Hermetically sealed hardened glass envelope and method of manufacturing the same

Abstract

The invention relates to a gastight closed housing comprising a base substrate and a cover substrate forming at least one part of the housing, at least one functional area enclosed by the housing, wherein at least the cover substrate preferably comprises a vitreous material, wherein the base substrate and the cover substrate are joined in a gastight manner with at least one laser bond, wherein the laser bond has a height HL perpendicular to its connection plane, wherein at least the cover substrate has a hardening layer, preferably a chemical hardening layer, on its surface at least on the side opposite to the laser bond, wherein the hardening layer preferably exerts compressive stress onto the cover substrate.

Description

Technical Field

[0001] The present invention relates to a transparent covering layer for a housing, a transparent housing, and a method for providing a plurality of airtight sealed housings. Background Technology

[0002] Hermetically sealed enclosures can be used to protect sensitive electronic devices, circuits, or, for example, sensors. Therefore, they can be used in medical implants, for example, in the heart region, the retina, or in biological processors. To date, enclosures made of titanium have been manufactured and used for these purposes.

[0003] Sensors can be protected with housings to withstand particularly harsh environmental conditions. This field also includes, for example, MEMS (microelectromechanical systems) and barometers.

[0004] Another area of ​​application for the casing according to the invention can be found in casings for smartphones, in the field of virtual reality glasses, and in similar devices.

[0005] The common thread among the aforementioned purposes is the high demand for robustness in electronic devices. Therefore, these devices are protected from environmental influences. Furthermore, it is necessary to ensure optical exchange with the internal areas of the enclosure, i.e., the cavity formed by the enclosure, where the enclosure must be at least partially transparent.

[0006] It is generally known that multiple parts are joined together and arranged such that a receiving area is created in the intermediate space that can accommodate the components. For example, European Patent EP 3 012 059 B1 discloses a method for manufacturing a transparent part for protecting optical components. A novel laser method is used here. Summary of the Invention

[0007] In this context, the invention should be considered as a modification of the housing and, in particular, a more resistant construction. This improves robustness against environmental influences and, for example, mechanical loads.

[0008] In other words, the object of this invention is to provide an improved housing for cavities to withstand more adverse environmental conditions and effects. Particular attention is paid to the mechanical stress on the housing to, for example, prevent edge breakage.

[0009] Another aspect of the invention is that it provides improvements to the housing in a particularly cost-effective, yet reliable and durable manner, because the improved housing must also maintain its position in a competitive market environment.

[0010] Therefore, within the scope of this invention, a method for providing multiple hermetically sealed housings is proposed. Although the method could also be easily modified to manufacture only a single housing, it is economically worthwhile to produce multiple housings in the same process sequence, as this saves time, cost, and raw materials.

[0011] According to the present invention, a hermetically sealed housing is provided, the housing comprising at least a base substrate and a cover substrate constituting at least a portion of the housing. In other words, for example, the cover substrate is laid flat on the base substrate such that the base substrate and the cover substrate are stacked. Preferably, this can be a wafer stack.

[0012] The housing surrounds at least one functional area, which can be configured to perform various tasks. For example, the functional area may include an active surface. The functional area preferably has a cavity, i.e., a hollow space surrounded by the housing. The cavity can be configured to mount or accommodate functional components, thereby involving a accommodating cavity.

[0013] The cover substrate preferably comprises at least partially a vitreous material. The vitreous material of the cover substrate is further preferably at least partially transparent, particularly transparent for a specific wavelength range. In one example, the cover substrate consists of glass that is transparent in the wavelength range of 350 nm to 1800 nm. Furthermore, the cover glass has a double-sided anti-reflective coating, a so-called anti-reflective coating (AR-Coating), which reduces Fresnel reflection in the 1000 nm to 1100 nm range from 5% to less than 1%. Most glasses have high transmittance in this wavelength range. The final transmittance is determined by the subsequently applied coating, which can be designed according to its specific characteristics.

[0014] The substrate and the cover substrate are hermetically bonded using at least one laser bonding line. Therefore, the substrate can be hermetically bonded to the cover substrate in close proximity and directly using the laser bonding line.

[0015] The laser-bonded line here has a height HL perpendicular to its bonding plane. In other words, the laser-bonded line can be understood as a continuous molten line with a typically elliptical cross-section (height HL+AF up to 100 μm, width 10-20 μm), caused by heat accumulation from the bead-like structure emitted by the laser. Generally, the molten line is created above the laser-emitting bead string. The laser-emitting bead string AF is located below the bonding plane, such that the cross-section of the resulting molten zone penetrates the bonding plane. Therefore, the molten line has a certain degree of extension. In this example, the vertical distance in one direction from the bonding plane to the end of the bonding zone of the laser-bonded line is called HL. Laser welding preferably uses a laser with a high repetition rate. The bead string of laser inclusions is generally no longer visible, and the spacing between the beads only indirectly (through heat accumulation) enters the geometry of the molten line.

[0016] The cover substrate has a hardened layer, preferably a chemically hardened layer, on its surface at least on the side opposite to the laser bonding line, wherein the hardened layer preferably applies compressive stress to the cover substrate.

[0017] In other words, in the first step, a first (substrate) and at least one second substrate (cover substrate) are provided to provide a housing, wherein the at least one second substrate is made of a transparent material, i.e., at least partially or partially transparent for at least a certain wavelength range. At least two substrates are arranged directly abutting or overlapping each other, wherein the cavity to be sealed is covered by at least one second substrate, and the respective underside of each housing is formed by the first substrate. At least one contact surface is formed between the at least two substrates, such that each housing has at least one contact surface. The cavity is then hermetically sealed by bonding at least two substrates along the contact surface(s) of each housing, particularly along lines at the edges of each housing. The housings can advantageously be co-manufactured, for example, from a common starting substrate, for example, in the form of stacked wafers. The separation of the respective housings is then achieved in the method by means of a cutting or separating step.

[0018] The substrate layers are stacked adjacent to each other and in direct contact, i.e., arranged close together. Foreign material is excluded as much as possible between the substrate layers to create the closest possible and flattest contact from one substrate layer to the adjacent substrate layer. For example, in the case of two substrates, the base substrate is arranged in direct contact with the cover substrate, especially where there is no other material or spacing between the base substrate and the cover substrate. For example, it is tolerable if there is a spacing of less than 5 μm, preferably less than 2 μm, more preferably less than 1 μm between the substrate layers, which may also be due to substrate inhomogeneity.

[0019] In examples with more than two substrates, the base substrate is arranged adjacent to the intermediate substrate layer or the first of the intermediate substrate layers, and the cover substrate is arranged adjacent to the intermediate substrate layer or the last of the intermediate substrate layers.

[0020] The substrates are then bonded together using a novel laser bonding process. Here, flat substrate layers are bonded directly to each other with adjacent flat substrate layers, without the need for any external, non-flat, or intermediate material layers. Thus, the substrates are directly bonded to each other. The resulting laser bonding line, introduced in the flat contact area between the two substrate layers, connects the directly abutting substrate layers inseparably. The fusion zone of the laser bonding line is therefore located in both substrates and seamlessly merges from the first substrate into the adjacent second substrate, i.e., from the base substrate into the cover substrate.

[0021] Therefore, a transition from one substrate layer to the next is formed between adjacent, flat, or even completely flat layers, such as substrate-substrate transitions or glass-glass transitions. Locally defined volumes are formed as bonding regions or laser-bonded lines, where material transfer or mixing occurs between adjacent, especially flat, substrate layers. In other words, the material of the first substrate, such as the overlay substrate, permeates into the adjacent substrate, such as the intermediate substrate or base substrate, and vice versa, i.e., material from the adjacent substrate permeates into the first substrate, resulting in complete material mixing between the adjacent substrates in the bonding region. The bonding region can therefore also be called a convection region.

[0022] The novel laser bonding technique for creating inseparable substrate-substrate transitions advantageously eliminates the need for intermediate layers, glass frits, films, or adhesives that must be introduced between substrates in previously known methods. More precisely, an inseparable bond can be created without corresponding intervening intermediate layers or additional materials. This saves on the use of extra materials, increases the achievable hardness of the final product, and enables reliable hermetic sealing of functional areas or cavities / multiple cavities. The laser-bonded area can be verified in the finished product, for example, through specific localized refractive index changes in the material within small molten regions.

[0023] In the housing, the base substrate and the cover substrate can be hermetically bonded to each other using the same laser bonding lines. Alternatively, one or more intermediate substrates can be arranged between the base substrate and the cover substrate, wherein the base substrate is then bonded to the lowermost intermediate substrate and the cover substrate is bonded to the uppermost intermediate substrate.

[0024] At least one laser bonding line can preferably surround the functional area at a distance DF. The laser bonding line can also be introduced as, for example, an S-shaped curve into the area of ​​the contact surface between the material or two substrates, such that it partially enters the hardened area or hardened region of the hardened material where necessary. Surprisingly, it has been found that the bonding of materials using laser bonding processes also works when the tensile stress established in the material due to hardening is high.

[0025] The hardened layer may have a hardened layer thickness DoL. The cover substrate may preferably have a minimum material thickness MM above the laser bonding line up to the hardened layer. For the total thickness DA of the cover substrate, it is also possible to satisfy the condition: DA - HL - DoL ≥ MM. Therefore, the total thickness DA minus the height of the laser bonding line extending into the cover substrate by HL, and further minus the hardened layer thickness DoL, leaves at least the minimum material thickness MM of the cover substrate. The distance MM ensures that thermal annihilation does not occur in the hardened region.

[0026] The hardened layer thickness DoL is the depth at which the stress crosses zero on the stress curve. Surprisingly, the weld line can even be within the DoL of the cover glass without affecting strength. This is due to the small achievable lateral extension of the laser-bonded line in the range of less than 50 μm, for example, 10 to 50 μm or 10 to 20 μm. The weld line can protrude into the hardened surface because it preferably only “softens” unimportant areas there. In other words, when the laser-bonded line is adjusted or set to have only a small lateral extension, it can be part of the hardened surface.

[0027] For safety reasons, a minimum material thickness MM can be provided above the laser bonding line, which separates the laser bonding line from the hardened surface. The minimum material thickness is preferably greater than or equal to 100 μm, more preferably greater than or equal to 50 μm, and even more preferably greater than or equal to 20 μm. On the other hand, it has been found that a minimum material thickness MM above the laser bonding line of less than 200 μm, preferably less than 100 μm, and more preferably less than 50 μm is sufficient.

[0028] The cover substrate can be advantageously hardened on both sides, such that the cover substrate has a second hardened layer with a hardened layer thickness DoLb on its side facing the functional area and / or on the bonding surface with the base substrate.

[0029] The height HL of the laser bonding line can be greater than the thickness DoLb of the second hardened layer.

[0030] The cover substrate is preferably hardened on all sides, particularly on its entire outer circumference. In other words, the cover substrate has one or more hardened layers on all sides, surrounding the functional area, particularly circumferentially. In this respect, the packaging is subsequently hardened.

[0031] The hardened layer may then have a hardened layer thickness DoLa, the second hardened layer may have a hardened layer thickness DoLb, and the third hardened layer may have a hardened layer thickness DoLc on the surrounding edge of the housing. In one example, the thicknesses DoLa, DoLb, and DoLc may be the same.

[0032] Laterally, the minimum lateral distance DB between the laser bonding line and the hardened layer thickness DoLa, towards the functional area, can be, for example, 5 to 10 μm. Since this transition should not soften, it is advantageous to maintain at least half the module width laterally towards the corresponding hardened edge. Because the laser bonding line can be taller, for example with an HL of 100 µm or less, the ratio of the bonding area to the edge area is less advantageous. Therefore, it is best to avoid extending the laser bonding line into the hardened area in the first place.

[0033] The cover substrate may have this or other functional areas. In other words, functional areas may be arranged within the cover substrate. For example, a functional area may include an active surface applied to the underside of the cover substrate, such as a reflective layer. Alternatively, the functional area may be cut out of the cover substrate by a suitable method. Sandblasting is suitable for this purpose.

[0034] The substrate may also have a hardened layer DoLd on its underside opposite the laser bonding line.

[0035] Each shell can form a cavity surrounded by the lateral surrounding edges, lower side, and upper side of the shell. In other words, such a cavity is surrounded by the shell on all sides, such that the shell for the cavity forms surrounding edges, lower side, and upper side.

[0036] The cavity can be specifically constructed as a accommodating cavity. This means, for example, that electronic circuits, sensors, or MEMS can be used in the corresponding cavity, i.e., they are housed there. These aforementioned devices, such as electronic circuits, sensors, or MEMS in particular, are thus surrounded by a housing on all sides because they are arranged within the accommodating cavity.

[0037] In the method according to the invention, at least two substrates are first provided, namely, a cover substrate and a base substrate, wherein at least one of the two substrates is composed of a transparent material or at least partially comprises a transparent material. The at least two substrates are arranged directly abutting each other or directly overlapping each other. In other words, the at least two substrates are arranged or attached to each other such that they are flatly abutting each other without any other layer between the at least two substrates.

[0038] Due to technical limitations, it may be impossible to avoid even minimal gas inclusions between the substrate layers, which is why the substrate layers may be uneven. The amount of gas inclusions can be further reduced, for example, by increasing pressure, particularly by pressing at least two substrates together, or by surface treatment of the substrate layers, such as grinding. Particularly preferred are gaps between the substrates that are less than or equal to 5 μm thick, more preferably less than or equal to 2 μm, and even more preferably less than or equal to 1 μm. Such gaps are caused, for example, by tolerances in substrate manufacturing, by thermal effects, or by inclusions of particles such as dust. Even in cases where such permissible gaps should be considered closely adjacent within the scope of this invention, laser bonding can be used such that the bonding area has a thickness between 10 and 50 μm, thereby ensuring an airtight seal. In this case, the bonding area also extends from the first substrate into the second substrate disposed adjacent to the first substrate. Thus, the bonding area is introduced in the contact area between the first and second substrates and directly fuses the substrates together into an inseparable composite structure. In other words, when adjacent substrates are joined in the bonding area, the materials of the two substrates located in the bonding area directly melt and the materials of the first substrate and the second substrate are mixed to form an inseparable, one-piece composite structure. Therefore, the housing manufactured in this way has a one-piece, i.e., integral composite structure between the substrates, in any case in the bonding area.

[0039] At least one transparent substrate forms the corresponding edge and corresponding upper side of the respective outer shell of the cavity to be sealed. In a preferred design, two transparent substrates placed close together are at least one transparent substrate, such that the first transparent substrate forms the edge of the respective cavity and the second transparent substrate forms the upper side of the respective cavity. In an alternative design, the transparent substrate has a recess or groove. The recess or groove can be introduced into the transparent substrate, for example, by means of a grinding method or other subtractive method, such as etching. The second substrate forms the corresponding lower side of the respective outer shell.

[0040] In a preferred embodiment, all three substrate layers are transparent, making the lower side, edges, and upper side, and thus the outer shell, entirely made of transparent material.

[0041] The process of sealing the hermetically tight cavity can be performed by bonding at least two substrates along the corresponding connection surfaces of each housing using a laser bonding method. In other words, energy can be deposited by laser at the connection surface or in the area of ​​desired penetration depth, particularly through localized deposition, a method that can be called cold bonding. Therefore, the heat energy provided for bonding is concentrated along the path of the connection surface and diffuses only slowly into the remaining material of the housing, preventing significant temperature increases, especially within the cavity. This prevents overheating of the electronic equipment housed within the cavity.

[0042] By using a laser, the materials of the two substrates are locally melted along the bonding surface in the respective housing region, thereby locally bonding at least the two substrates. For this purpose, those skilled in the art may refer, for example, to EP 3 012 059 B1, which is incorporated herein by reference.

[0043] The corresponding outer casings are separated by a cutting or separation step. This means that the substrate is cut or separated in a manner that separates each casing from the rest of the material.

[0044] The outer shell is eventually chemically hardened on its surface through a chemical solution bath.

[0045] The inventors have discovered that chemically hardening the surface by immersion in a chemical solution can significantly increase the breakage resistance of the corresponding shell, and thereby particularly reduce edge breakage. This is surprising for several reasons.

[0046] First, surprisingly, the chemical solution did not penetrate the joint, and therefore the joint was not subjected to chemical stress. This could have a detrimental effect, and this had to be assumed initially. Therefore, it was previously considered technically infeasible to use a method of chemically curing a shell by bonding two or more substrates together, as the shell was expected to crack when separated from the substrate. The inventors also discovered this in their initial experiments. Using the method described herein, and in a particularly preferred case, in conjunction with the use of lasers for the bonding and / or separating steps, this is now surprisingly possible.

[0047] Furthermore, it was surprisingly discovered that the sealed cavity, which is laser-bonded, can easily withstand internal pressures of 2 atmospheres or higher, for example, when the outer shell is heated in a hardening bath.

[0048] The housing preferably comprises first and second transparent substrates, wherein the first transparent substrate forms a corresponding edge of the cavity, and the second transparent substrate forms a corresponding upper side of the cavity. In other words, the first transparent substrate forms a cover substrate and the second transparent substrate forms an intermediate substrate. When two transparent substrates are used, the first is used to form the edge and the second is used to form the upper side, thus providing two surrounding optically transparent areas for each housing. In this case, the respective cavities are hermetically sealed by using a laser bonding method along two boundary surfaces: one between the cover substrate and the intermediate substrate, and the other between the intermediate substrate and the base substrate. The first and second transparent substrates, as well as the base substrate, are then firmly welded together, simultaneously hermetically sealing the cavities.

[0049] Preferably, at least two, more preferably three, substrates are provided in the form of a wafer stack having at least two, more preferably three wafers. Multiple hermetic-sealed housings can then be jointly manufactured from the wafers or wafer stacks in the same working process. This procedure has proven to be particularly economical due to the significantly reduced waste and consequent material loss.

[0050] At least two wafers are preferably made of glass, or at least one wafer is made of glass and the second wafer is made of a material of a different type than glass. In other words, the wafer forming the lower side of the cavity can be provided of an optically non-transparent material, which may have other properties, such as conductivity, if necessary. However, the edges and upper side of the housing are made of a transparent material. It is further preferred that all substrates are made of a transparent material. In the case of a transparent housing made of glass or mainly of glass, especially borosilicate glass, it is particularly advantageous that it is chemically inert.

[0051] The edge hardness of the airtight sealed housing can be measured using a four-point bending test method. The edge hardness of the housing reinforced according to the method of the present invention is therefore particularly durable, at least 150 MPa or even greater than 150 MPa.

[0052] Preferably, the separation of the respective housings is performed using a laser, i.e., by means of laser cutting or laser separation methods. This allows for cleaner separation of the housings, resulting in fewer fractures and cleaner separation points. The same laser used in the joining step can preferably be used for separation.

[0053] In addition to glass, at least one transparent substrate may also include glass ceramic, silicon or sapphire or a combination of the above materials, that is, for example, glass-silicon, glass / silicon / sapphire combination or silicon / sapphire combination.

[0054] One or more substrates may also have a coating. For example, an AR coating, a protective coating, a bioactive film, an optical filter, or a conductive layer made of ITO or gold may be used, provided that transparency or at least partial transparency is maintained for the laser's radiating region and for the wavelength of the laser used.

[0055] The chemical hardening step of the shell preferably includes at least one of the following sub-steps: providing an acidic or alkaline solution, particularly containing or composed of KNO3; introducing the shell into the acidic or alkaline solution; heating the acidic or alkaline solution to a temperature of at least 650 K, preferably at least 700 K, more preferably at least 720 K; and immersing the shell in the acidic or alkaline solution for at least 6 hours, preferably at least 8 hours, more preferably at least 9 hours, and preferably up to 12 hours.

[0056] Acidic or alkaline solutions may also contain other potassium salts. In principle, the exchange of sodium ions with rubidium, cesium, francium, or similar substances is also possible. During the curing process, care should be taken to minimize the number of contact points between the outer casing and other objects in the bath, such as the tub, the shelf used, or other objects in the bath, as these contact points may reduce the effectiveness of the curing bath.

[0057] According to the present invention, a housing having an hermetically sealed accommodating cavity therein is also provided, which is manufactured according to the method described above.

[0058] The housing manufactured according to the above method can be used advantageously as a medical implant or as a sensor, especially as a barometer.

[0059] Within the scope of this invention, there is also a particularly transparent housing having a hermetically sealed accommodating cavity for accommodating a contained object, such as an electronic circuit, sensor, or MEMS.

[0060] The housing according to the invention has a laterally surrounding edge made of a transparent material, as well as a lower and upper side, which together completely surround the receiving cavity.

[0061] At least one of the lateral surrounding edge, lower side, or upper side is at least partially transparent to a certain wavelength range in this case. In other words, it is sufficient if at least one sub-element of the housing is transparent to a preferred wavelength range at least in a sub-region of the sub-element, wherein the wavelength range is known in advance and, if desired, the material can be adjusted accordingly to the laser wavelength to be used.

[0062] The outer shell is joined to the hermetically sealed outer shell using a laser bonding method. In other words, the edges, bottom, and top are composed of more than one component, such as two, three, or more components, which are laser-bonded together to produce the outer shell.

[0063] The outer casing is at least partially and / or partially chemically hardened. For example, one surface of the casing, i.e., the upper side, is chemically hardened. The upper side and the edges may also be chemically hardened. Particularly preferably, not only the upper side, but also the edges and the lower side are chemically hardened, such that not only the corresponding surfaces of the upper or lower side, but also the corresponding edges are chemically hardened.

[0064] The lateral surrounding edges can preferably be made of a first substrate, the lower side of a second substrate, and the upper side of a third substrate. The outer casing is then manufactured by stacking wafers.

[0065] Preferably, in the case of a transparent housing, the lateral surrounding edges and / or the lower and / or upper sides can be chemically hardened, or more preferably, the entire surface of the housing is chemically hardened.

[0066] The chemical hardening of the shell is preferably achieved by partially or completely exchanging sodium ions present in a layer thickness of 30 μm or less, or 20 μm or less, or preferably 10 μm or less.

[0067] Preferably, the housing undergoes chemical hardening after being separated from other housings manufactured together with the housing, for example in a manufacturing method, particularly in the aforementioned manufacturing method.

[0068] The housing may include a lateral surrounding edge made of transparent material by a first part, a lower side made of a second part, and an upper side made of a third part, which together completely surround the receiving cavity.

[0069] Then, a laser bonding method is used to bond the above-mentioned at least three components of the shell into an airtight shell.

[0070] Preferably, the outer casing has an edge hardness of at least 150 MPa or greater than 150 MPa, wherein the edge hardness can be measured using a four-point bending test method.

[0071] Transparent housings can, for example, have dimensions of 3mm x 3mm or smaller, especially accommodating cavities with a diameter of 2mm or less. For instance, transparent housings can also have dimensions of 0.2mm x 0.2mm or smaller. On the other hand, depending on the application, transparent housings can also be manufactured larger, with lengths reaching several centimeters or even more. Size limitations arising from practice are predicated on preferred manufacturing methods but should not be construed as size limitations in themselves, but rather as limitations on the size of the wafer to be cut. However, the use of wafers for manufacturing should only be understood as an example. For instance, it is entirely possible to manufacture transparent housings using glass plates, which can also have dimensions larger than typical wafer sizes. Attached Figure Description

[0072] In the attached image:

[0073] Figure 1a A top view of the open accommodating cavity is shown.

[0074] Figure 1b A 3D view of the enclosed shell is shown.

[0075] Figure 2a A cross-section through the shell is shown.

[0076] Figure 2b A detailed view of the bonding area is shown.

[0077] Figure 3 A top view of another embodiment of the housing is shown.

[0078] Figures 4a-8b As shown Figure 3The illustrated embodiment of the housing is shown along the cross section of line A->B or C->D.

[0079] Figure 9 The process for manufacturing the casing is shown.

[0080] Figure 10 The process of another method for manufacturing the casing is shown.

[0081] Figure 11-14 This is a photographic view of the casing implemented according to the present invention. Detailed Implementation

[0082] Figure 1a A conceived object 2 to be protected is shown, which is embedded in a substrate or lower wafer 3, surrounded or enclosed on its sides by an intermediate wafer 4, and to be covered by a cover substrate or upper wafer 5. Figure 1a In the example, the three wafers 3, 4, and 5 thus collectively form a housing 1 surrounding the object 2 arranged within the cavity 12. In other words, when in... Figure 1a In the example, when the upper wafer 5 is placed on the middle wafer 4, a receiving cavity 12 with all sides closed is formed and is to be hermetically sealed in a later step.

[0083] Figure 1b This illustrates a hermetically sealed, chemically hardened outer shell 1 constructed in this manner. (Example) Figure 1b In the example, the housing 1 has a base substrate or lower wafer 3, an intermediate substrate or intermediate wafer 4, and a cover substrate or upper wafer 5 stacked on top of each other. Contact surfaces or boundary surfaces 25 are respectively present between the lower wafer 3 and the intermediate wafer 4, and between the intermediate wafer 4 and the upper wafer 5. Figure 1a It can also be seen that the intermediate wafer layer 4 is discontinuous, so that the accommodating cavity 12 is formed at the height of the intermediate wafer layer 4.

[0084] refer to Figure 2a The cross-section of the hermetically sealed, chemically hardened outer shell 1 is shown. The lower wafer 3 forms the lower side 22 of the cavity 12, the intermediate wafer 4 forms the edge 21 of the cavity 12, and the upper wafer 5 ultimately forms the upper side 23 of the cavity 12. In other words, the lower wafer, intermediate wafer, and upper wafers 3, 4, and 5 together form a wafer stack 18 surrounding the accommodating cavity 12. The accommodating object 2 is arranged within the cavity 12.

[0085] Figure 2bA detailed view of the bonding area is shown, in which the laser bonding interface area 7 and the laser bonding area 8 are clearly visible. The laser bonding area 8 is located in the area of ​​the optical boundary surface 25. Environmental influences act on the housing from the outside of the housing 1, particularly at the corners 6 of the laser-bonded stack 18. These corners 6 also prevent, for example, chemical solutions from penetrating into the wafer stack 18 down to the laser bonding area 8. In other words, surprisingly, no chemical solution penetration occurs at the corners 6 of the laser-bonded stack 18.

[0086] Figure 3 A top view of the housing 1 according to the invention is shown, wherein the surrounding laser bonding area 8 surrounds the functional region 13. The functional region 13 can be constructed in different ways. Figures 4a to 8b Examples of the design for functional area 13 and other options for the casing can be found here. Various designs for functional area 13 can be found here. Figure 3 This graphic combination is used because all top views can be schematically shown in the same way. Sections are drawn on the AB or C->D line, which correspondingly... Figures 4a to 8b It was reproduced in the middle.

[0087] The functional area can perform various tasks, such as being an optical receiver or a technical, electromechanical, and / or electronic component arranged in the functional area 13. Multiple of these tasks can also be performed in the functional area 13. The housing 8 is covered on its upper side by the upper substrate 5. The laser bonding area 8 extends into the upper substrate 5.

[0088] refer to Figure 4a A first cross-sectional view of a first embodiment of the housing 1 is shown, wherein the upper substrate 5 has a first hardening layer 27 on its upper side. For example, the upper side of the cover substrate 5 may be immersed in a hardening bath before it is attached to the base substrate or after it is attached to the base substrate 3 (see example). Figure 9 This process causes the completed outer casing 1 to be chemically cured on one side, i.e., having at least one cured surface 27 and / or having at least one cured layer. In other words, the completed outer casing 1 is at least partially or at least partially cured, such as, in particular, chemically cured. During chemical curing, compressive stress is formed acting on the covering substrate 5.

[0089] Figure 4a The structure of a laser bonding line 8 from a series of laser pulse hit regions 16 is also shown, these laser pulse hit regions being closely arranged so that the materials of the substrate 3 and the cover substrate 5 are fused together without gaps. The first hardened layer 27 has a height DoL. The bonding region 8 has a height HL. A minimum material thickness MM remains between the hardened region 27 and the bonding region 8. Then, the entire thickness of the cover substrate 5 can be composed of HL + MM + DoL.

[0090] Figure 4b An embodiment of housing 1 is shown along the edge as shown. Figure 3 A cross-sectional view along the C->D line inserted in the middle. The cover substrate 5 has a first hardened layer 27 on its upper or outer side, which extends through a thickness DoL into the material of the cover substrate 5. In other words, the cover substrate 5 and therefore the outer shell 1 are hardened on the upper side or have a hardened area 27 there, such that the outer shell 1 is partially, i.e., hardened on one side.

[0091] Figure 4b A cross-section through functional regions 13, 13a is also shown, which extend, for example, as a continuous hollow space or cavity within the housing 1. In other words, the cavity extends from the base substrate 3 into the cover substrate 5 and, for example, takes the form of a recess made of the base substrate 3 and / or the cover substrate 5. For example, functional region 13a may also include an active layer, such as a conductive layer, and functional region 13 includes a cavity. A laser bonding region 8 is arranged around functional regions 13, 13a, by means of which functional regions 13, 13a are closed on all sides. It is conceivable that open areas are left in the laser bonding region 8 so that functional regions 13, 13a are not completely closed on all sides, for example, maintaining open communication channels through which fluid communication, for example, with the environment can be established. In other words, it can be specified that the pre-planned orientation or location is not closed by the focused laser beam 9, but by other means, such as by using an adhesive to establish an airtight seal there. Preferably, functional regions 13, 13a are closed on all sides without gaps.

[0092] refer to Figure 5a Another embodiment is shown, wherein a laser bonding region 8 is generated along the contact surface 25 by means of a laser pulse hit 16, on which a cover substrate 5 is welded or bonded to a base substrate 3. In this embodiment, the cover substrate 5 has a first hardening layer 27 on its upper side and a second hardening layer 28 on its lower side. To achieve this, the cover substrate 5 is first placed in a hardening solution without contacting other substrates and chemically hardened on its two opposing surfaces. In this embodiment, the cover substrate 5 is thus bonded directly in the region of the hardening layer 28. Surprisingly, bonding within the hardening layer 28 is entirely possible.

[0093] Figure 5b Another embodiment of housing 1 is shown, wherein along Figure 3The cross-sectional view shown is along line C->D. The housing 1 has a first hardened layer 27 and a second hardened layer 28, both of which are introduced or applied into the covering substrate 5. Functional regions 13, 13a extend through the hardened layer 28, such that the hardened layer 28 defines an annular region around the functional regions 13, 13a. A bonding region 8 is partially located within the second hardened layer 28. The hardened layer 28 has a height DoLb. A separate laser pulse hits region 16, and therefore the bonding region 8, such that its height HL exceeds that of the second hardened region 28. This ensures that the bond penetrates into the unhardened region of the material, i.e., the end of the bonding region is no longer located in the pre-tightened region. The end of the bonding region 28 thus enters into the stress-free region of the material, i.e., particularly the stress-free region of the glass. In other words, the bonding region 8 has a protrusion above the second hardened layer 28, which extends into the unhardened material of region MM.

[0094] according to Figure 6a Another example of the housing 1 is shown, in which a first hardening layer 27, a second hardening layer 28, and a third hardening layer 29 are introduced. In this embodiment, the cover substrate 5 and the base substrate 3 are hardened, particularly chemically hardened, on both of their long sides. In other words, the substrates 3 and 5 are immersed in a hardening solution for chemical hardening on their respective long sides, i.e., on their respective upper and lower sides, respectively, to harden the long sides. After hardening, the two substrates 3 and 5 are arranged overlapping each other, i.e., stacked, such that the base substrate 3 is pressed against the lower side of the cover substrate 5. The hardened area disposed on the upper side of the base substrate 3 is thus pressed against the hardened area disposed on the lower side of the cover substrate 5. The substrates 3 and 5 are then directly bonded in the areas of the hardened material, i.e., particularly in the areas of the hardened glass.

[0095] Assume that material relaxation occurs in the region of the corresponding laser pulse hit area 16 through the laser bonding process, such that if the laser pulse hit area exceeds the height of the hardened area 28 at its height HL, the protrusion still exists, thus extending from the first substrate 3 above the corresponding pulse hit area and into the second substrate 5 where continuous relaxed material exists. In the finished stack of the housing 1, the first hardened layer 27 is therefore disposed on its upper side, the second hardened layer 28 is disposed on the contact surface 25, and the third hardened layer 29 is not disposed on its lower side.

[0096] Figure 6b Another embodiment is shown in the C->D region of the cross section, which has three hardened regions 27, 28, and 29. Functional regions 13 and 13a are also arranged in this embodiment such that they extend from the base substrate 3 into the cover substrate 5, for example, as recesses in the respective substrates. These recesses 13 and 13a can be introduced, in particular, by sandblasting. A bonding line 8 is arranged around the recesses 13 and 13a such that the recesses 13 and 13a are hermetically sealed on all sides.

[0097] Figure 7a Another embodiment of the housing 1 in the region of section A->B is shown, wherein the cover substrate 5 has a first hardened layer 27 on its upper side and a second hardened layer 28 on its narrow side or edge 14. Thus, for example, the upper side of the cover substrate 5 is immersed in a hardening solution for chemical hardening, either alone or after bonding with the base substrate 3, and this immersion extends to the height of the second hardened layer 28. In this example, the base substrate 3 has no hardened area. In this example, the lateral hardened area 28 terminates directly in the region of the contact surface 25 between the cover substrate 5 and the base substrate 3. The bonding along the bonding line 8 is introduced inside the hardened area 28, i.e., introduced in the relaxed material.

[0098] Figure 7b Another embodiment of the housing 1 is shown, wherein the first long side has a hardened layer 27 and the first narrow side 14 partially has a hardened layer 28. The hardened layer 28 may extend around the housing 1, for example, closing around the functional region 13. Figure 3 In contrast, a cross-section is shown along the line C->D drawn there, i.e., passing through functional region 13. In this embodiment, functional region 13 is limited by the size of the cover substrate 5 and therefore does not extend into the base substrate 3. The base substrate 3 is bonded directly and adjacent to the cover substrate 5, such that no additional layer or additional substrate is disposed between the base substrate 3 and the cover substrate 5. Functional region 13 is designed as a cavity. For example, the cavity can be introduced into the cover substrate 5 by means of sandblasting, typically using grinding methods. Chemical etching is also possible to introduce the cavity into the substrate.

[0099] Figure 8a Another embodiment of the housing 1 is shown, wherein... Figure 3 The cross-section in the region shown by the A->B line is the cross-section along or through the bonding line 8. In this embodiment, all outer surfaces of the outer shell 1 are hardened, meaning that not only do the two opposing long sides have hardened layers 27 and 29, but the surrounding edge 14 of the shell also has a hardened layer 28, wherein the surrounding edge 14 extends circumferentially around the outer shell 1. In other words, in the case of a cuboid shell, all four narrow sides of the cuboid are understood as edges 14. Edges 14 can also be understood or referred to as the edge 21 of the shell, which extends around the cavity. Figure 8a The outer casing 1 shown can be obtained, for example, by immersing the casing, comprising the completed bond of the covering substrate 5 and the base substrate 3, in a curing solution and, in particular, chemically curing there. The curing layers 27, 28, and 29 are thus disposed directly on the outer side of the outer casing 1. Areas for the bonding lines 8 are therefore reserved on the inner sides of the curing layers 27, 28, and 29, which, if necessary, are introduced at a certain distance from the curing layers 27, 28, and 29.

[0100] Figure 8b An embodiment of the housing 1 is shown, with a cross-section along line C->D. The housing 1 is chemically hardened on all sides, meaning it has hardened regions 27, 28, 29 on all surfaces. For example, a first hardened layer 27 is disposed on a first long side, which may be the upper side of the covering substrate 5, a third hardened layer 29 is disposed on a second long side, which may be the lower side of the base substrate 3, and a second hardened layer 28 is disposed around the edge 21 or around the edge 14. The upper side 23 of the cavity is disposed inside the first hardened layer 27, the edge 21 of the cavity is disposed inside the second hardened layer 28, and the lower side 22 of the cavity is disposed inside the third hardened layer 29. The cavities or functional regions 13, 13a are thus surrounded on all sides by the hardened material 27, 28, 29. (Refer to...) Figure 9 This illustrates a first embodiment of a method for manufacturing a housing 1. In step A, a wafer and a receiving object 2 to be housed are aligned. Here, a cover substrate or upper wafer 5 is pressed against an intermediate wafer 4, and the intermediate wafer is in turn pressed against a base substrate or lower wafer 3 in such a manner as to form a wafer stack 18. Since the intermediate wafer 4, which includes a recess in which a cavity 12 is constructed, is arranged in the middle in this case, the receiving cavity 12 is surrounded by wafer material on all sides. In other words, when the wafer is aligned in step A, all lateral enclosures of the cavity 12 are formed by the edge 21, the lower side 22, and the upper side 23 of the cavity.

[0101] Figure 3 Step B of the method shown illustrates a stack 18 having cavities 12 located therein for accommodating the object 2, arranged overlapping each other. This wafer stack 18 can be supplied to the bonding process in this closed configuration.

[0102] Step C illustrates the laser bonding of the respective accommodating cavities 12, i.e., the closure of cavities 12 along all sides of the contact surface 25. For this purpose, a laser unit 15 is guided from above the wafer stack 18 above the surface of the wafer stack 18, and the focused laser beam 9 is gradually directed onto the area to be bonded. The laser bonding lines 8 can be designed, for example, as a grid of intersecting lines. If this proves beneficial, for example, depending on the material, for subsequent separation, two or more parallel laser bonding lines 8 can also be used. After step C of the manufacturing method is completed, all cavities 12 are hermetically sealed.

[0103] Step D illustrates the step of separating or cutting the wafer stack 18 to separate the housing 1. In this case, the wafer stack is cut or separated along the separation or cutting line 10.

[0104] In step E, the outer shell 1 is chemically cured in a bath 11 containing an acidic or alkaline curing solution. The bath 11 preferably has temperature regulation to maintain a preset temperature.

[0105] Step F concludes by showing an airtight, chemically hardened outer shell 1 with a accommodating cavity 12 disposed therein.

[0106] refer to Figure 10 Another method is shown, by which an hermetically sealed, chemically hardened shell 1 can be obtained. In step A of this method, the wafer stack 18 is constructed by arranging and oriented individual wafer layers 3, 4, and 5 overlapping each other. The receiving object 2 is arranged in the receiving cavity 12.

[0107] Step B shows the completed fabricated wafer stack 18, in which the lower wafer 3, the middle wafer 4 and the upper wafer 5 are laid flat and overlapping each other in direct contact with each other.

[0108] The stacked wafers are fed into a bath 11 containing an acidic or alkaline hardening solution in step C and hardened in the bath.

[0109] In step D, a laser bonding process is performed, wherein each cavity 12 is hermetically sealed by bonding three wafer layers 3, 4, and 5. The laser here bonds the wafer layers 3, 4, and 5 circumferentially along the optical boundary and around each individual cavity 12.

[0110] A laser cutting process is used in step E. The laser is guided along the cutting line 10, allowing the wafer to be cut. This cutting method yields edges with a specific strength. Preferably, the edges remain smooth and intact. However, edges with a finely ground roughness can also be obtained, for example, by using short-pulse laser perforation.

[0111] Step F demonstrates the presence of a hermetically sealed and chemically hardened outer shell 1.

[0112] Figure 11 A top view of a first example of a hardened shell 1 made by Schott D263T eco is shown. A circular, essentially circular, and closed-on-all-side cavity 12 inside the shell 1 can be clearly identified. In this example, the cavity 12 has a horizontal diameter of approximately 4 mm. The shell has an edge length of approximately 5.5 mm. The sample shown was hardened in a 100% KNO3 solution at 450 °C for 9 hours.

[0113] Figure 12 A side view of the hardened edge 14 of the outer casing 1, manufactured by Schott D263T eco, is shown. For perspective purposes, the cavity 12 is... Figure 12 It is not visible in the view. (See reference) Figure 13 The diagram also shows a top view of the outer casing 1, in which the orientation of the edge 14 can also be identified.

[0114] Figure 14 Finally, a side view of a cross-section of the housing 1 according to the invention is shown, which is manufactured by Boro33 and has a closed cavity 12. Figure 14 The sample shown was also hardened in 100% KNO3 solution at 450°C for 9 hours. Figure 14 The contact surface 25 between the substrate layers can also be clearly identified. This contact surface is located between the lower substrate 3 and the intermediate layer 4 on one side, and between the intermediate layer 4 and the upper substrate 5 on the other side. The upper and lower inserts are bonded to the glass chip to prepare the PMMA sheet for cross-section. Figure 14 The area framed in the middle shows the glass housing 1. Plastic is placed next to it as part of the sample preparation.

[0115] It will be apparent to those skilled in the art that the above embodiments should be understood as exemplary and that the invention is not limited to these embodiments, but can be varied in many ways without departing from the scope of the claims. Furthermore, it is apparent that regardless of whether the described features are disclosed in the specification, claims, drawings, or otherwise, these features also individually define the essential components of the invention, even if they are described together with other features. In all the drawings, the same reference numerals represent the same objects, thus, if necessary, a description of an object in only one, or in any case not mentioned in all the drawings, can be transferred to those drawings where the object is not explicitly described in the description.

[0116] List of reference numerals

[0117] 1. Hermetically sealed hardened shell

[0118] 2. Containment Object

[0119] 3. Substrate or substrate or wafer

[0120] 4. Intermediate substrate or intermediate wafer

[0121] 5. Top substrate or cover substrate or wafer

[0122] 6 lasers combined with stacked 18 angles

[0123] 7 Laser bonding interface area

[0124] 8 laser bonding area

[0125] 9-Focused Laser Beam

[0126] 10 Separation or Cutting Line

[0127] 11. Soak in acidic or alkaline hardening solutions

[0128] 12 accommodating cavities

[0129] 13 functional areas

[0130] 13a Second Functional Area

[0131] 14 edges

[0132] 15 laser units for joining and / or cutting

[0133] 16 laser pulses hit area

[0134] 18 stacks or chip stacks

[0135] 21 Edge

[0136] 22 Lower side of the cavity

[0137] The upper side of cavity 23

[0138] 25. Contact surface or boundary surface

[0139] 27 Hardened Zone or First Hardened Layer

[0140] 28 Hardened Zone or Second Hardened Layer

[0141] 29 Hardened Zone or Third Hardened Layer

Claims

1. A hermetically sealed housing (1), comprising: The base substrate (3) and the cover substrate (5) form at least one part of the housing; At least one functional area (12, 13, 13a) surrounded by the outer shell. At least one of the covering substrates includes a vitreous material. The substrate and the cover substrate are hermetically sealed together using at least one laser bonding line (8). The laser bonding wire has a height HL perpendicular to its bonding plane. At least the covering substrate (5) has a hardened layer on its surface at least on the side opposite to the laser bonding line; The at least one laser bonding line comprises a mixture of materials from the bonded substrate penetrating into an adjacent bonded substrate.

2. The hermetically sealed outer casing (1) according to claim 1, wherein, The hardened layer is a chemically hardened layer.

3. The hermetically sealed housing (1) according to claim 1, wherein, The hardened layer applies compressive stress to the covering substrate (5).

4. The hermetically sealed outer shell (1) according to claim 1. in, The substrate (3) is hermetically bonded to the cover substrate (5) using the same laser bonding lines (8), and / or The at least one laser bonding line (8) surrounds the functional area (12, 13, 13a) at a certain spacing (DF).

5. The hermetically sealed housing (1) according to any one of claims 1 to 4. in, The hardened layer has a hardened layer thickness DoL, and the cover substrate (5) has a minimum material thickness MM above the laser bonding line (8) up to the hardened layer, and wherein the total thickness DA of the cover substrate is subject to the condition: DA - HL - DoL ≥ MM.

6. The hermetically sealed housing (1) according to any one of claims 1 to 4. in, The cover substrate (5) is hardened on both sides, such that the cover substrate has a second hardened layer (28) with a hardened layer thickness DoLb on the connection surface (25) with the base substrate (3).

7. The hermetically sealed housing (1) according to claim 6. in, The height HL of the laser bonding line (8) is greater than the thickness DoLb of the second hardened layer (28).

8. The hermetically sealed housing (1) according to any one of claims 1 to 4. in, At least the cover substrate (5) has a hardened layer on all sides, wherein the hardened layer includes a first hardened layer (27) and a second hardened layer (28), the first hardened layer (27) having a hardened layer thickness DoLa and the second hardened layer (28) having a hardened layer thickness DoLb.

9. The hermetically sealed housing (1) according to claim 8, wherein, The hermetically sealed housing includes a hardened layer with a third hardened layer (29) on its outer side, the third hardened layer (29) having a hardened layer thickness DoLc on the surrounding edge (14) of the housing.

10. The hermetically sealed housing (1) according to claim 8, wherein, At least the covering substrate (5) has the first hardened layer (27) and the second hardened layer (28) on its entire outer peripheral surface.

11. The hermetically sealed housing (1) according to claim 9, wherein, The thicknesses DoLa, DoLb, and DoLc are the same.

12. The hermetically sealed housing (1) according to any one of claims 1 to 4, wherein, The covering substrate (5) has the functional areas (12, 13, 13a).

13. The hermetically sealed housing (1) according to any one of claims 1 to 4, wherein, The substrate has a hardened DoLd layer on its underside opposite to the laser bonding line.

14. The hermetically sealed housing (1) according to any one of claims 1 to 4. in, An intermediate substrate is disposed between the base substrate and the cover substrate. Wherein, the base substrate is bonded to the intermediate substrate in the connecting plane, and wherein the cover substrate is bonded to the intermediate substrate in the second connecting plane.

15. The hermetically sealed housing (1) according to any one of claims 1 to 4. in, The outer casing is hardened on all sides of the functional area, and / or The outer shell has a hardened layer on each of its outer surfaces.

16. The hermetically sealed housing (1) according to any one of claims 1 to 4, wherein, The functional area includes a hermetically sealed accommodating cavity (12) for accommodating the object (2).

17. The hermetically sealed housing (1) according to claim 16, wherein, The accommodating object (2) includes electronic circuits, sensors, or microelectromechanical systems (MEMS).

18. The hermetically sealed housing (1) according to claim 16. in, An intermediate substrate is disposed between the base substrate and the cover substrate. Wherein, the base substrate is bonded to the intermediate substrate in the connecting plane, and wherein the cover substrate is bonded to the intermediate substrate in the second connecting plane; The covering substrate forms the upper side (23) of the accommodating cavity, the intermediate substrate (4) forms the lateral surrounding edge (21) of the accommodating cavity, and the base substrate forms the lower side (22) of the accommodating cavity, together completely surrounding the accommodating cavity, and at least one of the lateral surrounding edge, the lower side, or the upper side is at least partially transparent for a wavelength range.

19. The hermetically sealed housing (1) according to any one of claims 1 to 4. in, The outer shell is joined into the hermetically sealed outer shell by a laser bonding process, namely, by using at least one laser bonding line to bond the substrate and the cover substrate together.

20. The hermetically sealed housing (1) according to claim 19, wherein, The outer shell is joined into the hermetically sealed outer shell by a laser bonding process, namely by joining the base substrate, the cover substrate and one or more intermediate substrates together with each other using at least one laser bonding line.

21. The hermetically sealed housing (1) according to any one of claims 1 to 4. in, The hardening of the outer shell is achieved by partially or completely exchanging sodium ions present in a layer thickness of 30 μm or less with potassium ions.

22. The hermetically sealed housing (1) according to claim 21, wherein, The thickness of the layer is 20 μm or less.

23. The hermetically sealed housing (1) according to claim 21, wherein, The thickness of the layer is 10 μm or less.

24. The hermetically sealed housing (1) according to any one of claims 1-4, wherein, The hermetically sealed outer shell is a transparent shell.

25. The hermetically sealed housing (1) according to claim 24. in, The transparent shell undergoes chemical hardening after being separated from other transparent shells.

26. A method for providing a plurality of hermetically sealed housings (1), wherein, Each housing provides a functional area surrounded by a lateral surrounding edge (21), a lower side (22), and a upper side (23) of the housing, and the method comprises the following steps: - Provide at least two substrates, said at least two substrates including a base substrate (3) and a cover substrate (5), wherein at least said cover substrate (5) includes at least partially transparent material, wherein said at least two substrates are arranged directly abutting or overlapping each other. - The functional area is hermetically sealed by bonding at least two substrates along the bonding line using a laser bonding process. - Separate the respective outer shells using a separation step. - The surface of the corresponding shell is chemically hardened by immersion in a chemical solution (11); The bonding line includes a mixture of materials from one bonded substrate permeating into an adjacent bonded substrate.

27. The method of claim 26, wherein the respective outer shells are separated by means of a cutting step.

28. The method according to claim 26, wherein, Each housing provides a functional area, wherein the functional area is a accommodating cavity (12).

29. The method according to claim 26, wherein, The at least two substrates are provided as a wafer stack (18) having at least two wafers to manufacture multiple hermetically sealed housings (1) together from the wafers in the same working process.

30. The method according to claim 29, wherein, The at least two substrates are provided as a wafer stack (18) having three wafers to manufacture multiple hermetically sealed housings (1) together from the wafers in the same working process.

31. The method according to claim 29, in, The at least two wafers are made of glass, glass-ceramic, silicon, or sapphire, or At least one wafer comprises different types of materials.

32. The method according to any one of claims 26 to 31, wherein, The step of separating the corresponding outer shell (1) is performed by means of laser cutting or laser separation steps.

33. The method according to claim 32, wherein, The same laser used in the combining step is used to perform the step of separating the respective outer shell (1).

34. The method according to any one of claims 26 to 31, wherein at least one transparent substrate forms a corresponding edge and a corresponding upper side of the corresponding outer shell of the cavity to be sealed.

35. The method according to claim 34, wherein, The at least one transparent substrate is composed of glass, glass ceramic, silicon, or sapphire, or a combination of the foregoing materials.

36. The method according to any one of claims 26 to 31, wherein, The chemical hardening step of the outer shell (1) includes at least one of the following sub-steps: Provide acidic or alkaline solutions (11); The outer shell is introduced into the acidic or alkaline solution; The acidic or alkaline solution is heated to a temperature of at least 650 Kelvin; The outer shell is immersed in the acidic or alkaline solution for at least 6 hours.

37. The method according to claim 36, wherein the acidic or alkaline solution (11) comprises or is composed of KNO3.

38. The method of claim 36, wherein the acidic or alkaline solution is heated to a temperature of at least 700 Kelvin.

39. The method of claim 36, wherein the acidic or alkaline solution is heated to a temperature of at least 720 Kelvin.

40. The method of claim 36, wherein the outer shell is immersed in the acidic or alkaline solution for at least 8 hours.

41. The method of claim 36, wherein the outer shell is immersed in the acidic or alkaline solution for at least 9 hours.

42. The method of claim 36, wherein the outer shell is immersed in the acidic or alkaline solution for a maximum of 12 hours.

43. An hermetically sealed housing (1) manufactured by the method of any one of claims 26 to 42, comprising a hermetically sealed functional area enclosed therein.

44. The hermetically sealed housing (1) according to claim 43, wherein, The hermetically sealed outer shell (1) includes a accommodating cavity (12).

45. Use of the housing (1) manufactured by the method according to any one of claims 26 to 42, wherein the housing has an hermetically sealed functional area enclosed therein.

46. ​​The use according to claim 45, wherein the housing includes a receiving cavity (12).

47. The use according to claim 45, wherein the housing includes a receiving cavity (12) for a medical implant or sensor.

48. The use according to claim 45, wherein the housing includes a receiving cavity (12) for a barometer.

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