HERMETICALLY SEALED GLASS PACKAGE

Abstract

A package for encapsulating a functional area against an environment includes a base substrate and a cover substrate, the base substrate together with the cover substrate defining at least part of the package or defining the package, and furthermore including the at least one functional area provided in the package, and a blocking way for reducing permeation between the environment and the functional area. The package may include at least one laser bonding line, and the substrates of the package can be hermetically joined to one another by the at least one laser bonding line, and the laser bonding line has a height (HL) perpendicular to its bonding plane.

Claims

1. A package for encapsulating at least one functional area against an environment, the package comprising: a base substrate; a cover substrate, the base substrate together with the cover substrate defining at least a part of the package or defining the package, the at least one functional area being provided inside the package; and at least one blocking way configured for reducing a permeation between the environment and the at least one functional area.

2. The package of claim 1, further comprising at least one laser bonding line, the base substrate and the cover substrate being hermetically joined to one another by the at least one laser bonding line, the laser bonding line having a height (HL) perpendicular to a bonding plane of the at least one laser bonding line.

3. The package of claim 1, wherein at least one of: (a) the package further comprising at least one intermediate substrate disposed between the base substrate and the cover substrate; and (b) the at least one functional area comprising at least one of at least one cavity and at least one functional layer.

4. The package of claim 1, wherein the at least one blocking way comprises or is formed as a barrier layer, which at least partially encloses the at least one functional area.

5. The package of claim 4, further comprising at least one intermediate substrate disposed between the base substrate and the cover substrate, wherein at least one of: the barrier layer is disposed (a) on at least one of the base substrate, the cover substrate, and the at least one intermediate substrate, or (b) on an inner side, of at least one of the base substrate, the cover substrate, and the at least one intermediate substrate, facing the at least one functional area; and the barrier layer (a) directly encloses the at least one functional area, against at least one of the base substrate, the cover substrate, and the at least one intermediate substrate, or (b) completely encloses the at least one functional area.

6. The package of claim 1, wherein at least one of: the base substrate is made of a material of low permeability; and the cover substrate comprises a material which has a higher permeability than the base substrate.

7. The package of claim 1, wherein at least one of: the at least one blocking way comprises SiO.sub.2, Si.sub.3N.sub.4, Al.sub.2O.sub.3, or AlN; the at least one blocking way comprises a metallic material; the at least one blocking way comprises SiO.sub.xN.sub.y or AlO.sub.xN.sub.y; and the at least one blocking way comprises SiAl.sub.xN.sub.y, SiAl.sub.xO.sub.y, or SiAl.sub.xO.sub.yN.sub.z.

8. The package of claim 1, wherein the at least one blocking way has a thickness of 1 μm or less, 500 nm or less, 100 nm or less, or 50 nm or less.

9. The package of claim 1, wherein the at least one blocking way is adapted or adjusted so as to reduce a permeability between the at least one functional area and the environment by at least 30%.

10. The package of claim 1, wherein the at least one blocking way reduces a permeability for water and hydrogen.

11. The package of claim 1, further comprising at least one intermediate substrate disposed between the base substrate and the cover substrate, the package further comprising two directions of penetration, wherein the at least one blocking way reduces a permeability in the two directions of penetration through the at least one blocking way and through the base substrate, the cover substrate, and the at least one intermediate substrate of the package.

12. The package of claim 1, wherein the at least one blocking way comprises a first barrier layer and a second barrier layer; and wherein the at least one functional area is arranged between the first barrier layer and the second barrier layer.

13. The package of claim 1, further comprising at least one intermediate substrate disposed between the base substrate and the cover substrate, wherein at least one of the base substrate, the at least one intermediate substrate, and the cover substrate comprises a vitreous material, a polycrystalline material, a glass, a glass ceramic, silicon, aluminum oxide, sapphire, aluminum nitride, or a combination thereof.

14. The package of claim 1, further comprising at least one laser bonding line, the base substrate and the cover substrate being hermetically joined to one another by the at least one laser bonding line, wherein the at least one laser bonding line circumferentially surrounds the at least one functional area at a distance (DF) therefrom.

15. The package of claim 1, wherein the at least one functional area is configured for accommodating at least one accommodation item, such as an electronic circuit, a sensor, or a micro-electromechanical system (MEMS), so that the at least one accommodation item is disposed inside the package.

16. The package of claim 15, wherein the at least one accommodation item comprises a power semiconductor chip, which is selected from the group consisting of a GaN LED, a SiC power transistor, a GaAs power transistor, and a GaN power transistor.

17. The package of claim 15, wherein the at least one functional area comprises at least one cavity, wherein at least one of: the accommodation item is disposed in the at least one cavity; and the at least one cavity including a plurality of the cavity configured for accommodating at least one of the accommodation item in each respective one of the plurality of the cavity.

18. The package of claim 1, further comprising at least one intermediate substrate disposed between the base substrate and the cover substrate, the package further comprising at least one laser bonding line, wherein the laser bonding line extends into a material of at least one of the base substrate, the cover substrate, and the at least one intermediate substrate provided above the laser bonding line over a height (HL), and wherein the base substrate, the at least one intermediate substrate, and the cover substrate are joined together by being fused to one another.

19. The package of claim 1, wherein the package is transparent for a range of wavelengths at least one of at least partially and in portions thereof.

20. The package of claim 1, wherein the at least one functional area of the package is adapted for accommodating at least one accommodation item having a size of 10 mm×10 mm or less, 5 mm×5 mm or less, 2 mm×2 mm or less, or 1 mm×1 mm or less.

21. The package of claim 1, further comprising at least one intermediate substrate disposed between the base substrate and the cover substrate, wherein the base substrate, the cover substrate, and the intermediate substrate of the package are hermetically joined together by anodic bonding, bonding with an organic adhesive, glass frit bonding, or fusing using a CO.sub.2 laser.

22. A method for providing a package, wherein the package encloses at least one functional area, the method comprising the steps of: providing a base substrate and a cover substrate, the cover substrate being transparent for at least one range of wavelengths at least partially or in portions thereof and therefore being a transparent cover substrate; arranging the cover substrate on the base substrate and above the at least one functional area thereby creating at least one contact area between the base substrate and the cover substrate, so that the package has at least one contact area; hermetically sealing the at least one functional area including at least one cavity by forming at least one laser bonding line along the at least one contact area of the package; and arranging a blocking way at least one of between the at least one functional area and the cover substrate and between the at least one functional area and the base substrate.

23. The method of claim 22, further comprising, prior to the step of arranging the cover substrate on the base substrate, a step of arranging the blocking way at least one of on the cover substrate, on the at least one functional area, and on the base substrate.

24. The method of claim 22, wherein at least one of: the step of providing the cover substrate comprises providing the cover substrate already equipped with the blocking way; and the step of providing the base substrate comprises providing the base substrate already equipped with the blocking way.

25. The method of claim 22, wherein the method is employed to form the package, which is configured for encapsulating the at least one functional area against an environment, the package comprising: the base substrate; the cover substrate, the base substrate together with the cover substrate defining at least a part of the package or defining the package, the at least one functional area being provided inside the package; and at least one blocking way configured for reducing a permeation between the environment and the at least one functional area.

26. The method of claim 22, wherein a laser beam is directed around the at least one functional area to form the at least one laser bonding line so that the at least one functional area is hermetically sealed circumferentially along the at least one contact area; wherein at least one of (a) the laser beam is directed circumferentially around a plurality of times, and (b) a plurality of the laser bonding line is formed.

27. A package, comprising: at least one cavity which is at least one hermetically sealed accommodation cavity, the package being produced by a method, wherein the package encloses at least one functional area including the at least one cavity, the method comprising the steps of: providing a base substrate and a cover substrate, the cover substrate being transparent for at least one range of wavelengths at least partially or in portions thereof and therefore being a transparent cover substrate; arranging the cover substrate on the base substrate and above the at least one functional area thereby creating at least one contact area between the base substrate and the cover substrate, so that the package has at least one contact area; hermetically sealing the at least one functional area including the at least one cavity by forming at least one laser bonding line along the at least one contact area of the package; and arranging a blocking way at least one of between the at least one functional area and the cover substrate and between the at least one functional area and the base substrate.

28. A method of using a package, with at least one cavity enclosed therein, the at least one cavity being formed as at least one hermetically sealed accommodation cavity, the method comprising the steps of: providing that the package encloses at least one functional area including the at least one cavity; producing the package by a method of production, comprising the steps of: providing a base substrate and a cover substrate, the cover substrate being transparent for at least one range of wavelengths at least partially or in portions thereof and therefore being a transparent cover substrate; arranging the cover substrate on the base substrate and above the at least one functional area thereby creating at least one contact area between the base substrate and the cover substrate, so that the package has at least one contact area; hermetically sealing the at least one functional area including the at least one cavity by forming at least one laser bonding line along the at least one contact area of the package; and arranging a blocking way at least one of between the at least one functional area and the cover substrate and between the at least one functional area and the base substrate; and using the package as a medical implant or as a sensor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0072] The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

[0073] FIG. 1 shows a plan view of a package;

[0074] FIG. 2 shows a sectional side view of a package;

[0075] FIG. 3 is a detailed view of a bonding zone;

[0076] FIG. 4 is a sectional side view through the functional area of a package;

[0077] FIG. 4a is a sectional side view as in FIG. 4, but with two accommodation items;

[0078] FIG. 5 is a sectional side view through a further embodiment of a package;

[0079] FIG. 5a is a sectional side view through a further embodiment of a package;

[0080] FIG. 6 is a sectional side view through yet another embodiment of a package;

[0081] FIG. 6a is a sectional plan view as indicated in FIG. 6;

[0082] FIG. 7 is a sectional side view through yet another embodiment of a package; and

[0083] FIGS. 8A, 8B, 8C, and 8D show exemplary steps for producing a package.

[0084] Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION OF THE INVENTION

[0085] FIG. 1 shows a plan view of a package 1 according to the present invention, with the circumferential laser welding zone 8 surrounding the functional area 13. Functional area 13 may be implemented in different ways. Examples of different configurations of the functional area 13 can also be found in FIGS. 3 through 7, which show sectional views and thus permit to illustrate the vertical structure of functional area 13. The various implementations of functional area 13 can all be schematically illustrated as in FIG. 1, as they will be represented similarly in a schematic plan view. Functional area 13 is rectangular in the example of FIG. 1. Depending on the technique to produce the functional area 13 of the package, the functional area 13 can assume different shapes. For example, cavities produced by abrasive processes can be formed so as to be lens-shaped.

[0086] Functional area 13 may fulfill various tasks, for example it may be implemented as an optical receiver or it may include a technical, optical, electro-mechanical, and/or electronic component 2 which is disposed in the functional area 13. It is also possible to implement a plurality of such tasks in the functional area 13. On the upper side, the package 1 is covered by the upper substrate 5. The or at least one laser welding zone 8 extends into this upper substrate 5.

[0087] Referring to FIG. 2 which shows a first sectional view of a first embodiment of a package 1, which includes a base substrate 3 and a cover substrate 5. In other words, package 1 is made up or composed of two layers, namely base layer 3 and cover layer 5. FIG. 2 also shows the structure of laser welding line 8 in the form of a string of multiple laser pulse impact areas 16 which are placed so close to one another that the material of the base substrate 3 and of the cover substrate 5 seamlessly fuses to one another thereby hermetically sealing the functional area 13 or the cavity 12 (located behind the laser welding line 8 in this view).

[0088] FIG. 3 shows a detail of the joining area, illustrating the interface zone, i.e. the contact area 25 and the laser welding zone 8. Laser welding zone 8 is provided in the contact area 25 to bond the two substrates 3, 5 to one another.

[0089] FIG. 4 shows a sectional view of an embodiment of a package 1 along line C-D as indicated in FIG. 1. Thus, FIG. 4 shows a sectional view through functional area 13, 13a which extends inside the package 1, for example in the form of a continuous hollow space or cavity. In other words, the cavity extends from base substrate 3 into the cover substrate 5 and, for example, is in the form of a recess made in the base substrate 3 and/or in the cover substrate 5. Here, functional area 13 is formed as a recess in cover substrate 5, functional area 13a has been formed as a recess in base substrate 3, for example by an abrasive process such as a sandblasting process. In other words, the base substrate 3 has a recess 13a.

[0090] For example, the functional area 13a may include an active layer, e.g. an electrically conductive layer 34. The active layer of functional area 13a may also include a photoreceiver, for example in the form of a photovoltaic cell, so as to be adapted to generate electrical power. In this case, the package 1 can be a self-sufficient package 1.

[0091] The laser welding zone 8 provided circumferentially around the functional area 13a seals the functional area 13a all around along the lateral sides thereof. It is conceivable to leave gaps in the laser welding zone 8 so that the functional area 13a will not be sealed all around, for example in order to keep open a communication channel or space for an electrical connection, which may however also be used to establish fluid communication with the environment, for example. In other words, it might be contemplated to not seal predefined locations or points using the focused laser beam 9, but to rather achieve a hermetic seal by other ways there. Optionally, however, like shown in FIG. 1, the functional area 13, 13a is sealed along all of its sides and without any gaps, in order to ensure hermetic sealing of the functional area 13, 13a.

[0092] FIG. 4 furthermore shows a first embodiment of a blocking way 6, and this blocking way 6 is disposed on the underside of the cover substrate 5 and thus directly adjoins the functional area 13a. The blocking way of the embodiment of FIG. 4 therefore improves the permeability regarding penetration of the cover substrate. In this example, the material of the base substrate has a lower permeability than the cover substrate, so that a circumferential blocking way 6 or a blocking way 6 enclosing the functional area 13a on all sides is not necessary. It is sufficient to reduce or enhance the permeation as seen from the functional area 13a towards the cover substrate 5.

[0093] FIG. 4a shows the embodiment of FIG. 4, with two accommodation items 2 arranged in cavity 12. The accommodation items 2 may include an electronic component, for example. The two embodiments may also be combined with one another. For example, if the active layer 34 is an electrically conductive layer 34, the components 2 can be arranged on the conductive layer 34 and connected to one another.

[0094] Referring to FIG. 5 which shows a further sectional view through a package 1 within the range of functional area 13, 13a. The package 1 includes two substrate layers, namely base substrate 3 and cover substrate 5. A functional layer 13a is arranged over the entire surface area between the base substrate 3 and the cover substrate 5, and the blocking way 6 is disposed above functional layer 13a.

[0095] In fact, as the functional area 13a is implemented as a functional layer 13a here, it is therefore not protected on two sides, i.e. its circumferential narrow sides. However, this might be tolerable, depending on the application and the material of the functional layer 13a, for example if the functional layer is an optical frequency filter or an anti-reflective coating.

[0096] By contrast, FIG. 5a shows an embodiment similar to FIG. 5, here, however, with the functional layer 13a surrounded on all of its sides by the package. In this case, i.e. if the base substrate 3 has the lower permeability compared to the cover substrate 5, it is still sufficient for the blocking way 6 to be arranged above the functional layer 13a towards the cover substrate 5. The functional area 13 is in the form of a cavity 12, and the cavity 12 may contain one or a plurality of components 2 or of any accommodation items 2 as well as a medication dose 2 disposed therein.

[0097] FIG. 6 shows a further embodiment of the encapsulation solution according to the present invention, with the package including three substrate layers, namely base substrate 3, an intermediate substrate 4, and cover substrate 5. The intermediate substrate 4 may either be made up of spacer pieces, for example, or it may be a continuous substrate, i.e. a sheet with inner cutouts which is also referred to as a spacer 4.

[0098] The package of the embodiment of FIG. 6 includes a first blocking way 6 which is arranged at the upper side of cavity 12 and thus on the underside of cover substrate 5. The package 1 furthermore includes a second blocking way 6a on the bottom of cavity 12, which is disposed on the upper surface of base substrate 3. Such an arrangement of two blocking ways 6, 6a on either side of the functional area 12, 13, 13a to be enclosed can be chosen, for example, when both the base substrate 3 and the cover substrate 5 exhibit rather high permeability. In this case, both substrates can be blocked by the blocking ways 6, 6a, that is, the permeability through the respective substrate is reduced. In the example of FIG. 6, the blocking ways 6, 6a do not enclose the intermediate substrate 4, so this represents a simplified embodiment which is particularly simple and easy to implement in terms of manufacture. Depending on the given implementation of the intermediate substrate, it may be possible to omit the blocking way on the intermediate substrate, so as to dispense with any complicated application or deposition processes on the intermediate substrate 4. However, 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 blocking ways 6, 6a, since the surface area of the intermediate substrate 4 which is in contact with the functional area 12, 13, 13a is fairly small. Diffusion in particular depends on the size of the item, i.e. the size through which the gas or fluid has to flow. However, if the surface area is only small, only a small amount of fluid will pass through the intermediate substrate 4, so that, depending on the application, the blocking ways 6, 6a can be omitted on the latter. On the other hand, complete enclosure of the functional area is of course also conceivable, see FIG. 7.

[0099] FIG. 6a shows the embodiment of FIG. 6, rotated about 90°, in a sectional plan view. Thus, this sectional view cuts through the intermediate substrate 4 and the functional area 13 in the form of cavity 12.

[0100] FIG. 7 shows yet another embodiment of the present invention, again with the functional area 13 in the form of a cavity 12 which has a non-planar bottom here. For example, the cavity 12 has the shape of a lens, in the case as shown in FIG. 7 a plano-convex lens. In other words, the cavity 12 is adapted such that a convex recess 12 is hollowed out in the base substrate 3, for example by an abrasive process, so that the base substrate has a concave upper side. In this way, an optical property of the package can be created and may have impacts for the accommodation item 2 arranged inside the cavity 12 (see, for example, FIG. 4a). The package of FIG. 7 includes a blocking way 6 in the form of a barrier layer. The barrier layer can be considered or implemented as a consistent peripheral barrier layer surrounding the cavity 12, but it may also be implemented by two separate process steps, for example on the underside of cover substrate 5 in the form of a first barrier layer 6, and as a second barrier layer 6a that is applied to the upper surface of base substrate 3. So, it may include coating layers that are applied to the respective substrate. On the other hand, the blocking way 6 may also be arranged on the respective substrate, for example by being glued thereto or attached in some other way. In the example of FIG. 7, the functional area 13 is completely enclosed by the blocking way, i.e. on all sides, so that permeation is reduced in all spatial directions.

[0101] Referring to FIGS. 8A to 8D, FIGS. 8A to 8D show an embodiment of the method for producing a multitude of packages 1. What shall be explained here is the fabrication of packages 1 like those illustrated in the preceding figures, for example. It will be obvious for a person skilled in the art that it is likewise possible to produce just one single package 1 with the method, depending on process requirements.

[0102] In a step A (FIG. 8A), a shared base substrate 3 is provided, as a carrier substrate, which has a plurality of recesses 12 corresponding to the later cavities 12, and which were introduced into the base substrate 3 by an abrasive process, for example. The cavities 12 may, for example, be introduced into the base substrate 3 by a sandblasting process, that is to say hollowed out of the base substrate 3, more generally using an abrasive process. Chemical etching is also possible for introducing the cavity 12 into the base layer 3. Accommodation items 2 such as a sensor, actuator, processor, or medication can be placed in the recesses 12, for example.

[0103] A blocking way 6, 6a can be provided on the base substrate 3 as well as on the cover substrate and/or optionally on the intermediate substrate, for example in the form of a coating layer 6. For example, PVD or CVD or other thin-film coating techniques can be employed to provide at least one side of a substrate 3, 4, 5 with a thin barrier layer 6, 6a, optionally the side facing the cavity. This layer may include SiO.sub.2 in order to optionally reduce the penetration of water or water vapor. It may also include Si.sub.3N.sub.4 or Al.sub.2O.sub.3 or Al. On the other hand, the blocking way 6, 6a may also be placed on a substrate 3, 4, 5, optionally on the side facing the functional area 13, 13a. For example, a thin layer or a thin element can be placed there to be joined with the other substrates 3, 5 and optionally 4 in step C.

[0104] In a step B (FIG. 8B), a shared cover substrate 5 is attached on the base substrate 3, i.e. a cavity 12 is created for each recess, by covering the base substrate 3 with the cover substrate 5 and then hermetically joining them by step C. It is possible to accommodate a plurality of accommodation items 2 in a respective shared cavity 12.

[0105] In step C (FIG. 8C), the substrates are joined directly to one another by respective laser bonding lines 8. In this way, two closed-loop circumferential laser welding zones 8 can be established by directing the laser 9 twice around each cavity 12 along the contact surfaces 25, i.e. along the periphery of the cavities 12, but not on an exactly identical path. Rather, the laser 9 can be guided along a laterally offset path during each revolution around the cavity 12, so that two adjacent laser welding zones 8 are created. The micro-bonding zones 8 may have dimensions of, e.g., 5 μm×10 μm or smaller, or 10 μm×50 μm or smaller.

[0106] Thus, the finished substrate stack is bonded together using a laser, so that the respective accommodation cavities 12 are hermetically sealed, which means the sealing of the cavities 12 all around along contact areas 25 and the introduction of the at least one laser bonding line 8 per package 1. For this purpose, a laser unit 15 is moved over the surface of the cover substrate 5 from above the cover substrate 5, and a focused laser beam 9 is selectively directed to the zones to be joined, that is for example to the contact areas 25. Once step C of the manufacturing process has been completed, all of the cavities 12 will have been hermetically sealed. Following step C, the individual packages 1 can be separated from one another by a cutting process, so as to obtain individual separate packages 1.

[0107] In step D (FIG. 8D), the components are separated from one another along separation or cutting lines 10. Optionally, the same laser as for the laser welding in step C may be used for this purpose. However, a conventional cutting technique may also be employed, if this is advantageous.

[0108] For example, the pressure, which due to the permeability builds up in the cavity 12 towards a substrate 3, 4, 5 of the package 1 or towards the environmental conditions around the package 1, can be composed as

[00001]$Q=\Delta p\circ \left(1-e^{-\frac{\mathrm{KA}2D}{2\mathrm{DVd}+{\mathrm{KAd}}^2}t}\right)$

wherein D and K depend on the temperature, and wherein [0109] Δp is the partial pressure difference between the interior of the cavity and the environment, [0110] K is the permeability, [0111] D is the diffusion coefficient, [0112] A is the surface area of the package 1 or of the corresponding substrate 3, 4, 5 to be penetrated, in cm.sup.2, [0113] V is the volume of cavity 12, in cm.sup.3, [0114] d is the wall thickness of substrate 3, 4, 5 or package 1, in cm, [0115] t is the time, in seconds.

[0116] It will be apparent to a person skilled in the art that the embodiments described above are meant to be exemplary and that the invention is not limited thereto but may be varied in many ways without departing from the scope of the claims. Furthermore, it will be apparent that irrespective of whether disclosed in the description, the claims, the figures, or otherwise, the features individually define essential components of the invention, even if they are described together with other features. Throughout the figures, the same reference numerals designate the same features, so that a description of features that are possibly only mentioned in one or at least not in conjunction with all figures can also be transferred to such figures with regard to which the feature has not explicitly been described in the specification.

LIST OF REFERENCE NUMERALS

[0117] 1 Package, for example hermetically sealed [0118] 2 Accommodation item, functional component [0119] 3 Lower substrate, layer or wafer, base substrate, or lower cover [0120] 4 Intermediate layer [0121] 5 Upper substrate, layer or wafer, cover substrate, or upper cover [0122] 6, 6a Blocking way [0123] 8 Laser welding zone, laser bonding line [0124] 9 Focused laser beam [0125] 10 Separation or cutting line [0126] 12 Accommodation cavity [0127] 13 Functional area [0128] 13a Second functional area [0129] 14 Rim [0130] 15 Laser unit for welding and/or cutting [0131] 16 Laser pulse impact area [0132] 18 Substrate stack [0133] 21 Rim of cavity [0134] 22 Bottom of cavity [0135] 23 Upper side of cavity [0136] 25 Contact area

[0137] While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.