 and the tip 130 moves laterally in the "x" direction, contacting the surface 124 in a certain direction and for a distance d1. The tip 130 also moves a distance and in a direction d2 in the depth direction (in the "y" direction) in the direction in which the door 106 moves towards the body 102. The contact and movement between the tip 130 and the surface 124 creates the possibility of particle debris being generated at the tip 130, and the particle debris can be dispersed within the interior of the container 100 and exposed to the wafers within the interior.

[0036] With the sealing section 120 held between the first surface 132 and the second surface 124, the sealing section 120 is subjected to a set of forces applied from the first and second surfaces. For example, the surface 140 of the sealing section 120 can experience tension due to spreading, and portions of the surface 142 can experience compression. The tension along the surface 140 causes the surface of the length of the sealing section 120 to stretch along the surface 140 and creates the possibility of particle debris being generated at the surface 140, and the particle debris can be dispersed within the interior of the wafer container 100. The interior of the sealing section 120 between the tip 130 and the heel 132 along line L does not experience a significant amount of compression, although some amount of compression may exist, particularly near the heel 132 in contact with the flat portion 108. Cycling the door to seal and unseal the container by flexing the gasket sealing section 120 creates a certain amount of strain on the sealing section 120, and this strain causes a relaxation of the force required to flex the gasket sealing section 120 when it is repeatedly applied and released. The sealing force of the sealing section 120 decreases with the cycling of opening and closing the door 106.

[0037] In contrast, during the use of the gasket sealing section of the present invention, the forces applied to the sealing section include a significant amount of compression along the length of the sealing section between the tip and the heel at the interior portion of the sealing section, including a greater amount of compression along line L of the sealing section 120 in FIG. 1B. Preferably, the sealing section is compressed at a location along the line that extends between the heel of the sealing section at the point of contact with the surface of the recess and the tip of the sealing section at the point of contact with the second surface of the container.

[0038] Figure 2A, example gasket designs are shown in the cross-sections of 2B and 2C. Each gasket 210 includes a body 212, a sealing section 220, and an attachment section 218. The attachment section 218 is adapted to fit within a channel (“gland”) on the surface of a wafer container such as a channel of a door, where the channel is adjacent to a groove also located at the surface, as described. The sealing section 220 is connected to one end of the body 212 opposite the attachment section 218. The body 212 includes an elongate portion 214 between the attachment section 218 and the sealing section 220, where the length of the elongate portion 214 is sufficient to position a portion of the sealing section 218 within the groove when the attachment section 218 is held within the channel. When the gasket 210 is installed at the surface and the attachment section 218 is held within the channel, the sealing section 220 is positioned at a location contacting the surface of the groove.

[0039] The sealing section 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 section 220 can be any shape that will allow the sealing section to function as described herein. Figure 2A An example sealing section 220 of the gasket 210 is substantially circular or spherical and includes a heel 232 adapted to contact a groove on a first surface of the wafer container, and a tip 230 located in position to contact a second surface of the wafer container. An example sealing section 220 of each gasket 210 in FIGS. 2B and 2C is elongate and also includes a heel 232 adapted to contact a groove on a first surface of the wafer container, and a tip 230 located in position to contact a second surface of the wafer container.

[0040] Figure 3A and 3B Examples of gaskets as described are shown. 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 a groove 238 in the door 206 and the surface 224 of the container body 202 (specifically by pressing the sealing section 220 of the gasket 210 between these surfaces of the body 202 and the door 206). The sealing section 220 includes a surface at the tip 230 contacting the surface 224 and a surface at the heel 232 contacting the surface 222 of the groove 238. The attachment section 218 is located within a channel (“gland”) 216 to secure the gasket 210 to the door 206.

[0041] As Figure 3AAs shown, gasket 210 includes a body 212 fixed to door 206 (in this instance, the door is the “first surface” of the container), including an elongated portion 214 adjacent to flat portion 208. Gasket 210 also includes a seal section 220, which is connected to one end of body 212 and is positioned in both the surface 222 within groove 238 that contacts door 206 and the surface 224 of wafer container body 202.

[0042] When door 206 is separated from container body 202, seal section 220 is not flexed. No force is acting on seal section 220. As in Figure 3A , an example of the length L' between tip 230 and heel 232 measured with seal section 220 not flexed can range from 2 to 5 centimeters, such as from 3 to 4 centimeters.

[0043] Referring to Figure 3B , when door 206 is placed above opening 204 to seal the interior of container 200, door 206 moves in the direction of container body 202. The surface of tip 230 contacts surface 224, and tip 230 moves laterally in the “x” direction, contacting surface 224 in a certain direction and distance d1'. Tip 230 also moves in the depth direction (in the “y” direction) in the direction of movement of door 206 towards door 206 by a distance and direction d2'.

[0044] Compared to seal section 120 of gasket 110 (Figures 1A and 1B), seal section 220 of gasket 210 has a shorter length (L') between the relevant heel surfaces 132, 232 at the positions of contacting surfaces 122, 222 and the surfaces of tips 130, 230 at the positions of contacting surfaces 124, 224. As illustrated, distance d1' can be less than distance d1, and distance d2' can be less than distance d2'. In the case where distance d1' is less than distance d1 and distance d2' is less than distance d2, compared to tip 130 of gasket 110, the shorter contact movement distance between tip 230 and surface 224 results in a reduced likelihood of particle debris generated by friction at tip 230.

[0045] According to useful or preferred examples of the seal section of the present invention, when the seal section is pressed between the surfaces of the door and the container body to form a useful seal, distance d1' (the movement distance of tip 230 in the x direction) can be less than 1 millimeter, such as less than 0.8 millimeter. Also according to useful or preferred examples of the seal section, when pressed between the surfaces of the door and the container body to form a useful seal, distance d2' (the movement distance of tip 230 in the y direction) can be less than 3 millimeters, such as less than 2 millimeters.

[0046] As a further comparison, when compressed between surfaces 230 and 232, the sealing section 220 of gasket 210 experiences a greater degree of compression along length L' compared to the level of compressive force present along the length L of the sealing section 120. With the sealing section 220 pressed and held between the first surface 222 and the second surface 224, the sealing section 220 experiences a set of forces applied from the first and second surfaces. The surface 240 of the sealing section 220 may experience tension due to stretching, and the surface 242 may experience compression. A large portion of the interior of the sealing section 220 between the tip 230 and the heel 232 along line L' is compressed along the length of L'. The angle Z between the flat portion 208 and line L' is at least 30 degrees, for example, at least 40 degrees, indicating the compressive force along line L'.

[0047] Thus, in Figure 3A , the length L' between the tip 230 and the heel 232 measured with the sealing section 220 is in an uncompressed (relaxed) state and is greater than the length L' between the tip 230 and the heel 232 measured with the sealing section 220 pressed between the surfaces 222 and 224 as shown in Figure 2B. The length difference between the compressed state ( Figure 3B ) and the uncompressed state ( Figure 3A ) can be at least 0.1 mm, 0.2 mm, or 0.3 mm (millimeters), for example, a difference in the range from 0.1 to 0.5 millimeters. In contrast, when the sealing section 120 is pressed between the first and second surfaces (as shown in Figure 1B), the length of the sealing section 120 in Figures 1A and 1B does not decrease relative to the length of the relaxed section 120 (shown in Figure 1A).

[0048] Compared to the sealing section 120, the design of the sealing section 220 can result in improved performance of the sealing section 220 relative to the sealing section 120. The sealing section 220 can exhibit a more consistent closing force over many door closing and opening cycles and can exhibit reduced dimensional changes over many door closing and opening cycles or both.

[0049] Figure 4 An additional example of gasket 210 is shown. Gasket 210 includes a body 212 fixed to a door 206 (in this example, the door is the "first surface" of the container). The body 212 includes an elongated portion 214 adjacent to the flat portion 208. Figure 4 The other features and functions of the gasket 210 of Figure 3A and 3B are similar to the features and functions of the gasket 210 of

[0050] When the door 206 is separated from the container body 202, the sealing section 220 is not deflected. In the case where the door 206 is placed above the opening 204 as in Figure 4 to seal the interior of the container 200, the surface of the tip 230 contacts the surface 224, and the tip 230 moves laterally in the "x" direction and contacts the surface 224 in a direction and by a distance d1' relative to the non-deflected position. The tip 230 also moves in the depth direction (in the "y" direction) toward the door 206 in the direction of movement of the door 206 by a distance and in a direction d2' relative to the non-deflected position. With the sealing section 220 pressed and held between the first surface 222 and the second surface 224, the sealing section 220 is subjected to a set of forces applied from the first and second surfaces. The surface 240 of the sealing section 220 may be subjected to tension due to stretching, and the surface 242 may be subjected to compression. A large portion of the interior of the sealing section 220 between the tip 230 and the heel 232 along the line L' is compressed along the length of L'.

[0051] Figure 5 Compare data of a gasket design (labeled "POR") having a sealing section that is substantially deflected and substantially not compressed along the interior of the sealing section (e.g., as shown in FIGS. 1A and 1B) with the sealing section of the present invention that has less deflection and experiences a greater amount of compression, length shortening, or both along the interior of the sealing section (e.g., as Figure 3A and 3B shown).

[0052] Figure 5 The table of Figure 5 shows the degradation data of the dimensions of the sealing section over time when the sealing section of the gasket is continuously compressed in the door of the container for two weeks. For the control seal (POR) and the inventive seal, an altimeter of the gasket initially installed in the door is used to measure the height of the sealing section relative to the door peripheral surface. The door is placed above the opening of the container, and the sealing section is pressed between the door peripheral surface of the container and the opening peripheral surface. After being pressed between the surfaces for two weeks, the height of the sealing section is measured again. As

[0053] Figure 6 shows an exploded view of a wafer container as described. The wafer container 1 includes a container body (e.g., a housing) 2, an interior 18, an opening 4, and an opening peripheral surface 14. The wafer container 1 also includes a door 6 having a door peripheral surface 16 extending along the periphery of the door 6, a groove 16 extending along the periphery of the door 6, and a channel 10 extending along the periphery of the door 6. The gasket 8 is held in place by an attachment section (not specifically indicated) of the gasket 8, and the gasket 8 fits into the channel 10.

[0054] When the door 6 is placed above the opening 4, the gasket 8 can be used to seal the opening of the container body 2. The gasket 8 is shown attached to the perimeter of the door 6, but the gasket 8 can alternatively be attached to the surface of the body 2 surrounding the opening 4.

[0055] The wafer container 1 can be used to transport, contain, or store semiconductor wafers (i.e., "in-process" wafers) processed by a series of processing steps between a series of processing steps. As illustrated, the wafer container 1 is a front-opening container, e.g., a front-opening unified pod (FOUP).

[0056] The container body 2 defines an interior 18 within the wafer container 1, and an open end 4 is provided on one side of the container body 2 to allow access to the interior. The open end 4 allows a plurality of wafers to be placed in or removed from the interior of the container body 2.

[0057] 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 using the gasket 8 between the door and the container. The sealed interior of the wafer container 1 is a microenvironment that is protected from contaminants outside the wafer container 1.

[0058] The gasket 8 is a gasket as described herein, e.g., the gasket 210 as shown in Figure 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 perimeter surface 16) and the surface of the door 6 (the door perimeter surface 14). One surface (i.e., the heel) of the sealing section of the gasket 8 contacts the surface of the groove 12 of the door perimeter surface 16. The surface at the tip of the sealing section contacts the opening perimeter surface 14. When held between the door perimeter surface 16 and the opening perimeter surface 14, the sealing section compresses along the length between the tip and the heel, and the length of the sealing section between the tip and the heel decreases.

[0059] The gasket 8 can be made of any suitable material for forming a seal, e.g., a polymeric material. Example 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.

[0060] As Figure 6 shown, the door 6 includes a channel (or "gland" 10) formed in the door perimeter surface 16 that faces the container body 2 and the opening perimeter surface 14 when the door 6 and the container 2 are assembled to close the opening 4. The channel 10 is configured to hold the gasket 8. The channel 10 is a groove configured to receive a protrusion or "attachment section" of the gasket 8. Although the channel 10 is shown on the door 6, it should be understood that the channel can be located in any suitable position to hold the gasket 8 such that the gasket 8 forms a seal between the door 6 and the container body 2, e.g., at the perimeter of the opening 4.

[0061] Example gaskets of the present invention can be used to form a seal between a door and an opening of a wafer container, which is effective for commercial use of the wafer container. The effectiveness of this type of seal formed by an elastic gasket is sometimes referred to as "true air conductance", and has a flow rate unit per atmosphere, such as volume per time per pressure difference, such as liters per second per atmosphere. Example gaskets of the present invention can effectively form a seal having an air conductance of no more than 0.2 liters per second per atmosphere (L / s / atm) or no more than 0.1 liters per second per atmosphere.

[0062] During use, when the gasket is pressed between the door and the container body, the gasket will generate a force. This force can be referred to as "sealing force". Devices and methods for measuring the sealing force are commercially known. A useful device includes a device called a "load port", which is an analytical device that removes and replaces the door when measuring the relevant force. The door can be closed relative to the container body to different positions. At different positions, different forces are applied to the gasket and different "sealing forces" are generated. By closing the door to a position 165.5 millimeters from the face reference plane (center of a 300 mm wafer) contained in the wafer container, the gasket as described above can generate a sealing force in the range of 15 to 20 pounds (force).

Claims

1. A wafer container, which comprises: A container body, which includes an opening and an opening peripheral surface extending around the opening, A door, which is adapted to cover the opening and includes a door peripheral surface adapted to face the opening peripheral surface, A flat portion and a groove, both of which extend around the opening peripheral surface or the door peripheral surface, and a gasket, which includes: A gasket body, which contacts the flat portion, and A sealing section, which is attached to the gasket body, the sealing section includes a heel and a tip, Wherein, when the door is positioned to cover the opening and press the sealing section between the opening peripheral surface and the door peripheral surface, the heel contacts the surface of the groove.

2. The wafer container according to claim 1, wherein the door peripheral surface includes the groove, and when the door is positioned to seal the opening: The heel contacts the surface of the groove at the heel contact area, The tip contacts the opening peripheral surface at the tip contact area, and The sealing section is compressed between the heel contact area and the tip contact area.

3. The wafer container according to claim 1, wherein: The door peripheral surface includes a channel adjacent to the groove, The gasket includes an insertion section connected to the body section, and The insertion section is located in the channel to fix the gasket to the door peripheral surface.

4. The wafer container according to any one of claims 1, wherein when the door seals the opening, the air conductance through the door hinge is less than 0.2 liters / s / atmosphere.

5. The wafer container according to any one of claims 1, wherein the gasket includes a thermoplastic elastomer with a Shore A hardness of 50 to 80 durometers.

6. The wafer container according to any one of claims 1, wherein the gasket has a sealing force in the range of 15 to 20 pounds force.

7. The wafer container according to any one of claims 1, wherein the sealing section has a length in the range of 3 to 4 cm between the heel and the tip.

8. The wafer container according to any one of claims 1, wherein the sealing section is spherical.

9. The wafer container according to any one of claims 1, wherein the sealing section is elongated.

10. A method for closing the door of a wafer container, the wafer container comprises: An opening and an opening peripheral surface extending around the opening, A door, which is adapted to cover the opening and includes a door peripheral surface adapted to face the opening peripheral surface, A flat surface and a groove, both of which extend around the opening peripheral surface or the door peripheral surface, and a gasket, which includes: A gasket body, which contacts the flat portion, and A sealing section, which is attached to the gasket body, the sealing section includes a heel and a tip, The method includes placing the door above the opening to press the gasket between the heel and the tip and seal the opening, and the heel contacts the surface of the groove.

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

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

13. The method according to any one of claims 10, wherein the sealing section is spherical.

14. The method according to any one of claims 10, wherein the sealing section is elongate.

15. The method according to any one of claims 10, wherein: the door peripheral surface includes the groove, the tip contacts the opening peripheral surface, and in the case where the door is in a position covering and sealing the opening, the sealing section is compressed between the heel and the tip.

16. The method according to claim 15, which comprises: pressing the tip against the opening peripheral surface to compress the sealing section, wherein the tip contacts the opening peripheral surface and moves a distance of less than 1 mm along the opening peripheral surface.

17. The method according to any one of claims 10, wherein the sealed opening has an air conductance of less than 0.2 l / s / atmosphere.

18. The method according to any one of claims 10, wherein the gasket comprises a thermoplastic elastomer having a Shore A hardness of 50 to 80 durometers.

19. The method according to any one of claims 10, wherein the gasket has a sealing force in the range from 15 to 20 lbf.

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