Hermetically sealed housing made of tempered glass and method for manufacturing the same

Abstract

The present invention relates to a hermetically sealed housing comprising a base substrate and a cover substrate forming at least a portion of the housing, and at least one functional area surrounded by the housing, wherein at least the cover substrate preferably comprises a glass-like material, the base substrate and the cover substrate are hermetically joined by at least one laser bond line, the laser bond line having a height HL perpendicular to the bonding planes, and at least the cover substrate comprises a strengthening layer, preferably a chemically strengthened layer, on a surface thereof, at least on a side opposite the laser bond line, the strengthening layer preferably applying a compressive stress to the cover substrate.

Description

Technical Field

[0001] Description Field of the Invention The present invention relates to a transparent cover layer for a housing, a transparent housing, and a method for providing a plurality of hermetic housings.

[0002] Background and Summary of the Invention Hermetically sealed housings can be used to protect delicate electronic devices, circuits, or sensors, for example. For example, medical implants can be used in areas such as the heart or retina, or in bioprocessors. Conventionally, housings made of titanium have been fabricated and used for such purposes.

[0003] In particular, in adverse environmental conditions, sensors can be protected by a housing. Such fields also include, for example, MEMS (Micro-Electro-Mechanical Systems) and barometers.

[0004] Further fields of use for the housing according to the present invention include fields such as smartphone covers and virtual reality glasses.

[0005] What is common to the foregoing applications is that high demands are placed on the robustness of the electronic device. Therefore, it is necessary to protect the electronic device from the influence of the environment. Furthermore, it may be required that the optical interaction with the region inside the housing, i.e., the cavity formed by the housing, is guaranteed, i.e., the housing is at least partially transparent.

[0006] In principle, a plurality of members can be combined and arranged such that a storage area capable of accommodating components is created in the intermediate space. For example, European Patent No. 3012059 shows a method for manufacturing a transparent member for protecting optical components. Here, a novel laser process is used.

[0007] The present invention should be recognized within the framework of improving the housing, particularly in terms of enhancing durability. In this way, it is possible to increase the robustness against environmental influences and, for example, mechanical loads.

[0008] Thus, in other words, the present invention is based on the problem of providing an improved housing for a cavity in order to withstand more adverse environmental conditions and influences. In this regard, particular attention is paid to the mechanical stress on the housing, for example, so that the edges do not break.

[0009] Since the improved housing must maintain an advantage even in the competitive market situation, a further aspect of the present invention is to provide the improvement of the housing, particularly inexpensively, but also showing reliability and durability.

[0010] Therefore, in the present invention, a method for providing a plurality of hermetically sealed housings is presented. Although it is easily possible to modify this method so that only a single housing is manufactured, manufacturing a plurality of housings in the same process sequence can save time, labor, and raw materials, so such manufacturing is reasonable from an economic perspective.

[0011] According to the present invention, there is provided a hermetically sealed housing comprising at least a base substrate and a cover substrate forming at least a part of the housing. That is, for example, the cover substrate is placed flat on the base substrate so that the base substrate forms a stack with the cover substrate. Preferably, this may be a wafer stack.

[0012] The housing surrounds at least one functional area, and this functional area may be prepared so that various tasks can be executed. For example, the functional area can include an active surface. Preferably, the functional area has a cavity, that is, an empty space surrounded by the housing. This cavity may be prepared for the installation or accommodation of functional components and serves as an accommodation cavity.

[0013] At least the cover substrate preferably contains a glassy material in at least a specific region. Further, the glassy material of the cover substrate is preferably transparent to at least a specific wavelength range in at least a specific region. In one example, the cover substrate is made of glass that is transparent to the wavelength range of 350 nm to 1800 nm. Further, an antireflection coating, so-called AR coating, is applied to both surfaces of the cover glass, whereby Fresnel reflection in the range of 1000 nm to 1100 nm is reduced to less than 1% from 5% respectively. Most glasses have high permeability to this wavelength range. The final permeability is determined by the coating applied later and can be designed according to each characteristic.

[0014] The base substrate and the cover substrate are joined in a hermetically sealed state by at least one laser bonding line. Therefore, the base substrate and the cover substrate can be directly joined in a hermetically sealed state by the laser bonding line.

[0015] Here, the laser bonding line has a height HL perpendicular to its bonding surface. In other words, the laser bonding line can be understood as a continuous molten line, usually having an elliptical cross-section (the height HL + AF is at most 100 μm, the width is 10 - 20 μm), caused by the heat accumulation of a kind of bead string of laser emission. Generally, the molten line is formed above the bead string of laser emission. Here, since the position AF of the bead string of laser emission is below the bonding surface, the cross-section of the obtained molten zone passes through the bonding surface. Therefore, the molten line has a certain spread. In this example, the vertical distance in one direction from the bonding surface to the end of the bonding zone of the laser bonding line is called HL. In laser welding, preferably, the laser is used at a high repetition rate. Usually, the bead string of laser emission can no longer be visually recognized, and the bead interval is only indirectly incorporated into the geometry of the molten line (by heat accumulation).

[0016] At least the cover substrate has a strengthening layer, preferably a chemically strengthened layer, on its surface, at least on the side opposite to the laser bonding line, and the strengthening layer preferably applies compressive stress to the cover substrate.

[0017] In other words, when providing the housing, in the first step, a first substrate (base substrate) and at least one second substrate (cover substrate) are prepared. At this time, at least one second substrate is made of a transparent material, that is, at least in a specific region or partially, it is transparent to at least one wavelength range. At this time, at least two substrates are arranged so as to be in direct contact with each other or overlap each other. The cavity to be sealed is covered by at least one second substrate, and the lower surface of each housing is formed by the first substrate. At least one contact surface is formed between at least two substrates, and each housing has at least one contact surface. Then, by joining at least two substrates along the contact surface of each housing, particularly along the line at the edge of each housing, the cavity is hermetically sealed. Advantageously, the housing can be manufactured together, for example, in the form of wafers of a wafer stack, for example, from a common starting substrate. And in this process, each housing is individualized by a cutting or separating step.

[0018] The substrate layers are laminated so as to be in direct contact with each other, that is, arranged to be in contact with each other. By eliminating different materials between the substrate layers as much as possible, the contact between one substrate layer and the adjacent substrate layer becomes as close and flat as possible. For example, when there are two substrates, the base substrate and the cover substrate are arranged so as to be in direct contact with each other, especially without other materials or gaps between the base substrate and the cover substrate. For example, if the distance between the substrate layers, which may also be caused by the unevenness of the substrates, is less than 5 μm, preferably less than 2 μm, and more preferably less than 1 μm, it is considered acceptable.

[0019] In the example of three or more substrates, the base substrate is arranged so as to be directly adjacent to the intermediate substrate layer or the first intermediate substrate layer, and the cover substrate is arranged so as to be directly adjacent to the intermediate substrate layer or the last intermediate substrate layer.

[0020] Thereafter, the base materials are joined to each other by a new laser joining process. In this case, without the provision or requirement of dissimilar materials, non-planar materials, or intermediate material layers for this purpose, one planar base material layer is directly joined to a planar base material layer arranged to be directly adjacent thereto. Therefore, the base materials are directly joined to each other. The generated laser joining lines introduced into the planar contact region between the two base material layers join the base material layers arranged to be in direct contact with each other in a non-separable state. Therefore, the fusion region of the laser joining lines exists in both base materials and seamlessly connects, for example, from a first base material to a second base material arranged to be directly adjacent thereto, such as from a base substrate to a cover substrate.

[0021] In this way, a direct, planar, or even complete transition, such as a substrate-substrate transition or a glass-glass transition, is formed from one base material layer to the next. A locally limited volume is formed as a joining zone or a laser joining line, where material movement or mixing occurs, particularly between adjacent planar base material layers. In other words, the material of the first base material, for example, the cover substrate, penetrates into the adjacent base material, for example, the intermediate substrate or the base substrate, and vice versa, i.e., the material of the adjacent base material penetrates into the first base material. Therefore, complete material mixing occurs between the adjacent base materials in the joining zone. Therefore, the joining zone can also be called a convection zone.

[0022] Here, in this new laser bonding technology for generating inseparable substrate-to-substrate transitions, particularly advantageously, no intermediate layer, glass frit, foil, or adhesive that had to be introduced between the substrates in conventional known methods is used. Without using the corresponding additional intermediate layer or additional material, an inseparable bond can be generated. This enables increasing the achievable strength of the final product without using additional materials and reliably hermetically sealing functional areas or cavities. Here, the laser bond can be detected in the completed final product, for example, by a specific local change in the refractive index of the material in a small fusion area.

[0023] In the housing, the base substrate and the cover substrate can be joined to each other in a hermetically sealed state with the same laser bonding line. On the other hand, one or more intermediate substrates may be arranged between the base substrate and the cover substrate. In this case, the base substrate is joined to the lowermost intermediate substrate, and the cover substrate is joined to the uppermost intermediate substrate.

[0024] At least one laser bonding line preferably can At a distance surround the periphery of the functional area. Also, the laser bonding line can be drawn, for example, as an S-shaped curve in the area of the material or the contact surface of the two substrates. In this case, if necessary, it is partially drawn into the strengthening area or the strengthening zone of the strengthening material. Surprisingly, it has been found that the material bonding by the laser bonding process is effective even when the tensile stress accumulated in the material due to strengthening is large.

[0025] The strengthening layer can have a strengthening layer thickness DoL. The cover substrate can preferably have a minimum material thickness MM up to the strengthening layer above the laser bonding line. Also, for the total thickness DA of the cover substrate, DA - HL - DoL ≥ MM can hold. Therefore, even if the height of the laser bonding line that penetrates HL into the cover substrate is subtracted from the total thickness DA and further the strengthening layer thickness DoL is subtracted, at least the minimum material thickness MM of the cover substrate remains. This distance MM ensures that heat dissipation in the strengthening area does not occur.

[0026] The strengthening layer thickness DoL is the depth at which the stress curve passes through zero stress. Surprisingly, the weld line can be present within the DoL of the cover glass without affecting the strength. This exists in the achievable slight lateral spread of the laser bond line in the range of less than 50 μm, for example 10 - 50 μm or 10 - 20 μm. The weld line may protrude up to the strengthening surface. This is because it preferably only "de-strengthens" an area that is not significant there. In other words, if the laser bond line is prepared or adjusted to have only a slight lateral spread, the laser bond line may be part of the strengthening surface.

[0027] However, for safety reasons, a minimum material thickness MM separating the laser bond line and the strengthening surface may be provided above the laser bond line. The minimum material thickness is preferably 100 μm or more, more preferably 50 μm or more, and even more preferably 20 μm or more. On the other hand, it has been found that it is sufficient if the minimum material thickness MM above the laser bond line is less than 200 μm, preferably less than 100 μm, and more preferably less than 50 μm.

[0028] The cover substrate may advantageously be strengthened on both sides, and as a result, the cover substrate is provided with a second strengthening layer having a strengthening layer thickness DoLb on the surface facing its functional area and / or the bonding surface with the base substrate.

[0029] The height HL of the laser bond line can be made greater than the strengthening layer thickness DoLb of the second strengthening layer.

[0030] At least the cover substrate is preferably strengthened throughout, that is, in particular, its entire outer peripheral surface is strengthened. In other words, the cover substrate is provided throughout with one or more strengthening layers surrounding, in particular completely surrounding, the functional area. In that regard, the package is strengthened afterwards.

[0031] And the strengthening layer has a strengthening layer thickness DoLa, the second strengthening layer has a strengthening layer thickness DoLb, and the third strengthening layer can have a strengthening layer thickness DoLc at the peripheral portion of the housing. In one example, the thicknesses DoLa, DoLb, and DoLc may be the same.

[0032] On the side of the functional area, the minimum lateral distance DB between the laser bonding line and the strengthening layer thickness DoLa can be, for example, 5 to 10 μm. Since this transition portion is not demagnetized, it is advantageous that at least half of the module width is maintained on the side of each strengthened edge. The laser bonding line can be as high as, for example, HL of 100 μm or less, so that the ratio of the welding area to the edge area becomes more disadvantageous. Therefore, it is better here not to let the laser bonding line protrude into the strengthening zone at all.

[0033] The cover substrate can include the aforementioned or another functional area. That is, a functional area may be arranged on the cover substrate. For example, the functional area can include an active surface applied to the lower surface of the cover substrate, such as a reflective layer. For example, by hollowing out the cover substrate by an appropriate process, the functional area may be formed on the cover substrate. For this purpose, a sandblasting process may be suitable.

[0034] Also, the base substrate may be provided with a strengthening layer DoLd on its lower surface on the side opposite to the laser bonding line.

[0035] Each housing can form a cavity surrounded by the lateral peripheral portion, the lower surface, and the upper surface of the housing. In other words, such a cavity is completely surrounded by the housing, and the housing forms the peripheral portion, the lower surface, and the upper surface of the cavity.

[0036] This cavity may be formed as a receiving cavity in particular. That is, for example, an electronic circuit, a sensor, or MEMS can be inserted into each cavity and housed therein. In particular, the aforementioned devices such as electronic circuits, sensors, or MEMS are arranged in the receiving cavity and thus are completely surrounded by the housing.

[0037] In the method according to the present invention, first, at least two base materials, for example a cover base material and a base base material, are prepared, and at least one of the two base materials is made of a transparent material or contains a transparent material in at least a specific region. The at least two base materials are arranged so as to be in direct contact with each other or to directly overlap each other. In other words, the at least two base materials are arranged or attached so as to be in contact with each other such that there is no other layer between the at least two base materials and they are in flat contact with each other.

[0038] For technical reasons, it may not be possible to avoid a slight gas ingress between the base material layers, which is also due to the unevenness of the base material layers. For example, the amount of the entrapped gas can be further reduced by increasing the pressure, for example, by pressing at least two base materials against each other, or by performing a surface treatment of the base material layer such as a polishing process. The thickness of the possible gap generated between the base materials is particularly preferably 5 μm or less, more preferably 2 μm or less, and even more preferably 1 μm or less. Such a gap is generated, for example, due to tolerances during the production of the base material, the influence of heat, or the ingress of particles such as dust. Even within such an allowable interval, in the present invention, since they are regarded as being directly adjacent to each other, laser bonding can be performed so that the thickness of the bonding zone becomes 10 to 50 μm, thereby ensuring airtight sealing. Also in this case, the bonding zone reaches from the first base material to the second base material arranged adjacent to the first base material. In this way, a bonding zone is introduced into the contact area between the first base material and the second base material, and the base materials are directly fused to each other to form an inseparable bond. That is, by bonding the adjacent base materials with the bonding zone, the materials of both base materials in the bonding zone are directly melted, and the material of the first base material and the material of the second base material are mixed to form an integral bond that cannot be separated. Therefore, the housing thus manufactured has an integral, that is, monolithic bond between the base materials in any case in the bonding zone.

[0039] At least one transparent substrate forms each edge and each upper surface of each housing of the cavity to be sealed. In a preferred embodiment, the at least one transparent substrate is two transparent substrates in contact with each other, whereby the first transparent substrate forms the edges of each cavity and the second transparent substrate forms the upper surfaces of each cavity. In another embodiment, the transparent substrate has depressions or recesses. These depressions or recesses can be introduced into the transparent substrate by other subtractive processes such as, for example, a grinding process or an etching process. The second substrate forms the lower surface of each housing.

[0040] In a preferred embodiment, since all three substrate layers are transparent, in addition to the lower surface and the edges, the upper surface and thus the entire housing are made of a transparent material.

[0041] The step of hermetically sealing the cavity can be performed by joining at least two substrates along each joint surface of each housing using a laser bonding process. In other words, energy can be applied in a local manner, such as a cold welding process, using a laser in the joint surface or the region of the desired penetration depth. In this way, the thermal energy provided for joining is intensively applied to the extension of the joint surface and diffuses slowly only to the remaining material of the housing, so that a large temperature rise does not occur, especially in the cavity. This prevents overheating of the electronic devices arranged in the cavity.

[0042] By locally melting the materials of both substrates along the joint surface in the region of each housing using a laser, at least two substrates are locally joined. A person skilled in the art can refer to, for example, European Patent No. 3012059 in this regard, and the content thereof is incorporated herein by reference.

[0043] Each housing is individualized by a cutting or separating step. This means cutting or separating the substrate so that each housing is individualized from other materials.

[0044] Finally, the housing is chemically strengthened on its surface by a bath containing the chemical solution.

[0045] The inventors have found that by immersing the housing in a chemical solution to chemically strengthen the surface, the fracture resistance of each housing can be significantly improved, and in particular, the breakage of the edges is reduced thereby. This is surprising for several reasons.

[0046] First, it is surprising that the chemical solution does not penetrate to the joints of the bonding and does not impose a chemical load on the joints of the bonding. This could have a deteriorating effect, which had to be first assumed. Therefore, heretofore, in the process of bonding two or more base materials to each other, it was considered that a chemically strengthened housing could not be technically realized because the housing was expected to be damaged when the housing was individualized from the base material. This was also pointed out by the inventors at the initial prototype stage. However, by the method presented herein, particularly in the case of using a laser in the bonding and / or separation step, this has now become possible in a surprising manner.

[0047] Furthermore, surprisingly, it has been found that the cavity sealed by laser bonding can easily withstand an internal pressure of 2 atmospheres or more that may occur, for example, when heating the housing in a strengthening bath.

[0048] The housing preferably includes first and second transparent base materials. The first transparent base material forms each edge of the cavity, and the second transparent base material forms each upper surface of the cavity. That is, the first transparent base material forms a cover base material, and the second transparent base material forms an intermediate base material. When two transparent base materials are used, the first forms the edge and the second forms the upper surface, so that two circumferential optically transparent regions are already assigned to each housing. In this case, on the one hand, by bonding along the two interfaces between the cover base material and the intermediate base material and on the other hand between the intermediate base material and the base material by laser bonding, each cavity is hermetically sealed. In this case, in addition to the first transparent base material and the second transparent base material, the base materials are also firmly welded to each other, and at the same time the cavity is hermetically sealed.

[0049] Preferably, at least two, preferably three substrates are provided in the form of a wafer stack comprising at least two, preferably three wafers. Thereafter, in the same working process, a plurality of hermetic enclosures can be manufactured collectively from the wafers or wafer stack. This method has proven to be particularly economical since there is particularly little waste and material loss.

[0050] At least two wafers preferably consist of glass, or at least one wafer consists of glass and the second wafer consists of a material different from glass. In other words, the wafer forming the lower surface of the cavity can be prepared from a material that is not optically transparent but has other properties such as, in particular, electrical conductivity if required. In contrast, the edges and upper surface of the enclosure are composed of a transparent material. Even more preferably, all substrates are prepared from a transparent material. In the case of a transparent enclosure made of glass or a glass-based material, in particular a transparent enclosure made of borosilicate glass, it is particularly advantageous to be chemically inert.

[0051] The edge strength of the hermetic enclosure can be measured by the four-point bending test method. The edge strength of the enclosure strengthened by the method of the present invention is at least 150 MPa, or even more than 150 MPa, and thus particularly highly durable.

[0052] The individualization of each enclosure is preferably carried out using a laser, i.e., using a laser cutting or laser separation process. Thereby, the enclosures can be separated more cleanly, with less breakage and a cleaner separation location being obtained. Preferably, the same laser used in the bonding step may also be used for separation.

[0053] In addition, at least one transparent substrate can include, in addition to glass, glass ceramic, silicon, or sapphire, or a combination of the foregoing materials, and can consist of, for example, a combination of glass and silicon, a combination of glass / silicon / sapphire, or a combination of silicon / sapphire.

[0054] One or more substrates may be coated. In the laser irradiation region, if transparency or at least partial transparency is ensured with respect to the wavelength of the laser used, for example, an AR coating, a protective coating, a bioactive film, an optical filter, such as a conductive layer made of ITO or gold, can be used.

[0055] The step of chemically strengthening the housing preferably includes at least one of the following sub-steps: preparing an acidic or basic solution, particularly a solution containing or consisting of KNO3; introducing the housing into the acidic or basic solution; heating the acidic or basic solution to a temperature of at least 650 K, preferably at least 700 K, more preferably at least 720 K; immersing the housing in the acidic or basic solution for at least 6 hours, preferably at least 8 hours, more preferably at least 9 hours, and preferably at most 12 hours.

[0056] The acidic or basic solution may contain other potassium salts. In principle, it is also possible to exchange sodium ions with rubidium, cesium, francium, etc. During strengthening, care should be taken to minimize the contact between the housing and, for example, the tank, the rack used, or other objects in the bath. This is because the effect of the strengthening bath may be reduced at the corresponding contact points.

[0057] According to the present invention, there is also provided a housing manufactured by the above method and having a hermetically sealed and airtight accommodation cavity therein.

[0058] The housing produced by the above method can be advantageously used as a medical implant or as a sensor, in particular as a barometer.

[0059] Similarly, particularly transparent housings with a hermetically sealed cavity for accommodating an object are also within the scope of the present invention. The object to be accommodated is, for example, an electronic circuit, a sensor or a MEMS.

[0060] The housing according to the invention comprises a lateral peripheral part, a lower face and an upper face made of a transparent material, which together completely surround the cavity.

[0061] Here, at least one of the lateral peripheral part, the lower face or the upper face is transparent for at least a specific region in a certain wavelength range. In other words, it is sufficient if at least one partial element of the housing is transparent for at least a certain partial region of that partial element in a preferred wavelength range, where the wavelength range is known in advance and, if desired, the material can be adjusted according to the wavelength of the laser used.

[0062] The housing is joined by a laser bonding process to form a hermetically sealed housing. In other words, the edge, the lower face and the upper face consist of two or more members, for example two or three or more members, which are joined by laser to complete the housing.

[0063] The housing is chemically strengthened at least partially and / or in specific regions. For example, one surface of the housing, i.e. the upper face for example, is chemically strengthened. Also, the upper face and the edge may be chemically strengthened. Particularly preferably, in addition to the upper face, the edge and the lower face are also chemically strengthened, so that not only each surface of the upper face or the lower face, but also each edge, i.e. the edge, is chemically strengthened.

[0064] The lateral peripheral part may preferably be made of a first substrate, where the lower face is made of a second substrate and the upper face is made of a third substrate. Thereafter, the housing is also manufactured from a wafer stack.

[0065] Preferably, in the transparent housing, the lateral peripheral portion and / or the lower surface and / or the upper surface may be chemically strengthened, or more preferably, the entire surface of the housing is chemically strengthened.

[0066] The chemical strengthening of the housing 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 with potassium ions.

[0067] The housing is preferably subjected to chemical strengthening, for example, by a certain manufacturing method, particularly after separation from a further housing manufactured together with the housing by the above manufacturing method.

[0068] The housing can include a lateral peripheral portion made of a transparent material made from a first member, a lower surface made from a second member, and an upper surface made from a third member, which together completely surround the accommodation cavity.

[0069] In that case, at least the three above-mentioned members of the housing are joined by a laser bonding process to form a hermetically sealed housing.

[0070] Preferably, the housing has an edge strength of at least 150 MPa or more than 150 MPa, and the edge strength can be measured using a four-point bending test method.

[0071] The transparent housing can have a size of, for example, 3 mm × 3 mm or less. In particular, the receiving cavity has a diameter of 2 mm or less. For example, the transparent housing can also have a size of 0.2 mm × 0.2 mm or less. However, depending on the field of use, it is also possible to manufacture the transparent housing in a sufficiently larger size, and a length of several centimeters or more is also possible. The practical size limitation is due to the preferred manufacturing method and should not be understood as a size limitation per se. This is simply the size of the wafer to be cut. However, the use of wafers for manufacturing should be understood only as an example. For the manufacture of a transparent housing that can have dimensions larger than the typical wafer size, it is also fully possible to use, for example, sheet glass.

Brief Description of the Drawings

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[0073] Detailed Description of the Invention FIG. 1a shows a state where the housing object 2 to be protected is embedded on the base substrate or the lower wafer 3, the intermediate wafer 4 covers it or surrounds its side surfaces, and the cover substrate or the upper wafer 5 covers it. In this way, the three wafers 3, 4, and 5 are integrated to form the housing 1 around the housing object 2 disposed in the cavity 12 in the example of FIG. 1. In other words, in the example of FIG. 1a, when the upper wafer 5 is placed on the intermediate wafer 4, a completely closed housing cavity 12 is formed, which will be hermetically sealed in subsequent steps.

[0074] Figure 1b shows the hermetically sealed housing 1 thus formed. In this housing 1, as in the example of Figure 1, the base substrate or lower wafer 3, the intermediate substrate or intermediate wafer 4, and the cover substrate or upper wafer 5 are laminated so as to overlap. On the one hand, a contact surface or interface 25 is provided between the lower wafer 3 and the intermediate wafer 4, and on the other hand, a contact surface or interface 25 is provided between the intermediate wafer 4 and the upper wafer 5. Also, as can be seen from Figure 1a, since the intermediate wafer layer 4 is not formed in a continuous form, the accommodation cavity 12 is formed at the height of the intermediate wafer layer 4.

[0075] Referring to Figure 2a, a cross-section of the hermetically sealed housing 1 is shown. The lower wafer 3 forms the lower surface 22 of the cavity 12, the intermediate wafer 4 forms the edge 21 of the cavity 12, and finally the upper wafer 5 forms the upper surface 23 of the cavity 12. That is, the lower wafer, the intermediate wafer, and the upper wafers 3, 4, 5 are integrated to surround the accommodation cavity 12 as a wafer stack 18. An accommodation object 2 is disposed in the cavity 12.

[0076] Figure 2b shows a detailed cross-sectional view of the bonding region, clearly showing the laser-bonded interface zone 7 and the laser-bonded zone 8. The laser-bonded zone 8 is disposed in the region of the optical interface 25. From the outside of the housing 1, the influence of the environment can act on the housing, particularly on the corners 6 of the laser-bonded stack 18. At this time, these corners 6 also prevent, for example, the penetration of chemical solutions into the wafer stack 18 up to the laser-bonded zone 8. In other words, surprisingly, chemical solution penetration does not occur at the corners 6 of the laser-bonded stack 18.

[0077] Figure 3 shows a top view of the housing 1 according to the present invention, with the surrounding laser bonding zone 8 surrounding the functional area 13. The functional area 13 may be constructed in various ways. Examples of the configuration of the functional area 13 and other options of the housing are shown in FIGS. 4a to 8b. In FIG. 3, since all top views are schematically illustrated in the same manner, different configurations of the functional area 13 can be combined and shown together in the figure. Cross-sections are shown along line A-B or C->D, which are shown in FIGS. 4a to 8b.

[0078] The functional area can perform different tasks, which may be, for example, an optical receptor or technical, electromechanical and / or electronic components arranged in the functional area 13. Some of these tasks can also be realized in the functional area 13. The housing 8 is covered from above by the upper substrate 5. The laser bonding zone 8 penetrates into this upper substrate 5.

[0079] Referring to FIG. 4a, a first cross-sectional view of the first embodiment of the housing 1 is shown, and the upper substrate 5 has a first reinforcement layer 27 on its upper surface. For example, before or after bonding the cover substrate 5 to the base substrate 3, the upper surface of the cover substrate 5 can be immersed in a strengthening bath (see, for example, FIG. 9), whereby the completed housing 1 has one side chemically strengthened, that is, it has at least one strengthening surface 27 and / or at least one strengthening layer. In other words, the completed housing 1 is strengthened at least in a specific area or at least partially, for example, particularly chemically strengthened. During chemical strengthening, a compressive stress is formed on the cover substrate 5.

[0080] Figure 4a further shows the structure of the laser bonding line 8 composed of a plurality of consecutive laser pulse hit regions 16, and these laser pulse hit regions 16 are arranged close to each other so that the materials of the base substrate 3 and the cover substrate 5 are fused to each other without gaps. The first reinforcement layer 27 has a height DoL. The bonding zone 8 has a height HL. A minimum material thickness MM remains between the reinforcement zone 27 and the bonding zone 8. The total thickness of the cover substrate 5 can be composed of HL + MM + DoL.

[0081] Figure 4b shows a cross-sectional view of an embodiment of the housing 1 along the line C->D inserted in Figure 3. The cover substrate 5 is provided with a first reinforcement layer 27 on its upper surface or outside, and this first reinforcement layer 27 extends into the material of the cover substrate 5 over a thickness DoL. That is, since the cover substrate 5, and thus the housing 1, has an enhanced upper surface or is provided with a reinforcement zone 27 there, the housing 1 is reinforced in a specific area, that is, one side is reinforced.

[0082] Figure 4b further shows a cross-section of the functional regions 13, 13a extending in the housing 1, for example as continuous voids or cavities. In other words, the cavity extends from the base substrate 3 to the cover substrate 5 and exists, for example, in the form of recesses in the base substrate 3 and / or the cover substrate 5. Also, for example, the functional region 13a may also include an active layer, such as a conductive layer, and the functional region 13 may include a cavity. A laser bonding zone 8 is arranged around the functional regions 13, 13a, whereby the functional regions 13, 13a are sealed laterally over the entire circumference. It is conceivable to leave an open region in the laser bonding zone 8 so that the functional regions 13, 13a are not completely sealed, for example, to open a communication channel that can establish fluid communication with the environment. That is, instead of sealing at a pre-planned location or position with a focused laser beam 9, it may be designed to set an airtight seal there with other means such as an adhesive. It is preferable that the functional regions 13, 13a are completely sealed without gaps.

[0083] Referring to FIG. 5a, a further embodiment is shown, in which a laser bonding zone 8 is formed along the contact surface 25 by laser pulse hits 16, and at this time the cover substrate 5 is welded or bonded to the base substrate 3. In this embodiment, the cover substrate 5 is provided with a first strengthening layer 27 on its upper surface and a second strengthening layer 28 on its lower surface. To achieve this, the cover substrate 5 was first placed in a strengthening liquid without contacting other substrates, and its two opposing surfaces were chemically strengthened. In this embodiment, in this way, the cover substrate 5 is directly bonded in the region of the strengthening layer 28. It is very surprising that bonding in the strengthening layer 28 is generally possible.

[0084] FIG. 5b shows a further embodiment of the housing 1, and a cross-sectional view taken along the line C->D shown in FIG. 3 is shown. The housing 1 is provided with a first strengthening layer 27 and a second strengthening layer 28, and both strengthening layers are introduced or applied to the cover substrate 5. The functional regions 13, 13a extend through the strengthening layer 28 such that the strengthening layer 28 is limited to an annular region around the functional regions 13, 13a. The bonding zone 8 is partially present within the second strengthening layer 28. The strengthening layer 28 has a height DoLb. The individual laser pulse hit regions 16, and thus the bonding zone 8, may be adjusted such that its height HL exceeds that of the second strengthening zone 28. Thereby, it is possible to ensure that the joint enters the non-strengthened region of the material, that is, the end of the joint region does not enter the pre-compression region. In this way, the end of the bonding zone 28 enters the non-stress region of the material, that is, especially of the glass. In other words, the bonding zone 8 is provided with a protrusion on the second strengthening layer 28, and this protrusion extends into the non-strengthened material in the region MM.

[0085] According to FIG. 6a, a further example of the housing 1 is shown, in which a first reinforcing layer 27, a second reinforcing layer 28, and a third reinforcing layer 29 are introduced. In this embodiment, the cover substrate 5, and further the base substrate 3 as well, have their two long sides reinforced, particularly chemically strengthened in a strengthening liquid. That is, each long side of the substrates 3, 5, i.e., for example, each upper surface and lower surface, is individually immersed in a strengthening liquid for chemical strengthening to strengthen the long sides. After strengthening, the two substrates 3, 5 are overlapped, i.e., laminated, so that the upper surface of the base substrate 3 contacts the lower surface of the cover substrate 5. In this way, the reinforcing zone arranged on the upper surface of the base substrate 3 lies on the reinforcing zone arranged on the lower surface of the cover substrate 5. And the substrates 3, 5 are directly joined in the region of the reinforcing material, i.e., particularly in the region of the reinforced glass.

[0086] By the laser bonding process, relaxation of the material occurs in the region of each laser pulse hit zone 16. When the height of the laser pulse hit zone exceeds the height of the reinforcing zone 28 at its height HL, a protrusion remains, and it is assumed that there is material that continuously relaxes from the first substrate 3 into the second substrate 5 beyond the region of each pulse hit zone 16. Therefore, in the stack of the completed housing 1, the first reinforcing layer 27 is arranged on its upper surface, the second reinforcing layer 28 is arranged on the contact surface 25, and the third reinforcing layer 29 is arranged on its lower surface.

[0087] FIG. 6b shows a further embodiment in the region of the cross-section C->D, which has three reinforcing zones 27, 28, 29. Also, the functional regions 13, 13a are arranged to penetrate from the base substrate 3 into the cover substrate 5 and extend, for example, as recesses in each substrate. Such recesses 13, 13a can be introduced particularly by a sandblasting process. Since the bonding line 8 is arranged around these recesses 13, 13a, the recesses 13, 13a are hermetically sealed overall.

[0088] Figure 7a shows another embodiment of the housing 1 in the region of the cross-section A->B. The cover substrate 5 has a first reinforcing layer 27 on its upper surface and a second reinforcing layer 28 on its short side or edge 14. ´ For example, the cover substrate 5 is immersed in a strengthening liquid for chemical strengthening, either individually or after bonding to the base substrate 3, and is immersed to a level reaching the height of the second reinforcing layer 28. ´ In this example, the base substrate 3 does not have a strengthening zone. In this example, the lateral strengthening zone 28 ´ ends immediately in the region of the contact surface 25 between the cover substrate 5 and the base substrate 3. The joint along the joint line 8 is introduced into the inside of the strengthening zone 28, ´ i.e., into the relaxed material.

[0089] Figure 7b shows another embodiment of the housing 1. The first long side has a reinforcing layer 27, and the first short side 14 has a reinforcing layer 28 in a specific region. ´ The reinforcing layer 28 ´ can extend around the housing 1 and is closed, for example, around the functional area 13. When compared with Figure 3, a cross-section along the line C->D drawn there, i.e., through the functional area 13, is shown. In this embodiment, the functional area 13 is limited to the dimensions of the cover substrate 5, i.e., it does not penetrate into the base substrate 3. Since the base substrate 3 is directly and immediately bonded to the cover substrate 5, no additional layer or additional substrate is arranged between the base substrate 3 and the cover substrate 5. The functional area 13 is designed as a cavity. The cavity can be introduced into the cover substrate 5, for example, by a sandblasting process, generally a polishing process. It is also possible to introduce a cavity into the substrate by chemical etching.

[0090] Figure 8a shows another embodiment of the housing 1, showing a cross-section of the region along line A->B shown in Figure 3, i.e., a cross-section along or through the joining line 8. In this embodiment, the housing 1 is strengthened on all outer surfaces, i.e., two opposite long sides are provided with strengthening layers 27 and 29, and the edge 14 around the housing is provided with a strengthening layer 28 ´ and the surrounding edge 14 extends around the housing 1. That is, in the case of a rectangular parallelepiped housing, the four short sides of the rectangular parallelepiped are all combined to form the edge 14. Also, the edge 14 can be interpreted or referred to as the edge 21 of the housing extending around the cavity. The housing 1 as shown in Figure 8a can be obtained, for example, by immersing a completed joined housing including a cover base material 5 and a base base material 3 in a strengthening liquid and chemically strengthening it particularly there. The strengthening layers 27, 28 ´ , 29 are thus directly arranged on the outside of the housing 1. Therefore, a region for the joining line 8 remains inside the strengthening layers 27, 28 ´ , 29, and this region is introduced at an appropriate distance from the strengthening layers 27, 28 ´ , 29.

[0091] Figure 8b shows an embodiment of the housing 1, showing a cross-section along line C->D. The housing 1 is chemically strengthened throughout, in other words, all surfaces are provided with strengthening regions 27, 28 ´ , 29. For example, a first strengthening layer 27 is arranged on the first long side which may be the upper surface of the cover base material 5, a third strengthening layer 29 is arranged on the second long side which may be the lower surface of the base base material 3, and a second strengthening layer 28 ´ is arranged on the peripheral edge 21 or the surrounding edge 14. The upper surface 23 of the cavity is arranged inside the first strengthening layer 27, the edge 21 of the cavity is arranged inside the second strengthening layer 28 ´ , and the lower surface 22 of the cavity is arranged inside the third strengthening layer 29. In this way, the cavity or the functional regions 13, 13a are strengthened throughout by the strengthening materials 27, 28 ´, It is surrounded by 29. Referring to FIG. 9, a first embodiment of the manufacturing method of the housing 1 is shown. In step A, alignment is performed between the wafer and the housing object 2 to be housed. At this time, the cover base material or the upper wafer 5 is placed on the intermediate wafer 4, and this is placed on the base base material or the lower wafer 3, thereby forming a wafer stack 18. Here, since the intermediate wafer 4 including the recess in which the cavity 12 is formed is disposed at the center, the housing cavity 12 will then be entirely surrounded by the wafer material. That is, when aligning the wafers in step A, the complete enclosure of the cavity 12 is formed by the edge 21, the lower surface 22, and the upper surface 23 of the cavity.

[0092] Step B of the method shown in FIG. 3 shows the wafer stack 18 arranged to overlap, which includes a cavity 12 for housing the housing object 2 therein. This wafer stack 18 can be supplied to the bonding process in this closed form.

[0093] Step C shows the laser bonding of each housing cavity 12, that is, the complete sealing of the cavity 12 along the contact surface 25. For this purpose, the laser unit 15 is guided from above the wafer stack 18 through the surface of the wafer stack 18, and at this time, the focused laser beam 9 is directed in a spot shape onto the zone to be bonded. The laser bonding line 8 can be implemented, for example, as a raster of intersecting lines. Also, it is possible to draw two or more laser bonding lines 8 in parallel if it has been found to be advantageous, for example, depending on the material to be individualized later. When step C of the manufacturing method is completed, all the cavities 12 are in a hermetically sealed state.

[0094] Step D shows the step of separating or cutting the wafer stack 18 to individualize the housing 1. Here, the wafer stack is cut or separated along the separation or cutting line 10.

[0095] In step E, the housing 1 is chemically strengthened in a bath 11 containing an acidic or basic strengthening liquid. Preferably, the bath 11 is provided with a temperature control unit so as to be able to maintain a predetermined temperature.

[0096] Finally, step F shows the chemically strengthened hermetically sealed housing 1 in which the accommodation cavity 12 is arranged.

[0097] Referring to FIG. 10, a further method is shown by which a chemically strengthened hermetically sealed housing 1 can be obtained. In step A of the method, the individual wafer layers 3, 4, 5 are arranged so as to overlap and are aligned to form a wafer stack 18. An accommodation object 2 is arranged in the accommodation cavity 12.

[0098] Step B shows the manufactured completed wafer stack 18, in which the lower wafer 3, the intermediate wafer 4 and the upper wafer 5 are in direct contact with each other and overlap.

[0099] In step C, this wafer stack is supplied to a bath 11 containing an acidic or basic strengthening liquid and is strengthened in this bath.

[0100] In step D, a laser bonding process is performed, in which the three wafer layers 3, 4, 5 are bonded to hermetically seal each cavity 12. Here, the wafer layers 3, 4, 5 are bonded around each cavity 12 along the optical interface by a laser.

[0101] In step E, a laser cutting process is performed. The laser is guided along a cutting line 10 so as to be able to cut the wafer. In this cutting process, a particularly strong edge is obtained. It is preferable that the edge remains smooth and unbroken. However, for example, by using a short-pulse laser drilling method, an edge with a roughness such as that obtained by finish grinding can also be obtained.

[0102] Step F shows the presence of the chemically strengthened hermetically sealed housing 1.

[0103] FIG. 11 shows a top view of a first example of an embodied reinforced housing 1 made of Schott D263T eco. A round, i.e., substantially circular and fully enclosed cavity 12 inside the housing 1 can be clearly seen. In this example, the horizontal diameter of the cavity 12 is about 4 mm. The length of the edge of the housing is about 5.5 mm. The sample shown was strengthened at 450° C. for 9 hours in a 100% KNO3 solution.

[0104] FIG. 12 shows a side view of the reinforced edge 14 of the housing 1 made of Schott D263T eco. Due to perspective reasons, the cavity 12 cannot be seen in the view of FIG. 12. Referring to FIG. 13, another top view of the housing 1 is shown, where the extent of the edge 14 can also be seen.

[0105] Finally, FIG. 14 shows a side cross-sectional view of the housing 1 according to the invention made of Boro33 with a sealed cavity 12. The sample shown in FIG. 14 was also strengthened at 450° C. for 9 hours in a 100% KNO3 solution. Also, in FIG. 14, a contact surface 25 occurring between the substrate layers, on the one hand, between the lower substrate 3 and the intermediate layer 4 and, on the other hand, between the intermediate layer 4 and the upper substrate 5, can be clearly seen. The upper and lower squares are PMMA disks adhered to glass chips to align the cross-section. Only the portion enclosed by the frame in FIG. 14 shows the glass housing 1. Adjacent to it, plastic is arranged as a residue of sample preparation.

[0106] The above-described embodiments should be understood as exemplary, and the present invention is not limited thereto. It is obvious to those skilled in the art that various modifications may be made without departing from the scope of protection of the claims. Furthermore, each feature, whether or not it is disclosed in this specification, the claims, the drawings, etc., is also clearly capable of defining the essential components of the present invention individually even when described together with other features. In all the drawings, the same reference numerals represent the same objects, and the description of an object that may be referred to in only one drawing or, in any case, not necessarily in relation to all the drawings can be transferred to the drawings in which the object is not explicitly described in the specification.

Explanation of Signs

[0107] 1 Reinforced hermetic housing 2 Contained object 3 Lower substrate or base substrate or lower wafer 4 Intermediate substrate or intermediate wafer 5 Upper substrate or cover substrate or upper wafer 6 Corner of the laser-bonded stack 18 7 Laser-bonded interface zone 8 Laser-bonding zone 9 Focused laser beam 10 Separation or cutting line 11 Bath containing acidic or basic strengthening liquid 12 Containment cavity 13 Functional region 13a Second functional region 14 Edge 15 Laser unit for bonding and / or cutting 16 Laser pulse hit region 18 Stack or wafer stack 21 Rim 22 Lower surface of the cavity 23 Upper surface of the cavity 25 Contact surface or interface 27 Strengthening zone or first strengthening layer 28 Reinforcement zone or second reinforcement layer 29 Reinforcement zone or third reinforcement layer

Claims

1. A hermetically sealed housing (1), wherein the hermetically sealed housing (1) comprises: a base substrate (3) and a cover substrate (5) forming at least a part of the hermetically sealed housing (1); at least one functional region (12, 13, 13a) surrounded by the hermetically sealed housing (1); and is provided with; the cover substrate (5) is a glass material, and the base substrate (3) is made of a material selected from the group consisting of glass, glass ceramic, silicon, and sapphire; the base substrate (3) and the cover substrate (5) are joined in a hermetically sealed state by at least one laser bonding line (8); the at least one laser bonding line (8) has a height HL perpendicular to its bonding surface, and the at least one laser bonding line (8) includes the penetration of the mixed material from each of the adjacent sealed substrates to the other of the adjacent sealed substrates; the cover substrate (5) is provided with a strengthening layer (27) on its surface, at least on the surface opposite to the at least one laser bonding line (8), the strengthening layer (27) is a chemically strengthened layer, the strengthening layer (27) applies compressive stress to the cover substrate (5), and the functional regions (12, 13, 13a) include a hermetically sealed accommodation cavity (12) for accommodating an object to be accommodated, the hermetically sealed housing (1).

2. The base substrate (3) and the cover substrate (5) are joined in a hermetically sealed state with each other by the same laser bonding line (8), and / or the at least one laser bonding line (8) surrounds the periphery of the functional regions (12, 13, 13a) at a distance, the hermetically sealed housing (1) according to Claim 1.

3. The strengthening layer (27) has a strengthening layer thickness DoL, the cover substrate (5) has a minimum material thickness MM up to the strengthening layer above the laser bonding line (8), and for the total thickness DA of the cover substrate (5), DA - HL - DoL ≥ MM holds, the hermetically sealed housing (1) according to Claim 1 or 2.

4. Both surfaces of the cover substrate (5) are strengthened, and as a result, the cover substrate (5) is provided with a second strengthening layer (28) having the strengthening layer thickness DoLb on the bonding surface (25) with the base substrate (3), the hermetically sealed housing (1) according to any one of Claims 1 to 3.

5. The height HL of the laser bonding line (8) is greater than the reinforcement layer thickness DoLb of the second reinforcement layer (28), the hermetically sealed housing (1) according to claim 4.

6. The hermetically sealed housing (1) according to any one of claims 1 to 3, wherein at least the cover substrate (5) is entirely provided with a reinforcement layer.

7. The hermetically sealed housing (1) according to any one of claims 1 to 6, wherein the cover substrate (5) is provided with the or another functional region (12, 13, 13a).

8. The hermetically sealed housing (1) according to any one of claims 1 to 7, wherein the base substrate (3) is provided with a reinforcement layer having a reinforcement layer thickness DoLd on its lower surface on the side opposite to the laser bonding line (8).

9. An intermediate substrate (4) is disposed between the base substrate (3) and the cover substrate (5), The base substrate (3) is joined to the intermediate substrate (4) at the joint surface, and the cover substrate (5) is joined to the intermediate substrate (4) at a second joint surface, the hermetically sealed housing (1) according to any one of claims 1 to 8.

10. The hermetically sealed housing (1) is reinforced over the entire surface of the functional region (12, 13, 13a), and / or The hermetically sealed housing (1) according to any one of claims 1 to 9, wherein the hermetically sealed housing (1) is provided with a reinforcement layer on all its outer surfaces.

11. The cover substrate (5) forms the upper surface (23) of the accommodation cavity (12), the intermediate substrate (4) forms the lateral peripheral edge portion (21) of the accommodation cavity (12), and the base substrate (3) forms the lower surface (22) of the accommodation cavity (12), and these are integrated to completely surround the accommodation cavity (12), and at least one of the lateral peripheral edge portion, the lower surface or the upper surface is transparent to a certain wavelength range at least in a specific region, the hermetically sealed housing (1) according to claim 10.

12. In a method for providing a plurality of hermetically sealed housings (1), each hermetically sealed housing (1) provides a functional region (12, 13, 13a), and the functional region (12, 13, 13a) is surrounded by the lateral peripheral edge portion (21), the lower surface (22) and the upper surface (23) of the hermetically sealed housing (1), and the method includes - Preparing at least one cover substrate (5) and a base substrate (3), wherein the cover substrate (5) is a transparent glass material at least in a specific region, the base substrate (3) is made of a material selected from the group consisting of glass, glass ceramic, silicon, and sapphire, and the at least two substrates (3, 4, 5) are arranged to be directly in contact with each other or to overlap each other; - Hermetically sealing the functional regions (12, 13, 13a) by joining the at least two substrates (3, 4, 5) along a bonding line by a laser bonding process; - Individualizing each of the hermetically sealed housings (1) by a cutting or separating step; - Chemically strengthening the surface by immersing each of the hermetically sealed housings (1) in a chemical solution (11); A method comprising the above steps.

13. The method according to claim 12, wherein the at least two substrates (3, 4, 5) are prepared as a wafer stack (18) comprising at least two wafers, and a plurality of hermetically sealed housings (1) are collectively manufactured from the wafers in the same working process.

14. The method according to claim 13, wherein the wafer stack (18) comprising the at least two wafers comprises three wafers.

15. The method according to any one of claims 12 to 14, wherein the step of individualizing each of the hermetically sealed housings (1) is performed by a laser cutting or laser separating step.

16. The method according to claim 15, wherein the step of individualizing is performed using the same laser as used in the joining step.

17. The method according to any one of claims 12 to 16, wherein the strengthening of the hermetically sealed housing (1) is achieved by partially or completely exchanging sodium ions with potassium ions over a layer thickness of 30 μm or less.

18. The step of chemically strengthening the hermetically sealed housing (1) comprises the following sub-steps: Preparing an acidic or basic solution (11); Introducing the hermetically sealed housing (1) into the acidic or basic solution; Heating the acidic or basic solution to a temperature of at least 650 Kelvin; Immersing the hermetically sealed housing (1) in the acidic or basic solution for at least 6 hours and at most 12 hours. The method according to any one of claims 12 to 17, comprising at least one of **Claim 19** Use of the hermetically sealed housing (1) provided with hermetically sealed functional areas (12, 13, 13a) enclosed therein, produced by the method according to any one of claims 1 to 11 or according to any one of claims 12 to 18, as a medical implant or as a sensor.

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