Hermetically sealed transparent cavity and its housing

Abstract

The present invention relates to a hermetically sealed housing (1), the housing (1) comprising at least one cover substrate (5), a substrate arranged adjacent to the cover substrate (5) and together forming at least a part of the housing (1), and at least one functional area (12, 13, 13a) surrounded by the housing (1), wherein at least the cover substrate (5) preferably comprises a glass-like material, the cover substrate (5) is thermally strengthened, and the cover substrate (5) and the substrate arranged adjacent to the cover substrate (5) are hermetically joined together at at least one laser bond line (8), the cover substrate (5) being made of a material having a coefficient of thermal expansion (CTE) characteristic value different from that of the substrate arranged adjacent to the cover substrate (5), and the housing (1) is thermally strengthened, and the thermal strengthening preferably imparts a compressive stress to the cover substrate (5).

Description

[Technical Field]

[0001] explanation FIELD OF THE INVENTION The present invention relates to a method for providing a plurality of airtight enclosures, and to a transparent enclosure.

[0002] Background and Summary of the Invention Hermetically sealed enclosures can be used to protect sensitive electronics and circuits, or for example sensors, for example in medical implants, for example in the heart region or the retina, or in bioprocessors. Bioprocessors made from titanium are known and in use.

[0003] In particularly adverse environmental conditions, sensors can be protected by the housing according to the invention, including, for example, MEMS (micro-electromechanical systems) and barometers.

[0004] Further areas of use for the housing according to the invention include smartphone covers, virtual reality glasses, etc. The housing according to the invention can also be used for the manufacture of flow cells, for example in electromobility. However, the housing according to the invention can also be used in the aerospace industry, high-temperature applications, and in the field of micro-optics.

[0005] What the aforementioned applications have in common is the high demands placed on the robustness of the electronics. This means that they need to be protected from adverse environmental influences. Furthermore, it may be required that communication with the area inside the housing, i.e., the cavity formed by the housing, is guaranteed. The housing is at least partially transparent, i.e., transparent at least in a specific area and / or for at least one wavelength range. This transparency allows communication with, data or energy transmission from, and measurements by, electronics or sensors located within the cavity. In particular, optical communication methods or optical transmission of data or energy can be enabled.

[0006] In principle, multiple elements can be combined and arranged so that intermediate spaces create storage areas for components. For example, EP 3012059 describes a method for manufacturing transparent elements for protecting optical components. A novel laser process is used.

[0007] The invention should be seen in the framework of improving housings, in particular increasing their durability, so that they are more robust against environmental influences and, for example, mechanical loads.

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

[0009] Since the improved housing must remain competitive in the marketplace, a further aspect of the present invention is to provide an improved housing that is particularly inexpensive, but also reliable and durable.

[0010] Therefore, in the present invention, a method for providing multiple hermetic enclosures is presented. Although it is easily possible to modify the method so that only a single enclosure is produced, it is economically rational to produce multiple enclosures using the same process sequence. This saves time, labor, and raw materials.

[0011] A hermetically sealed enclosure according to the present invention comprises at least one cover substrate and a substrate disposed adjacent to the cover substrate and together forming at least a portion of the enclosure, preferably the at least two substrates being disposed so as to overlap, i.e., stacked.

[0012] According to the present invention, the housing encloses the functional area, and at least the cover substrate preferably comprises a glass-like material. The cover substrate is thermally strengthened and hermetically bonded to a substrate disposed adjacent to the cover substrate by at least one laser bond line.

[0013] The cover substrate is made of a material having a different coefficient of thermal expansion (CTE) characteristic than the adjacently disposed substrate, thereby providing thermal enhancement to the housing.

[0014] The housing is preferably positioned such that this thermal strengthening imparts compressive stress to the cover substrate. Further, the at least one laser bond line can surround the periphery of the functional area by a distance DF such that the functional area is completely surrounded.

[0015] The adjacently arranged substrate is preferably a base substrate. In this case, the base substrate and the cover substrate can be hermetically bonded to each other at a common laser bonding line. Alternatively, the adjacently arranged substrate may be an intermediate substrate arranged between the cover substrate and the base substrate. In this case, the base substrate and the intermediate substrate are bonded to each other at a first bonding surface, and the cover substrate and the intermediate substrate are bonded to each other at a second bonding surface.

[0016] At least one intermediate portion, i.e., intermediate substrate, may have a higher coefficient of thermal expansion (CTE) characteristic than both the cover substrate and the base substrate. Thermal strengthening is preferably achieved by using materials with different CTEs and at an appropriate temperature. The moderate temperature and functional element distinguish the claimed method from prior art, such as U.S. Patent Application Publication No. 2017210662, which also uses a combination of different CTEs and an appropriate temperature coating, but in a hot forming process and for strengthening glass wafers without cavities for functional elements.

[0017] The functional area preferably comprises a hermetically sealed cavity for housing an object such as an electronic circuit, a sensor, or a MEMS. Preferably, the cover substrate forms the top surface of the cavity, the intermediate substrate forms the lateral periphery of the cavity, and the base substrate forms the bottom surface of the cavity, which together completely enclose the cavity. Furthermore, at least one of the lateral periphery, the bottom surface, or the top surface may be transparent to a certain wavelength range, at least in a specific region.

[0018] According to the invention, each housing defines a cavity bounded by its lateral periphery, its lower surface and its upper surface, in other words, such a cavity is completely surrounded by the housing, which defines the periphery, lower surface and upper surface of the cavity.

[0019] For purposes of this application, the lower surface or upper surface refers to a geometric configuration that can refer to either surface relative to the final position of the housing. Alternatively, the upper surface can be referred to as the first surface, the lower surface as the second surface opposite the first surface, and the edge can be referred to as the intermediate region between the first surface and the second surface, with the edge typically being substantially perpendicular to the first surface and / or the second surface. However, in the following, the terms upper surface, lower surface, and edge will be used as described to facilitate understanding of the present invention and provide an approximate representative description.

[0020] The upper surface of the cavity may be formed by an upper layer, such as a substrate, disc, or plate. The periphery of the cavity may further be formed by a second or intermediate substrate, disc, or plate, the second substrate having a hole that will later become the cavity. Finally, the lower surface of the cavity may be formed by a lower layer, substrate, disc, or plate, by placing the lower layer below the intermediate layer.

[0021] The cavities are formed in particular as receiving cavities, i.e., for example, an electronic circuit, a sensor or a MEMS can be inserted into each cavity, and the aforementioned device, in particular the electronic circuit, the sensor or the MEMS, is arranged in the receiving cavity and is therefore surrounded on all sides by the housing.

[0022] In a method for providing a plurality of hermetic enclosures according to the present invention, the first step involves preparing a first substrate and at least one second substrate, wherein the at least one second substrate is made of a transparent material and has a coefficient of thermal expansion (CTE) different from that of the first substrate. The at least two substrates are arranged directly adjacent to or overlapping each other, with the at least one second substrate forming the edges of each enclosure of the cavity to be sealed and the first substrate forming the underside of each enclosure. At least one contact surface is formed between the at least two substrates, thereby providing each enclosure with at least one contact surface. The cavities are then hermetically sealed by joining the at least two substrates along the contact surfaces of each enclosure, particularly along the edge lines of each enclosure. Finally, each enclosure is separated by a cutting or separation step.

[0023] In one embodiment of the method according to the present invention, first a first substrate, at least one intermediate substrate and a third substrate are provided, wherein the at least one intermediate substrate is preferably made of a transparent material and is a transparent substrate, and the at least one intermediate substrate has a characteristic value of coefficient of thermal expansion (CTE) different from that of the first and / or third substrate.

[0024] At least three substrates are arranged so that they directly contact one another or overlap one another. In other words, at least two substrates are arranged or attached so that they are in contact with one another, so that they are flat and in contact with one another without any other layers between them. For technical reasons, it may be unavoidable to have a small amount of gas trapped between the substrate layers, which may also be due to unevenness of the substrate layers. For example, the amount of gas trapped between flatly placed substrate layers, i.e., especially at the contact surface, can be further reduced by increasing the pressure, especially by pressing the at least two substrates together, or by surface treatment of the substrate layers, such as by a polishing process. Prior evacuation is advantageous. Depending on the process parameters and the materials used, it may also be advantageous to fill the space with a gaseous or liquid substance.

[0025] Thus, the substrate layers are stacked, i.e., positioned so that they directly contact each other. By eliminating dissimilar materials as much as possible between the substrate layers, the contact between one substrate layer and the adjacent substrate layer is as intimate and flat as possible. For example, in the case of two substrates, the base substrate and the cover substrate are positioned so that they directly contact each other, particularly with no other material or gap between them. In the case of three or more substrates, the base substrate is positioned so that it is directly adjacent to the middle or first middle substrate layer, and the cover substrate is positioned so that it is directly adjacent to the middle or last middle substrate layer.

[0026] The substrates are then joined in a new laser joining process. A planar substrate layer is directly joined to a directly adjacent planar substrate layer without the need for or provision of a dissimilar or non-planar material or intermediate layer for this purpose. The substrates are thus directly joined. The resulting laser join line, introduced in the planar contact area between the two substrate layers, inseparably joins the directly adjacent substrate layers to one another. The fused area of ​​the laser join line is thus present in both substrates, seamlessly connecting the first substrate to the directly adjacent second substrate, e.g., from the base substrate to the cover substrate if the cover substrate is positioned adjacent to the base substrate.

[0027] In this way, direct, planar, or even complete transitions are formed from one substrate layer to the next, such as substrate-to-substrate or glass-to-glass transitions. A locally defined volume is formed as a bond zone or laser bond line, where material transfer or intermixing occurs between adjacent, particularly planar, substrate layers. In other words, the material of a first substrate, such as a cover substrate, penetrates into an adjacently arranged substrate, such as an intermediate substrate or base substrate, and vice versa, resulting in a complete intermixing of the materials of the adjacently arranged substrates in the bond zone.

[0028] The new laser joining technique for creating an inseparable substrate-to-substrate transition is particularly advantageous because it does not require the use of intermediate layers, glass frits, foils, or adhesives that must be introduced between the substrates in previously known methods. An inseparable bond can be created without the use of corresponding extra intermediate layers or additional materials. This increases the achievable strength of the final product without the use of additional materials and ensures hermetic sealing of functional areas or cavities.

[0029] It is particularly preferred if the thickness of any gaps that may occur between the substrates is 5 μm or less, and even more preferably 1 μm or less. Such gaps can arise, for example, due to tolerances during substrate manufacturing, thermal effects, or the inclusion of particles such as dust. Even gaps within this tolerance range are considered directly adjacent in the present invention, and therefore can be laser-bonded to form a bond zone with a thickness of 10 to 50 μm, thereby ensuring a hermetic seal. In this case, the bond zone extends from the first substrate to the second substrate positioned adjacent to the first substrate. In this way, a bond zone is introduced at the contact area between the first and second substrates, directly fusing the substrates to each other and forming an inseparable bond. In other words, by bonding adjacently positioned substrates at the bond zone, the materials of both substrates at the bond zone are directly melted, and the materials of the first substrate and the second substrate are intermixed to form an inseparable, integral bond. Therefore, the housing manufactured in this manner has an integral, i.e., monolithic, bond between the substrates at the bond zone.

[0030] At least one intermediate substrate forms the edge of each housing of the cavity to be sealed. The remaining two substrates form the bottom and top surfaces of each housing. Contact surfaces or interfaces are formed between at least two, preferably three, substrates, so that each housing has at least one, preferably two, contact surfaces. The contact surfaces can extend over the entire surface of each substrate. Each housing is assigned at least two contact surfaces. That is, even though the transparent substrate as a whole has a common contact surface that extends over the entire substrate and contacts the second substrate, this contact surface is conceptually divided or subdivided into each housing, so that each housing is assigned a portion of this interface.

[0031] The interface does not need to be optically transparent. It is also advantageous if the transparent substrate is made opaque in the visible wavelength range. Only the substrate through which the laser passes and reaches the interface has at least one spectral window, so that at least the wavelength of the laser used can pass through the substrate partially or in a specific region. The interface is in a state in which the laser can apply energy to this surface. For example, the surfaces of two substrates that come into contact with each other can be joined by optical contact and can have a roughness, for example, in the nm range. The laser is at least partially absorbed by this surface, so that energy can be introduced thereto. In general, the interface in the sense of this application should be understood as a surface at which the incident laser beam can apply energy, and thus the joining process can be carried out along this interface. A simple example of such an interface is the interface between two substrates that come into contact with each other.

[0032] In a preferred embodiment, all three substrate layers are transparent, so that the top surface as well as the bottom surface, edges, and therefore the housing, are all made of transparent material.

[0033] The substrates are glued or bonded together to form a common housing and hermetically seal the cavity.

[0034] The step of hermetically sealing the cavity can be achieved by joining at least three substrates along two contact surfaces of each housing using a laser bonding process. In other words, energy can be applied to the contact surface area using a laser in a localized manner, known as a cold bonding process. In this way, the thermal energy provided for bonding is concentrated in the interface extension and diffuses relatively slowly into the remaining housing material, preventing a significant temperature rise, especially in the cavity. This prevents overheating of the electronic device placed in the cavity.

[0035] At least two substrates are locally bonded by using a laser to locally melt the materials of both substrates in the region of each housing along the contact surface. Those skilled in the art can refer to, for example, European Patent No. 3012059, the contents of which are incorporated herein by reference. When at least two transparent substrates are used, one forms the edge and the second forms the top surface, so that each housing is assigned two circumferential contact surfaces. In this case, each cavity is hermetically sealed by preferably joining along the two contact surfaces using a laser welding method. In this case, in addition to the first substrate, the middle and third transparent substrates are also firmly welded to each other, hermetically sealing the cavity.

[0036] Each housing is singulated by a cutting or separation step, which means cutting or separating the substrate so that each housing is singulated from the other materials.

[0037] In a preferred embodiment, the at least one intermediate substrate may include two or more transparent substrates that together form the edges of the cavity, for example, three intermediate substrate layers may be disposed between the first substrate and the third substrate, and these three intermediate substrate layers may together form the edges of the cavity.

[0038] Preferably, at least three substrates are prepared in the form of a wafer stack with at least three wafers. Then, in the same process, several airtight enclosures can be manufactured from the wafers or wafer stacks. This method has proven to be particularly economical, as it results in particularly low waste and material loss.

[0039] The at least three wafers are preferably made of glass, glass ceramic, silicon, sapphire, or a combination of the aforementioned materials. Alternatively, at least one wafer is made of a material different from the intermediate wafer. Preferably, the wafer forming the lower surface of the cavity can be made of a material that is not optically transparent but has other properties, such as electrical conductivity, if necessary. In contrast, the edges and upper surface of the housing are preferably made of a transparent material. Even more preferably, all substrates are made of a transparent material. In the case of a transparent housing made of glass or glass-based material, especially a transparent housing made of borosilicate glass, chemical inertness is particularly advantageous.

[0040] One or more of the substrates may be coated with a coating, such as an AR coating, a protective coating, a bioactive film, an optical filter, or a conductive layer, such as ITO or gold, that is at least partially transparent to the wavelength of the laser used in the laser irradiation area.

[0041] The edge strength of the airtight enclosure can be measured by a four-point bending test. 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 is thus particularly durable.

[0042] Preferably, the singulation of each housing is performed using a laser, i.e., using a laser cutting or laser separation process, which allows for a cleaner separation of the housings, resulting in less damage and a cleaner separation point. Preferably, the same laser used for the joining step may be used for the separation.

[0043] Furthermore, at least one transparent substrate is preferably made of glass, glass ceramic, silicon, or sapphire, or a combination of the aforementioned materials, such as a combination of glass and silicon, a combination of glass / silicon / sapphire, or a combination of silicon / sapphire.The above or further substrates can include or consist of Al2O3, sapphire, Si3N4, or AlN.By combining a transparent substrate with a different type of substrate, for example, semiconductor properties can be achieved.For example, coatings can be used, such as piezo-resistive Si layers for pressure sensing, or thick layers for micromechanical applications such as MEMS pulse measurement.

[0044] The first substrate and / or the third substrate preferably have a thickness of less than 500 μm, preferably less than 300 μm, more preferably less than 120 μm, even more preferably less than 80 μm.

[0045] Here, at least one of the lateral edges, the bottom surface or the top surface is transparent to a wavelength range at least in a specific region, 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, where the wavelength range is known in advance and, if desired, can be adjusted by the material depending on the wavelength of the laser used.

[0046] The housing is bonded to a hermetically sealed housing by a laser bonding process, in other words, the edges, bottom surface and top surface are made up of two or more pieces, for example, two or three or more pieces, that are laser bonded together to form the housing.

[0047] In a further embodiment, the housing may be chemically strengthened at least partially and / or in certain regions. For example, one surface of the housing, i.e., the top surface, for example, may be chemically strengthened. Alternatively, the top surface and edges may be chemically strengthened. Particularly preferably, in addition to the top surface, the edges and bottom surface are also chemically strengthened, so that not only each surface of the top or bottom surface but also each edge, i.e., the edges, are chemically strengthened.

[0048] Prior to performing the laser bonding process, the housing is preferably heated to a temperature above the subsequent use temperature of the housing, e.g., prior to performing the laser bonding process, the housing is heated to a temperature above ambient temperature.

[0049] In particular, heating before laser bonding is performed to a temperature 5 K higher, 10 K higher, preferably 20 K higher, or even more preferably 70 K higher than the subsequent use temperature, after which the housing is cooled to ambient temperature.

[0050] Furthermore, the step of singulating the housing is preferably performed before the step of cooling the housing to ambient temperature.

[0051] Those skilled in the art will understand that structures with an inverse ratio of the thermal expansion coefficients are also possible. If at least one intermediate substrate has a characteristic value of a lower thermal expansion coefficient than the upper and / or lower surface, and at the same time the laser bonding process is carried out at a low bonding temperature, i.e., the bonding temperature is below the subsequent use temperature of the housing or below ambient temperature, an inverse pressure distribution will occur, which will also lead to a strengthening of the housing. In this case, at the use temperature of the housing, tensile stress will be generated in the upper and / or lower surface, while compressive stress will be generated in the at least one intermediate substrate.

[0052] The present invention also provides an enclosure having a hermetically sealed containment cavity enclosed therein, produced by the above method.

[0053] The housings produced by the above method can be advantageously used as medical implants or as sensors, especially barometers.

[0054] Likewise, within the scope of the present invention is a transparent enclosure with a hermetically sealed containment cavity for containing an object, such as an electronic circuit, a sensor, or a MEMS.

[0055] The transparent housing of the present invention comprises a first member having a lateral periphery made of a transparent material, a bottom surface made of a second member, and a top surface made of a third member, which together completely enclose a storage cavity.

[0056] At least one intermediate member of the housing is, according to the invention, made of a material having a different characteristic value of coefficient of thermal expansion (CTE) than the first substrate and / or the third substrate.

[0057] Furthermore, these three components are thermally strengthened. Furthermore, these three components may additionally be chemically strengthened.

[0058] Finally, the at least three components of the housing are joined together in a laser bonding process to form a hermetically sealed housing.

[0059] Preferably, the transparent housing has an edge strength of at least or greater than 150 MPa, which can be measured using a four-point bending test method.

[0060] Prior to the step of joining the at least two, preferably three, substrates, the substrates may be at least temporarily bonded to one another along the contact surfaces of their respective housings by optical contact.

[0061] The transparent housing can have a size of, for example, 3 mm x 3 mm or less, and in particular, the receiving cavity has a diameter of 2 mm or less. For example, the transparent housing can have a size of 0.2 mm x 0.2 mm or less. However, depending on the field of use, the transparent housing can also be manufactured in a significantly larger size, even several centimeters in length. The practical size limitation is due to the preferred manufacturing method, but should not be understood as a size limitation per se, but 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 example, sheet glass can also be used to manufacture a transparent housing that can have dimensions larger than the typical wafer size.

[0062] Preferably, the first, second and / or third member may have a marker inserted therein.

[0063] Thermal strengthening can preferably be achieved by the targeted use of materials with different thermal expansion coefficients, which can be further enhanced or achieved by appropriate temperatures.

[0064] It is also within the scope of the present invention to provide an arrangement particularly suitable for the manufacture of housings, comprising a first substrate made of a transparent material at least in certain regions and a second substrate arranged directly adjacent to the first substrate, the first substrate being joined to the second substrate by a laser joining process at a joining temperature, the first substrate being compressively stressed towards the second substrate at a temperature below the joining temperature, or the first substrate being compressively stressed towards the second substrate at a temperature above the joining temperature.

[0065] In the construction, the second substrate can be made of a material having a different coefficient of thermal expansion (CTE) characteristic value, particularly the second substrate having a higher coefficient of thermal expansion.

[0066] In the structure, the first substrate may be a glass substrate or a glass-ceramic substrate, and the second substrate of the structure may be under tensile stress. [Brief explanation of the drawings]

[0067] [Figure 1a] FIG. 10 is a top view showing the open receiving cavity. [Figure 1b] A 3D view of the closed enclosure. [Figure 2a] FIG. [Figure 2b] FIG. 10 is a detailed view of the bonding zone. [Figure 2c] FIG. 1 illustrates an embodiment of a housing with three intermediate layers. [Figure 3] FIG. 10 is a top view of a further embodiment of the housing. [Figure 4a] 4 is a cross-sectional view of the embodiment of the housing shown in FIG. 3 along line A->B. [Figure 4b] 4 is a cross-sectional view of the embodiment of the housing shown in FIG. 3 along line C->D. [Figure 5a] 4 is a cross-sectional view of the embodiment of the housing shown in FIG. 3 along line A->B. [Figure 5b] 4 is a cross-sectional view of the embodiment of the housing shown in FIG. 3 along line C->D. [Figure 6] 4 is a cross-sectional view of the embodiment of the housing shown in FIG. 3 along line C->D. [Figure 7] 10A to 10C are diagrams illustrating a manufacturing method of the housing. [Figure 8] FIG.

[0068] Detailed Description of the Invention FIG. 1a shows an object 2 to be protected embedded in a lower substrate 3, surrounded by an intermediate substrate 4, which is then covered by an upper substrate 5. The three substrates 3, 4, and 5 together form an enclosure 1 around the object 2 placed in a cavity 12. In other words, in the example of FIG. 1a, when the upper substrate 5 is placed on the intermediate substrate 4, a closed enclosure cavity 12 is formed, which will be hermetically sealed in a subsequent step. The intermediate substrate 4 is made of a different material from the lower substrate 3 and the upper substrate 5. In the example shown here, the intermediate substrate 4 has a higher coefficient of thermal expansion (CTE) than the other layers shown. The illustrated layers 3, 4, and 5 may be wafer disks, and the enclosure is formed by stacking three wafer disks as a wafer stack and bonding or welding them together. The substrates 3, 4, and 5 are preferably flat glass components that are part of a singulated chip. The wafer is preferably a large-area glass component, which can be singulated into chips containing multiple substrates. Then, by singulating as shown in Figure 7, multiple parts made of different substrates can be produced at low cost.

[0069] Figure 1b shows the thus-formed chemically strengthened hermetically sealed housing 1. In this housing 1, a lower substrate 3, an intermediate substrate 4, and an upper substrate 5 are laminated so as to overlap each other, and an interface 25 exists between the lower substrate 3 and the intermediate substrate 4 on the one hand, and between the intermediate substrate 4 and the upper substrate 5 on the other hand. As can be seen from Figure 1a, the intermediate substrate layer 4 is not formed in a flat, continuous shape, so the storage cavity 12 is formed at the height of the intermediate substrate layer.

[0070] Referring to FIG. 2a, a cross section of a reinforced hermetically sealed enclosure 1 is shown. A lower substrate 3 forms a lower surface 22 of a cavity 12, an intermediate substrate 4, which in this example has a different coefficient of thermal expansion (CTE) characteristic than substrates 3 and 4, forms an edge 21 of the cavity 12, and finally an upper substrate 5 forms an upper surface 23 of the cavity 12. The lower, intermediate, and upper substrates 3, 4, and 5 together form a substrate stack 18 that encloses the containment cavity 12. A containment object 2 is disposed within the cavity 12. The substrates 3, 4, and 5 may again be wafer disks, whereby the enclosure is formed by three wafers that together form the wafer stack 18 that encloses the containment cavity 12 and forms the enclosure 1.

[0071] 2b shows a detailed cross-section of the bonding area, clearly showing the laser-bonded interface zone 7 and the laser-bonded zone 8. The laser-bonded zone 8 is arranged in the area of ​​the contact surface 25. From the outside, environmental influences can act on the housing 1, in particular on the corners 6 of the laser-bonded stack 18 in this case. These corners 6 also prevent, for example, chemical liquids from penetrating into the substrate stack 18 up to the laser-bonded zone 8.

[0072] 2c shows a detailed cross section of a further embodiment of a substrate stack 18 or housing 1, with three intermediate layers 4a, 4b, and 4c disposed above a bottom layer 3. All three intermediate layers 4a, 4b, and 4c have different CTE characteristics than the bottom layer 3 and top layer 5. This embodiment allows for a graded stress profile across the layers 4a, 4b, and 4c, as well as for providing non-laser bonded components where the glass layers are compressed.

[0073] FIG. 3 shows a top view of a housing 1 according to the invention, with a peripheral laser-bonded zone 8 surrounding a functional area 13. The functional area 13 can be constructed in various ways. Examples of functional area 13 configurations and other housing options are shown in FIGS. 4a to 8b. In FIG. 3, all top views are shown in the same schematic format, so that different configurations of the functional area 13 can be combined in the figures. Cross sections are shown along the lines AB or C->D, which are shown in FIGS. 4a to 8b.

[0074] The functional areas can fulfill different tasks, which can be, for example, optical receptors or technical, electromechanical and / or electronic components arranged in the functional areas 13. Several of these tasks can also be fulfilled in the functional areas 13. The housing 8 is covered from above by an upper substrate 5. The laser bonding zone 8 extends into this upper substrate 5.

[0075] Referring to Figure 4a, a first cross-sectional view of a first embodiment of a housing 1 is shown, the housing 1 having a base substrate 3 and a cover substrate 5. That is, the housing is constructed or composed of two layers: a base layer 3 and a cover layer 5. Figure 4a also shows the structure of a laser bond line 8, which is composed of a plurality of contiguous laser pulse hit regions 16, which are positioned closely together such that the materials of the base substrate 3 and the cover substrate 5 are fused together without any gaps.

[0076] Figure 4b shows a cross-section of one embodiment of the housing 1 along the line C->D inserted in Figure 3. The cover substrate 5 is provided with a first reinforcing layer 27 on its top or outer surface, which first reinforcing layer 27 extends through the thickness DoL into the material of the cover substrate 5. This means that the cover substrate 5, and thus the housing 1, is reinforced or provided with a reinforced zone 27 on its top surface, so that the housing 1 is reinforced in a specific area, i.e. on one side.

[0077] FIG. 4b further shows a cross section of the functional area 13, 13a, which extends into the housing 1, for example, as a continuous void or cavity. In other words, the cavity extends from the base substrate 3 to the cover substrate 5 and exists, for example, in the form of a recess in the base substrate 3 and / or the cover substrate 5. It is also possible, for example, for the functional area 13a to also include an active layer, such as a conductive layer, and for the functional area 13 to include a cavity. The laser bonding zone 8 is arranged around the functional area 13, 13a, thereby sealing the functional area 13, 13a laterally all around. It is conceivable to leave open areas within the laser bonding zone 8 so that the functional area 13, 13a is not completely sealed, for example, to leave open communication channels through which fluid communication with the environment can be established. That is, rather than sealing pre-planned locations or positions with the focused laser beam 9, it is possible to design a hermetic seal there using other means, such as an adhesive. It is preferable that the functional area 13, 13a be completely sealed without any gaps.

[0078] 5a, a further embodiment is shown in which the laser pulse hits 16 create a laser bonding zone 8 along the contact surface 25, whereby the cover substrate 5 is welded or bonded to the base substrate 3. This embodiment has the further feature that the surfaces of the first substrate 3 and the second substrate 5 are reinforced all around, i.e., provided with reinforcement layers 27, 28 and 29.

[0079] For example, the surface of the cover substrate 5 can be immersed in a strengthening bath before or even after bonding the cover substrate 5 to the base substrate 3, so that the finished housing 1 is chemically strengthened, i.e., has at least one strengthening surface 27 and / or has at least one strengthening layer. In other words, the finished housing 1 is strengthened at least in certain areas or at least partially, for example, is particularly chemically strengthened. During chemical strengthening, compressive stresses are formed on the cover substrate 5. The first strengthening layer 27 has a height DoL. The bonding zone 8 has a height HL. A minimum material thickness MM remains between the strengthening zone 27 and the bonding zone 8. The total thickness of the cover substrate 5 can be composed of HL + MM + DoL.

[0080] The functional areas 13, 13 a extend within the reinforcing layers 27, 28, 29, and the reinforcing layer 28 is arranged in an annular region around the functional areas 13, 13 a. Thus, in the embodiment shown in Figures 5a and 5b, the cover substrate 5, and also the base substrate 3, have their two long sides strengthened, in particular chemically strengthened in a strengthening liquid. That is, each long side of the substrates 3, 5, i.e., each upper and lower surface, for example, has been individually immersed in a strengthening liquid for chemical strengthening to strengthen the long sides.

[0081] In the embodiment shown in FIG. 5a, the housing 1 is reinforced on all exterior surfaces, i.e., two opposing long sides are provided with reinforcing layers 27 and 29, and the peripheral edge 14 of the housing is provided with a reinforcing layer 28, which extends around the perimeter of the housing 1. In other words, in the case of a rectangular parallelepiped housing, the four short sides of the rectangular parallelepiped are combined to form the edge 14. The edge 14 can also be interpreted or referred to as the housing edge 21 that extends around the cavity. The housing 1 shown in FIG. 5a can be obtained, for example, by immersing the completed bonded housing, including the cover substrate 5 and the base substrate 3, in a strengthening liquid and subjecting it to chemical strengthening therein. The strengthening layers 27, 28, and 29 are thus arranged directly on the exterior of the housing 1. Therefore, an area for the bond line 8 remains inside the strengthening layers 27, 28, and 29, which is appropriately spaced apart from the strengthening layers 27, 28, and 29.

[0082] FIG. 5b shows an embodiment of the housing 1, showing a cross section along the line C->D. Also in this embodiment, the functional areas 13, 13a are arranged so as to extend from the base substrate 3 into the cover substrate 5, for example as recesses in each substrate. Such recesses 13, 13a can be introduced, in particular, by a sandblasting process (see FIGS. 7 to 14). The recesses 13, 13a are hermetically sealed all over, since the joining line 8 is arranged around them.

[0083] Similar to the embodiment of FIG. 5a, the housing 1 is chemically strengthened on all sides, i.e., all surfaces are provided with reinforced regions 27, 28, and 29. For example, a first reinforcement layer 27 is disposed on a first long side, which may be the top surface of the cover substrate 5; a third reinforcement layer 29 is disposed on a second long side, which may be the bottom surface of the base substrate 3; and a second reinforcement layer 28 is disposed on the periphery 21 or peripheral edge 14. The top surface 23 of the cavity is disposed inside the first reinforcement layer 27, the edge 21 of the cavity is disposed inside the second reinforcement layer 28, and the bottom surface 22 of the cavity is disposed inside the third reinforcement layer 29. In this way, the cavity or functional area 13, 13a is completely surrounded by reinforcements 27, 28, and 29.

[0084] 6a shows a further embodiment of the housing 1 along the section line C->D, in this example the functional area 13 or cavity 12 is arranged in the cover substrate 5. For example, in this example only the cover substrate 5 may be hollowed out by sandblasting, while the base substrate 3 does not need to be further processed. As a result, fewer parts of the housing need to be processed, simplifying manufacturing.

[0085] In the example of FIG. 6, the cover substrate 5 is provided with a reinforcing layer 27 on its long sides and a reinforcing layer 28 on its edge 14. For example, the cover substrate 5, either separately or after joining to the base substrate 3, is immersed on its upper surface in a chemical strengthening solution until the level of the second reinforcing layer 28 is reached. In this example, the base substrate 3 does not have a reinforcement zone. In this example, the lateral reinforcement zones 28 end immediately in the area of ​​the contact surface 25 between the cover substrate 5 and the base substrate 3. The bond along the bond line 8 is introduced inside the reinforcement zone 28, i.e., into the relaxed material. This means that the first long side of the housing 1 is provided with a reinforcing layer 27, and the first short side 14 is provided with a reinforcing layer 28 in a specific area. The reinforcing layer 28 can extend around the periphery of the housing 1, for example, around the functional area 13. Compared to FIG. 3, a cross section along the line C->D drawn therein, 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. does not extend into the base substrate 3. The base substrate 3 is directly and immediately bonded to the cover substrate 5, so that no further layers or substrates are 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, or in general by a polishing process; it is also possible to introduce the cavity into the substrate by chemical etching.

[0086] Referring to FIG. 7, a first embodiment of a method for manufacturing a reinforced housing 1 is shown. The method begins in a temperature range lower than the temperature at which the housing will subsequently be used. In step A, wafers 3, 4, and 5 are aligned with the object 2 to be accommodated. Here, the upper wafer 5 is placed on the intermediate wafer 4, which is then placed on the lower wafer 3, forming a substrate stack or wafer stack 18. Here, the intermediate layer 4 has a different coefficient of thermal expansion (CTE) characteristic value than the lower layer 3 and the upper layer 5. Here, since the intermediate substrate 4, including the recess in which the cavity 12 is formed, is centrally located, the accommodation cavity 12 is then completely surrounded by the substrate material. That is, during the alignment of the substrates in step A, a complete enclosure is formed by the cavity's edge 21, lower surface 22, and upper surface 23. Optionally, the substrates can be bonded to each other, particularly by optical contact, for example, to secure the position.

[0087] Step B of the method shown in Figure 7 shows a stack of wafers 18 arranged one above the other, with cavities 12 therein for receiving the object 2. Optionally, the substrate or wafer stack 18 is bonded by optical contact. In this closed configuration, the substrate or wafer stack 18 can be fed to a bonding process, whereby the layers are bonded together to form a tightly bonded stack 18 from which the one-piece housing 1 is obtained.

[0088] Step C shows the laser welding of each receiving cavity 12, i.e., the complete sealing of the cavity 12 along the contact surface. For this purpose, a laser unit 15 is guided from above the stack 18 through the surface of the stack 18, directing a focused laser beam 9 in the form of a spot onto the zones to be welded. The laser welding lines can be implemented, for example, as a raster of intersecting lines. It is also possible to draw two or more parallel laser welding lines, if this proves to be advantageous, for example, depending on the material to be subsequently separated. Once step C of the manufacturing method is completed, all cavities are hermetically sealed.

[0089] Step D shows the step of separating or cutting the stack 18 to individualize the housing 1. Here, the stack 18 is cut or separated along the separation or cutting lines 10. Up until this step, the temperature is preferably kept constant or always in a temperature range slightly lower than the subsequent use temperature of the housing.

[0090] Finally, step E shows the reinforced hermetically sealed housing 1 in which is located the receiving cavity 12. After completion of the aforementioned processing steps, the temperature can be returned to normal, i.e., in particular, ambient temperature.

[0091] 8, a detailed view of the bond area or cross-sectional side view of housing 1 is shown, with bond fusion area 8 shown in the area of ​​contact surface 25. Middle layer 4 has a higher characteristic value of coefficient of thermal expansion CTE than bottom layer 3 and top layer 5, resulting in thermal strengthening across the illustrated Z direction, again resulting in a stronger finished housing 1.

[0092] In this case, the existing reinforcement of the substrate stack is not eliminated by the laser bonding, since the fusion of the bond profile of the laser bond line, which is typical of the present invention, is very limited by the ultrashort pulse, and the laser bond line does not eliminate the reinforcement in its plane. In this case, the laser bond zone can be detected in the finished end product, for example, by a specific local refractive index change of the material in the small fused area.

[0093] The above-described embodiments should be understood as illustrative, and the present invention is not limited thereto, and it is clear to those skilled in the art that various modifications may be made without departing from the scope of protection of the claims. Furthermore, it is also clear that each feature, whether described together with other features or individually, defines an essential component of the present invention, regardless of whether they are disclosed in the specification, claims, drawings, etc. In all drawings, the same reference signs represent the same objects, and the description of an object that is sometimes mentioned in only one drawing, or in any case not mentioned in relation to all drawings, can also be transferred to drawings in relation to which the object is not explicitly described in the specification. [Explanation of symbols]

[0094] 1 Chemically strengthened hermetically sealed housing 2. Contained Object 3 Lower substrate, lower layer or lower wafer, base substrate, or lower cover 4. Intermediate substrate, intermediate layer or intermediate wafer 5 Top substrate, top layer or top wafer, cover substrate, or top cover 6 Corner of laser bonded stack 18 7 Laser bonded interface zone 8 Laser Bonding Zone 9. Focused laser beam 10 Separation or cutting lines 12. Storage cavity 13 Functional Areas 13a Second Functional Area 14 Edge 15 Laser unit for joining and / or cutting 16 Laser pulse hit area 18 stacks 21 Edge 22 Underside of cavity 23 Top of cavity 25 The contact or interface between two substrates 27 Reinforcement Zone or First Reinforcement Layer 28 Reinforcement Zone or Second Reinforcement Layer 29 Reinforcement Zone or Third Reinforcement Layer

Claims

1. A hermetically sealed housing (1), said housing (1) comprising: At least one cover substrate (5), and a substrate arranged adjacent to the cover substrate (5) and forming at least a part of the housing (1) together; At least one functional area (12, 13, 13a) surrounded by the housing (1); It is equipped with At least the cover substrate (5) comprises a glassy material; The cover substrate (5) is heat-strengthened, The cover substrate (5) and a substrate disposed adjacent to the cover substrate (5) are hermetically sealed and joined together by at least one laser joining line (8), The cover substrate (5) is made of a material having a characteristic coefficient of thermal expansion (CTE) different from that of the adjacently disposed substrate, the housing (1) is thermally strengthened, and the thermal strengthening imparts compressive stress to the cover substrate (5), the adjacently disposed substrate being an intermediate substrate (4, 4a, 4b, 4c) disposed between the cover substrate (5) and a base substrate (3), and the thermal strengthening of the cover substrate (5) is caused by the difference in the thermal expansion coefficients of the intermediate substrates (4, 4a, 4b, 4c) and the cover substrate (5).

2. 2. The hermetically sealed enclosure (1) according to claim 1, wherein the at least one laser joining line (8) surrounds the periphery of the functional area (12, 13, 13a) at a distance (DF).

3. 2. The hermetically sealed housing (1) according to claim 1, wherein the base substrate (3) is joined to the intermediate substrate (4, 4a, 4b, 4c) at a first joining surface, and the cover substrate (5) is joined to the intermediate substrate (4, 4a, 4b, 4c) at a second joining surface.

4. 4. The hermetically sealed enclosure (1) according to claim 3, wherein the at least one intermediate substrate (4, 4a, 4b, 4c) has a higher coefficient of thermal expansion (CTE) characteristic value than both the cover substrate (5) and the base substrate (3).

5. 2. The hermetically sealed enclosure (1) according to claim 1, wherein a marker is inserted into at least one of said substrates (3, 4, 4a, 4b, 4c, 5).

6. The hermetically sealed enclosure (1) according to any one of claims 1 to 5, wherein the thermal strengthening can be achieved by using materials with different coefficients of thermal expansion (CTE) and by appropriate temperatures.

7. 7. The hermetically sealed enclosure (1) according to claim 1, wherein the functional area (12, 13, 13a) comprises a hermetically sealed storage cavity (12) for storing a storage object (2).

8. The hermetically sealed enclosure (1) according to claim 7, wherein the contained object (2) is an electronic circuit, a sensor or a micro-electromechanical system (MEMS).

9. 2. The hermetically sealed enclosure (1) of claim 1, wherein the functional area (12, 13, 13a) comprises a hermetically sealed storage cavity (12) for storing an object (2), the cover substrate (5) forming an upper surface (23) of the storage cavity, the intermediate substrate forming a lateral periphery (21) of the storage cavity, and the base substrate (3) forming a lower surface (22) of the storage cavity, which together completely surround the storage cavity.

10. 10. The hermetically sealed housing (1) according to claim 9, wherein at least one of the lateral rims, the bottom surface or the top surface is transparent to a wavelength range, at least in a specific region.

11. 2. A construction for manufacturing a housing (1) according to claim 1, said construction comprising: a first substrate (3) made of a transparent material at least in certain areas; A second substrate (4) disposed so as to be immediately adjacent to the first substrate (3), The first substrate (3) is bonded to the second substrate (4) by a laser bonding process at a bonding temperature, the bonding temperature being higher or lower than the operating temperature of the housing (1); The first substrate (3) is compressively stressed towards the second substrate (4) at a temperature below the bonding temperature; or The structure, wherein the first substrate (3) is compressively stressed towards the second substrate (4) at a temperature above the bonding temperature.

12. the second substrate (4) is made of a material with a different coefficient of thermal expansion (CTE) characteristic, in particular a higher coefficient of thermal expansion (CTE); and / or said first substrate (3) is a glass substrate or a glass-ceramic substrate; and / or 12. The construction according to claim 11, wherein the second substrate (4) is under tensile stress.

13. A method for providing a plurality of gas-tight enclosures (1) according to claim 1, each enclosure (1) accommodating a functional area (12, 13, 13a) or forming a cavity (12), said cavity (12) being bounded by a lateral periphery (21), a bottom surface (22) and a top surface (23) of said enclosure (1), said cavity being formed as an accommodating cavity, in particular for accommodating an electronic circuit, a sensor or a MEMS, said method comprising: - providing first and at least one second substrate (3, 4, 5), wherein the at least one second substrate (4) is made of a transparent material and is a transparent substrate, the at least one second substrate (4) having a characteristic coefficient of thermal expansion (CTE) different from the characteristic value of the CTE of the first substrate (3), the at least two substrates being arranged directly on each other or overlapping each other, the at least one second substrate (4) forming the edges of each housing (1) of the cavity to be sealed, the first substrate (3) forming the respective underside of each housing (1), and the contact surfaces between the at least two substrates (3, 4) forming contact surfaces (7, 25), so that each housing (1) has at least one contact surface; hermetically sealing said cavity by laser joining said at least two substrates (3, 4) along said contact surface of each housing (1), in particular along the line of said edge of each housing (1); - individualizing each of said housings (1) by a cutting or separation step; Each housing (1) further includes a cover substrate (5), and the at least one second substrate (4) is an intermediate substrate disposed between the cover substrate (5) and the first substrate (3), and the method includes the steps of: The method includes the step of heating the housing (1) to a bonding temperature that is higher or lower than the temperature at which the housing (1) will be used in the future, before sealing the cavity by laser bonding, and performing the laser bonding process at said temperature, so that the cover substrate (5) is under compressive stress when the housing (1) is at the use temperature.

14. 14. The method of claim 13, wherein the at least one intermediate substrate (4) comprises two or more transparent substrates, which together form the edges (21) of the cavity.

15. 15. The method according to claim 13 or 14, wherein the at least one transparent substrate (3, 4, 4a, 4b, 4c, 5) consists of glass, glass ceramic, silicon, sapphire or a combination of the aforementioned materials, or the at least one transparent substrate consists of a ceramic material, in particular an oxide ceramic material.

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

17. said at least two wafers (3, 4, 4a, 4b, 4c, 5) are made of glass, glass ceramic, silicon, sapphire or a combination of the aforementioned materials; and / or At least one wafer comprises a different material than the intermediate wafer; and / or 17. The method of claim 16, wherein all wafers are made of a transparent material.

18. 18. Method according to any one of claims 13 to 17, wherein the step of individualizing each housing (1) is performed by a laser cutting or laser separation step.

19. 19. The method according to any one of claims 13 to 18, wherein the first substrate (3) and / or the third substrate has a thickness of less than 500 μm, or less than 300 μm, or less than 120 μm, or less than 80 μm.

20. 20. The method according to any one of claims 13 to 19, wherein the bonding temperature is 5K higher, or 10K higher, or 20K higher, or 70K higher than the temperature of the subsequent use of the housing (1).

21. 21. The method according to any one of claims 13 to 20, wherein the step of singulating the housing (1) is carried out before the housing (1) is cooled to ambient temperature.

22. 22. The method according to any one of claims 13 to 21, wherein prior to the step of joining the at least two substrates, the substrates (3, 4, 4a, 4b, 4c, 5) are at least temporarily bonded to one another along the contact surfaces (7, 25) of the respective housings (1) by optical contact.

23. 23. An enclosure (1) with a hermetically sealed receiving cavity (12) enclosed therein, manufactured by a method according to any one of claims 13 to 22.

24. 23. Use of a housing (1) manufactured by the method according to any one of claims 13 to 22 with a hermetically sealed receiving cavity (12) enclosed therein as a medical implant or as a sensor, in particular as a barometer.

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