HERMETICALLY SEALED TRANSPARENT CAVITY AND PACKAGE FOR SAME

Abstract

A method for providing a plurality of hermetically sealed packages, including the steps of: providing at least two substrates including a first substrate and a second substrate, at least one of the at least two substrates being a transparent substrate, the two substrates being arranged directly adjoining each other or on top of one another, the transparent substrate defining a circumferential rim and an upper side of each package, the bottom of the package being defined by the second substrate, a respective contact area being defined at contact surfaces between the two substrates; sealing each functional area in a hermetically tight manner by bonding the two substrates along the contact area of each package; and dicing each package by a cutting step or a separating step, a particle jet being used to abrasively remove a material from the transparent substrate by the particle jet.

Claims

1. A hermetically sealed package, comprising: a base substrate; a cover substrate, the base substrate and the cover substrate defining at least two parts respectively of the hermetically sealed package, the at least two parts of the hermetically sealed package being joined, at least indirectly, together by at least one laser bonding line to form the hermetically sealed package; at least one functional area enclosed by the hermetically sealed package; at least one of: the cover substrate integrally defining both a lateral circumferential rim and an upper side of the package, and the base substrate being hermetically joined to the cover substrate by the at least one laser bonding line, such that the hermetically sealed package is formed by only two of the at least two parts; and at least one of the lateral circumferential rim and a plurality of rim faces of the hermetically sealed package having a flank angle relative to a surface normal of the base substrate of between 10 and 45 degrees, between 15 and 30 degrees, or between 18 and 25 degrees relative to the surface normal of the base substrate.

2. The hermetically sealed package of claim 1, wherein at least one of: the hermetically sealed package further comprises an intermediate substrate which defines the lateral circumferential rim of the hermetically sealed package; and the at least one laser bonding line encloses the at least one functional area circumferentially at a distance therefrom.

3. The hermetically sealed package of claim 2, wherein the at least one functional area comprises a hermetically sealed cavity, formed as a hermetically sealed accommodation cavity configured for accommodating an accommodation item formed as an electronic circuit, a sensor, or a micro-electromechanical system; wherein the hermetically sealed cavity has a depth in a direction of the surface normal to the cover substrate; and at least one of: wherein the depth of the hermetically sealed cavity varies over a surface area of the hermetically sealed cavity by less than 30% or less than 15% of the depth; and wherein the depth of the hermetically sealed cavity varies by more than 10%, more than 5%, or more than 2% over the surface area of the hermetically sealed cavity.

4. The hermetically sealed package of claim 2, wherein at least one of the base substrate, the cover substrate, and the intermediate substrate is transparent at least in portions thereof and at least for one range of wavelength.

5. The hermetically sealed package of claim 2, wherein at least one of: the base substrate, the cover substrate, and at least one of the intermediate substrate are welded together by the at least one laser bonding line using a laser welding process; and at least one of the base substrate, the intermediate substrate, and the cover substrate are made of a glass, glass ceramics, silicon, sapphire, or a combination of thereof.

6. The hermetically sealed package of claim 1, wherein at least one of: the at least one functional area has been introduced into the cover substrate by an abrasive process; and the hermetically sealed package is configured for having been separated from further hermetically sealed packages by an abrasive process.

7. The hermetically sealed package of claim 1, further comprising a support structure for a tissue for promoting a bond between the hermetically sealed package and the tissue; wherein the support structure is provided on the lateral circumferential rim of the hermetically sealed package; wherein at least the cover substrate comprises a vitreous material.

8. A method for providing a plurality of hermetically sealed packages, each respective hermetically sealed package defining a functional area that is enclosed by a laterally circumferential rim, a bottom, and an upper side of each respective hermetically sealed package, the method comprising the steps of: providing at least two substrates including a first substrate and a second substrate, at least one of the at least two substrates being a transparent substrate, the at least two substrates being arranged directly adjoining each other or on top of one another, the at least one transparent substrate defining the circumferential rim and the upper side of each respective hermetically sealed package, the bottom of the respective hermetically sealed package being defined by the second substrate, a respective contact area being defined at a plurality of contact surfaces between the at least two substrates; sealing each respective functional area in a hermetically tight manner by bonding the at least two substrates along the contact area of each respective hermetically sealed package; and dicing each respective hermetically sealed package by a cutting step or a separating step, a particle jet being used to abrasively remove a material from the transparent substrate by the particle jet.

9. The method of claim 8, wherein at least one of: the sealing of each respective functional area hermetically is achieved using a laser welding process; and each respective hermetically sealed package provides a cavity which is defined by the laterally circumferential rim, the bottom, and the upper side of each respective hermetically sealed package, wherein the cavity is formed as an accommodation cavity configured for accommodating an electronic circuit, a sensor, or a micro-electromechanical system.

10. The method of claim 9, wherein at least one of: hollowing out the at least one transparent substrate using the particle jet to produce the respective functional area or the respective cavity; and wherein the particle jet comprises a blasting medium that has an abrasive effect on the at least one transparent substrate, the blasting medium being silicon carbide; wherein the respective functional area is introduced into the cover substrate by the particle jet being used to abrasively remove the material; and wherein each respective one of the plurality of hermetically sealed packages is separated from other ones of the plurality of hermetically sealed packages by the particle jet being used to abrasively remove the material.

11. The method of claim 10, wherein the at least one transparent substrate has a substrate thickness; and at least one of: wherein the particle jet removes at least 30% of the substrate thickness from the at least one transparent substrate, at least 50% of the substrate thickness from the at least one transparent substrate, or at least 70% of the substrate thickness from the at least one transparent substrate to produce the respective cavity in the at least one transparent substrate; and wherein the particle jet removes at least 100 nm, at least 150 nm, at least 200 nm, or at least 250 nm of the substrate thickness of the at least one transparent substrate, and less than 300 nm of the substrate thickness for producing the respective cavity in the at least one transparent substrate.

12. The method of claim 11, wherein the particle jet is guided so as to achieve an ablation depth in a transparent material of the at least one transparent substrate, which provides a depth of the respective cavity that is as uniform as possible, wherein the depth of the respective cavity varies by less than 30% of the depth over the surface area of the respective cavity or by less than 15% of the depth over a surface area of the respective cavity, and wherein the depth of the respective cavity varies by more than 5% over the surface area of the respective cavity or by more than 2% over the surface area of the respective cavity.

13. The method of claim 12, wherein the at least two substrates are formed as a wafer stack which comprises at least two wafers or three wafers, in order to jointly produce the plurality of hermetically sealed packages from the wafer stack in a same fabrication process.

14. The method of claim 13, wherein each respective hermetically sealed package includes at least three substrates including a base substrate, an intermediate substrate, and a cover substrate, wherein at least one of: at least one of the base substrate, the intermediate substrate, and the cover substrate is made of a glass, glass ceramics, silicon, sapphire, or a combination thereof; and either at least one of the at least three substrates comprises a material different from the at least one transparent substrate, or all of the at least three substrates are made of the transparent material.

15. The method of claim 14, wherein the at least one transparent substrate comprises a first transparent substrate and a second transparent substrate, with the first transparent substrate defining the respective circumferential rim and the second transparent substrate defining the respective upper side of the respective functional area.

16. The method of claim 15, wherein the step of dicing each respective hermetically sealed package is performed using a particle jet cutting process, which abrasively removes a material from the respective hermetically sealed package such that the respective hermetically sealed package becomes separated.

17. The method of claim 16, wherein at least one of: the particle jet is directed circumferentially around the respective functional area; and the particle jet is alternately directed onto an upper side of the at least one transparent substrate and onto a lower side of the at least one transparent substrate, such that the respective hermetically sealed package is separated both from the upper side of the at least one transparent substrate and from the lower side of the at least one transparent substrate.

18. The method of claim 17, wherein the particle jet is directed so as to produce a flank angle of between 10 and 45 degrees, between 15 and 30 degrees, or between 18 and 25 degrees relative to a surface normal of the at least one transparent substrate on the hermetically sealed package.

19. The method of claim 18, wherein the particle jet is configured for being guided so as to freely define an outer contour of the hermetically sealed package.

20. The method of claim 19, wherein the at least one transparent substrate has a thickness of less than 500 μm, less than 300 μm, less than 120 μm, or less than 80 μm.

21. The method of claim 20, wherein a resist is applied to the hermetically sealed package in a plurality of areas thereof, by a lithographic process, so that the resist protects the hermetically sealed package against abrasion in the plurality of areas provided with the resist during a material ablation, for the dicing.

22. A package, comprising: a hermetically sealed accommodation cavity enclosed within the package, the package being produced by a method for providing a plurality of the package, which is a hermetically sealed package, each respective hermetically sealed package defining a functional area, which is the hermetically sealed accommodation cavity, that is enclosed by a laterally circumferential rim, a bottom, and an upper side of each respective hermetically sealed package, the method comprising the steps of: providing at least two substrates including a first substrate and a second substrate, at least one of the at least two substrates being a transparent substrate, the at least two substrates being arranged directly adjoining each other or on top of one another, the at least one transparent substrate defining the circumferential rim and the upper side of each respective hermetically sealed package, the bottom of the respective package being defined by the second substrate, a respective contact area being defined at a plurality of contact surfaces between the at least two substrates; sealing each respective functional area in a hermetically tight manner by bonding the at least two substrates along the contact area of each respective hermetically sealed package; and dicing each respective hermetically sealed package by a cutting step or a separating step, a particle jet being used for the method to abrasively remove a material from the transparent substrate by the particle jet.

23. The package of claim 22, wherein the package is configured for being used as a medical implant, a sensor, or a barometer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0075] 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:

[0076] FIG. 1a is a view of the opened accommodation cavity from above;

[0077] FIG. 1b is a perspective view of a sealed package;

[0078] FIG. 1c is a further view of an opened accommodation cavity;

[0079] FIG. 2 is a detail of the joining area of a package that includes three substrates;

[0080] FIG. 3 shows a plan view of a further embodiment of a package;

[0081] FIG. 4a is a sectional view along line A-B of an embodiment of a package as shown in FIG. 3;

[0082] FIG. 4b is a sectional view along line C-D of an embodiment of a package as shown in FIG. 3;

[0083] FIG. 5a is a sectional view along line A-B of an embodiment of a package as shown in FIG. 3;

[0084] FIG. 5b is a sectional view along line C-D of an embodiment of a package as shown in FIG. 3;

[0085] FIG. 6 is a sectional view along line C-D of an embodiment of a package as shown in FIG. 3;

[0086] FIG. 7 illustrates a method for dicing a package according to the invention;

[0087] FIG. 8 illustrates another method for producing a package according to the invention;

[0088] FIG. 9 shows a sectional view through a package that includes three substrate layers;

[0089] FIG. 10 shows a sectional view through a further embodiment of the package which includes two substrate layers;

[0090] FIG. 11 is a sectional view of a typical rim profile;

[0091] FIG. 12a shows an exemplary design of a wafer with free shaping;

[0092] FIG. 12b shows an exemplary circular package;

[0093] FIG. 12c shows an exemplary oval package;

[0094] FIG. 13a shows an exemplary design of the second wafer with free shaping;

[0095] FIG. 13b shows an exemplary shape of a circular package;

[0096] FIG. 13c shows an exemplary shape for an oval package;

[0097] FIG. 14 shows a micrograph of a transparent substrate with hollowed-out cavity and particle-blasted rim;

[0098] FIG. 15 shows a micrograph illustrating the surface roughness of a particle-blasted cavity.

[0099] 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

[0100] FIG. la shows the accommodation item 2 to be protected, embedded by an intermediate substrate 4 on a lower substrate 3. The accommodation item 2 is covered by an upper substrate 5 to close the cavity 12. Thus, the three substrates 3, 4, 5 jointly define the package 1 around the accommodation item 2, which is disposed in the cavity 12. In other words, when the upper substrate 5 is placed on the intermediate substrate 4 in the example of FIG. la, a closed accommodation cavity 12 is formed, which will have to be hermetically sealed in subsequent steps. Here, the intermediate substrate 4 can be made of a different material than the lower substrate 3 and the upper substrate 5. Optionally, the intermediate substrate 4 and the upper substrate 5 are made of the same material. The illustrated layers 3, 4, 5 can be in the form of wafer discs, so that the package is formed by stacking three wafer discs on top of one another to form a wafer stack and by joining or welding them together.

[0101] FIG. 1b shows a hermetically sealed package 1 formed in this way. This package 1 includes the lower substrate, the intermediate substrate 4, and the upper substrate 5 stacked on top of one another, with a respective contact area 25 defined between the lower substrate 3 and the intermediate substrate 4 on the one hand, and between the intermediate substrate 4 and the upper substrate 5 on the other hand. As can also be seen from FIG. 1a, the intermediate substrate layer 4 is not a continuous layer; rather the accommodation cavity 12 is defined at the level of the intermediate substrate layer.

[0102] FIG. 1c shows a further embodiment of a package 1, with the accommodation item 2 disposed on the lower substrate 3. The upper substrate 5 is designed such that it has a hollowed out interior so as to define a collar, and the collar 5a is arranged around the accommodation item 2 when the package 1 is closed. Collar 5a of substrate 5 thus defines the rim and the upper side of the cavity 12 in which the accommodation item 2 is arranged.

[0103] FIG. 2 shows a detail of the joining area, in which the laser-bonded interface zone 7 and the laser welding zone 8 can be seen. Laser welding zone 8 is located in contact area or interface 25. Environmental influences can act on the package 1 from outside the package 1, in particular at the corners 6 of the laser-welded stack 18. The laser-welded zones 8 prevent the ingress of, for example, chemical solutions into the substrate stack 18 as far as to the accommodation cavity 12 and hence to the accommodation item 2.

[0104] FIG. 3 shows a plan view of a package 1 according to the invention, with the circumferential laser welding zone 8 surrounding the functional area 13. Functional area 13 may be implemented in different ways. Exemplary embodiments of functional area 13 as well as for other options of a package can be seen in FIGS. 4a through 6. The various designs of functional area 13 can all be schematically illustrated as in FIG. 3, as they will be similar in such a plan view. Lines A-B and C-D indicate section lines along which the sectional views of FIGS. 4a to 6 will be reproduced.

[0105] The functional area may implement various tasks, for example it may include an optical receiver or a technical, electro-mechanical, and/or electronic component 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 upper substrate 5. The laser welding zone 8 extends into this upper substrate 5.

[0106] Referring to FIG. 4a, there is shown a first sectional view of a first embodiment of a package 1, which includes the base substrate 3 and the cover substrate 5. In other words, the package consists of or is composed of two layers, namely base layer 3 and cover layer 5. FIG. 4a 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.

[0107] FIG. 4b shows a sectional view of an embodiment of a package 1 taken along line C-D as indicated in FIG. 3. Cover substrate 5 has a first toughened layer 47 at its upper or outer surface, which extends over a thickness DoL into the material of the cover substrate 5. In other words, cover substrate 5 and thus the package 1 is toughened at its upper surface, i.e. it has a toughened zone 47 there, so that the package 1 is toughened in sections thereof, namely on one side.

[0108] FIG. 4b furthermore shows a section through the functional area 13, 13a which extends inside the package 1, for example as a continuous cavity or hollow space. 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. The functional area 13a may, for example, also include an active layer such as an electrically conductive layer, and the functional area 13 includes the cavity. The laser welding zone 8 provided circumferentially around the functional area 13, 13a seals the functional area 13, 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 13, 13a will not be sealed all around, for example in order to keep open a communication channel which can 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, such as by an adhesive. Optionally, the functional area 13, 13a is sealed along all of its sides and without any gaps.

[0109] Referring to FIG. 5a which shows a further embodiment in which incident laser pulses 16 create the laser welding zone 8 where the cover substrate 5 is welded or joined to the base substrate 3 along contact area 25. This embodiment has the further special feature to have the surfaces of the first substrate 3 and of the second substrate 5 toughened all around, that is to have toughened layers 47, 48, and 49.

[0110] For example, the cover substrate 5 can be dipped into a toughening bath with its upper side before being bonded to the base substrate 3, or else after having been bonded to the base substrate 3, so that the finished package 1 will be chemically toughened, i.e. will have at least one toughened surface 47 and/or at least one toughened layer. In other words, the finished package 1 is toughened at least partially or at least in sections thereof, in particular chemically toughened. With the chemical toughening, a compressive stress is established on the cover substrate 5. The first toughened layer 47 has the height DoL. The welding zone 8 has the height HL. A minimum material thickness MM remains between toughening zone 47 and welding zone 8. The entire thickness of cover substrate 5 may then be added up of HL+MM+DoL.

[0111] The functional area 13, 13a extends inwards of the toughened layers 47, 48, 49, with the toughened layer 48 being provided in an area laterally surrounding the functional area 13, 13a. Thus, in the embodiment shown in FIGS. 5a, 5b, the cover substrate 5 and also the base substrate 3 were toughened on both of its major sides, in particular chemically toughened in a toughening solution. In other words, the substrates 3, 5 were dipped into a toughening solution for being chemically toughened at their respective major sides, i.e. the respective upper and lower surfaces, for toughening the major sides.

[0112] In the embodiment shown in FIG. 5a, the package 1 is toughened on all outer surfaces, i.e. both the two opposite major surfaces have toughened layers 47 and 49, and the circumferential rim 14 of the package has a toughened layer 48, the circumferential rim 14 extending circumferentially around the package 1. In other words, in the case of a cuboid package, all four narrow sides that are found on a cuboid jointly form the rim 14. The rim 14 can also be understood or referred to as an edge 21 of the package, which extends around the cavity 12. A package 1 as shown in FIG. 5a can be obtained, for example, by immersing the finally welded package including the cover substrate 5 and the base substrate 3 in a toughening solution and in particular chemically toughening it there. The toughened layers 47, 48, 49 are thus disposed directly at the outer surfaces of the package 1. Thus, inwards of the toughened layers 47, 48, 49 there remains an area for the welding line 8, which is introduced with a spacing to the toughened layers 47, 48, 49, if possible.

[0113] FIG. 5b shows an embodiment of the package 1 in a sectional view taken along line C-D. Again, in this embodiment, the functional area 13, 13a is arranged such that it extends from the base substrate 3 into the cover substrate 5, for example in the form of a recess in the respective substrate. Such a recess 13, 13a can in particular be produced by a sandblasting process (see FIGS. 7 to 14). Welding line 8 is provided all around the recess 13, 13a, so that the recesses 13, 13a are hermetically sealed on all sides.

[0114] As in the embodiment of FIG. 5a, the package 1 is chemically toughened on all sides, in other words, it has a toughened zone 47, 48, 49 on all surfaces thereof. For example, a first toughened layer 47 is provided at the first major side which may be the upper surface of the cover substrate 5, a third toughened layer 49 is provided on a second major side which may be the lower surface of the base substrate 3, and the second toughened layer 48 is provided at the circumferential edge 21 or circumferential rim 14. The upper side 23 of the cavity is located inwards of the first toughened layer 47, the edge 21 of the cavity is located inwards of the second toughened layer 48, and the bottom 22 of the cavity is located inwards of the third toughened layer 49. Thus, the cavity or functional area 13, 13a is enclosed by toughened material 47, 48, 49 on all of its sides.

[0115] FIG. 6 shows a further embodiment of a package 1 along section line C-D, and in this example the functional area 13 or the cavity 12 is provided in the cover substrate 5. For example, only the cover substrate 5 may be hollowed out by the sandblasting process in this example, whereas the base substrate 3 does not have to be treated any further. Thus, manufacturing can be simplified since fewer parts of the package have to be processed.

[0116] In this example of FIG. 6, the cover substrate 5 has the toughening layer 47 on its major side and the toughening layer 48 on its rim 14. For example, the cover substrate 5 was dipped into a toughening solution, individually or after having been joined to the base substrate 3, with the upper surface of cover substrate 5 immersed in a toughening solution for chemical toughening to such an extent that the height of the second toughened layer 48 is achieved. In the present example, the base substrate 3 does not have any toughened zones. In this example, the lateral toughened zone 48 terminates directly at the contact area 25 between cover substrate 5 and base substrate 3. The joint along welding line 8 was made inwards of the toughening zone 48, that is in relaxed material. In other words, a first major side of the package 1 has the toughened layer 47, and a first minor side 14 has the toughened layer 48 along a section thereof. The toughened layer 48 may extend circumferentially around the package 1, for example around functional area 13. The sectional view shown here is taken along line C-D as indicated in FIG. 3, that is cutting through the functional area 13. In this embodiment, the functional area 13 is limited to the dimensions of cover substrate 5, so it does not extend into base substrate 3. The base substrate 3 is directly joined to the cover substrate 5, i.e. there is no further layer or no further substrate arranged between base substrate 3 and cover substrate 5. Functional area 13 is in the form of a cavity. The cavity may be introduced into the cover substrate 5 by a sandblasting process, for example, more generally by using an abrasive technique. Chemical etching is also possible for creating the cavity in the substrate.

[0117] Referring to FIG. 7 which shows a first embodiment of the method for producing a package according to the invention. In a step A, the substrates 3, 4, 5 and the accommodation items 2 to be accommodated are aligned. The upper substrate 5 is placed on the intermediate substrate 4 which in turn is placed on the lower substrate 3 such that a substrate stack 18 is formed. Since the intermediate substrate 4 which includes the recesses that define the cavities 12 is arranged in a sandwiched relationship, the accommodation cavities 12 will subsequently be enclosed by substrate material on all sides inside the substrate stack 18. In other words, aligning the substrates 3, 4, 5 in step A creates the enclosed nature of the cavity 12 surrounded all around by edge 21, bottom 22, and upper side 23. Optionally, the substrates may be joined to one another, in particular fixed by optical contact bonding, for example, to secure them in position.

[0118] Step B of the method illustrated in FIG. 7 shows the stack of substrates 18 arranged one above the other, with cavities 12 for holding accommodation items 2 provided in the interior thereof. Optionally, the substrate stack 18 is bonded by optical contact bonding, for example by using water on the surface and involving the generation of hydrogen bridge bonds. In this closed form, this substrate stack 18 can be fed to the joining process, in which the layers are welded together to form a firmly bonded stack 18, so that packages 1 are obtained from this substrate stack 18. Substrates 3, 4, 5 may be wafer discs, for example, so that the package is formed by the wafers enclosing the accommodation cavity 12 together as a wafer stack 18 and forming the package 1.

[0119] Step C shows the laser welding of the respective accommodation cavities 12, that is the sealing of the cavities 12 on all sides along the contact areas 25. For this purpose, a laser unit 15 is guided over the surface of the substrate stack 18 from above the substrate stack 18 and a focused laser beam 9 is selectively directed to the zones to be joined. The laser welding lines may, for example, be created in the form of a grid of intersecting lines. Drawing two or more laser welding lines in parallel can also be implemented if this proves to be advantageous for later dicing, for example, depending on the material. Once step C of the fabrication process has been completed, all of the cavities 12 will have been hermetically sealed.

[0120] At the latest after step C, optionally even earlier, the surface of substrate 5, onto which the particle jet 28 will subsequently impinge, can be treated with a protective agent 32. For example, a protective resist 32 is applied to the substrate 5 at the locations where no material should be removed. In this example, the majority of the surface would be provided with the protective resist 32 since the particle jet process is only intended to achieve the separation or dicing of the packages 1. The treatment of the surface with protective agent 32 can optionally be followed by a lithography step.

[0121] Step D shows the step of separating or cutting the substrate stack 18 for dicing the packages 1. The cutting is effected using a particle jet 28 which is provided by a particle jet generator 27. For example, the particle jet 28 can be directed along separating or cutting lines 10, and the substrate stack can be cut or separated by the abrasive effect of the particle jet 28 on the substrate. It has turned out to be advantageous if the particle jet 28 is provided as a widely fanned compressed air jet which is directed onto the surface of the package 1. Remaining areas are defined by applying resist, for example a lithography resist, to areas such as webs on the surface of the package 1 to be irradiated, i.e. to areas that must not be ablated or should be significantly less ablated by the particle jet 28. The particle jet 28 may include SiC particles. The lithography resist can be applied in a layer thickness of 17 for example, i.e. in particular in a thickness between 5 and 25 for example depending on how deep the cavity or the functional areas 13 are to be hollowed out.

[0122] Finally, step E shows the individual, hermetically sealed packages 1 with accommodation cavities 12 provided inside thereof.

[0123] Referring to FIG. 8 which shows a further embodiment of the method for producing packages 1 according to the invention. The substrate 5 as provided has already been provided with a resist 32 on the surface that will later be exposed to the particle jet 28, for example by spin-coating, and has been subjected to a lithography step. Then, in a step A, cavities can be produced in the substrate 5 using the particle jet 28 and particle jet generator 27. The particle jet 28 is directed over the substrate 5 in such a way that the cavities are removed from the substrate 5, by particles of the particle jet ablating small particles of the substrate 5 in an abrasive manner. With increasing exposure time of the substrate 5 to the particle jet 28, the penetration depth and ablation depth of the particle jet increases. In the case of a narrow particle jet 28, the latter is directed onto the areas in which a cavity 12 is to be produced. It is also possible to adjust the size of the cavity 12 through the emission range of the particle jet 28 and to set the respective depth of the respective cavity 12 through the duration of impact of the particle jet 28 on the respective cavity 12. Optionally, a large-area particle jet 28 is used in this case, and the protective agent or resist 32 is applied to the substrate 5 in such a way that the dimensions of the respective functional areas 12, 13, 13a are exposed to the abrasive process.

[0124] In other words, the method presented herein allows to produce a cavity 12 that can be freely designed in terms of its shape, geometric dimensions, and depth. For example, a cavity may even have a bump on its top, by only briefly directing the particle jet 28 onto the central area of the cavity, or in the case of resist application, some area can be protected with resist there, so that more material will be retained there than in the adjoining areas of the cavity 12 onto which the particle jet 28 is directed for a longer time duration or which are not provided with protective resist. With regard to its shape, the cavity 12 can be adapted to the requirements, so that circular, oval, polygonal, and any other desired shape of the cavity can be adjusted in addition to the typical square shape. As already mentioned above in conjunction with other embodiments, the aforementioned shapes can also be obtained by an advantageous application of resist, so that the areas to which resist is applied are not removed by the particle jet 28 but rather define remaining areas.

[0125] In step B, the two substrates 3 and 5 are aligned with one another, with the accommodation items 2 that are to be arranged inside the cavities 12 that were provided in substrate 5 already placed on the lower substrate 3.

[0126] Step C shows the substrate stack 18 superimposed, with the accommodation items 2 countersunk in the cavities 12 in alignment, so that they are surrounded on all sides by substrate material.

[0127] Step D of the method shows the hermetic sealing of the respective individual cavities 12 using the laser welding process during which a laser beam 9 is guided by laser beam generator 15 around each cavity 12 along the interface 25. In other words, the substrate materials are welded together around each cavity 12 by the joining method according to the invention using the laser 9. Subsequent to step D, a resist 32 can again be applied in order to protect the areas of the substrate from which little or no substrate material should be removed.

[0128] Step E shows the separation of the wafer 18 or dicing of the packages 1. For this purpose, the laser 9 which was also used for laser welding the accommodation cavities 12 in step D can be employed to cut the substrate, for example, or the particle jet 28 can be used for separating the packages 1.

[0129] Step F shows the separated, hermetically sealed packages 1 with accommodation cavities 12 provided inside thereof.

[0130] FIG. 9 is a sectional view through a hermetically sealed package 1. The lower substrate 3 defines the bottom 22 of cavity 12, the intermediate substrate 4 defines the edge 21 of cavity 12, an upper substrate 5 defines the upper side 23 of cavity 12. In other words, the lower substrate 3, the intermediate substrate 4, and the upper substrate 5 in the form of a substrate stack 18 conjointly enclose the accommodation cavity 12. The accommodation item 2 is disposed inside of cavity 12. In this example, all three substrates 3, 4, 5 are glass substrates, i.e. they are optically transparent. Intermediate substrate 4 may in particular be a Flexinity® wafer. The three substrates 3, 4, 5 are joined together by microbonding. The substrate stack 18 has a typical thickness of between 1 and 3 mm, the typical substrate format may assume a typical wafer format of between 1 inch and 12 inches, for example.

[0131] Vias, also known as Through Glass Vias (TGVs) may be provided in the bottom 22 of cavity 12, that is, for example, hermetic, electrically conductive connections for establishing electrical contact to the accommodation items 2. Substrate 3 may be in the form of a wafer, for example, which may contain vertical needles made of tungsten or platinum (also known as a HERMES wafer), or in the form of a glass substrate that includes laser-drilled holes, for example, which were filled with metal using a screen printing or stencil printing process, for example. A second package is located to the left of the described package.

[0132] The separation area between the two packages was cut out using a particle jet 28. When the particle jet 28 is used for the cutting process, flanks 37 will be formed on the outer surfaces of the substrate stack 18 at the separation site 35.

[0133] Referring to FIG. 10 which shows a sectional view of a further embodiment, in which a lower substrate 3 has been joined to an upper substrate 5 by a laser welding process. Two accommodation items 2 are disposed in cavity 12, and this cavity 12 was hollowed out of the upper substrate 5 using the particle jet 28. This method involving hollowing out the cavity from the upper substrate 5 using a particle jet 28 provides for a further reduction in the number of components of the package for the later intended use, i.e. for example the microsensor or bio-implant. Only two substrate layers are required in this example, whereas at least three substrate layers would typically be necessary without the use of the abrasive process.

[0134] The edges were also cut using the particle jet process, so that the flanks 37 according to the invention are formed on the lateral side of the package 1.

[0135] By way of example, FIG. 11 shows the flank angle a of the flank 37 as a result of the sandblasting process using particle jet 28. A typical flank angle α of 20° relative to the normal to the substrate surface has been found experimentally; it can be adjusted to be inclined between 10° and 45° relative to the normal to the substrate surface.

[0136] The cavities 12 can also be etched into a substrate such as a wafer 4, 5 using an appropriate solvent, although the particle jet process using the particle jet 28 has been found to be better controllable and to provide a better shape distribution of the cavities 12, since both the shape and the depth of the cavity can be adjusted via beam parameters.

[0137] In summary, the present invention provides a significant improvement of the prior art method of manufacturing packages, since fewer materials can now be used, i.e. in particular one substrate layer or one wafer less, and secondary materials such as adhesives can also be dispensed with in this way. Alternatively or cumulatively, the present invention shows the generation of flank angles on the outer edges of the package 1, which can ensure better material compatibility, i.e. in particular biocompatibility. Moreover, the edges that have flanks 37 are less prone to breaking out, so that both the resistance and likewise the robustness to mechanical impacts is increased. Sharp edges, by contrast, tend to break out more frequently during handling and use. The use of the particle jet 28 for dicing the individual packages 1 moreover allows to produce any arbitrary contours or shapes of the packages 1, such as circular, oval, polygonal shapes. This is another advantage compared to former sawing process, more generally cutting process.

[0138] FIG. 12a shows an exemplary design of an upper substrate 5, into which cavities 12 have been introduced using the particle jet 28. The individual cavities differ in terms of their shape and size. In this example, circular and oval shapes were chosen. The wafer 5 of the illustrated example has an exemplary overall diameter of 100 mm. Support points for a support which holds the wafer during the welding and/or separation step are provided in the corners indicated on the wafer.

[0139] FIG. 12b shows an example of a cavity that was introduced at the location designated by digit 1 in FIG. 12a. The cavity has an inner diameter of 6 mm, for example. Referring to FIG. 12c, a further exemplary cavity 12 is shown, which is arranged at the location designated by digit 2 in FIG. 12a.

[0140] Referring to FIG. 13a which shows a lower substrate 3 that is marked, for example by separation lines, for receiving accommodation items 2 at intended locations in the wafer. The separation lines may advantageously also be used for the laser welding process. Referring to FIG. 13b, the cavity is shown which is provided at the location indicated by digit 1 in FIG. 13a. FIG. 13c shows the cavity 12 indicated by the digit 2.

[0141] Referring to FIG. 14 which shows a micrograph of a substrate 4 in which both the cavity 12 was hollowed out using a particle jet and the separation was achieved using a particle jet 28, so that the flanks 37 according to the invention have been formed.

[0142] Referring to FIG. 15 which shows a micrograph of the cavity 12 from one side, such that the microscopically small unevenness at the upper surface of the cavity 12 becomes evident. The illustrated surface roughness of the cavity may be loaded by fine dust at the upper surface 23 thereof, for example. Within the context of the invention it was demonstrated that rinsing or wetting the surface with a liquid is already sufficient for the cavity to become optically transparent.

[0143] 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 symbols designate the same pieces of subject-matter, so that a description of pieces of subject-matter 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 piece of subject-matter has not explicitly been described in the specification.

LIST OF REFERENCE NUMERALS

[0144] 1 Hermetically sealed, chemically toughened package

[0145] 2 Accommodation item

[0146] 3 Lower substrate, lower wafer, lower cover

[0147] 4 Intermediate substrate, intermediate wafer

[0148] 5 Upper substrate, upper wafer, upper cover

[0149] 6 Corner of laser-welded stack 18

[0150] 7 Laser-welded interface zone

[0151] 8 Laser welding zone, laser bonding line

[0152] 9 Focused laser beam

[0153] 10 Separation or cutting lines

[0154] 12 Accommodation cavity

[0155] 13 Functional area

[0156] 13a Second functional area

[0157] 14 Rim

[0158] 15 Laser unit for welding and/or cutting

[0159] 16 Laser pulse impact area

[0160] 18 Stack

[0161] 21 Edge

[0162] 22 Bottom of cavity

[0163] 23 Upper side of cavity

[0164] 25 Contact area or interface

[0165] 27 Particle jet generator

[0166] 28 Particle jet

[0167] 30 Microchannel

[0168] 35 Separation site or separation zone

[0169] 37 Flank

[0170] 47 Toughened zone or first toughened layer

[0171] 48 Toughened zone or second toughened layer

[0172] 49 Toughened zone or third toughened layer

[0173] 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.