A container for receiving a substrate in an effectively hermetic seal.

Abstract

To provide a container for accommodating a substrate necessary for semiconductor production, so that the substrate is not contaminated with, e.g. particles in the air.SOLUTION: The invention discloses a container (300) for accommodating a substrate. The container (300) includes a base (310) having at least one first supporting surface (312) and a lid (320) having at least one second supporting surface (322) to engage with the first supporting surface (312) of the base, so as to define an accommodating space for the substrate. The first supporting surface of the base and the second supporting surface of the lid have the same slope with a flatness of 0.04 mm or less, so that an effective hermetic seal between the first supporting surface and the second supporting surface is formed when the two surfaces contact each other.SELECTED DRAWING: Figure 5A

Description

[Technical Field]

[0001] The present disclosure (the present invention) relates to a two-part nested container used to transport reticles, including a transport pod used to transport patterned substrates, particularly a reticle pod that can provide effective hermetic sealing, precision marking, and stable retention. [Background technology]

[0002] Substrates required for semiconductor manufacturing (e.g., substrates for wafers and reticles) are housed in special containers during transport to prevent the substrates from becoming contaminated by contaminants, such as airborne particles, that can cause defects in the semiconductor manufacturing process in the non-vacuum environment during transport.

[0003] FIG. 1 shows a prior art EUV reticle pod, which includes an inner pod assembly 110 and an outer pod assembly 150. The inner pod assembly 110 is used to house a reticle (R) and includes a lower lid 120 and an upper lid 130. The lower lid 120 has four support members 121 for supporting the reticle (R). The upper lid 130 is coupled to the lower lid 120 and includes four pressure units 140 corresponding to the four support members 121 for pressing against the surface of the reticle (R). The pressure units 140 include pressure members having a pressure force receiving portion and a pressure portion. In particular, the pressure force receiving portion is exposed at the top surface of the upper lid 130 to receive downward pressure pins 171 provided on an outer lid 170 of the outer pod assembly 150. After the pressure-receiving portion is pressed downward, the pressure portion protrudes from the bottom surface of the top cover 130 and presses against the surface of the reticle (R). The outer pod assembly 150 is used to receive the inner pod assembly 110, and this outer pod assembly includes a base 160 and an outer cover 170. The base 160 has a number of pillars 190 that support the bottom cover 120 of the inner pod assembly 110, and the base 160 is also coupled to the outer cover 170 to form a hermetic seal with the outer cover 170. The outer cover 170 has four downward pressure pins 171 provided on the inside of its bottom surface. The four downward pressure pins 171 correspond to the four pressure units 140, and these four downward pressure pins are used to contact the surface of the pressure-receiving portion provided on the pressure member of each pressure unit 140. When the inner pod assembly 110 storing the reticle (R) is received in the outer pod assembly 150, the downward pressure pin 171 applies force to the pressure force receiving portion of the pressure member of the pressure unit 140, thereby enabling the pressure unit 140 and the support member 121 to maintain a stable holding state of the reticle (R).

[0004] The inner pod assembly 110 of the prior art EUV reticle pod 100 has the following technical problems to be solved. First, the pressure members of each pressure unit 140 are exposed at the top surface of the top lid 130, and the pressure members may protrude from the bottom surface of the top lid 130, creating a risk that particles may fall onto the top lid 130 and pass through the space housing the pressure members. The particles may eventually enter the inner cavity and contaminate the reticle (R). Second, when the inner pod assembly 110 housing the reticle (R) is not placed in the outer pod assembly 150, the pressure portions of the pressure members provided on the four pressure units of the top lid 130 do not protrude from the bottom surface of the top lid 130. At this point, the reticle (R) is not firmly held by the pressure units 140 and the support members 121, increasing the risk of generating a large number of particles due to misplacement or impact of the reticle (R). Third, when the inner pod component 110 containing the reticle (R) is placed at the base 160 of the outer pod component 150, the pressure pin 171 may easily collide with the reticle (R) through the clamp unit 140 when the outer lid 170 is positioned downward, thereby increasing the risk of generating many particles due to displacement or impact of the reticle (R).

[0005] Prior art Taiwan Patent Application Publication No. 200304051 discloses a two-part container for housing a reticle. The container comprises an outer pod and an inner pod, with the inner pod disposed within the outer pod and the reticle disposed within the inner pod. Most often, reticles are manufactured in a high-vacuum environment, and thus the container housing the reticle may transition between a vacuum environment and an atmospheric pressure environment during transport. Alternatively, the container may be transported to an atmospheric pressure environment after the vacuum is evacuated. To maintain a pressure difference between the inside and outside of the container to prevent airflow from blowing particles into the inner cavity housing the reticle, a filtering or filter channel is provided between the inner cavity and the outer space to filter out particles. As a result, an airtight seal between the inner cavity and the outer space of the container, other than the filter passage, prevents the pressure difference between the inside and outside of the container from causing airflow to pass through areas other than the filter channel and blow particles into the area housing the reticle. The above-mentioned patent application publication discloses sealing means that provide a particle seal (e.g., an O-ring) between the inner pod and the outer pod and a gas seal (e.g., another O-ring) at the contact interface between the lid and base of the outer pod. These configurations provide an improved barrier to prevent contaminants from entering the reticle area in a vacuum environment. While the patent application publication discloses that the inner pod has a pod lid and a base that together define a receiving space for the reticle, no O-ring is provided at the contact interface between the inner pod lid and the base. In other words, the sealing quality of the inner pod is determined solely by the contact interface between the pod lid and the base. Furthermore, the patent application publication does not disclose or teach how to configure or adjust the contact interface to achieve effective sealing.

[0006] Taiwan Patent No. 1391304 (titled "Reticle Pod") describes that prior art seals are often made of elastomeric materials, which themselves can be a source of particles or contamination. Furthermore, the patent states that the prior art requires the use of certain structures (e.g., grooves and raised bumps) to form a seal using an elastomeric seal. While such structures are widely used, they can have the drawback of retaining particulate contaminants or chemicals within the gap. The patent proposes a structure for forming flat surfaces near the periphery of each of the door and cover. When the cover and door are mated, the flat surfaces abut against each other to form a seal that prevents particles from entering the interior of the pod from the environment outside the pod, thereby eliminating the need for a traditional elastomeric seal. According to the teachings of the patent, the surface for sealing should have an acceptable roughness average (Ra) of up to 0.50 microinches (1.27 x 10 -6 The surface finish is preferably in the range of 0.20 to 0.40 Ra.

[0007] However, based on common general knowledge familiar to those skilled in the art, the roughness average value (Ra) applied to define the roughness of the surface finish as described in the above-mentioned patent specification is "an expression for surface roughness obtained by calculating the mean absolute deviation based on the center line of the roughness curve" and "the average value of the deviations from the center line to measurement points within a certain length of the sample, as shown in Figure 8-3-1," as specified on page 212 of "Precision Measurement," first published November 10, 1998, and written / edited by Fan Kuang-chao and Chang Kuo-yi. Figure 2 of the present application shows the above-mentioned Figure 8-3-1, excerpted from this publication. When the cover and door of a reticle pod are engaged, whether the flush upper and lower surfaces can achieve a hermetic seal is actually determined by the gap between the upper and lower surfaces. In the above-mentioned patent specification, the "roughness average (Ra)" is applied to evaluate the roughness of the surface finish, and this roughness average represents the surface roughness based only on the linear segment length. Such a roughness average (Ra) can hardly be used to evaluate the roughness of the gap between the upper and lower surfaces of the cover and door, respectively, because these surfaces are flush against each other within a large area. In other words, the roughness average (Ra) of the surface roughness disclosed in the above-mentioned patent specification is not a good indicator for evaluating whether the upper and lower surfaces of the mated cover and door of a reticle pod achieve a hermetic seal.

[0008] The aforementioned publication, "Precision Measurement," discusses the factors that determine surface texture and notes that no matter how precisely a workpiece surface is machined, there will always be certain differences between the finished surface and the ideal surface. The reasons behind these unavoidable differences include low-frequency vibrations caused by machining processes, machine chatter, and machine / workpiece deflection, as well as irregular surfaces with high-frequency roughness caused by machining processes such as turning, milling, grinding, sandblasting, and flames. The degree of roughness is expressed as a curved wave, the center line of which is a straight line. The aforementioned center line, Ra, is used as the baseline for calculating the average absolute value of the roughness deviation. Therefore, the Ra value cannot reflect the maximum value of the roughness deviation, which is smaller than the amplitude of the waveform. Therefore, as those skilled in the art know, assuming that the workpiece surface cannot avoid impacts from low and high frequency factors resulting from actual processing, the workpiece surface will necessarily contain waviness and Ra. Thus, in terms of determining whether an effective hermetic seal is formed between two workpieces, the prior art only discloses using an Ra value that is smaller than the magnitude of the waviness to evaluate the "sealing surface," and the Ra value is not sufficient to ensure an effective seal.

[0009] It is known that the base and lid of a reticle pod are made of metal. While grinding or polishing can improve the surface finish of metal surfaces (or surfaces treated with electroless nickel plating), the production yield (in terms of effective hermetic sealing) of reticle pods with surfaces having a Ra of 0.5 or even 0.20-0.40 Ra produced using existing grinding or polishing techniques is unlikely to improve, resulting in a steep increase in production equipment costs. Furthermore, as noted above, it is clear that it is not possible to guarantee the effectiveness of hermetic sealing when the Ra value alone is used as one of the design objectives for achieving a sealing surface.

[0010] In addition, the reticle pod is oriented directionally when opened for use. Thus, when the reticle pod is sent to a lithography machine, detecting not only the position but also the orientation of the reticle pod is necessary to avoid misalignment of the exposure location during the lithography process. Therefore, to ensure accurate alignment of the reticle pod position, the lithography machine sends an optical signal to the surface of the reticle pod, and then a sensor obtains a reflected signal of the optical signal for identification. In the prior art, due to the smooth surface or bottom structure design of the reticle pod, the sensor may not obtain a stable reflected signal, thereby failing to accurately identify whether the feature area of ​​the reticle pod is in the correct position. Prior art approaches use a crosshair reticle to mark the surface of the reticle pod. However, when the optical signal sent by the lithography machine hits the 3D structure on the pod surface at a specific angle, it may be difficult to determine whether the crosshair reticle is related to the 3D structure surface based on the reflected signal detected by the sensor. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Taiwan Patent Application Publication No. 200304051 [Patent Document 2] Taiwan Patent No. 1391304 [Non-patent literature]

[0012] [Non-Patent Document 1] "Precision Measurement," written and edited by Fan Kuang-chao and Chang Kuo-yi, first published November 10, 1998 Summary of the Invention [Problem to be solved by the invention]

[0013] Thus, in an effort to solve the various technical problems discussed above, the present invention provides reticle storage pods and reticle transport pods with features including effective hermetic sealing, precision marking, and stable retention. [Means for solving the problem]

[0014] The present invention aims to provide a hermetic seal by adjusting the "flatness" of the contact interface between the lid and base of a reticle container. Research by the inventors has shown that prior art techniques that only improve the average surface roughness (Ra) of the contact interface between the base and lid cannot guarantee a seal between the lid and base when they come into contact with each other. The inventors further point out that the processed surfaces of the base and lid have corrugations with amplitudes greater than the amplitude of the average surface roughness (Ra). Thus, one factor determining whether a hermetic seal can be achieved between the base and lid upon contact is the maximum height (Rz) between the upper and lower contact surfaces (i.e., the distance between the maximum peak and the lowest valley). The Rz of the contact interface creates a gap when these surfaces are in contact with each other, which becomes an airflow channel and can damage the hermetic seal between the lid and base. Furthermore, if the surface deflection cannot be adjusted, the treated surface will also contain a maximum height (Rz), thereby creating gaps, i.e., air flow channels.

[0015] As used herein, "flatness" refers to the offset between the actual surface of a particular workpiece and an ideal plane (true plane). Referring to FIG. 3, a schematic diagram showing the flatness of the surface corrugation of a particular workpiece is shown. According to the definition of "flatness," the distance (d) between two parallel imaginary planes 101 and 102 sandwiching the actual plane (100) of the workpiece can be expressed as the maximum height (Rz) of the actual plane (100), with the upper and lower planes touching the maximum peak and minimum valley of the actual plane, respectively. The actual plane (100) is the surface of a workpiece (103) as shown, and this surface has surface deflections caused by low-frequency factors in actual processing, which appear as significant height differences. In addition, there are surface deflections caused by low-frequency factors in actual processing, as shown in FIG. 4. The definition of "flatness" refers to the distance (d) between two imaginary planes (201, 202) that sandwich the actual plane (200) of the workpiece (203), and in particular the coverage of the actual plane (200) is determined by an area of ​​a specific length (L) and width (W), e.g., 100 mm x 100 mm. This area measure can, in some cases, determine the distance (d) between the two imaginary surfaces (201, 202), and such distance can be assumed to determine the corresponding measurement of flatness. Similarly, the distance (d) represents the maximum height (Rz) of the actual plane (200).

[0016] One object of the present invention is to provide a container for housing a substrate. The container has a base and a lid. The base has a top horizontal surface and at least one first support surface surrounding the top horizontal surface. The lid covers the top horizontal surface and engages with the first support surface to define a housing space for housing the substrate. The lid has at least one filter channel and at least one second support surface surrounding the housing space. The second support surface is configured to match the first support surface, and the first support surface of the base and the second support surface of the lid have a consistent slope relative to the slope of the top horizontal surface. Both the first support surface of the base and the second support surface of the lid have a flatness of less than 0.04 mm, thereby forming a hermetic seal when the first support surface contacts the second support surface.

[0017] Another object of the present invention is to provide a container for housing a substrate. The container has a base and a lid. The base has a horizontal surface. The lid has at least one filter channel and a storage space. The lid contacts the base, and the storage space and the top horizontal surface form a storage space for housing the substrate. At least one contact interface is formed between the lid and the base, surrounding the top horizontal surface and thereby sealing the storage space. The contact interface has a gap of less than 0.08 mm.

[0018] Another object of the present invention is to provide a container for housing a substrate. The container has a base and a lid. The base has a top horizontal surface and at least one first support surface surrounding the top horizontal surface. The lid has at least one filter channel, a bottom surface, and a flange surrounding the bottom surface. The flange has at least one second support surface surrounding the bottom surface, and the second support surface at least partially contacts the first support surface of the base, so that the bottom surface, flange, and top horizontal surface form a housing space for housing a substrate. The first and second support surfaces have a flatness of less than 0.04 mm, thereby forming a hermetic seal for the housing space.

[0019] Another object of the present invention is to provide a container for accommodating a substrate. The container has a base and a lid. The base has a top horizontal surface. The lid has at least one filter channel and a storage space. The lid contacts the base, and the storage space and the top horizontal surface form an accommodation space for accommodating the substrate. At least one contact interface is formed between the lid and the base, surrounding the top horizontal surface and thereby sealing the accommodation space. The contact interface has a gap that, when the first channel is closed, defines a pressure difference between the accommodation space and an external space of the container, the pressure difference exceeding 100 Pa.

[0020] Another object of the present invention is to provide a container for housing a substrate. The container has a base and a lid. The base has a top horizontal surface. The lid has at least one filter channel and a storage space. The lid contacts the base. The storage space and the top horizontal surface form a storage space for housing the substrate. At least one contact interface is formed between the lid and the base, surrounding the top horizontal surface. The contact interface has a gap, and a vacuum is drawn in the storage space. During a gas return process to the space outside the container, the gap determines the air flow entering the container, and 90% of the air flow enters the container through the filter channel.

[0021] Another object of the present invention is to provide a method for adjusting airflow into a container. The container has a base with a top horizontal surface and a lid with at least one filter channel. The lid contacts the base to form a storage space. The method includes forming at least one contact interface between the base and the lid to enclose the storage space, the contact interface having a gap, adjusting the gap when the filter channel is closed to establish a pressure difference of more than 100 Pa between the storage space and an outer space of the container, and performing a gas return process to the outer space of the container, wherein the gas return process draws a vacuum in the storage space and opens the filter channel, thereby generating airflow into the container, with 90% of the airflow passing through the filter channel.

[0022] The present invention can be more fully understood with reference to the accompanying drawings and the description given below. Various embodiments, which are not intended to be limiting and exclusive, are described with reference to the drawings. The elements shown in the drawings are not necessarily drawn to scale, for the purpose of illustrating the construction and principles of integrity. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is an exploded perspective view of a prior art EUV reticle pod. [Figure 2] 1 is a schematic diagram showing how to obtain the roughness average value (Ra) based on the center line of the roughness curve. [Figure 3] 1 is a diagram showing the waviness of the workpiece surface, which is related to flatness. [Figure 4] 10 is a diagram illustrating another workpiece surface deflection, which is related to flatness. [Figure 5A] 1 is an exploded perspective view of a container (eg, a reticle pod) for housing substrates. [Figure 5B] FIG. 10 shows a cross section of the container at the edge when the lid and base are joined together. [Figure 6A] 1 is a diagram illustrating the contact interface between the base and the lid according to one embodiment of the present invention. [Figure 6B] 6B is a cross-sectional view showing various examples of a contact interface between a base and a lid taken along the A-A section line shown in FIG. 6A based on the embodiment shown in FIG. 6A. [Figure 6C] 6B is a cross-sectional view showing another example of a contact interface between a base and a lid taken along the A-A section line shown in FIG. 6A based on the embodiment shown in FIG. 6A. FIG. [Figure 6D] 6B is a cross-sectional view showing another example of a contact interface between a base and a lid taken along the A-A section line shown in FIG. 6A based on the embodiment shown in FIG. 6A. FIG. [Figure 6E]6B is a cross-sectional view showing another example of a contact interface between a base and a lid taken along the A-A section line shown in FIG. 6A based on the embodiment shown in FIG. 6A. FIG. [Figure 7A] 10 is a schematic diagram illustrating the contact interface between the base and the lid according to another embodiment of the present invention. [Figure 7B] 7B is a cross-sectional view showing various examples of the contact interface between the base and the lid taken along the B-B section line shown in FIG. 7A based on the embodiment shown in FIG. 7A. [Figure 7C] 7B is a cross-sectional view showing another of various examples of the contact interface between the base and the lid taken along the B-B section line shown in FIG. 7A based on the embodiment shown in FIG. 7A. [Figure 7D] 7B is a cross-sectional view showing another of various examples of the contact interface between the base and the lid taken along the B-B section line shown in FIG. 7A based on the embodiment shown in FIG. 7A. [Figure 8A] 10 is a schematic diagram illustrating the contact interface between a base and a lid according to yet another embodiment of the present invention. [Figure 8B] 8B is a cross-sectional view showing various examples of the contact interface between the base and the lid taken along the CC section line shown in FIG. 8A based on the embodiment shown in FIG. 8A. [Figure 8C] 8B is a cross-sectional view showing another example of a contact interface between a base and a lid taken along the CC section line shown in FIG. 8A based on the embodiment shown in FIG. 8A. FIG. [Figure 8D] 8B is a cross-sectional view showing another example of a contact interface between a base and a lid taken along the CC section line shown in FIG. 8A based on the embodiment shown in FIG. 8A. FIG. [Figure 9A] 10 is a schematic diagram illustrating the contact interface between a base and a lid according to yet another embodiment of the present invention. [Figure 9B]9B is a cross-sectional view showing various examples of the contact interface between the base and the lid taken along the line D-D shown in FIG. 9A based on the embodiment shown in FIG. 9A. [Figure 10] 10A-10C show examples of how to inspect the pressurized inside and outside of a container for housing substrates. [Figure 11A] 10 is a schematic diagram illustrating gaps between contacting surfaces caused by deflection when the lid and base are joined together. [Figure 11B] 1 is a schematic enlarged view of the gap and associated corrugations between the lid and base when the lid and base are joined together and in contact with each other. FIG. [Figure 11C] 1 is a schematic diagram illustrating the respective flatness of a first support surface of a base and a second support surface of a lid (in this case, the base and lid are not joined to one another). DETAILED DESCRIPTION OF THE INVENTION

[0024] A more complete description of the present invention is provided below with reference to the accompanying drawings, in which examples are provided to demonstrate exemplary embodiments. Nevertheless, the claimed subject matter of the present invention can be embodied in a variety of forms, and therefore, configurations of claimed subject matter within the scope of the present invention should not be limited to any exemplary embodiments disclosed herein, which are provided by way of example only. At the same time, the present invention is intended to provide as broad a scope as reasonably possible in relation to claimed subject matter within the scope of the present invention. Furthermore, for example, the claimed subject matter can be embodied as a method, apparatus, or system. Thus, particular embodiments can take the form of, for example, hardware, software, firmware, or any combination thereof (known as non-software).

[0025] The term "embodiment" as used herein does not necessarily refer to the same exact embodiment, and the term "other (some / certain) embodiments" as used herein does not necessarily refer to different embodiments. The purpose of this specification is to describe the claimed subject matter using examples that include combinations of all or part of the illustrated embodiments. The term "contact interface" as used herein refers to the interface where an "upper contact surface" and a "lower contact surface" come into contact with each other. The upper contact surface and lower contact surface described herein refer to the actual surface of the workpiece, not an ideal surface. Therefore, the "upper contact surface" and the "lower contact surface" each have a "flatness" that represents the maximum height (Rz) of the actual surface, and the "contact interface" may include a gap or clearance defined by the respective flatnesses of the "upper contact surface" and the "lower contact surface."

[0026] FIG. 5A shows a container (300) for accommodating a substrate, which may be a reticle pod. In an embodiment of the present invention, the container (300) is suitable for serving as an inner pod assembly for a reticle pod. The container (300) has a base (310) and a lid (320). The base (310) has a top horizontal surface (311) and at least a first support surface (312) surrounding the top horizontal surface (311). The top horizontal surface (311) is a flat surface suitable for supporting a substrate (e.g., a reticle). The top horizontal surface (311) further has a plurality of support assemblies (313), each of which includes pillars that limit the sides of the substrate and bumps (not shown) typically located between two pillars that support the bottom surface of the substrate. As shown in Figure 5A, the first support surface (312) is an annular plane located adjacent the periphery of the top horizontal surface (311). The first support surface (312) is a substantially continuous upward-facing surface adapted to contact a corresponding surface of the lid (320).

[0027] The lid (320) has a second support surface (322) that surrounds the top horizontal surface (311) of the base (310) and engages the first support surface (312). The lid (320) has a receiving space that, together with the top horizontal surface (311), defines a receiving space for receiving a substrate. Methods for achieving engagement include contacting the top and bottom surfaces, using a bump and groove structure, or bonding two complementary structures together. Although other aspects of the lid (320) are not shown herein, those skilled in the art will appreciate that the lid (320) has at least a downwardly extending annular portion that, when the base (310) and the lid (320) are joined together, contacts the base (310) and surrounds the top horizontal surface (311) of the base, while the second support surface (322) is the underside of the annular portion. In one embodiment, the lid (320) may have at least one filter channel (321) and at least one annular-shaped second support surface (322). The second support surface (322) is adapted to mate with the support surface (312) of the base (310). The contour of the second support surface (322) substantially matches that of the first support surface (312), and the second support surface (322) may have an area slightly larger or smaller than that of the first support surface (312).

[0028] When the base 310 engages the lid 320, the first and second support surfaces 312 and 322 come into contact with each other. As shown in FIG. 5B, the base 310 is in contact with the lid 320, and a cross-section CS1 along the edge of the container 300 shows a contact interface 701 formed between the base 310 and the lid 320. Visually, the contact interface 701 appears to be a straight line. However, as shown in FIG. 4, low-frequency factors during machining cause deflection of the first and second support surfaces 312 and 322 of the base 310 and lid 320, respectively. Therefore, the contact interface 701 shown in the cross-section CS1 view may not actually be a perfectly straight line. The following paragraphs will discuss how to achieve an effective seal with deflected surfaces. Also, as shown in FIG. 5B, when the container (300) is viewed from another cross section (CS2) at a different position, other relationships between the first support surface (312) and the second support surface (322) can be observed, details of which are provided in the following paragraphs.

[0029] As shown in cross section (CS2) of FIG. 5B, the first support surface (312) of the base (310) and the second support surface (322) of the lid (320) can be designed to have different slopes. In one embodiment, the first support surface (312) of the base (310) and the second support surface (322) of the lid (320) have a consistent slope relative to the top horizontal surface (311). For example, the first support surface (312) is horizontal, and the second support surface (322) is also horizontal, as shown in FIGS. 6B and 6C. Alternatively, in another embodiment, the first support surface (312) is inclined downward toward the top horizontal surface (311), and the second support surface (322) is also inclined, as shown in FIGS. 6D and 6E. In a preferred embodiment of the present invention, to achieve an effective seal between the base (310) and the lid (320), the first support surface (312) and the second support surface (322) each have a flatness of less than 0.04 millimeters (mm) to form a hermetic seal between the first support surface (312) and the second support surface (322) when the first support surface (312) and the second support surface (322) are in contact with each other. Preferably, the flatness is in the range of 1 micron (μm) to 0.04 mm. Flatness can be measured by known methods, which will not be repeated here.

[0030] In an embodiment of the present invention, an effective hermetic seal between the base (310) and the lid (320) can be achieved by adjusting the respective flatnesses of the first support surface (312) and the second support surface (322). The better the hermetic seal at the contact interface between the base (310) and the lid (320), the greater the pressure differential between the inside and outside of the container that can be achieved during the gas return process, in which the container is placed in a vacuum environment with the filter channels closed. A good hermetic seal also allows a greater amount of gas to pass through the open filter channels during the gas return process. Specifically, when the flatness of each support surface is in the range of 1 μm to 0.04 mm and an effective hermetic seal is achieved between the base (310) and the lid (320), the volume of gas surrounding the container (300) begins to increase from a vacuum state, with at least 90% of the incoming gas entering the storage space of the container (300) entering through the unblocked filter channel (321) and less than 10% of the incoming gas entering the storage space entering through the gap G between the first support surface (312) and the second support surface (322) or through other window gaps, i.e., gaps in the lid (320) associated with the pressurizing unit, etc. Because other window gaps and gaps on the lid (320) associated with the pressurizing unit are often provided with sealing rings to promote an airtight seal, less than 10% of the incoming gas entering the storage space entering primarily through the gap G between the first support surface (312) and the second support surface (322).

[0031] In order to evaluate whether the respective flatness of the first support surface (312) and the second support surface (322) allows at least 90% of the incoming gas entering the receiving space of the container (300) to enter through the non-blocking filter channel (321), the present invention now provides a test method as shown in FIG. 10. A cavity (800), which may be considered a cavity in a gas exchange chamber of an EUV exposure machine, is provided. The gas volume in the cavity (800) can begin to increase by opening a valve (801) and closing another valve (802) to adjust the gas supply. A vacuum can be obtained in the cavity (800) by closing the valve (801) and opening the other valve (802) to adjust the gas supply. The test method of the present invention measures the volume of the receiving space (P) of the container (300) when the container (300) is placed in the cavity (800). inside ) and the pressure in the void (800) (P outside The same vacuum pump / gas increase curve-control valves (801, 802) are used to monitor the difference between the pressure P inside is the pressure P outside When a vacuum is obtained in the cavity (800), the pressure P inside is the pressure P outside Higher than.

[0032] When the filter channel (321) is not closed, the channel (321) becomes the primary fluid passageway for the receiving space of the container (300) when the container (300) of the present invention is placed in the cavity (800). When the filter channel (321) is closed, the primary fluid passageway between the receiving space of the container (300) and the space located outside the container (300) becomes the gap G between the first support surface (312) and the second support surface (322) as described above when the container (300) of the present invention is placed in the cavity (800). It should be noted that the fluid passageways formed around other window gaps and other gaps in the lid (320) associated with the pressurizing unit can be ignored or are considered to be controllable and predictable influencing factors. In the test method provided by the present invention, the container (300) is placed in the cavity (800) with the filter channel (321) not closed. The same vacuum pump / gas build-up curve-control valves (801, 802) are used to measure the pressure P inside and pressure P outside This test method monitors the difference between the pressure P and the pressure P by controlling the pumping / filling of gas per second and monitoring the change in pressure. inside and pressure P outside First, the gas in the cavity (800) is pumped out to create a vacuum, and the pressure P outside The pressure P reaches 500 Pa. Then, with the base (310) engaged with the lid (320), the gas is pumped back into the cavity (800). inside and pressure P outside If a difference of more than 100 Pa can be observed between the first support surface (312) and the second support surface (322), then at least 90% of the airflow entering the storage space passes through the unclosed filter channel (321) and less than 10% of the airflow entering the storage space passes through the gap (G) between the first support surface (312) and the second support surface (322).

[0033] In a preferred embodiment of the present invention, when the flatness of each of the first support surface (312) and the second support surface (322) is in the range of 1 μm to 0.04 mm, the gas volume in the container (300) begins to increase from a vacuum state, and at least 90% of the incoming gas entering the accommodating space can enter through the unclosed filter channel (321), or alternatively, less than 10% of the incoming gas entering the accommodating space can enter the gap G between the first support surface (312) and the second support surface (322). In another embodiment of the present invention, preferably, the first support surface (312) and the second support surface (322) each further have a surface roughness (Sa) in the range of 13 nm to 100 nm. Such surface roughness can promote an effective airtight seal between the base (310) and the lid (320), and further so that when the gas volume within the container (300) of the present invention begins to increase from a vacuum state, at least 90% to 95% of the incoming gas entering the storage space will enter through the unclosed filter channel (321), or alternatively, less than 5% to 10% of the incoming gas entering the storage space will enter through the gap G between the first support surface (312) and the second support surface (322).

[0034] It should be understood that, in the present invention, an effective hermetic seal does not mean that no gas passes through the seal formed by the first support surface (312) and the second support surface (322). Instead, an effective hermetic seal means that, in a particular environment, the container (300) of the present invention can achieve a hermetic seal with the requirements set forth above to meet the requirements of a particular process or facility.

[0035] FIG. 6A is a schematic diagram of a contact interface between a base and a lid according to an embodiment of the present invention. In this embodiment, an annular contact interface (701) is formed between the base (310) and the lid (320) shown in FIG. 5A. The contact interface (701) surrounds the top horizontal surface (311) of the base (310). The lower contact surface (first support surface (312)) and the upper contact surface (second support surface (322)) of the contact interface (701) have the same slope compared to the top horizontal surface (311). The contact interface (701) has a gap G, as shown in the enlarged partial view of FIG. 11B. Preferably, the gap G of the contact interface (701) does not exceed 0.08 mm, thereby achieving the effective hermetic seal described in the present invention. Additionally, the upper and lower contact surfaces of the contact interface (701) each have a surface roughness (Sa) ranging from 13 nm to 100 nm, which can further promote an effective hermetic seal between the base (310) and the lid (320).

[0036] FIG. 6B is a cross-sectional view of the contact interface between the base (310) and the lid (320) taken along the line A-A in FIG. 6A. Based on the embodiment shown in FIG. 6A, the base (310) of the present invention can have different embodiments as shown in FIGS. 6C-6E. The contact interface (701) can be parallel to the top horizontal surface (301) or can be inclined relative to the top horizontal surface (311). In one embodiment, the base (310) of the present invention has an annular groove (700) formed surrounding the top horizontal surface (311), such that the annular groove (700) is positioned between the top horizontal surface (311) and the contact interface (701). The grooves (700) are used to capture fine dust particles that enter the gap G from the space located outside the contact interface (701), so that the fine dust particles fall onto the bottom of the grooves (700) before reaching the top horizontal surface (311).

[0037] FIG. 7A is a schematic diagram of a contact interface between a base and a lid according to another embodiment of the present invention. In this embodiment, two annular contact interfaces (701, 702) surrounding the top horizontal surface (311) of the base (310) are formed between the base (310) and the lid (320), and the base (310) has an annular groove (400) formed between the two annular contact interfaces (701, 702). The function and effect of the annular groove (400) are the same as those of the annular groove (700) shown in FIGS. 6C-6E. Based on the B-B section shown in FIG. 7A for this embodiment, the base (310) of the present invention can have different implementations, as shown in FIGS. 7B-7D. The lower and upper contact surfaces of each of the contact interfaces (701, 702) have the same slope relative to the top horizontal surface (311). For example, as shown in Fig. 7B, the contact interfaces (701, 702) and the top horizontal surface (311) are at the same height; as shown in Fig. 7C, the contact interfaces (701, 702) are at different heights from the top horizontal surface (311), and an annular groove (700) is formed between the contact interface (702) and the top horizontal surface (311) to increase the chance of particle capture; and as shown in Fig. 7D, the contact interfaces (701, 702) are at different heights from each other, and an annular groove (700) is formed between the contact interface (702) and the top horizontal surface (311) to increase the chance of particle capture. Preferably, the gap G of at least one of the contact interfaces (701, 702) does not exceed 0.08 mm, thereby achieving an effective hermetic seal according to the present invention. Furthermore, the upper and lower contact surfaces of the contact interfaces (701, 702) each have a surface roughness (Sa) ranging from 13 nm to 100 nm, which can further promote an effective hermetic seal between the base (310) and the lid (320).

[0038] FIG. 8A is a schematic diagram of a contact interface between a base and a lid according to yet another embodiment of the present invention. In this embodiment, two annular contact interfaces (701, 702) surrounding the top horizontal surface (311) of the base (310) are formed between the base (310) and the lid (320), and the base (310) has an annular groove (400) formed between the two annular contact interfaces (701, 702) at different heights. The function and effect of the annular groove (400) are identical to those of the annular groove (700) shown in FIGS. 6C-6E. Based on the cross-sectional line CC shown in FIG. 8A for this embodiment, the base (310) of the present invention may have different implementations, as shown in FIGS. 8B-8D. The lower and upper contact surfaces of each of the contact interfaces (701, 702) have the same slope relative to the top horizontal surface (311). For example, as shown in FIG. 8B, the contact interface (702) and the top horizontal surface (311) are at the same height, while the contact interface (701) is parallel to the top horizontal surface (311) but at a different height. Also, as shown in FIG. 8C, the contact interface (701) is parallel to the top horizontal surface (311) but at a different height, while the contact interface (702) is tilted relative to the top horizontal surface (311). And, as shown in FIG. 8D, the contact interface (702) and the top horizontal surface (311) are at different heights, while the contact interface (701) is tilted relative to the top horizontal surface (311). Preferably, the gap G of at least one of the contact interfaces (701, 702) does not exceed 0.08 mm, thereby achieving the effective hermetic seal described in the present invention. Furthermore, the upper and lower contact surfaces of the contact interfaces (701, 702) each have a surface roughness (Sa) ranging from 13 nm to 100 nm, which can further promote an effective hermetic seal between the base (310) and the lid (320).

[0039] FIG. 9A is a schematic diagram of a contact interface between a base and a lid according to yet another embodiment of the present invention. In this embodiment, three adjacent contact annular interfaces (701, 702, 703) are formed between the base (310) and the lid (320) to surround the top horizontal surface (311) of the base (310). Based on the D-D section shown in FIG. 9A for this embodiment, the base (310) may have the structure shown in FIG. 9B, in which the base (310) has an annular groove (700) formed between the top horizontal surface (311) and the contact interface (703) to capture fine dust particles that enter the gap G from the space outside the contact interface. The lower and upper contact surfaces of the contact interfaces (701, 702, 703) have the same slope, and the structures of the lower and upper contact surfaces are complementary to each other. Preferably, the gap G of at least one of the contact interfaces (701, 702, 703) does not exceed 0.08 mm, so that an effective hermetic seal according to the present invention can be achieved. Furthermore, the upper and lower contact surfaces of the contact interfaces (701, 702, 703) each have a surface roughness (Sa) ranging from 13 nm to 100 nm, which can further promote an effective hermetic seal between the base (310) and the lid (320).

[0040] As will be appreciated by those skilled in the art, in the embodiment shown in Figures 6A-9B, the configuration of each first support surface (312) is matched to the configuration of each second support surface (322). In this way, at least one or more contact interfaces (which may be located at different horizontal levels or heights) can be achieved, and further, all of the first support surfaces are in contact with all of the second support surfaces when the lid is engaged with the base.

[0041] Figure 11A is a cross-sectional view based on cross-section (CS1) shown in Figure 5B, illustrating that by selecting the appropriate flatness of the base (310) and lid (320) when they are joined together, an effective hermetic seal can be achieved. As Figure 11A shows, even when viewed more closely, the base (310) and lid (320) are not in total contact with each other due to flexure. That is, the first support surface (312) and the second support surface (322) may contact each other at their two end points, but each may have a slight recess near their midpoint, resulting in a gap due to flexure. According to an embodiment of the present invention, when the first support surface (312) and the second support surface (322) each have a flatness of, for example, 0.015 mm, the base (310) and the lid (320) can still achieve an effective hermetic seal even if a gap exists between them due to deflection while they are joined together.

[0042] FIG. 11B is a partially enlarged schematic diagram based on the cross section (CS2) shown in FIG. 5B, showing the first support surface (312) and the second support surface (322) when they are in contact. Due to waviness caused by low-frequency factors during machining, the contact interface between the first support surface (312) and the second support surface (322) has a gap G. It should be understood that the above-mentioned waviness is different from deflection. The flatness adjustment according to the present invention can achieve an effective hermetic seal even when gaps occur due to waviness or deflection within the container. FIG. 11C is also a schematic diagram based on the cross section (CS2) shown in FIG. 5B, showing the respective flatnesses of the first support surface (312) of the base (310) and the second support surface (322) of the lid (320). The flatness of the first bearing surface (312) of the base (310) is denoted as d1, and the flatness of the second bearing surface (322) of the lid (320) is denoted as d2. When the base (310) is engaged with the lid (320), the contact interface formed between the first bearing surface (312) and the second bearing surface (322) has a variable gap G, where G is less than or equal to d1 + d2. Thus, in an embodiment of the present invention where the flatness of each is 0.04 mm, G will not exceed 0.08 mm, thereby achieving an effective hermetic seal.

[0043] Based on the above-described embodiment, the hermetic seal between the base and lid of the container is achieved simply by contact between two surfaces, particularly between two metal surfaces, while the flatness and / or roughness (Sa) of the relevant surfaces are limited using the technical means disclosed in the present invention. Therefore, the hermetic seal formed between the relevant surfaces allows at least 90% of the gas contained in the container's storage space to enter through the filter channel in the lid, and less than 10% of the gas to enter through the gap between the contacting surfaces. Such a hermetic seal is considered effective and successful in certain relevant manufacturing processes or environments. [Explanation of symbols]

[0044] 110 inner pod assembly 120 Top lid 130 Lower lid 140 Pressure Unit 150 outer pod assembly 160 base 300 containers 310 base 312 first support surface 313 Support assembly 320 Lid 321 Filter Channel 322 Second Support Surface 700 Annular groove 701 Contact Interface 800 vacant spaces 801, 802 Control valve

Claims

1. A container for accommodating a substrate, a container having a base and a lid, the base having a first support surface, the lid having a second support surface and a filter channel, the first support surface of the base contacting the second support surface of the lid when the base and the lid are combined to thereby define a storage space, and the filter channel being operable to be in a closed or open state such that the storage space is in communication with an exterior space of the container via the filter channel; the first support surface and the second support surface each have a flatness, the flatness being in a range of 1 μm to 0.04 mm, and the flatness forms an effective seal between the first support surface and the second support surface; When the container is operated under a gas return operation, the container allows the gas to enter the storage space defined by the base and the lid, and 90% to 95% of the gas enters the storage space through the filter channel in an unclosed state, and 5% to 10% of the gas enters the storage space through a gap defined between the first support surface and the second support surface by the flatness.

2. 2. The container of claim 1, wherein the first support surface has a first area and the second support surface has a second area, the flatness of the first support surface being defined by a maximum height (Rz) across the first area and the flatness of the second support surface being defined by a maximum height across the second area.

3. 3. The container of claim 2, wherein the first support surface and the second support surface are each annular support surfaces, and the first region and the second region are each annular regions.

4. The container of claim 1 , wherein the base has an annular groove formed thereon and surrounded by the first support surface.

5. The container of claim 1 , wherein the first support surface and the second support surface both have corrugation features due to low frequency processing factors and roughness features due to high frequency processing factors.

6. The container of claim 5, wherein the first support surface and the second support surface have a surface roughness (Sa) in the range of 13 nm to 100 nm.

7. 6. The container of claim 5, wherein the gap defined between the first support surface and the second support surface is less than 0.08 mm.

8. The base has a top horizontal surface, The container of claim 1 , wherein the first support surface and the second support surface are inclined relative to the top horizontal plane.

9. When the container is operated under a vacuum, a pressure difference is generated between the storage space and the external space of the container, The container of claim 6 , wherein the pressure difference exceeds 100 Pa due to the flatness and the surface roughness.

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