Hermetically sealed glass enclosure

Description

Field of invention

[0001] The invention relates to an enclosure for encapsulating a functional area from an environment and to a method for providing such a glass enclosure. Background and general description of the invention

[0002] Enclosures, especially those that can be hermetically sealed, can be used, for example, to protect sensitive electronics, circuits, optical and optoelectronic components (e.g., OLEDs), or sensors. This allows for the use of medical implants, such as those in the heart, retina, or for bioprocessors. Bioprocessors made of titanium are known to exist. Alternatively, a medication or other substance can also be encapsulated in an enclosure, particularly if hermetically sealed. Once implanted in the body, these implants can then deliver precisely dosed medications over an extended period.

[0003] Sensors can be protected from particularly harsh environmental conditions by an enclosure according to the invention. Examples include MEMS (micro-electro-mechanical systems), barometers, blood gas sensors, glucose sensors, etc. Another application area for an enclosure according to the invention is in smartphone cases, virtual reality glasses, and similar devices. An enclosure according to the invention can also be used for the production of flow cells, for example, in the field of electromobility. Furthermore, enclosures according to the invention can be used in aerospace, high-temperature applications, and micro-optics.

[0004] The aforementioned applications all share the common characteristic of harsh operating conditions, thus placing high demands on the robustness of the components, compared to when they were exposed to these environmental influences unprotected. To enable the use of components that are not expected to withstand these external influences, an enclosure can be used to protect them from such adverse environmental conditions.

[0005] Furthermore, it may be required that an exchange with the interior of the enclosure, for example, a cavity formed by the enclosure, is ensured, i.e., with electromagnetic radiation, particularly in the visible and / or microwave ranges. This means the enclosure must be at least partially transparent—that is, at least in certain areas and / or for a specific wavelength range. This transparency allows for communication methods, data or energy transmission, and measurements of and with the electronics or sensors located in the cavity. In particular, optical communication methods and optical data or energy transmission may be enabled.

[0006] It is generally known to join several parts together and arrange them in such a way that a receiving area is created in the space between them, in which components can be housed. For example, EP 3 012 059 B1 discloses a method for manufacturing a transparent part for protecting an optical component. A novel laser process is used in this process.

[0007] International patent application WO 2008 / 103338 A1 describes hermetically sealed enclosures in which a frit heated by a high-power laser is used to join the components. DE 102 35 372 A1 discloses a component with a silicon layer and a further layer of silicon or glass, wherein the layers are joined without an adhesive layer by means of laser welding. A surface micromechanical structure is produced in the silicon layer and a complementary cavern structure in the further layer, wherein the layers are joined such that at least the surface micromechanical structure is covered by the cavern structure of the further layer.

[0008] In the context of the present further development of enclosures according to the invention, it has been identified that the materials used to form an enclosure exhibit non-zero permeability. Therefore, gases or liquids enclosed in the cavity can escape from the enclosure to the outside, or such substances or fluids from the environment can penetrate the enclosure. This can be caused, for example, by a concentration gradient, i.e., the build-up of osmotic pressure, or by pressure differences. The more impermeable an enclosure material is, the longer the penetration time required for a corresponding substance or fluid to permeate the enclosure material.

[0009] Although the expected time constants for glass are on the order of years, this can be particularly relevant for products with a long lifespan, such as implants or medical packaging.

[0010] For calculating time constants with given materials, geometries, and environmental conditions, the concentration of impurities in a cavity after a specific time can be used as a measure. For example, in the case of simple electronics, this could be a value below 5000 ppm in a hermetically sealed housing. This impurity could be water vapor. Other limits can be defined for different applications, gases, or fluids.

[0011] Until now, the most important factors in choosing the material for the casing have been cost, strength, CTE (corrective elastomer resistance), formability, and inertness to enclosed substances. Since the excellent materials already discovered by the applicant are to be gradually made available for other applications, such as long-lasting implants, the invention aims to provide an improved casing that only minimally affects the aforementioned important factors.

[0012] The present invention therefore deals with improving enclosures and, in particular, making them more resistant. In other words, the present invention is concerned with providing an improved enclosure, and one way to achieve this has been found to be by improving the permeation of the enclosure material.

[0013] An enclosure according to the invention for encapsulating a functional area from its environment comprises a base substrate and a cover substrate, wherein the base substrate together with the cover substrate forms at least part of the enclosure or the housing itself. Furthermore, at least one functional area enclosed by the enclosure is arranged within the enclosure. The functional area is, in particular, hermetically sealed by the enclosure.

[0014] The enclosure according to the invention further comprises a barrier device for reducing permeation between the environment and the functional area. According to the invention, such a barrier device includes a barrier layer which is arranged around the functional area.

[0015] The hermetic sealing of the enclosure is achieved using a laser bonding process developed by SCHOTT. Depending on the application requirements, other glass-to-glass bonding methods can also be used; these include, for example, anodic bonding, glass-frit bonding, or melting using a CO₂ laser. Laser bonding is described below as a representative application example because an enclosure according to the invention has at least one laser bonding line, and the substrates of the enclosure according to the invention are hermetically sealed together by means of this at least one laser bonding line.

[0016] The enclosure according to the invention is specified in claim 1 and comprises at least one laser bonding line, such that the substrates of the enclosure are hermetically sealed together by means of the at least one laser bonding line. Each laser bonding line preferably has a height HL perpendicular to its bonding plane. Preferably, the laser bonding line extends with height HL into the material of the substrate arranged above the laser bonding line. Opposite, the laser bonding line extends into the material of the substrate located below the laser bonding line. In other words, the laser bonding line extends into the two substrates that are to be joined together or that are joined together by means of the laser bonding line.

[0017] For example, the covering substrate is fused together with the base substrate by melting.

[0018] In other words, during the joining step, or in the laser bonding line, material from one substrate melts and mixes with material from the other substrate to create a solid and inseparable hermetic bond between them. In another example, an intermediate substrate is initially placed between the base substrate and the cover substrate. In this example, the base substrate and the intermediate substrate are joined in a first bonding plane by means of at least one laser bonding line, and the cover substrate and the intermediate substrate are joined in a second bonding plane by means of at least one second laser bonding line.

[0019] The enclosure according to the invention additionally has a barrier device, which is arranged, for example, directly around the cavity, in order to reduce the permeation of the enclosure so that an even longer service life of the components or medications or housing objects arranged in the cavity can be achieved.

[0020] The enclosure preferably comprises an intermediate substrate arranged between the base substrate and the cover substrate. In this case, the enclosure has three layers arranged one above the other and joined together. The functional area of ​​the enclosure can include at least one cavity and / or at least one functional layer. In other words, a cavity can be formed within the enclosure in which housing objects can be arranged, so that these are housed and protected by the enclosure. The functional area can alternatively or cumulatively include at least one functional layer, for example, an electrically active layer or a photoresistive layer or the like, for example, also a layer that generates electricity by means of irradiation with suitable radiation, i.e., a photovoltaic layer.

[0021] The barrier device of the enclosure according to the invention comprises a barrier layer. The barrier layer at least partially encloses the functional area. . For example, if the first substrate is made of a different material than the second substrate, it may be sufficient to protect or block the cavity or functional area from only one of the two substrates. The barrier layer can comprise a coating layer; in other words, the barrier layer can be applied as a coating to at least one of the substrates, for example, by vapor deposition, so that this substrate acquires reduced permeability by means of the barrier layer.

[0022] The barrier layer is therefore arranged, in particular, on at least one of the base substrate and / or cover substrate and / or intermediate substrate. Furthermore, the barrier layer is preferably arranged on an inner surface oriented towards the functional area.

[0023] The barrier layer can directly enclose the functional area, meaning that the barrier layer forms at least part of the surrounding inner walls of the functional area or cavity. The barrier layer can, for example, enclose the functional area towards at least one of the substrates, or it can completely enclose the functional area on all sides.

[0024] The base substrate of the enclosure preferably consists of a low-permeability material. The cover substrate can comprise a material with a higher permeability than the base substrate. This is a typical example of an enclosure design in which a cavity is created or integrated into the base substrate and then sealed by placing the cover substrate on top. The cover substrate can be a different material, particularly one with different optical properties than the base substrate. Typically, the laser bond line is projected from above the stack of substrates—for example, the stacked wafers that will later form the enclosure—using a laser to create the bond lines within the enclosure.The laser must therefore be able to penetrate the cover substrate, but it is not necessary for the laser to be able to penetrate the base substrate.

[0025] This allows for the use of a different material for the cover substrate than for the base substrate, which may have properties that the base substrate lacks, and vice versa. In such an arrangement, it may only be necessary to improve the permeability of the cover substrate using the barrier device.

[0026] Suitable materials for the substrate(s) include, for example, those that are preferably biocompatible or chemically resistant oxide materials. The substrates—that is, the cover substrate, the intermediate substrate, and / or the base substrate—can comprise silicon-based oxides and / or nitrides, preferably SiO₂ and / or Si₃N₄, and / or aluminum-based oxides and / or nitrides, preferably Al₂O₃ and / or Al₃N₄. In addition to glass, polycrystalline wafers made of Al₂O₃, crystallized oxides, or polysilicon are also preferred. Such materials already exhibit high barrier functionality. For example, the cover substrate can comprise at least one of the aforementioned materials, while the base substrate comprises a different substrate material or is essentially composed of a different substrate material.In this case, it makes sense to further improve the permeability of the base substrate using the barrier device.

[0027] For this purpose, the barrier device can, for example, also comprise a material or a material mixture, which is preferably biocompatible or chemically resistant oxide materials. The barrier device(s) can thus comprise silicon-based oxides and / or nitrides and / or oxynitrides, preferably SiO₂ and / or Si₃N₄, and / or aluminum-based oxides and / or nitrides or oxynitrides, preferably Al₂O₃ and / or Al₃N₄. Furthermore, a barrier layer can also comprise oxides, nitrides, or oxynitrides based on silicon and aluminum, i.e., SiAlₓN₅, SiAlₓO₅, or SiAlₓO₅N₾. A thin layer hermetically bonded or joined to the adjacent substrate can also function as a barrier device.The barrier device can comprise a metallic material and / or Si3N4 or SiOxNy (silicon oxynitride), in particular a layer composed thereof, which can be deposited, for example, by plasma-enhanced chemical vapor deposition (PECVD), sputtering technology, or atomic layer deposition (ALD). The barrier device can, for example, have a thickness of 1 µm or less, more preferably 500 nm or less, more preferably 100 nm or less, and most preferably 50 nm or less. The barrier layer or barrier device can also be designed to be 30 nm or thinner to achieve the effect according to the invention.

[0028] The barrier device is able to reduce the permeability between the functional area and the environment by at least 30%. In other words, the barrier device influences the substrate material on which it is arranged or applied as a barrier layer, reducing—i.e., improving—the permeability of this substrate by, for example, at least 30%.

[0029] The barrier layer can be designed to reduce permeability in both directions of penetration through the enclosure. This means that the barrier layer reduces both the permeability for a gas, substance, or gaseous mixture enclosed in the cavity with respect to escape to the environment, and also the permeability for a gas, substance, or gaseous mixture in the environment with respect to penetration into the cavity.

[0030] The barrier device can further comprise a second barrier layer. The functional area can be arranged between the first and second barrier layers. For example, the first barrier layer can be applied to the cover substrate, and the second barrier layer can then be arranged or applied to the base substrate, so that the functional area is completely enclosed by the first and second barrier layers. Preferably, the barrier layers are arranged on the sides facing the functional area.

[0031] The second barrier layer can also be arranged or applied on top of the first barrier layer, so that the two barrier layers complement each other in the same direction. This allows for differentiated protection for specific materials, depending on the choice of barrier material. For example, one layer of the barrier can comprise SiO₂ and the second Si₃N₄, thus achieving complementary protection by applying both barrier layers to the same side of the cavity.

[0032] The base substrate, one or more intermediate substrates, and / or the cover substrate can comprise a glass-like material. This can be, for example, glass or glass-ceramic, silicon, aluminum oxide, sapphire, or a combination of the aforementioned materials. Glass and glass-like materials, in particular, have proven especially advantageous because they are highly biocompatible, meaning they are chemically compatible with the human body, have no known interactions with the human organism, and simultaneously offer excellent insulating properties. Furthermore, glass can be made transparent to radiation, thus enabling, for example, wireless information exchange via radiation or wave information, or contactless charging of electronics or batteries that may be located within the enclosure.If a substrate – especially the cover substrate – is transparent in the optical wavelength range, for example, an optically transparent substrate, energy can be supplied to the enclosure optically, for instance, by means of a photovoltaic cell or another type of optical receptor arranged within the enclosure to provide electrical energy. The enclosure can then be described as self-contained. To create the hermetic seal, particularly around the functional area, one of the laser bonding lines can encircle the functional area at a distance DF. In one example, the distance DF around the functional area is constant, so that the laser bonding line lies at approximately the same distance around the functional area on all sides. However, the distance DF can also vary depending on the application.This can be more advantageous from a production standpoint if multiple enclosures are joined simultaneously in a single operation, and, for example, straight joining lines or laser bonding lines are applied to the respective contact surfaces of the individual enclosures. This can also be the case if the functional area or enclosure is round or has any other shape, and the laser bonding line, which hermetically seals the functional area, is drawn in straight lines. In one example, the functional area could be designed as a cavity, and the cavity itself could have optical properties, such as being shaped like a lens, like a converging lens, with the laser bonding line drawn around the cavity in a different pattern.

[0033] The functional area of ​​the enclosure is designed to accommodate at least one housing object, such as an electronic circuit, a sensor, or MEMS, so that at least one housing object is located within the enclosure. The housing object can be electronics, such as a power semiconductor chip, for example, a GaN LED, or a SiC, GaAs, or GaN power transistor. The housing object can also be a drug or a fluid located within it, which is not intended to react with the environment, or at least not at a later or predefined time.

[0034] The housing object is preferably arranged in a cavity that is completely enclosed by the housing. The functional area or cavity can be incorporated into the base substrate, for example, by creating a depression in the base substrate, perhaps using an abrasive process, so that the functional area and / or at least one housing object is surrounded below and laterally by the base substrate material. Alternatively, the functional area or cavity can be arranged above the base substrate, for example, on top of it.

[0035] The enclosure can also comprise multiple cavities, for example, to house different components in different cavities. This allows, for instance, a battery or storage cell to be housed separately from other components within the enclosure. Alternatively, a medication can be located in one cavity, and control or dispensing electronics, such as a timer, in a second cavity, controlling the release of the medication into the environment, for example, at a specific time or upon the occurrence of a particular event.

[0036] The enclosure can incorporate glass feedthroughs, for example, in an intermediate substrate separating at least two cavities. These glass feedthroughs can electrically connect the housing objects arranged in different cavities. The glass feedthroughs can be through-glass vias (TGVs), where the vias are filled with electrically conductive material. The enclosure can also include an electrical connection layer, which can be arranged, for example, on an intermediate substrate. This makes it particularly easy to arrange and electrically connect the components or housing objects in the respective cavity. The electrical connection layer is, for example, located on the underside of the cavity(ies) and can be contacted via glass feedthroughs.

[0037] An example of a functional area that is not designed as a cavity is the application of an electrical interconnect layer to a substrate, which already forms a functional area without a cavity. Such an electrical interconnect layer can, for example, electrically connect two other functional areas, such as two cavities.

[0038] A substrate can also comprise multiple layers, thus forming a multilayer composite. Such a multilayer composite can then be joined to the other substrate(s) as one of the layers of the enclosure using laser welding. This can mean that the multilayer composite is prepared beforehand, for example, by applying a coating to a substrate to create a two-layer composite, and this two-layer or multilayer composite is then joined as a whole to the other layer(s) during the enclosure manufacturing process.

[0039] By using a multilayer composite in the housing, additional material properties can be added to the housing that would not be achievable with single-layer substrates. For example, the multilayer composite may already possess an internal stress or prestress, or a prestress direction, so that the amount of internal stress can be improved when the multilayer composite is laser-welded to at least one additional layer of the housing. This can, for example, improve the housing's resistance if a pre-cured multilayer composite is used. This can result in the housing as a whole assuming the properties of a hardened housing.

[0040] Additionally or alternatively, the multilayer composite can have one or more coating layers, for example, a coating that might cause complications if this layer had to be joined using the laser joining process. In other words, a substrate supplied as a multilayer composite is provided as a "pack" or "stack" with layers that are already bonded together.

[0041] Depending on the application requirements, methods other than laser bonding can be used for glass-to-glass joining. These include, for example, anodic bonding, glass-frit bonding, or melting using a CO₂ laser. Laser bonding is described below as a representative application example, since an enclosure according to the invention has at least one laser bond line, and the substrates of the enclosure are hermetically bonded together by means of this at least one laser bond line. The laser bonding process can be controlled locally in such a way that only a small or negligible amount of heat enters the functional area or cavity(ies) during the joining process. The laser bonding process thus takes place virtually at room temperature; that is, the enclosure is joined virtually at room temperature.

[0042] The laser bonding line extends, in particular to a height HL, into the material of the substrate positioned above it. A local melting process takes place within the material along the laser bonding line, so that if the laser bonding line extends partially into a first substrate and partially into a second, the two substrates are fused together by melting. In other words, the base substrate, the intermediate substrate(s), and the cover substrate are fused together by the laser bonding line(s) through melting.

[0043] In other words, the laser bonding line is arranged or constructed in such a way that it can bridge gaps in the hermetic seal of the enclosure, for example, by melting two components together using the laser bonding line. If the enclosure only consists of a base substrate and a cover substrate to completely enclose the functional area, the contact area between the base substrate and the cover substrate—that is, the point or area where the cover substrate and base substrate meet—is bridged or connected by the laser bonding line. As a result, the enclosure forms as if it were molded in one piece, with the joint between the components also hermetically sealed by the laser bonding line.

[0044] The enclosure is preferably at least partially and / or regionally transparent for a specific wavelength range. In a simple example, the covering substrate of the enclosure is optically transparent, i.e., see-through, in the visible wavelength range. However, transparency in the UV or IR range, for example, can also be advantageous. In other words, the covering substrate preferably comprises a non-conductive material, such as an oxide or nitride, a glass-like material, or even a metallic glass. The covering substrate is thus preferably transparent or permeable for at least one wavelength range, for example, optically transparent. Depending on the application, it can also be advantageous if, for example, the covering substrate is opaque, i.e., optically intransparent, like frosted glass or polycrystalline oxide ceramic. Reduced transparency or partial permeability may also be sufficient for the intended function.

[0045] In a preferred embodiment, the covering substrate is a glass plate, for example made of tempered glass, special glass or high-temperature resistant glass, for example from the applicant's product portfolio.

[0046] The enclosure can be designed such that at least one functional area of ​​the enclosure can be configured to accommodate at least one housing object. Housing objects for inclusion in the at least one functional area can, for example, have a size of 20 mm x 20 mm or smaller; they can be round or oval with a diameter of, for example, 15 mm or smaller. The housing objects can also have a size of 10 mm x 10 mm or smaller, preferably a size of 5 mm x 5 mm or smaller, more preferably 2 mm x 2 mm or smaller, or even 1 mm x 1 mm or smaller. The size of the enclosure then depends on the size and number of housing objects in the functional areas or cavities of the enclosure.For example, if one housing object of approximately 5mm x 5mm is arranged in each of a plurality of cavities of the enclosure, with, for example, two cavities arranged side by side and two cavities arranged one above the other, an enclosure can, for example, have a size of 13 mm x 13 mm or larger, so that the housing of the objects in the cavities is ensured.

[0047] The thickness of the substrates can be approximately 1 mm, approximately 0.7 mm, approximately 0.5 mm, approximately 0.1 mm, or less. In other words, the thickness of one of the substrates of the enclosure is, for example, less than or equal to 2 mm, preferably less than or equal to 1 mm, more preferably less than or equal to 0.5 mm, or less than or equal to 0.1 mm.

[0048] A practical size specification, dictated by the preferred manufacturing process but not intended as a size limitation per se, is the size of the wafers to be sliced. However, the use of wafers for manufacturing is merely an example. It is entirely possible, for instance, to use glass plates to produce the transparent housing, which can have larger or smaller dimensions than typical wafer sizes.

[0049] The barrier device of the enclosure includes at least a barrier layer, in particular a coating layer, which at least partially encloses the functional area. In other words, the barrier device can be designed as a barrier layer that is arranged between the cavity and the enclosure surrounding the cavity.

[0050] The barrier layer is preferably arranged on at least one of the base substrate, cover substrate, or intermediate substrate, for example, on the inner side facing the functional area. The barrier layer can then also be protected by the encapsulation material. This is advantageous if the barrier layer itself does not, for example, have the same mechanical or chemical resistance as the base or cover substrate material.

[0051] The barrier layer can therefore directly enclose the functional area, especially towards at least one of the substrates, or completely.

[0052] The base substrate can consist of a material with a relatively low permeability. The cover substrate can comprise a material with a higher permeability than the base substrate. In this case, it is advantageous to position the barrier between the functional area and the cover substrate, whereas in this example, the use of a barrier between the cavity or functional area and the base substrate would not be necessary.

[0053] The barrier device can comprise silicon-based oxides and / or nitrides and / or oxynitrides, preferably SiO₂ and / or Si₃N₄, and / or aluminum-based oxides and / or nitrides and / or oxynitrides, preferably Al₂O₃ and / or Al₃N₄. Furthermore, a barrier layer can also comprise silicon- and aluminum-based oxides, nitrides, or oxynitrides, i.e., SiAlₓN₅, SiAlₓO₅, or SiAlₓO₅N₅z.

[0054] The barrier device can, for example, have a thickness of 1 µm or less, more preferably 500 nm or less, more preferably 100 nm or less, and particularly preferably 50 nm or less. The barrier layer or barrier device can also be designed to be 30 nm or thinner to achieve the effect according to the invention.

[0055] The barrier device can be designed or configured to reduce the permeability between the functional area and the environment surrounding the enclosure by at least 30%. Preferably, the barrier device is configured to reduce permeation by at least 50%, and optionally by at least 75%. For example, the barrier device can reduce the permeability with respect to water or water vapor. The barrier device can, for instance, reduce the permeability in both directions of penetration through the barrier device. This means that both water vapor, gases, fluids, or substances in general that wish to penetrate the functional area from the external environment are prevented by the barrier device, as are fluids or substances that wish to escape from the functional area into the external environment.The "desire for the fluid to penetrate" is caused, for example, by osmotic pressure, or by a physical pressure difference, or by a superposition of both causes, which defines the permeability.

[0056] If the barrier device has a second barrier layer, the functional area can be located between the first and second barrier layers. In this example, the first barrier layer can be located on or attached to the cover substrate, and the second barrier layer can be located on the base substrate.

[0057] The second barrier layer can also be arranged on top of the first barrier layer, i.e., on the same side of the cavity as the first barrier layer. The first and second barrier layers can thus complement each other with regard to their achieved barrier effect.

[0058] According to the invention, a method for providing a hermetically sealed enclosure is also provided, wherein the enclosure encloses a functional area, in particular a cavity. The method has the features of claim 12.

[0059] The cover substrate is joined to the base substrate using laser bonding lines. In other words, the cover substrate is placed directly onto or into the base substrate without an intermediate layer and bonded to it immediately and directly via one or more shared laser bonding lines. In this case, the cover substrate and the base substrate together form the complete enclosure. In other words, no additional component is required to form or close the enclosure; the base substrate, the at least one laser bonding line, and the cover substrate together completely and hermetically seal the functional area or cavity. On the other hand, it can be advantageous to use one or more intermediate substrates, for example, to separate multiple cavities.

[0060] The at least two substrates, or the base substrate and the cover substrate, are arranged or attached to one another in such a way that they lie flat against each other, without any other layers, layers, or inclusions between the at least two substrates or between the base substrate, cover substrate, and any intermediate substrate. For technical reasons, minute gas inclusions between the layers in the contact area may be unavoidable, which may also result from any unevenness. For example, the amount of gas trapped in the area of ​​the flat contact surface can be further reduced by increasing the pressure, such as by pressing, or by surface treatment of the substrate layers, especially the contact surfaces, such as a grinding process. Prior evacuation is advantageous.Filling with a type of gas or liquid can also be advantageous, depending on the process parameters and materials to be used.

[0061] It is particularly preferred if the gap that may occur between the substrates is less than or equal to 5 µm thick, and more preferably less than or equal to 1 µm. Then it is possible to join with the laser in such a way that the joining zone has a thickness between 10 and 50 µm and a hermetic seal is ensured.

[0062] A contact surface need not be optically transparent. Furthermore, it is advantageous if the transparent substrate is opaque in the visible wavelength range. Only the substrate through which the laser passes to reach the contact surface has at least one spectral "window," allowing at least the wavelength of the laser to pass through the substrate, at least partially or at least in certain areas. The contact surface is designed such that the laser can deposition energy at it. For example, the surfaces of the two adjacent substrates can be roughened and preferably exhibit a roughness in the nanometer range. The laser is at least partially absorbed at this surface, allowing energy to be deposited there.In general, a contact surface within the meaning of this application is to be understood as a surface on which the incoming laser beam can deposit energy and thus a joining process can be carried out along a line within the contact surface.

[0063] The procedure may further include, prior to the step of arranging the cover substrate on the base substrate, the additional step of arranging the barrier device on the cover substrate and / or on the functional area.

[0064] The step of providing the cover substrate may include providing the cover substrate already equipped with the locking device, and / or the step of providing the base substrate may include providing the base substrate already equipped with the locking device.

[0065] Furthermore, the invention also includes the housing produced or formed by means of the aforementioned method.

[0066] To form the laser bond line, a laser beam is guided around the functional area, hermetically sealing the functional area along at least one contact surface. If necessary, the laser beam can be guided around the area multiple times and / or multiple laser bond lines can be formed.

[0067] The invention also includes the use of a housing produced according to the above-described method, with a hermetically sealed functional area or cavity enclosed therein, as a medical implant or bio-implant or as a sensor.

[0068] The invention will now be explained in more detail with reference to exemplary embodiments and the figures, whereby identical and similar elements are partially provided with the same reference numerals and the features of the different exemplary embodiments can be combined with one another. Brief description of the characters

[0069] They show: Fig. 1 Top view of an enclosure, Fig. 2 Side sectional view of an enclosure, Fig. 3 Detail view of a joining zone, Fig. 4 Side sectional view through the functional area of ​​an enclosure, Fig. 4a Side sectional view as Fig. 4 however, with two accommodation objects, Fig. 5 Side section view through another embodiment of an enclosure, Fig. 5a Side section view through another embodiment of an enclosure, Fig. 6 Side section view through yet another embodiment of an enclosure, Fig. 6a Top view of the section according to Fig. 6 , Fig. 7 Side sectional view through yet another embodiment of an enclosure, Fig. 8 Example of steps for the manufacture of an enclosure. Detailed description of the invention

[0070] Fig. 1Figure 1 shows a top view of an enclosure 1 according to an embodiment of the invention, wherein the circumferential laser joining zone 8 surrounds the functional area 13. The functional area 13 can have different configurations. Examples of different configurations of the functional area 13 can also be found in the following. Figures 3 to 7 , which show the sectional views and thus are able to resolve the vertical structure of functional area 13. The various designs of functional area 13 can be graphically represented in the Fig. 3 They can be combined in this way, since all views can be represented schematically in the same way. Functional area 13 is the example of the Fig. 1 The functional area 13 of the enclosure is rectangular in shape. Depending on the method used to form it, the functional area 13 can assume different shapes. For example, cavities produced by abrasive processes can be lenticular in shape.

[0071] Functional area 13 can perform various tasks; for example, it can be configured as an optical receptor or include a technical, optical, electromechanical, and / or electronic component 2 located within functional area 13. Several of these tasks can also be performed within functional area 13. The housing 1 is covered on the top by the upper substrate or cover substrate 5. The laser joining zone 8, or at least one of it, extends into this upper substrate 5.

[0072] Referring to Fig. 2 Figure 1 shows a first sectional view of a first embodiment of an enclosure 1, which has a base substrate 3 and a cover substrate 5. In other words, the enclosure 1 is composed of two layers, namely the base layer 3 and the cover layer 5. Fig. 2Furthermore, the figure shows the structure of the laser joining line 8 consisting of a series of multiple laser pulse hit areas 16, which are placed so close together that the material of the base substrate 3 and the cover substrate 5 merge seamlessly and thus hermetically seal the functional area 13 or the cavity 12 (arranged behind the laser joining line 8 in this view).

[0073] Fig. 3 Figure 1 shows a detailed view of the joining area, showing the interface zone (i.e., contact surface 25) and the laser joining zone 8. The laser joining zone 8 is located in the area of ​​contact surface 25 to join the two substrates 3 and 5 together.

[0074] Fig. 4 shows a sectional view of an embodiment of an enclosure 1 along the line C->D, as shown in Fig. 1 is shown. Fig. 4This shows a cross-section through functional area 13, 13a, which extends, for example, as a continuous cavity or void in the housing 1. In other words, the cavity extends from the base substrate 3 into the cover substrate 5 and is, for example, in the form of a recess in the base substrate 3 and / or the cover substrate 5. Functional area 13 is formed here as a recess in the cover substrate 5, and functional area 13a as a recess in the base substrate 3, for example, by means of an abrasive process such as sandblasting. In other words, the base substrate 3 has a depression 13a.

[0075] For example, functional area 13a can include an active layer, e.g., an electrically conductive layer 34. The active layer of functional area 13a can also include a photoreceptor, for example, in the form of a photovoltaic cell, so that it is configured to generate electrical power. Then the enclosure 1 can be a self-contained enclosure 1.

[0076] The laser joining zone 8 is arranged around the functional area 13a, by means of which the functional area 13a is completely sealed on the sides. It is conceivable to leave open areas in the laser joining zone 8 so that the functional area 13a is not completely sealed, for example, to leave open a communication channel or space for an electrical connection, which could also be used, for example, to establish fluid communication with the environment. In other words, it is possible not to seal pre-planned areas or positions with the focused laser beam 9, but to establish a hermetic seal there by other means. However, this is not part of the claimed invention. Preferably, however, as also in Fig. 1 shown to completely and seamlessly seal the functional area 13, 13a in order to ensure the hermetic closure of the functional area 13, 13a.

[0077] In Fig. 4 Furthermore, a first embodiment of a locking device 6 is shown, wherein the locking device 6 is arranged on the underside of the cover substrate 5 and thus directly adjoins the functional area 13a. The locking device of the embodiment of Figure 4 This therefore improves the permeability for penetration of the cover substrate. In this example, the base substrate material has a lower permeability than the cover substrate, so a circumferential barrier 6 or a barrier 6 completely sealing the functional area 13a is not necessary. It is sufficient to reduce or improve the permeation from the functional area 13a towards the cover substrate 5.

[0078] Fig. 4a shows the embodiment of the Figure 4, wherein two accommodation objects 2 are arranged in the cavity 12. The accommodation objects 2 can, for example, be an electronic component. The two versions can also be combined if the active layer 34 is, for example, an electrically conductive layer 34, because then the components 2 can be arranged on the conductive layer 34 and connected to each other.

[0079] Referring to Figure 5 A further sectional view through an enclosure 1 in the area of ​​functional areas 13, 13a is shown. The enclosure 1 has two substrate layers, namely the base substrate 3 and the cover substrate 5. A functional layer 13a is arranged over the entire surface between the base substrate 3 and the cover substrate 5; the barrier device 6 is arranged above the functional layer 13a.

[0080] Although the functional area 13a, implemented here as functional layer 13a, is thus not protected on two of its narrow sides, this may be acceptable depending on the application and the material of the functional layer 13a. For example, this is the case if the functional layer is an optical frequency filter or an anti-reflective coating.

[0081] The Figure 5a In contrast, it shows an embodiment which the Figure 5The situation is similar, except that in this case the functional layer 13a is completely enclosed by the housing. In this case, even if the base substrate 3 has a lower permeability compared to the cover substrate 5, it is still sufficient for the barrier device 6 to be located above the functional layer 13a in the direction of the cover substrate 5. The functional area 13 is designed as a cavity 12, in which one or more components 2 or any housing objects 2, as well as a drug dose 2, can be arranged.

[0082] Figure 6Figure 1 shows a further embodiment of the conversion solution according to the invention, wherein the housing comprises three substrate layers, namely the base substrate 3, an intermediate substrate 4, and the cover substrate 5. The intermediate substrate 4 can either be, for example, spacers or it can be a continuous substrate, i.e., a plate with internal cutouts. This is also referred to as spacer 4.

[0083] The housing of the embodiment of the Figure 6The enclosure 1 has a first barrier device 6, which is arranged on the upper side of the cavity 12 and thus on the underside of the cover substrate 5. The enclosure 1 also has a second barrier device 6a on the underside of the cavity 12, which is arranged on the upper side of the base substrate 3. Such an arrangement of two barrier devices 6, 6a on the two sides of the functional area 12, 13, 13a to be enclosed can be chosen, for example, if both the base substrate 3 and the cover substrate 5 have a comparatively high permeability. In this case, both substrates can be blocked by means of the barrier device 6, 6a, i.e., the permeability through the respective substrate is reduced. In the example of the Figure 6The barrier device 6, 6a does not include the intermediate substrate 4; this represents a simplified embodiment that is particularly simple and easy to manufacture. Depending on the properties of the intermediate substrate, it may be possible to exclude the intermediate substrate from the barrier device, thus eliminating the need for complicated application or coating processes on the intermediate substrate 4. Even if the intermediate substrate has a comparatively high permeability, it may be sufficient to block only the base substrate 3 and the cover substrate 5 with the barrier device 6, 6a, since the surface area of ​​contact between the intermediate substrate 4 and the functional area 12, 13, 13a is relatively small. Diffusion is particularly dependent on the size of the object, i.e., the size of the gas or fluid flowing through it.However, if the surface area is small, only a small amount of fluid will pass through the intermediate substrate 4, so that, depending on the application, it can be released by the barrier device 6, 6a. On the other hand, a complete closure of the functional area is of course also conceivable, compare . Figure 7 .

[0084] Fig. 6a shows the execution of the Figure 6 in a cross-sectional view rotated 90° from above. This cross-sectional view therefore passes through the intermediate substrate 4 and the functional area 13, which is designed as cavity 12.

[0085] Fig. 7 Figure 1 shows a further embodiment of the invention, wherein the functional area 13 is again configured as a cavity 12 and has a non-straight underside. For example, the cavity 12 has the shape of a lens, in this case shown in the Figure 7as a plano-convex lens. In other words, the cavity 12 is configured such that a convex recess 12 is hollowed out in the base substrate 3, for example by means of an abrasive process, so that the base substrate has a concave upper surface. This can create an optical property of the housing and have an effect on the housing object 2 arranged inside the cavity 12 (see, for example, Figure 4a have. The housing of the Figure 7The device features a barrier 6, designed as a barrier layer. The barrier layer can be considered or designed as a single, continuous barrier layer around the cavity 12. Alternatively, it can be applied in two separate process steps, for example, as a first barrier layer 6 on the underside of the cover substrate 5 and as a second barrier layer 6a on the top side of the base substrate 3. These can therefore be coating layers applied to the respective substrate. On the other hand, the barrier 6 can also be arranged on the respective substrate, for example, by being glued or otherwise positioned there. In the example of the Figure 7 The functional area 13 is completely enclosed, i.e. on all sides, by the barrier device, so that permeation in all spatial directions is reduced.

[0086] Referring to Fig. 8An embodiment of the method for producing a plurality of enclosures 1 is shown. The production of the enclosures 1, as illustrated, for example, in the preceding figures, is explained. It is clear to those skilled in the art that, depending on the process requirements, even a single enclosure 1 can be produced using this method.

[0087] In step A, a common base substrate 3 is provided as a carrier substrate, which has a plurality of depressions 12 corresponding to the later cavities 12. These depressions are created, for example, by an abrasive process. For instance, the cavities 12 can be created by sandblasting, i.e., by hollowing them out of the base substrate 3, generally using an abrasive process. Chemical etching is also possible for creating the cavity 12 in the base layer 3. For example, housing objects 2, such as a sensor, actuator, processor, or medication, can be arranged in each of the depressions 12.

[0088] A barrier device 6, 6a can be arranged on the base substrate 3 – as well as on the cover substrate and / or optionally on the intermediate substrate. This barrier device can be, for example, in the form of a coating layer 6. For example, at least one side of a substrate 3, 4, 5, preferably on the cavity side, can be provided with a thin barrier layer 6, 6a using PVD or CVD or other thin-film coating technologies. This barrier layer can comprise SiO₂ to preferably reduce the penetration of water or water vapor. It can also comprise Si₃N₄, or Al₂O₃, or Al. Alternatively, the barrier device 6, 6a can also be arranged on a substrate 3, 4, 5, preferably on the side facing the functional area 13, 13a. For example, a thin layer or element can be applied there and joined together with the other substrates 3, 5, and optionally 4 in step C.

[0089] In step B, a common cover substrate 5 is applied to the base substrate 3; that is, a cavity 12 is created for each depression by covering the base substrate 3 with the cover substrate 5, and then hermetically joined in step C. Several housing objects 2 can be housed in each common cavity 12.

[0090] In step C, the substrates are directly joined together using laser bonding lines 8. Two continuous laser bonding zones 8 can be formed by guiding the laser 9 twice around each cavity 12 along the contact surfaces 25 or along the outer edges of the cavities 12, but not along an exactly identical path. Rather, the laser 9 can be guided along a laterally offset path on each revolution around the cavity 12, resulting in two adjacent laser bonding zones 8. The microbonding zones 8 can have dimensions of, for example, 5 µm x 10 µm or smaller, or 10 µm x 50 µm or smaller.

[0091] The finished substrate stack is joined using a laser 9, so that the respective housing cavities 12 are hermetically sealed. This involves sealing the cavities 12 on all sides along the contact surfaces 25 and introducing at least one laser bond line 8 per housing 1. For this purpose, a laser unit 15 is guided from above the cover substrate 5 across its surface, and a focused laser beam 9 is directed at the zones to be joined, particularly at the contact surfaces 25. After completion of step C of the manufacturing process, all cavities 12 are hermetically sealed. It is possible to separate the individual housings 1 after step C using a cutting process, thus obtaining individual, separate housings 1.

[0092] In step D, the components are separated from each other along separation or cutting lines 10. The same laser can be used for this as for laser joining in step C. However, a conventional cutting method can also be used if this is advantageous.

[0093] For example, the pressure that forms due to the permeability in the cavity 12 in the direction of a substrate 3, 4, 5 of the enclosure 1 or in the direction of the environmental conditions around the enclosure 1 can be composed as Q = Δ p ∘ 1 − e − KA 2 D 2 DVd + KAd 2 t where D and K depend on the temperature, and where Δ pwhere K is the partial pressure difference between the interior of the cavity and the environment, D is the permeability, A is the diffusion coefficient, A is the surface area of ​​the enclosure 1 or the corresponding substrate 3, 4, 5 to be penetrated in cm², V is the volume of the cavity 12 in cm³, d is the wall thickness of the substrate 3, 4, 5 or the enclosure 1 in cm, and t is the time in seconds.

[0094] It is evident to those skilled in the art that the embodiments described above are to be understood as examples and that the invention is not limited to these, but can be varied in many ways without departing from the scope of the claims. In all figures, the same reference numerals denote the same features, so that descriptions of features that may only be mentioned in one figure, or at least not with respect to all figures, can also be applied to those figures for which the feature is not explicitly described. Reference symbol list:

[0095] 1 Enclosure, especially hermetically sealed 2 Housing object, functional component 3 Lower substrate, layer or wafer, base substrate or lower cover 4 Intermediate layer 5 Upper substrate, layer or wafer, cover substrate or upper cover 6, 6a Locking device 8 Laser joining zone 9 Focused laser beam 10 Separation or cutting line 12 Housing cavity 13 Functional area 13a Second functional area 14 Edge 15 Laser unit for joining and / or cutting 16 Laser pulse hit area 18 Substrate stack 21 Edge of the cavity 22 Bottom of the cavity 23 Top of the cavity 25 Contact surface

Claims

1. An enclosure (1) for encapsulating a functional area (13, 13a) against an environment, the enclosure comprising: a base substrate (3); a cover substrate (5), the base substrate together with the cover substrate defining at least part of the enclosure or defining the enclosure; the at least one functional area provided inside the enclosure; a blocking means (6, 6a) for reducing permeation between the environment and the functional area; wherein the enclosure (1) comprises at least one laser bonding line (8) and the substrates of the enclosure are hermetically joined to one another by said at least one laser bonding line; wherein the blocking means is disposed between the functional area and the cover substrate and / or between the functional area and the base substrate; wherein the blocking means (6, 6a) comprises a barrier layer enclosing the functional area against the environment at least partially in order to reduce permeation between the environment and the functional area.

2. The enclosure (1) according to the preceding claim, wherein the laser bonding line has a height (HL) perpendicular to its bonding plane; and / or wherein the barrier layer is a coating layer which at least partially encloses the functional area (13, 13a) ; and / or further comprising at least one intermediate substrate (4) disposed between the base substrate (3) and the cover substrate (5); and / or wherein the functional area (13, 13a) comprises at least one cavity (12) and / or at least one functional layer (13a).

3. The enclosure (1) according to the preceding claim, wherein said barrier layer (6, 6a) is disposed on at least one of the base substrate (3) and / or the cover substrate (5) and / or the intermediate substrate (4), in particular on an inner side facing the functional area (13, 13a); and / or wherein the barrier layer (6, 6a) directly encloses the functional area (13, 13a), in particular encloses it against at least one of the substrates (3, 4, 5), or encloses it completely.

4. The enclosure (1) according to at least one of the preceding claims, wherein the base substrate (3) is made of a low permeability material; and / or wherein the cover substrate (5) comprises a material which has a higher permeability than the base substrate.

5. The enclosure (1) according to at least one of the preceding claims, wherein the blocking means (6, 6a) comprises SiO2 or Si3N4 or Al2O3 or AlN; and / or wherein the blocking means (6, 6a) comprises a metallic material; and / or wherein the blocking means (6, 6a) comprises SiOxNy or AlOxNy; and / or wherein the blocking means (6, 6a) comprises SiAlxNy, SiAlxOy, or SiAlxOyNz.

6. The enclosure (1) according to at least one of the preceding claims, wherein the blocking means (6, 6a) has a thickness of 1 µm or less, preferably 1 µm or less, more preferably 100 nm or less, most preferably 50 nm or less; and / or wherein the blocking means (6, 6a) is adapted or adjusted so as to reduce the permeability between the functional area (13, 13a) and the environment by at least 30 %; and / or wherein the blocking means (6, 6a) reduces the permeability for water and / or hydrogen; and / or wherein the blocking means (6, 6a) reduces the permeability in both directions of penetration through the blocking means and through the substrate (3, 4, 5) of the enclosure.

7. The enclosure (1) as claimed in any of the preceding claims 3 to 6, wherein the blocking means (6, 6a) comprises a second barrier layer; and wherein the functional area (13, 13a) is arranged between the first barrier layer and the second barrier layer.

8. The enclosure (1) according to at least one of the preceding claims, wherein the base substrate (3), the one or more intermediate substrates (4) and / or the cover substrate (5) comprise a vitreous or polycrystalline material, for example glass, glass ceramics, silicon, aluminium oxide, sapphire, aluminium nitride, or a combination of the aforementioned materials and / or wherein the enclosure (1) is transparent for a range of wavelengths at least partially and / or in portions thereof.

9. The enclosure (1) according to at least one of the preceding claims, wherein at least one of the laser bonding lines (8) circumferentially surrounds the functional area (12, 13, 13a) at a distance (DF) therefrom; and / or wherein the functional area (12, 13, 13a) is adapted to accommodate at least one accommodation item (2) such as an electronic circuit, a sensor, or an MEMS, so that at least one accommodation item (2) is disposed inside the enclosure (1).

10. The enclosure (1) according to the preceding claim, wherein the at least one accommodation item (2) comprises a power semiconductor chip, e.g. a GaN LED, a SiC power transistor, a GaAs power transistor or a GaN power transistor; and / or wherein the accommodation item (2) is disposed in a cavity (12); and / or wherein the enclosure comprises a plurality of cavities (12) for accommodating at least one accommodation item (2) in a respective cavity.

11. The enclosure (1) according to at least one of the preceding claims, wherein the laser bonding line (8) extends into the material of the substrate (3, 4, 5) provided above the laser bonding line over a height (HL), and wherein the base substrate (3), the one or more intermediate substrates (4) and the cover substrate (5) are joined together by being fused to one another; and / or wherein the at least one functional area (13, 13a) of the enclosure is adapted for accommodating at least one accommodation item (2) having a size of 10 mm x 10 mm or less, preferably a size of 5 mm x 5 mm or less, more preferably 2 mm x 2 mm or less, or even 1 mm x 1 mm or less; and / or wherein the substrates of the enclosure are hermetically joined together by anodic bonding, bonding with organic adhesive, glass frit bonding, or by fusing using a CO2 laser.

12. A method for providing an enclosure (1), wherein the enclosure (1) encloses a functional area (13, 13a), in particular a cavity (12), comprising the steps of: - providing a base substrate (3) and a cover substrate (5), the cover substrate (5) being transparent for at least one range of wavelengths at least partially or in portions thereof and thus constituting a transparent cover substrate; - arranging the cover substrate (5) on the base substrate (3) and above the functional area thereby creating at least one contact area (25) between the base substrate (3) and the cover substrate (5), so that each enclosure (1) has at least one contact area; - hermetically sealing the cavities by forming at least one laser bonding line (8) along the at least one contact area of each enclosure (1); wherein a blocking means is disposed between the functional area and the cover substrate and / or between the functional area and the base substrate, which blocking means comprises a barrier layer enclosing the functional area against the environment at least partially in order to reduce permeation between the environment and the functional area.

13. The method according to the preceding claim, further comprising, prior to the step of arranging the cover substrate (5) on the base substrate (3), a step of arranging the blocking means (6, 6a) on the cover substrate and / or on the functional area and / or on the base substrate (3); and / or wherein the step of providing the cover substrate (5) comprises providing the cover substrate already equipped with the blocking means (6, 6a); and / or wherein the step of providing the base substrate (3) comprises providing the base substrate already equipped with the blocking means (6, 6a); and / or wherein a laser beam (9) is directed along the perimeter of the functional area (12, 13, 13a) to form the laser bonding line (8) so that the functional area is hermetically sealed circumferentially along the contact area (25), wherein optionally the laser beam can be directed circumferentially around repeatedly, and / or optionally a plurality of laser bonding lines (8) can be formed; and / or wherein an enclosure (1) according to any one of claims 1 to 19 is produced by said method.

14. Use of an enclosure (1) produced according to the method of claim 12 or 13, comprising a hermetically sealed accommodation cavity (12) enclosed therein, as a medical implant or as a sensor.