CONTAINER FOR ACCOMMODATING SUBSTRATE WITH EFFECTIVE HERMETIC SEALING

Abstract

The invention discloses a container for accommodating a substrate. The container includes a base having at least one first supporting surface and a lid having at least one second supporting surface to engage with the first supporting surface 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 respective 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.

Claims

1. A container for accommodating a substrate, comprising: a base having a top horizontal surface and at least one first supporting surface surrounding the top horizontal surface; and a lid covering the top horizontal surface and engaging with the first supporting surface to thereby define an accommodating space for accommodating the substrate, the lid having at least one filtering channel and at least one second supporting surface surrounding the accommodating space, wherein the second supporting surface is configured to match with the first support surface, the first supporting surface of the base and the second supporting surface of the lid have a consistent slope relative to that of the top horizontal surface, the first supporting surface of the base and the second supporting surface of the lid both have a flatness less than 0.04 mm to thereby form a hermetical seal when the first supporting surface contacts with the second supporting surface contact.

2. The container as claimed in claim 1, wherein the filter channel is closed, a pressure difference is created between the accommodating space and an outer space of the container with the flatness defined by the first supporting surface and the second supporting surface.

3. The container as claimed in claim 2, wherein the pressure difference is above 100 Pa.

4. The container as claimed in claim 1, wherein the accommodating space is vacuumed, and during a gas backfill process to an outer space of the container, the hermetical seal formed by the flatness of the first supporting surface and the second supporting surface causes an air flow entering the container with 90% thereof passing through the filter channel to enter the container.

5. The container as claimed in claim 1, wherein the accommodating space is vacuumed, and during a gas backfill process to an outer space of the container, the hermetical seal formed by the flatness of the first supporting surface and the second supporting surface causes an air flow entering the container with less than 10% thereof passing through a gap between the first supporting surface and the second supporting surface to enter the container.

6. The container as claimed in claim 1, wherein the first supporting surface of the base has a surface roughness (Sa) and the second supporting surface of the lid has a surface roughness, said surface roughness is of a range from 13 to 100 nm.

7. The container as claimed in claim 1, wherein the base has at least two supporting surfaces encircling the top horizontal surface, the first supporting surfaces and the second supporting surface have a consistent slope relatively to the top horizontal surface, and the first supporting surfaces have a largest flatness that is below 0.04 mm.

8. The container as claimed in claim 7, wherein the base has a groove defined by and between the first supporting surfaces encircling the top horizontal surface.

9. The container as claimed in claim 1, wherein the first supporting surface contacts with the second supporting surface to form at least one contact interface therebetween to encircle the top horizontal surface.

10. The container as claimed in claim 9, wherein the contact interface has a gap less than 0.08 mm.

11. The container as claimed in claim 9, wherein the contact interface has a plane that is not at a level identical to or parallel to that of the horizontal surface.

12. The container as claimed in claim 9, wherein the base has at least two first supporting surfaces encircling the top horizontal surface, the first supporting surfaces contact with the second supporting surface to form at least two contact interfaces encircling the top horizontal surface.

13. The container as claimed in claim 12, wherein the base has at least one groove defined between the two contact interfaces and encircling the top horizontal surface.

14. The container as claimed in claim 9, wherein the at least one contact interface has a plane that is not at a level identical to or parallel to that of the top horizontal surface.

15. A container for accommodating a substrate, comprising: a base having a top horizontal surface; and a lid having at least one filter channel and a storage space, wherein the lid contacts with the base, the storage space and the top horizontal surface define an accommodating space for accommodating the substrate, at least one contact interface is defined between the lid and base to encircle the top horizontal surface and thereby seal the accommodating space, the contact interface has a gap less than 0.08 mm.

16. The container as claimed in claim 15, wherein a surface of the base defining the contact interface and a surface of the lid defining the contact interface have a flatness less than 0.04 mm.

17. The container as claimed in claim 15, wherein the contact interface has a plane that is not at a level identical to or parallel to that of the top horizontal surface.

18. The container as claimed in claim 15, wherein the lid contacts with the base to define at least two contact interfaces, and the base has at least one groove encircling the top horizontal surface and spacing the contact interfaces and the top horizontal surface.

19. The container as claimed in claim 18, wherein one of the at least two contact interfaces has a plane that is not at a level identical to or parallel to that of the top horizontal surface.

20. The container as claimed in claim 15, wherein the filter channel is closed, a pressure difference is created between the accommodating space and an outer space of the container with a hermetical seal formed by the contact interface.

21. The container as claimed in claim 20, wherein the pressure difference is above 100 Pa.

22. The container as claimed in claim 15, wherein the accommodating space is vacuumed, and during a gas backfill process to an outer space of the container, the hermetical seal formed by the contact interface causes an air flow entering the container with 90% thereof passing through the filter channel to enter the container.

23. The container as claimed in claim 15, wherein the accommodating space is vacuumed, and during a gas backfill process to an outer space of the container, the hermetical seal formed by the contact interface causes an air flow entering the container with less than 10% thereof passing through a gap of the contact interface.

24. The container as claimed in claim 15, wherein a surface of the base defining the contact interface and a surface of the lid defining the contact interface have a surface roughness (Sa) that is of a range from 13 to 100 nm.

25. A container for accommodating a substrate, comprising: a base having a top horizontal surface and at least one first supporting surface encircling the top horizontal surface; and a lid having at least one filter channel, a bottom surface and a flange encircling the bottom surface, the flange having at least one second supporting surface encircling the bottom surface, the second supporting surface at least in part contacting with the first supporting surface of the base such that the bottom surface, the flange and the top horizontal surface define an accommodating space for accommodating the substrate, wherein the first supporting surface and the second supporting surface have a flatness less than 0.04 mm, which causes a hermetical seal to the accommodating space.

26. The container as claimed in claim 25, wherein the filter channel is closed, a pressure difference is created between the accommodating space and an outer space of the container with the hermetical seal formed by the flatness of first supporting surface and the flatness of second supporting surface.

27. The container as claimed in claim 26, wherein the pressure difference is above 100 Pa.

28. The container as claimed in claim 25, wherein the accommodating space is vacuumed, and during a gas backfill process to an outer space of the container, the hermetical seal formed by the flatness of the first supporting surface and the flatness of the second supporting surface causes an air flow entering the container with 90% thereof passing through the filter channel to enter the container.

29. The container as claimed in claim 25, wherein the accommodating space is vacuumed, and during a gas backfill process to an outer space of the container, the hermetical seal formed by the flatness of the first supporting surface and the flatness of the second supporting surface causes an air flow entering the container with less than 10% thereof passing through a gap between the first supporting surface and the second supporting surface.

30. The container as claimed in claim 25, wherein a surface of the base and a surface of the lid have a surface roughness (Sa) that is of a range from 13 to 100 nm.

31. The container as claimed in claim 25, wherein the first supporting surface and the second supporting surface have a consistent slope relatively to that of the top horizontal surface.

32. The container as claimed in claim 25, wherein the base has at least two first supporting surfaces encircling the top horizontal surface, and the first supporting surfaces have the flatness that is less than 0.04 mm.

33. The container as claimed in claim 32, wherein the base has a groove defined between the two first supporting surfaces and encircling the top horizontal surface.

34. The container as claimed in claim 32, wherein at least one of the first supporting surfaces has a plane that is not at a level identical to or parallel to that of the top horizontal surface.

35. The container as claimed in claim 25, wherein the first supporting surfaces contact with the second supporting surface to for at least one contact interface encircling the top horizontal surface.

36. The container as claimed in claim 35, wherein the contact interface has a gap less than 0.08 mm.

37. A container for accommodating a substrate, comprising: a base having a top horizontal surface; and a lid having at least one filter channel and a storage space, wherein the lid contacts with the base, the storage space and the top horizontal surface define an accommodating space for accommodating the substrate, and at least one contact interface is formed between the lid and the base to encircle the top horizontal surface to thereby seal the accommodating space, wherein the contact interface has a gap which determines a pressure difference between the accommodating space and an outer space of the container when the filter channel is closed, where the pressure difference is above 100 Pa.

38. A container for accommodating a substrate, comprising: a base having a top horizontal surface; and a lid having at least one filter channel and a storage space, wherein the lid contacts with the base, the storage space and the top horizontal surface define an accommodating space for accommodating the substrate, and at least one contact interface is formed between the lid and the base to encircle the top horizontal surface, wherein the contact interface has a gap, the accommodating space is vacuumed, and during a gas backfill process to an outer space of the container, the gap determines an air flow entering into the container has 90% thereof passing through the filter channel to enter the container.

39. A method for controlling air flow entering into a container, the container including a base having a top horizontal surface; and a lid having at least one filter channel, the lid contacting with the base to define an accommodating space, the method comprising: forming at least one contact interface between the base and the lid to encircle the accommodating space, the contact interface having a gap; controlling the gap, when the filter channel is closed, to determine a pressure difference between the accommodating space and an outer space of the container above 100 Pa; and performing a gas backfill process to the outer space of the container in which the accommodating space is vacuumed and the filter channel is opened, causing an air flow entering into the container with 90% thereof passing through the filter channel.

40. The method as claimed in claim 39 further comprising: controlling the gap pf the contact interface less to be than 0.08 mm.

41. The method as claimed in claim 39 further comprising: controlling a first supporting surface of the base to have a flatness less than 0.04 mm.

42. The method as claimed in claim 39 further comprising: controlling a second supporting surface of the lid to have a surface roughness (Sa) of a range from 13 to 100 nm.

43. The method as claimed in claim 39 further comprising: controlling a second supporting surface of the lid to have a flatness less than 0.04 mm.

44. The method as claimed in claim 39 further comprising: controlling a second supporting surface of the lid to have a surface roughness of a range from 13 to 100 nm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention can be understood more thoroughly with reference to the accompanying drawings and the descriptions given below. Various examples, which are not intended to be limiting and exhaustive, will be described with reference to the drawings. The elements shown in the drawings are not necessarily illustrated to actual scale for the purpose of explaining the structures and relevant principles.

[0022] FIG. 1 is an exploded perspective view of a prior art EUV reticle pod.

[0023] FIG. 2 is a schematic diagram showing the process of obtaining the roughness average (Ra) based on a center line of the roughness curve.

[0024] FIG. 3 is a schematic view showing the waviness, which is related to the flatness, in a workpiece surface.

[0025] FIG. 4 is a schematic view showing the deflection, which is related to the flatness, in another workpiece surface.

[0026] FIG. 5A is an exploded perspective view of a container (e.g., a reticle pod) for accommodating a substrate.

[0027] FIG. 5B shows cross-sections at the edges of the container when the lid and the base are joined together.

[0028] FIG. 6A is a schematic view showing the contact interface between the base and the lid according to one embodiment of the invention.

[0029] FIGS. 6B to 6E are cross-sectional views showing different examples of the contact interface between the base and the lid along the section line A-A shown in FIG. 6A, based on the embodiment illustrated in FIG. 6A.

[0030] FIG. 7A is a schematic view showing the contact interfaces between the base and the lid according to another embodiment of the invention.

[0031] FIGS. 7B to 7D are cross-sectional views showing different examples of the contact interfaces between the base and the lid along the section line B-B shown in FIG. 7A, based on the embodiment illustrated in FIG. 7A.

[0032] FIG. 8A is a schematic view showing the contact interfaces between the base and the lid according to yet another embodiment of the invention.

[0033] FIGS. 8B to 8D are cross-sectional views showing different examples of the contact interfaces between the base and the lid along the section line C-C shown in FIG. 8A, based on the embodiment illustrated in FIG. 8A.

[0034] FIG. 9A is a schematic view showing the contact interfaces between the base and the lid according to still another embodiment of the invention.

[0035] FIG. 9B is a cross-sectional view showing the contact interfaces between the base and the lid along the section line D-D shown in FIG. 9A, based on the embodiment illustrated in FIG. 9A.

[0036] FIG. 10 shows an example as to how the pressure inside and outside the container for accommodating a substrate is tested.

[0037] FIG. 11A is a schematic view showing the gap between the contacting surfaces resulting from deflections when the lid and the base are joined together.

[0038] FIG. 11B is a schematic enlarged view of the gap and the related waviness between the lid and the base when they are joined and in contact with each other.

[0039] FIG. 11C is a schematic view showing the respective flatness of the first supporting surface of the base and the second supporting surface of the lid (here, the base and lid are not joined together).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] A more complete description of the present invention is provided below with reference to the accompanying drawings, and examples are provided to demonstrate exemplary embodiments. Nevertheless, the claimed subject matter of the present invention can be implemented in various forms, and therefore the construction of the covered or claimed subject matters shall not be limited to any exemplary embodiment disclosed in this description; the exemplary embodiments are merely provided as examples. Likewise, the present invention is intended to provide a reasonably broad scope for the claimed or covered subject matters. Besides, for example, a claimed subject matter may be implemented as a method, device, or system. Therefore, a specific embodiment may be in the form of, for example, hardware, software, firmware, or any combination (known to be non-software) thereof.

[0041] The term “an embodiment” used in this description does not necessarily refer to exactly the same embodiment, and the term “other (some/certain) embodiments” used in this description does not necessarily refer to different embodiments. The purpose of this description is to explain the claimed subject matter using examples that include combinations of all or part of the exemplary embodiments. The term “a contact interface” used in this description shall refer to an interface where “an upper contacting surface” and “a lower contacting surface” contact each other. The upper contacting surface or lower contacting surface discussed in the present invention shall refer to the actual surfaces of a workpiece, not ideal ones. Therefore, the “upper contacting surface” and “lower contacting surface” each has a “flatness” that represents the maximum height (Rz) of the actual surfaces; the “contact interface” may contain an interstice or gap defined by the respective flatness of the “upper contacting surface” and “lower contacting surface.”

[0042] FIG. 5A shows a container (300) for accommodating a substrate; particularly, the container may be a reticle pod. In an embodiment of the present invention, the container (300) is suitable to serve as an inner pod assembly for a reticle pod. The container (300) comprises a base (310) and a lid (320). The base (310) comprises a top horizontal surface (311) and at least one first supporting surface (312) that surrounds the top horizontal surface (311), wherein the top horizontal surface (311) is a flat plane which is suitable for placing a substrate (e.g., a reticle) thereon. The top horizontal surface (311) also includes a plurality of supporting assemblies (313); each supporting assembly (313) has pillars for restricting a side surface of the substrate, and a bump (not shown), which is usually disposed between two pillars, for supporting the bottom surface of the substrate. As shown in FIG. 5A, the first supporting surface (312) is an annular plane adjacent to the periphery of the top horizontal surface (311). The first supporting surface (312) is substantially a continuous upward-facing surface intended to contact a corresponding surface of the lid (320).

[0043] The lid (320) comprises a second supporting surface (322), which surrounds the top horizontal surface (311) of the base (310) and engages with the first supporting surface (312). The lid (320) has a receiving space, which, together with the top horizontal surface (311), defines an accommodating space for accommodating the substrate. Methods to achieve the engagement include the contact of upper and lower surfaces, using a bump and groove structure, or having two complementary structures join together. Although other perspectives of the lid (320) are not shown herein, a person skilled in the art could understand that the lid (320) comprises at least an annular part extending downward, to the effect that when the base (310) and the lid (320) are joined together, the downwardly extending annular part of the lid (320) will contact the base (310) and surround the top horizontal surface (311) of the base, while the second supporting surface (322) is the lower surface of the annular part. In an embodiment, the lid (320) may have at least one filter channel (321) and at least one second supporting surface (322) with an annular shape. The second supporting surface (322) is employed to match with the supporting surface (312) of the base (310). The contour of the second supporting surface (322) is substantially consistent with the first supporting surface (312), and the second supporting surface (322) may have an area slightly larger or smaller than that of the first supporting surface (312).

[0044] When the base (310) engages with the lid (320), the first supporting surface (312) and the second supporting surface (322) will contact each other. As shown in FIG. 5B, the base (310) is in contact with the lid (320), and as a cross-section (CS1) along an edge of the container (300) in the figure shows, a contact interface (701) formed between the base (310) and the lid (320) can be seen. Visually speaking, the contact interface (701) demonstrates a straight line. However, as shown in FIG. 4, the low-frequency factors during machining will cause deflection of the first supporting surface (312) of the base (310) and the second supporting surface (322) of the lid (320) respectively. Therefore, the contact interface (701) shown from the view of the cross-section (CS1) may, in fact, not be a perfect straight line. How to achieve effective sealing with a deflected surface will be explained in the following paragraphs. Also, as shown in FIG. 5B, when the container (300) is viewed from another cross-section (CS2) at a different position, other relations between the first supporting surface (312) and second supporting surface (322) can be observed, and the details will be provided in the following paragraphs.

[0045] As the cross-section (CS2) in FIG. 5B shows, the first supporting surface (312) of the base (310) and the second supporting surface (322) of the lid (320) can be designed to have different slopes. In one embodiment, the first supporting surface (312) of the base (310) and the second supporting surface (322) of the lid (320) have consistent slopes relative to the top horizontal surface (311). For example, the first supporting surface (312) is a horizontal plane, and the second supporting surface (322) is also a horizontal plane, as shown in FIGS. 6B and 6C. Alternatively, in another embodiment, the first supporting surface (312) is inclined downward in the direction of the top horizontal surface (311), and the second supporting surface (322) is also inclined in the same way, as shown in FIGS. 6D and 6E. In a preferred embodiment of the present invention, in order to achieve effective sealing between the base (310) and the lid (320), the first supporting surface (312) and the second supporting surface (322) each has a flatness that is lower than 0.04 millimeters (mm), so as to form a hermetic seal between the first supporting surface (312) and the second supporting surface (322) when they are in contact. Preferably, the flatness ranges between 1 micron (μm) and 0.04 mm. The flatness can be measured with a known method, and will not be repeated here.

[0046] In the embodiments of the present invention, by controlling the respective flatness of the first supporting surface (312) and the second supporting surface (322), an effective hermetic seal between the base (310) and the lid (320) can be obtained. The better hermetic seal in the contact interface between the base (310) and the lid (320), the greater pressure difference between the inside and outside of the container can be done during gas backfill process in which the container is placed in a vacuum environment with the filter channel closed. Also, with the better hermetic seal, more amount of gas can pass through the filter channel which is opened during gas backfill process. In particular, if the flatness of each supporting surface ranges between 1 μm and 0.04 mm and an effective hermetic seal between the base (310) and the lid (320) is achieved, when the volume of gas around the container (300) begins to increase from a vacuum state, at least 90% of the incoming gas entering the accommodating space of the container (300) enters through the unclosed filter channel (321) and less than 10% of the incoming gas entering the accommodating space enters through the gap G between the first supporting surface (312) and second supporting surface (322), or through other window gaps, gaps on the lid (320) related to the pressing units, etc. Since other window gaps, and gaps on the lid (320) related to the pressing units are often given sealing rings to enhance hermetic sealing, the less than 10% incoming gas entering the accommodating space enters mainly through the gap G between the first supporting surface (312) and the second supporting surface (322).

[0047] To evaluate if the respective flatness of the first supporting surface (312) and the second supporting surface (322) can allow at least 90% of the incoming gas entering the accommodating space of the container (300) to enter through the unclosed filter channel (321), the present invention hereby provides a testing method, as shown in FIG. 10. A cavity (800), which can be regarded as a cavity within a gas exchange chamber of an EUV exposure machine, is provided. The gas volume within the cavity (800) could start to increase by opening a valve (801) and closing the other valve (802) to control the gas supply. By closing the valve (801) and opening the other valve (802) to control the gas supply, a vacuum within the cavity (800) can be obtained. The testing method of the present invention uses the same vacuum pump/gas increase curve-controlling valves (801, 802) to monitor the difference between the pressure of the accommodating space (P.sub.inside) of the container (300) and the pressure of the cavity (800) (P.sub.outside) when the container (300) is placed within the cavity (800). When a vacuum within the accommodating space is obtained and the gas volume in the cavity (800) starts to increase, the pressure P.sub.inside is lower than the pressure P.sub.outside. When a vacuum within the cavity (800) is obtained, the pressure P.sub.inside is higher than the pressure P.sub.outside.

[0048] In the case where the filter channel (321) is not closed, when the container (300) of the invention is placed within the cavity (800), the channel (321) will be the major fluid passage for the accommodating space of the container (300). In the case where the filter channel (321) is closed, when the container (300) of the present invention is placed within the cavity (800), the major fluid passage between the accommodating space of the container (300) and the space external to the container (300) will be the gap G between the first supporting surface (312) and second supporting surface (322) as described above. It should be noted that the fluid passages formed around other window gaps and around other interstices of the lid (320) related to the pressing units can be ignored or are considered as controllable and predictable affecting factors. In a testing method provided by the present invention, the container (300) is placed within the cavity (800) with the filter channel (321) unclosed. The same vacuum pump/gas increase curve-controlling valves (801, 802) are used to monitor the difference between the pressure P.sub.inside and the pressure P.sub.outside. The testing method includes determining whether the difference between the pressure P.sub.inside and the pressure P.sub.outside has reached 100 Pa and above by controlling the pumping out/filling of the gas per second and monitoring the pressure changes. The gas in the cavity (800) is first pumped out to create a vacuum with the pressure P.sub.outside reaching 500 Pa. Then, with the base (310) engaged with the lid (320), the gas is backfilled into the cavity (800) again. If more than 100 Pa difference between the pressure P.sub.inside and the pressure P.sub.outside can be observed, that ensures at least 90% of an airflow entering the accommodating space passing through the unclosed filter channel (321) and less than 10% of the airflow entering the accommodating space passing through the gap (G) between the first supporting surface (312) and second supporting surface (322).

[0049] In a preferred embodiment of the present invention, if the flatness of each of the first support surface (312) and the second support surface (322) ranges between 1 μm and 0.04 mm, when the gas volume within the container (300) begins to increase from a vacuum state, 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 through the gap G between the first supporting surface (312) and second supporting surface (322). In a further embodiment of the present invention, preferably, the first supporting surface (312) and the second supporting surface (322) each further has a surface roughness (Sa) ranging between 13 and 100 nm. Such surface roughness can enhance the effective hermetic sealing between the base (310) and the lid (320), and moreover, it can ensure that when the gas volume within the container (300) of the present invention begins to increase from a vacuum state, at least 90%-95% of the incoming gas entering the accommodating space enters through the unclosed filter channel (321), or that alternatively, less than 5%-10% of the incoming gas entering the accommodating space enters through the gap G between the first supporting surface (312) and second supporting surface (322).

[0050] It should be understood that in the present invention, the effective hermetic sealing does not mean that no gas will break through the seal formed by the first supporting surface (312) and the second supporting surface (322). Rather, it means that in certain specific environments, the container (300) of present invention can achieve hermetic sealing with the abovementioned conditions in order to meet the requirements of certain processes or equipment.

[0051] FIG. 6A shows a schematic view of a contact interface between the base and the lid according to an embodiment of the invention. In this embodiment, an annular contact interface (701) is formed between the base (310) and the lid (320) that are shown in FIG. 5A; the contact interface (701) surrounds a top horizontal surface (311) of the base (310), wherein the lower contacting surface (the first supporting surface (312)) and upper contacting surface (the second supporting surface (322)) of the contact interface (701) have the same slope compared with the top horizontal surface (311). The contact interface (701) has a gap G, as shown in the partial enlarged view of FIG. 11B. Preferably, the gap G of the contact interface (701) does not exceed 0.08 mm, and therefore can realize the effective hermetic sealing described in the present invention. In addition, the upper contacting surface and the lower contacting surface of the contact interface (701) each has a surface roughness (Sa) that ranges between 13 and 100 nm and can further enhance the effective hermetic sealing between the base (310) and the lid (320).

[0052] FIG. 6B shows a cross-sectional view illustrating the contact interface between the base (310) and the lid (320) along the section line A-A as shown in FIG. 6A. Based on the embodiment illustrated in FIG. 6A, the base (310) of the present invention can have different implementation examples, as shown in FIGS. 6C to 6E. The contact interface (701) may be parallel to the top horizontal surface (311), or inclined compared with the top horizontal surface (311). In one example, the base (310) of the present invention has an annular groove (700) formed surrounding the top horizontal surface (311), so that the annular groove (700) is positioned between the top horizontal surface (311) and the contact interface (701). The groove (700) is used to capture fine dust particles entering the gap G from the space external to the contact interface (701), so that the fine dust particles will fall on the bottom of the groove (700) before reaching the top horizontal surface (311).

[0053] FIG. 7A shows a schematic view of the contact interfaces between the base and the lid according to another embodiment of the invention. In this embodiment, two annular contact interfaces (701, 702) are formed between the base (310) and the lid (320) to surround a top horizontal surface (311) of the base (310), wherein 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 to 6E. Based on the section line B-B shown in FIG. 7A for this embodiment, the base (310) of the present invention can have different implementation examples, as shown in FIGS. 7B to 7D. The lower contacting surface and the upper contacting surface of each of the contact interfaces (701, 702) have the same slope compared with 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 a different height 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; as shown in FIG. 7D, the contact interfaces (701, 702) are at different heights, 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, so that the effective hermetic sealing according to the present invention can be realized. Furthermore, the upper contacting surface and the lower contacting surface of the contact interfaces (701, 702) each has a surface roughness (Sa) that ranges between 13 and 100 nm and can further enhance the effective hermetic sealing between the base (310) and the lid (320).

[0054] FIG. 8A shows a schematic view of the contact interfaces between the base and the lid according to yet another embodiment of the invention. In this embodiment, two annular contact interfaces (701, 702) are formed between the base (310) and the lid (320) to surround a top horizontal surface (311) of the base (310), wherein the base (310) has an annular groove (400) formed between the two annular contact interfaces (701, 702), which are at different heights from each other. The function and effect of the annular groove (400) are the same as those of the annular groove (700) shown in FIGS. 6C to 6E. Based on the section line C-C shown in FIG. 8A for this embodiment, the base (310) of the present invention can have different implementation examples, as shown in FIGS. 8B to 8D. The lower contacting surface and the upper contacting surface of each of the contact interfaces (701, 702) have the same slope compared with 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) and at a different height from it. And as shown in FIG. 8C, the contact interface (701) is parallel to the top horizontal surface (311) and at a different height from it, while the contact interface (702) is inclined compared with the top horizontal surface (311). And further 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 inclined compared with 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, so that the effective hermetic sealing according to the present invention can be realized. Furthermore, the upper contacting surface and the lower contacting surface of the contact interfaces (701, 702) each has a surface roughness (Sa) that ranges between 13 and 100 nm and can further enhance the effective hermetic sealing between the base (310) and the lid (320).

[0055] FIG. 9A shows a schematic view of the contact interfaces between the base and the lid according to still another embodiment of the invention. In this embodiment, three annular contact interfaces (701, 702, 703), which are continuously adjacent to one another, are formed between the base (310) and the lid (320) to surround a top horizontal surface (311) of the base (310). Based on the section line D-D shown in FIG. 9A for this embodiment, the base (310) can have a structure as shown in FIG. 9B, where 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 entering the gap G from the space external to the contact interface. Each lower contacting surface and upper contacting surface of the respective contact interfaces (701, 702, 703) has the same slope, with the structures of the lower contacting surface and the upper contacting surface being 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 the effective hermetic sealing according to the present invention can be realized. Furthermore, the upper contacting surface and the lower contacting surface of the contact interfaces (701, 702, 703) each has a surface roughness (Sa) that ranges between 13 and 100 nm and can further enhance the effective hermetic sealing between the base (310) and the lid (320).

[0056] A person having ordinary skill in the art would understand that in the embodiments shown in FIG. 6A through FIG. 9B, the structure of each first supporting surface (312) is adapted to match with that of each second supporting surface (322). In this manner, at least one or more contact interfaces (which can even be at different horizontal levels or heights) can be achieved; moreover, it can ensure that all the first supporting surfaces are in contact with all the second supporting surfaces when the lid is engaged with the base.

[0057] FIG. 11A is a schematic view based on the cross section (CS1) shown in FIG. 5B, showing that the base (310) and the lid (320), when joined together, can achieve an effective hermetic seal by choosing a respective proper flatness. As FIG. 11A shows, in an even closer observation, the base (310) and the lid (320) may not be in entire contact with each other due to deflections. That is, the first supporting surface (312) and the second supporting surface (322) may contact each other at the two end points; however, each of them may have a slightly dented portion near the midpoint, which leads to a gap resulted from deflections. According to the embodiments of the present invention, when the first supporting surface (312) and the second supporting surface (322) each has a flatness of 0.015 mm, for example, the base (310) and the lid (320) can still achieve an effective hermetic seal while they are joined together, even if there is a gap between them due to deflections.

[0058] FIG. 11B is a partially enlarged schematic view based on the cross section (CS2) shown in FIG. 5B, illustrating the first supporting surface (312) and the second supporting surface (322) when they are in contact. Due to the waviness caused by low-frequency factors during machining, the contact interface between the first supporting surface (312) and the second supporting surface (322) has a gap G. It should be understood that the waviness described above is different from a deflection. The flatness control according to the present invention can achieve an effective hermetic seal even if there is a gap resulted from a waviness or deflection in the container. FIG. 11C is also a schematic view based on the cross section (CS2) shown in FIG. 5B; FIG. 11C illustrates the respective flatness of the first supporting surface (312) of the base (310) and the second supporting surface (322) of the lid (320). The flatness of the first supporting surface (312) of the base (310) is defined as d1, and the flatness of the second supporting surface (322) of the lid (320) is defined as d2. When the base (310) is engaged with the lid (320), the contact interface formed between the first supporting surface (312) and the second supporting surface (322) has a variable gap G, and the gap G is smaller or equals d1+d2. Therefore, in an embodiment of the invention where the respective flatness is 0.04 mm, the gap G will not exceed 0.08 mm, and an effective hermetic seal can be achieved accordingly.

[0059] Based on the embodiments described above, it can be seen that a hermetic seal between the base and the lid of the container is achieved simply by the contact between two surfaces, in particular the contact between two metal surfaces; meanwhile, the flatness and/or roughness (Sa) of an involved surface is restricted using the technical means disclosed in the present invention. As such, a hermetic seal formed between relevant surfaces can allow at least 90% of the gas entering the accommodating space of the container to enter through the filter channel of the lid, and less than 10% of the gas to enter through the gap between the contacting surfaces. Such a hermetic seal would be considered effective and successful in certain related manufacturing processes or environments.