Method for producing a composite cap element, and composite cap element

Abstract

The invention relates to a method for producing a composite cap element, in particular for the encapsulation of a MEMS component, comprising: (a) providing a base substrate having at least one window formed through an opening within the base substrate, (b) providing a transparent cover substrate for transparently covering the at least one window in the base substrate, (c) wherein the base substrate and the cover substrate have different softening points and the softening point of the base substrate is lower than the softening point of the cover substrate, (d) producing a hermetic connection between the base substrate and the cover substrate in a connection region formed in a manner extending peripherally at least around the window, (e) heating the interconnected substrates at least in an edge region of the window to a temperature at which the base substrate becomes deformable and the cover substrate remains dimensionally stable, (f) displacing the dimensionally stable cover substrate in the region of the window while simultaneously deforming the deformable base substrate in a region around the window, and the invention relates to a corresponding composite cap element.

Description

[0001]Method for producing a composite cap element and composite cap element The invention relates to a method for producing a composite cap element, in particular for encapsulating a MEMS component, e.g. a MEMS mirror, and to a corresponding composite cap element. In the manufacture of microsystems, the manufacture of the housing plays a key role, as it determines the structure of the system and its protection against mechanical, chemical and other influences during processing and operation. A frequently used method is so-called wafer-level packaging (WLP), in which certain process steps are carried out before the wafer is cut. In the manufacture of housings for microsystems with moving parts, in particular micro-electromechanical systems (MEMS) or micro-opto-electromechanical systems (MOEMS), such as e.g.For accelerometers, gyroscopes, or micromirrors, cap elements with defined cavities are often used. Cap elements with optically transparent elements are used for the encapsulation of optoelectronic microsystems. These often place high demands on the surface and geometric properties, and in many cases, hermetic encapsulation is desirable. Furthermore, when manufacturing a large number of cap elements, a high degree of uniformity of the individual elements, particularly across the entire wafer surface, may be desirable. In the case of highly efficient MEMS mirrors for scanning applications, such as light projection or LiDAR or XR devices, housing geometries are often sought that reduce parasitic reflections that would otherwise lead to imaging artifacts.The present invention is based on the object of specifying a method for producing a composite cap element, in particular for the encapsulation of a MEMS component, e.g., a MEMS mirror, as well as a corresponding composite cap element, which enables high-precision manufacturing, in particular high-precision shaped, high-precision aligned and / or high-precision connected transparent elements, in particular in order to achieve high uniformity and optical quality, and furthermore enables efficient and scalable production, which in particular allows the number of process steps, in particular the post-processing steps, to be reduced. The object is achieved by the subject matter of the independent claims. Advantageous embodiments are defined in the subclaims. The invention relates to a method for producing a composite cap element, in particular for the encapsulation of a MEMS component, e.g.,a MEMS mirror. The method comprises providing a base substrate with at least one window formed by an opening within the base substrate, and providing a transparent cover substrate for transparently covering the at least one window in the base substrate. The base substrate and the cover substrate have different softening temperatures, wherein the softening temperature of the base substrate is lower than the softening temperature of the cover substrate. The method further comprises creating a, in particular hermetic, connection between the base substrate and the cover substrate in a connection region that is formed at least circumferentially around the window in order to hermetically seal the window.The method further comprises heating the interconnected substrates, at least in an edge region of the window, to a temperature at which the base substrate becomes deformable and the cover substrate remains dimensionally stable. Furthermore, the method comprises displacing the dimensionally stable cover substrate in the region of the window while simultaneously deforming the deformable base substrate in a region around the window in order to form the composite cap element. As described, the base substrate and the cover substrate have different softening temperatures. Within the context of the present invention, the softening temperature is understood to mean, in particular, a temperature above which the respective substrate becomes deformable. This is preferably understood to mean the temperature at which the respective substrate has a viscosity of 10. 7,6dPas (decipascal seconds). As described, the method described involves heating the interconnected substrates to a temperature at which the base substrate becomes deformable, but the cover substrate remains dimensionally stable. In particular, the interconnected substrates can be heated to a temperature at which the base substrate has a viscosity of less than 10 13 Pas (Pascal seconds), preferably to a temperature at which the base substrate has a viscosity of less than 10 12 Pas (Pascal seconds), particularly preferably to a temperature at which the base substrate has a viscosity of less than 10 11 Pas (Pascal seconds), more preferably to a temperature at which the base substrate has a viscosity of less than 10 9 Pas (Pascal seconds), more preferably to a temperature at which the base substrate has a viscosity of less than 10 8Pas (Pascal seconds), and wherein the covering substrate maintains a higher viscosity, in particular one of at least 10 1 Pas or 10 2Pas higher viscosity. In particular, the interconnected substrates are heated to a temperature that is above the softening temperature of the base substrate and below the softening temperature of the cover substrate. In principle, the temporal sequence of the aforementioned method steps is not fixed. However, it is preferably provided that the creation of the hermetic connection between the base substrate and the cover substrate takes place before the heating of the interconnected substrates takes place and / or before the displacement of the cover substrate in the region of the window with simultaneous deformation of the base substrate in an area around the window takes place. The hermetic connection, which is created between the base substrate and the cover substrate, can be produced in various ways.For example, the hermetic connection between the base substrate and the cover substrate can be made by laser welding and / or in such a way that the connection region surrounding the window is linear. However, the hermetic connection can also be made by anodic bonding and / or in such a way that the connection region surrounding the window is planar. As described, in the method, the window present in the base substrate is closed by the transparent cover substrate. In this case, the cover substrate is placed on the base substrate, particularly in the region of the window, with an edge-side overlap with the base substrate. In this case, one surface, in particular an annular one, of the cover substrate comes into contact with one surface, in particular annular one, of the base substrate. Preferably, at least the surfaces of the two substrates that come into contact with one another, or else the substrates as a whole, are flat orplanar. In particular, it can be provided that the base substrate is formed to be flat, in particular planar, at least in some regions and / or wherein the transparent cover substrate is formed to be flat, in particular planar, at least in some regions. By covering the window in the base substrate by the cover substrate, the transparent cover substrate thus comes into planar contact with the base substrate, preferably within a contact region around the at least one window. This contact region can have a width, in particular surrounding the window, of at least 10 µm, preferably of at least 50 µm, particularly preferably of at least 800 µm. In a preferred embodiment, it is provided that a bond quality index Q exists between the base substrate and the cover substrate, which is greater than or equal to 0.8, preferably greater than or equal to 0.9, even more preferably greater than or equal to 0.95.The bond quality index Q is Q = 1–(A–G) / A, where A denotes the area of ​​the contact region between the base substrate and the cover substrate and G denotes a good area within which the distance between the substrates is less than 5 µm, preferably less than 2 µm, even more preferably less than 1 µm, even more preferably less than 0.3 µm. Depending on whether the cover substrate already has a desired dimension when placed on the base substrate or whether a desired dimension is only created after placement, a method step can optionally be provided to adapt the dimension of the cover substrate. In particular, in some method variants the method comprises the introduction of a separation channel transversely through the cover substrate and circumferentially around the at least one window in the base substrate.The separation channel can be introduced into the cover substrate, in particular, after the hermetic connection between the base substrate and the cover substrate has been created. The separation channel can preferably run circumferentially around the connection region, in particular circumferentially around a linear connection region (e.g., in the case of laser welding), or within the connection region, in particular within a planar connection region (e.g., in the case of anodic bonding). The separation channel can be introduced into the cover substrate, for example, by means of laser ablation. Particularly with regard to MEMS mirrors, but fundamentally also independently thereof, an inclination of the cover substrate relative to the base substrate can be desirable in the final composite cap element.Against this background, the method can in particular be designed such that the displacement of the cover substrate in the region of the window with simultaneous deformation of the base substrate in an area around the window takes place such that the cover substrate assumes an inclined position relative to the base substrate in the region of the window. Such an inclined position of the cover substrate in the region of the window can in particular have an angle between 1 degree and 45 degrees, preferably an angle between 10 degrees and 25 degrees. A stamp can be used as a tool to carry out the displacement or deformation, which can act on the cover substrate or the base substrate, for example. The displacement of the cover substrate in the region of the window can thus take place by means of a stamp which exerts pressure on the cover substrate in such a way that the base substrate is deformed in an area around the window.Optionally, a counter surface can be provided opposite the stamp, against which the base substrate is pressed, e.g., to increase the bond quality index and / or strengthen the connection. The displacement of the cover substrate in the region of the window can alternatively or additionally be effected by means of a stamp, which exerts pressure on the base substrate in the region around the window, such that the base substrate is deformed in the area around the window. Optionally, a counter surface can again be provided opposite the stamp, against which the cover substrate is pressed. This counter surface can, e.g., be formed by another stamp. The stamp and / or the counter surface can each be designed as a circumferential collar, which acts on the respective substrate in particular in the region of the connection region and / or the contact region. This can, e.g.,an optically relevant area of ​​the cover substrate remains unaffected by the pressure. Furthermore, it can be provided that the stamp and / or the counter surface are heated, e.g. in order to increase the bond quality index and / or to strengthen the connection. In a further development of the invention, the cover substrate can be coated, e.g. by means of an anti-reflective coating and / or by means of certain filter layers, e.g. for RGB or NIR transmission, etc. Even in the case of such coatings, a stamp as a circumferential collar can be advantageous in order not to damage such layers. As described above, the base substrate and the cover substrate have different softening temperatures. The differing softening temperatures of the base substrate and the cover substrate can differ from one another, for example, by at least 50K, preferably by at least 100K, particularly preferably by at least 150K.Alternatively or additionally, it can also be provided that the differing softening temperatures of the base substrate and the cover substrate differ from each other in such a way that at the softening temperature of the base substrate and / or at the softening temperature of the cover substrate, the viscosity of the two substrates differs by at least 10. 0,5 Pas differs from each other, preferably by at least 10 1 Pas differs from each other, particularly preferably by at least 10 2Pas differs from each other. With regard to the materials, the base substrate can in particular comprise or consist of one of the following materials: glass, in particular borosilicate glass, soda-lime glass, alkali borosilicate glass, alkali borate glass, alkali phosphate glass, zinc borate glass, lead-containing glass, vanadate glass, zinc zinc phosphate glass. However, it is also possible for the base substrate to comprise or consist of at least one of the materials mentioned below for the cover substrate. The cover substrate can in particular comprise or consist of one of the following materials: glass, in particular aluminosilicate glass, aluminoborosilicate glass, rare earth aluminosilicate glass, alkaline earth aluminosilicate glass, glass ceramic, quartz glass, sapphire, silicon, germanium. However, it is also possible for the cover substrate to comprise or consist of at least one of the materials mentioned above for the base substrate.Some preferred embodiments are mentioned below. In some embodiments, the bond strength, particularly the shear strength at room temperature, between the base substrate and the cover substrate is preferably at least 10 MPa. In some embodiments, the thermal expansion coefficient of the base substrate is between 2 x 10-. 6 K -1 and 10 x 10 -6 K -1 In some embodiments, the thermal expansion coefficient of the cover substrate is between 2 x 10- 6 K -1 and 10 x 10 -6 K -1 In some embodiments, the absolute value of the difference in the thermal expansion coefficients of the base substrate and the cover substrate is less than 5 x 10- 6 K -1 , preferably less than 2 x 10 -6 K -1 , particularly preferably less than 1 x 10 -6 K -1. In some embodiments, the base substrate has a thickness that lies between 0.02 mm and 5 mm. In some embodiments, the cover substrate has a thickness that lies between 0.02 mm and 5 mm. In some embodiments, the at least one window in the base substrate has an area that lies between 0.5 mm x 0.5 mm and 50 mm x 50 mm. In some embodiments, the cover substrate has a surface that has a center line roughness R awhich is less than or equal to 15 nm, preferably less than or equal to 10 nm, particularly preferably less than or equal to 5 nm. In some embodiments, the cover substrate, in particular an optically relevant part of the window, has a flatness which is less than 20 µm. In some embodiments, the cover substrate has a thickness variation which is less than 5%, in particular of the average thickness over the area of ​​the window. In some embodiments, the cover substrate has a transmission for a wavelength between 300 nm and 2500 nm which is at least 90%. As described, the method comprises providing a base substrate with at least one window. In a further development, however, a plurality of windows can also be provided in the base substrate.Accordingly, in a further development, the base substrate can have a plurality of windows, each of which is formed by an opening within the base substrate, wherein the plurality of windows is preferably arranged in a regular grid. In this case, the transparent cover substrate can be provided to cover the plurality of windows simultaneously and / or a plurality of transparent cover substrates can be provided, each of which is provided to cover one or more windows. Preferably, a hermetic connection is created between the base substrate and the cover substrate around each of the windows, in particular by creating a linear connection region around each window, in particular by laser welding, and / or by creating a planar, e.g. full-surface, connection region, in particular by anodic bonding, between the substrates.The interconnected substrates are also preferably heated at least in the region of each window, e.g., successively in the region of a respective window or particularly preferably simultaneously. In addition, the cover substrates are preferably displaced in the region of each window while simultaneously deforming the base substrate, e.g., successively in the region of a respective window or particularly preferably all at the same time, wherein, for example, a plurality of stamps can be used for this purpose, which in particular define a uniform inclination for the plurality of displacements or deformations. The invention further relates to a method for producing an encapsulated MEMS component, comprising providing a carrier substrate with a MEMS component, e.g.,a MEMS mirror, and further comprising the application and, in particular hermetically, connection of a composite cap element, in particular a composite cap element which is produced as described above, to the carrier substrate, such that the MEMS component is, in particular hermetically, enclosed between the carrier substrate and the composite cap element. The invention further relates to a composite cap element for the encapsulation of a MEMS component, e.g. a MEMS mirror, produced or producible according to the method as described above. The invention further relates to a composite cap element for the encapsulation of a MEMS component, e.g. a MEMS mirror. The composite cap element comprises a base substrate with at least one window, which is formed by an opening within the base substrate, and a transparent cover substrate, which transparently covers the at least one window in the base substrate.The composite cap element further comprises a, in particular hermetic, connection between the base substrate and the cover substrate in a connection region which is formed at least circumferentially around the window, such that the window is, in particular, hermetically sealed. The base substrate has a deformation in a region around the window such that the cover substrate is positioned offset relative to the base substrate. Furthermore, the base substrate and the cover substrate have different softening temperatures, wherein the softening temperature of the base substrate is lower than the softening temperature of the cover substrate. The hermetic connection between the base substrate and the cover substrate can be linear, in particular as a laser weld seam. The hermetic connection between the base substrate and the cover substrate can be planar, in particular as an anodic bond.The base substrate is flat, in particular planar, at least in some regions. Furthermore, the transparent cover substrate is flat, in particular planar, at least in some regions. The transparent cover substrate is preferably in flat contact with the base substrate within a contact region around the at least one window in order to transparently cover the at least one window in the base substrate. The contact region can have a width, in particular surrounding the window, of at least 10 µm, preferably of at least 50 µm, particularly preferably of at least 800 µm. Between the base substrate and the cover substrate there is in particular a bond quality index Q which is greater than or equal to 0.8, preferably greater than or equal to 0.9, even more preferably greater than or equal to 0.95.The bond quality index Q is Q = 1–(A–G) / A, where A denotes the area of ​​the contact region between the base substrate and the cover substrate, and G denotes a good area within which the distance between the substrates is less than 5 µm, preferably less than 2 µm, even more preferably less than 1 µm, even more preferably less than 0.3 µm. The composite cap element can further comprise a separation channel which runs transversely through the cover substrate and circumferentially around the at least one window. The separation channel preferably runs circumferentially around the connection region, in particular circumferentially around the linear connection region, or within the connection region, in particular within the planar connection region.The deformation of the base substrate is preferably designed such that the cover substrate has an inclination relative to the base substrate in the region of the window, wherein the inclination of the cover substrate in the region of the window in particular has an angle between 1 degree and 45 degrees, preferably an angle between 10 degrees and 25 degrees. The differing softening temperatures of the base substrate and the cover substrate can differ from each other by at least 50K, preferably by at least 100K, particularly preferably by at least 150K. The base substrate can in particular comprise or consist of one of the following materials: glass, in particular borosilicate glass, soda-lime glass, alkali borosilicate glass, alkali borate glass, alkali phosphate glass, zinc borate glass, lead-containing glass, vanadate glass, zinc zinc phosphate glass.The cover substrate may in particular comprise or consist of one of the following materials: glass, in particular aluminosilicate glass, aluminoborosilicate glass, rare earth aluminosilicate glass, alkaline earth aluminosilicate glass, glass ceramic, quartz glass, sapphire, silicon, germanium. The bond strength, in particular the shear strength at room temperature, between the base substrate and the cover substrate may be at least 10 MPa. The thermal expansion coefficient of the base substrate may be between 2 x 10 -6 K -1 and 10 x 10 -6 K -1 The thermal expansion coefficient of the cover substrate can be between 2 x 10 -6 K -1 and 10 x 10 -6 K -1 The absolute value of the difference in the thermal expansion coefficients of the base substrate and the cover substrate may be less than 5 x 10 -6 K -1 , preferably less than 2 x 10 -6 K -1 , particularly preferably less than 1 x 10 -6K -1 The base substrate may have a thickness between 0.02 mm and 5 mm. The cover substrate may have a thickness between 0.02 mm and 5 mm. The at least one window in the base substrate may have an area between 0.5 mm x 0.5 mm and 50 mm x 50 mm. The cover substrate may have a surface having a mean roughness R awhich is less than or equal to 15 nm, preferably less than or equal to 10 nm, particularly preferably less than or equal to 5 nm. The cover substrate, in particular an optically relevant part of the window, can have a flatness which is less than 20 µm. The cover substrate can have a thickness variation which is less than 5%, in particular of the average thickness over the area of ​​the window. The cover substrate can have a transmission of at least 90% for a wavelength between 300 nm and 2500 nm. The base substrate can have a plurality of windows, each of which is formed by an opening within the base substrate and wherein the plurality of windows are preferably arranged in a regular grid. The transparent cover substrate can cover the plurality of windows simultaneously and / or a plurality of transparent cover substrates can be included, each of which covers one or more windows.Preferably, a hermetic connection between the base substrate and the cover substrate is included circumferentially around each of the windows. The base substrate preferably has a deformation in a region around each of the windows such that the cover substrates are positioned offset relative to the base substrate. The invention further relates to an encapsulated MEMS component comprising a carrier substrate with a MEMS component, e.g. a MEMS mirror, and a composite cap element, in particular according to the above description, which is applied to the carrier substrate and, in particular, hermetically connected such that the MEMS component is, in particular, hermetically enclosed between the carrier substrate and the composite cap element. The invention is explained in more detail below with reference to figures. Therein: Fig. 1, 2 show a schematic plan view of a base substrate with a window and a cover substrate, Fig.3-5 show a schematic sectional view of a first exemplary sequence of method steps for producing a composite cap element, Fig. 6-9 show a schematic sectional view of a second exemplary sequence of method steps for producing a composite cap element, Fig. 10-13 show a schematic sectional view of a third exemplary sequence of method steps for producing a composite cap element, Fig. 14-17 show a schematic sectional view of a fourth exemplary sequence of method steps for producing a composite cap element, Fig. 18, 19 show a schematic sectional view of alternative method steps for deformation with a stamp and a counter surface, Fig. 20, 21 show a schematic plan view of a base substrate with a plurality of windows and one or more cover substrates for covering the windows. Fig. 1, 2 each show a base substrate 100 with a window 110 and a cover substrate 200 which is placed onto the base substrate.In Fig. 1, the cover substrate 200 is already adapted to the geometry of the window 110. However, the cover substrate 200 is somewhat larger than the window 110 located in the base substrate 110, so that the window 110 is completely covered and an overlap of the two substrates is created around the window 110, within which overlap the substrates can be connected in a next step. In Fig. 2, the cover substrate 200 has a geometry like the base substrate 100 and thus covers it over its entire surface. Figs. 3-5 show a first exemplary sequence of method steps for producing a composite cap element. In the method step illustrated in Fig. 3, a connection 310 is produced between the base substrate 100 and the cover substrate 200 brought into contact with it, for example as shown in Fig. 1, in this case for example by laser welding.The connection 310 is formed circumferentially around the window 110 such that the window 110 is hermetically sealed by the cover substrate 200. In the method step illustrated in Fig. 4, the interconnected substrates are or will be heated, achieving a temperature at which the base substrate 100 becomes deformable, but the cover substrate 200 remains dimensionally stable. Hot forming is carried out using a stamp 500, which has a stamping surface inclined relative to the base substrate 100. Pressure is exerted on the deformable base substrate 100 in a region surrounding the window 110, which encompasses the connection 310, in order to deform the edge region of the base substrate 110 surrounding the window 110 and, at the same time, to displace and incline the cover substrate 200 attached there relative to the base substrate 100. Fig.5 shows the composite cap element thus obtained with a contact region 400 surrounding the window 110, comprising the linear connection 310, within which the two substrates are in contact with each other and preferably have a bond quality index Q that is greater than or equal to 0.8. Figs. 6-9 show a second exemplary sequence of method steps for producing a composite cap element, this sequence being similar to the first sequence in some aspects and differing therefrom in other aspects. In the method step shown in Fig. 6, a hermetic connection 310 surrounding the window 110 is produced between the substrates between a base substrate 100 and a cover substrate 200 applied over the entire surface, for example according to Fig. 2, in this example again by means of laser welding.In the method step illustrated in Fig. 7, a separation channel 250 is inserted transversely through the cover substrate 200 and circumferentially around the window 110, for example, by means of laser ablation. The separation channel 250 runs circumferentially around the linear connection 310. This adapts the geometry of the cover substrate 200 to the geometry of the window 110, and an excess outer portion of the cover substrate 200 can be discarded. In the method step illustrated in Fig. 8, the interconnected substrates are or will be heated again to perform hot forming using the stamp 500. In this example, pressure is exerted by the stamp 500 on the dimensionally stable cover substrate 200 to displace and tilt the cover substrate 200, thereby pulling out an edge region of the deformable base substrate 100 surrounding the window 110 and thereby forming the composite cap element shown in Fig. 9. Fig.10-13 show a third exemplary sequence of method steps for producing a composite cap element, wherein this sequence is similar to the first or second sequence in some aspects and differs therefrom in other aspects. In the method step shown in Fig. 10, a first hermetic connection 310 is produced between a base substrate 100 and a cover substrate 200 applied over the entire surface, for example according to Fig. 2, which runs around the window 110. In addition, in this example, a second hermetic connection 310 is produced between the substrates, wherein both connections 310 are produced as linear connections by means of laser welding. The second connection runs around the first connection. In the method step shown in Fig.In the method step illustrated in Fig. 11, a separating channel 250 is inserted transversely through the cover substrate 200 and circumferentially around the window 110, wherein the separating channel is introduced between the first and second circumferential connections 310. This defines the geometry of the cover substrate 200 for the window 110 to be pulled out, and at the same time, an outer part of the cover substrate 200 is connected to the base substrate. In the method step illustrated in Fig. 12, the substrates are or will be heated again, and the inner part of the dimensionally stable cover substrate 200, which is insulated from the outer part by the separating line 250, is displaced by means of the stamp 500 in order to produce the composite cap element shown in Fig. 13. Figures 14-17 show a fourth exemplary sequence of process steps for producing a composite cap element, this sequence being similar in some aspects to the first, second and third embodiments, respectively.third sequence and deviates therefrom in other aspects. In the method step shown in Fig. 14, a planar connection 310 is produced between a base substrate 100 and a cover substrate 200 applied over the entire surface, for example according to Fig. 2, in this example by means of anodic bonding. The connection 310 is produced over the entire surface in this example, thus in particular also in a contact region 400 of the two substrates surrounding the window 110. In the method step shown in Fig. 15, a separation channel 250 is inserted transversely through the cover substrate 200 and surrounding the window 110, wherein the separation channel runs through the planar connection 310. The separation channel 250 extends in particular also transversely to the substrate plane through the region of the planar connection 310.This defines, on the one hand, an inner part of the cover substrate 200 covering the window 110 and, on the other hand, an outer part separated therefrom by the parting line 250, which, like the inner part, is connected to the base substrate by the connection 310. In the method step shown in Fig. 16, the substrates are or will be heated again and the inner part of the dimensionally stable cover substrate 200 is displaced by means of the stamp 500 in order to produce the composite cap element shown in Fig. 17. Figs. 18 and 19 show a further development, in particular with regard to the displacement and deformation step. The stamp 500 is designed, for example, as a circumferential collar which is designed to exert the desired pressure on the circumferential contact region 400 between the substrates. This can, for example, improve the bond quality index.In addition, particularly in the case where pressure is exerted on the cover substrate 200, as shown in Fig. 19, an inner, particularly optically relevant, part of the cover substrate 200 can be displaced without contact with the stamp 500. As can also be seen, a counter surface 550 can be provided opposite the stamp 500, against which the contact area 400 between the two substrates is pressed. In this example, the counter surface 550 is also designed as a circumferential collar. However, this is merely an example. It is of course possible for the stamp 500 and / or the counter surface 550 to have a different shape. Figs. 20 and 21 each show a base substrate 100, similar to Figs. 1 and 2, but with a plurality of windows 110, and one or more cover substrates 200 for covering the windows.The process sequences described above can also be carried out starting from such substrates with a plurality of windows, in particular simultaneously.

Claims

Claim 1. A method for producing a composite cap element, in particular for encapsulating a MEMS component, e.g., a MEMS mirror, comprising: providing a base substrate (100) with at least one window (110) formed by an opening within the base substrate; providing a transparent cover substrate (200) for transparently covering the at least one window (110) in the base substrate (100), wherein the base substrate and the cover substrate have different softening temperatures and the softening temperature of the base substrate is lower than the softening temperature of the cover substrate; creating a connection (310), in particular a hermetic connection, between the base substrate (100) and the cover substrate (200) in a connection area (300) which is formed at least around the window (110) in order to hermetically seal the window.Heating the interconnected substrates, at least in an edge region of the window, to a temperature at which the base substrate becomes deformable and the cover substrate remains dimensionally stable, in particular to a temperature which is above the softening temperature of the base substrate and below the softening temperature of the cover substrate; shifting the dimensionally stable cover substrate in the area of ​​the window while simultaneously deforming the deformable base substrate in an area around the window in order to form the composite cap element.

2. A method according to the preceding claim, wherein the hermetic connection (310) between the base substrate (100) and the cover substrate (200) is created before the connected substrates are heated and / or before the cover substrate (200) is moved in the area of ​​the window (110) while the base substrate (100) is simultaneously deformed in an area around the window.

3. A method according to any one of the preceding claims, wherein the hermetic connection (310) between the base substrate and the cover substrate is created by laser welding, in particular such that the connection area surrounding the window is linear, and / or wherein the hermetic connection (310) between the base substrate and the cover substrate is created by anodic bonding, in particular such that the connection area surrounding the window is planar. 4.Method according to one of the preceding claims, wherein the base substrate is at least partially planar, in particular planar, and / or wherein the transparent cover substrate is at least partially planar, in particular planar, and / or wherein the transparent cover substrate is brought into planar contact with the base substrate within a contact area (400) around the at least one window in order to transparently cover the at least one window in the base substrate, and. wherein the contact area (400) has a width of at least 10 µm, preferably at least 50 µm, and particularly preferably at least 800 µm, particularly around the window, and wherein the bond between the base substrate and the cover substrate has a bond quality index Q of greater than or equal to 0.8, preferably greater than or equal to 0.9, and more preferably greater than or equal to 0.95, wherein the bond quality index Q is defined as Q = 1–(A–G) / A, where A denotes the area of ​​the contact area between the base substrate and the cover substrate, and G denotes a good area within which the distance between the substrates is less than 5 µm, preferably less than 2 µm, more preferably less than 1 µm, and more preferably less than 0.3 µm. 5.A method according to one of the preceding claims, further comprising: introducing a separation channel (250) transversely through the cover substrate (200) and circumferentially around the at least one window, wherein the separation channel (250) is introduced in particular into the cover substrate after the hermetic connection between the base substrate and the cover substrate has been created, and wherein the separation channel (250) preferably extends circumferentially around the connection area, in particular around the linear connection area, or extends within the connection area, in particular within the planar connection area, and. wherein the separation channel (250) is preferably introduced into the cover substrate by means of laser ablation.

6. Method according to one of the preceding claims, wherein the displacement of the cover substrate in the area of ​​the window is carried out with simultaneous deformation of the base substrate in an area around the window, such that the cover substrate assumes an inclination relative to the base substrate in the area of ​​the window, and wherein the inclination of the cover substrate in the area of ​​the window has in particular an angle between 1 degree and 45 degrees, preferably an angle between 10 degrees and 25 degrees. 7.A method according to one of the preceding claims, wherein the displacement of the cover substrate in the area of ​​the window is carried out by means of a punch (500) which exerts pressure on the cover substrate such that the base substrate is deformed in an area around the window, wherein optionally a counter surface (550) is provided opposite the punch (500) against which the base substrate (100) is pressed, and / or wherein the displacement of the cover substrate in the area of ​​the window is carried out by means of a punch (500) which exerts pressure on the base substrate in the area around the window such that the base substrate is deformed in the area around the window, wherein optionally a counter surface (550) is provided opposite the punch (500) against which the cover substrate (200) is pressed, and / or. wherein the plunger (500) and / or the counter surface (550) is designed as a circumferential collar which acts on the respective substrate in the area of ​​the connection region (300) and / or the contact region (400), and / or wherein the plunger (500) and / or the counter surface (550) are heated.

8. Method according to one of the preceding claims, wherein the different softening temperatures of the base substrate and the cover substrate differ from each other by at least 50 K, preferably by at least 100 K, particularly preferably by at least 150 K, and / or wherein the different softening temperatures of the base substrate and the cover substrate differ from each other such that at the softening temperature of the base substrate and / or at the softening temperature of the cover substrate, the viscosity of the two substrates differs by at least 10 0,5 Pas differs from each other, preferably by at least 10 1Pas differs from each other, especially preferably by at least 10 2 Pas differs from each other, wherein the base substrate in particular comprises or consists of one of the following materials: glass, in particular borosilicate glass, soda-lime glass, alkali borosilicate glass, alkali borate glass, alkali phosphate glass, zinc borate glass, leaded glass, vanadate glass, zinc phosphate glass, wherein the cover substrate in particular comprises or consists of one of the following materials: Glass, in particular aluminosilicate glass, aluminoborosilicate glass, rare earth aluminosilicate glass, alkaline earth aluminosilicate glass, glass ceramics, quartz glass, sapphire, silicon, germanium.

9. Method according to any one of the preceding claims, wherein the bond strength, in particular the shear strength at room temperature, between the base substrate and the cover substrate is at least 10 MPa, wherein the coefficient of thermal expansion of the base substrate is between 2 x 10 -6 K -1 and 10 x 10 -6 K-1 lies, and / or wherein the coefficient of thermal expansion of the covering substrate is between 2 x 10 -6 K -1 and 10 x 10 -6 K -1 lies, and / or where the absolute value of the difference in the thermal expansion coefficients of the base substrate and the cover substrate is less than 5 x 10 -6 K -1 , preferably less than 2 x 10- 6 K -1 , especially preferably less than 1 x 10 -6 K -1 , and / or wherein the base substrate has a thickness between 0.02 mm and 5 mm, and / or wherein the cover substrate has a thickness between 0.02 mm and 5 mm, and / or wherein the at least one window in the base substrate has an area between 0.5 mm x 0.5 mm and 50 mm x 50 mm.

10. Method according to any one of the preceding claims, wherein the cover substrate has a surface having a mean roughness R a exhibits which is less than or equal to 15 nm, preferably less than or equal to 10 nm, particularly preferably less than or equal to 5 nm, and / or wherein the covering substrate, in particular an optically relevant part of the window, has a flatness which is less than 20 µm, and / or wherein the covering substrate has a thickness variation which is less than 5%, in particular of the mean thickness over the area of ​​the window, and / or wherein the covering substrate has a transmission of at least 90% for a wavelength between 300 nm and 2500 nm. 11.A method according to one of the preceding claims, wherein the base substrate has a plurality of windows, each formed by an opening within the base substrate, and wherein the plurality of windows are preferably arranged in a regular grid, and wherein the transparent cover substrate is provided for simultaneously covering the plurality of windows, or wherein a plurality of transparent cover substrates are provided, each intended for covering one or more windows, and wherein preferably a hermetic connection is created around each of the windows between the base substrate and the cover substrate, in particular by creating a linear connection area around each window, especially by laser welding, and / or by creating an area-shaped, e.g., full-surface, connection area, in particular by Anodic bonding is generated between the substrates, wherein the interconnected substrates are preferably heated at least in the region of each window, e.g., successively in the region of each window or simultaneously all together, and wherein the cover substrates are preferably displaced in the region of each window while simultaneously deforming the base substrate, e.g., successively in the region of each window or all simultaneously.

12. Method for manufacturing an encapsulated MEMS component, comprising: providing a carrier substrate with a MEMS component, e.g., a MEMS mirror, and applying and hermetically bonding a composite cap element, producible or manufactured according to any one of the preceding claims, onto the carrier substrate, such that the MEMS component is hermetically enclosed between the carrier substrate and the composite cap element.

13. Composite cap element for encapsulating a MEMS component, e.g.,a MEMS mirror, manufactured or manufactureable according to any of the preceding claims.

14. Composite cap element for encapsulating a MEMS component, e.g., a MEMS mirror, comprising: a base substrate (100) with at least one window (110) formed by an opening within the base substrate (100), a transparent cover substrate (200) which covers the at least one window (110) in the base substrate. (100) transparently covers, a hermetic connection (310) between the base substrate (100) and the cover substrate (200) in a connection area (300) which is formed at least around the window, such that the window is hermetically sealed, wherein the base substrate has a deformation (150) in an area around the window, such that the cover substrate is positioned displaced relative to the base substrate, and wherein the base substrate and the cover substrate have different softening temperatures, the softening temperature of the base substrate being lower than the softening temperature of the cover substrate. 15.Composite cap element according to the preceding claim, wherein the hermetic connection (310) between the base substrate and the cover substrate is linear, in particular as a laser weld, and / or wherein the hermetic connection (310) between the base substrate and the cover substrate is planar, in particular as an anodic bond.

16. Composite cap element according to any one of the preceding claims, wherein the base substrate is planar at least in certain areas, and / or wherein the transparent cover substrate is planar at least in certain areas, and / or wherein the transparent cover substrate is within. a contact area (400) around the at least one window is in planar contact with the base substrate in order to transparently cover the at least one window in the base substrate, and wherein the contact area (400) has a width, in particular around the window, of at least 10 µm, preferably of at least 50 µm, particularly preferably of at least 800 µm, and wherein the bond between the base substrate and the covering substrate has in particular a bond quality index Q which is greater than or equal to 0.8, preferably greater than or equal to 0.9, more preferably greater than or equal to 0.95, wherein the bond quality index Q is defined as Q = 1–(A–G) / A, where A denotes the area of ​​the contact area between the base substrate and the covering substrate and G denotes a good area within which the distance between the substrates is less than 5 µm, preferably less than 2 µm, more preferably preferably smaller than 1 µm,preferably smaller than 0.3 µm.

17. Composite cap element according to one of the preceding claims, further comprising: A separation channel (250) transversely through the cover substrate (200) and circumferentially around the at least one window, wherein the separation channel (250) preferably extends circumferentially around the connection area, in particular around the linear connection area, or extends within the connection area, in particular within the planar connection area.

18. Composite cap element according to one of the preceding claims, wherein the deformation (150) of the base substrate is configured such that the cover substrate has an inclination relative to the base substrate in the area of ​​the window, and wherein the inclination of the cover substrate in the area of ​​the window has, in particular, an angle between 1 degree and 45 degrees, preferably an angle between 10 degrees and 25 degrees. 19.Composite cap element according to one of the preceding claims, wherein the different softening temperatures of the base substrate and the cover substrate differ from each other by at least 50 K, preferably by at least 100 K, and particularly preferably by at least 150 K, wherein the base substrate in particular comprises or consists of one of the following materials: glass, in particular borosilicate glass, soda-lime glass, alkali borosilicate glass, alkali borate glass, alkali phosphate glass, zinc borate glass, leaded glass, vanadate glass, zinc phosphate glass, wherein the cover substrate in particular comprises or consists of one of the following materials: glass, in particular aluminosilicate glass, aluminoborosilicate glass, rare earth aluminosilicate glass, alkaline earth aluminosilicate glass, glass ceramic, quartz glass, sapphire, silicon, germanium.

20. Composite cap element according to one of the preceding claims, wherein the bond strength, in particular the shear strength at room temperature, between the base substrate and the cover substrate is at least 10 MPa, wherein the coefficient of thermal expansion of the base substrate is between 2 x 10 -6 K -1 and 10 x 10 -6 K -1 lies, and / or wherein the coefficient of thermal expansion of the covering substrate is between 2 x 10 -6 K -1 and 10 x 10 -6 K -1 lies, and / or where the absolute value of the difference in the thermal expansion coefficients of the base substrate and the cover substrate is less than 5 x 10 -6 K -1 , preferably less than 2 x 10- 6 K -1 , especially preferably less than 1 x 10 -6 K -1, and / or wherein the base substrate has a thickness between 0.02 mm and 5 mm, and / or wherein the cover substrate has a thickness between 0.02 mm and 5 mm, and / or wherein the at least one window in the base substrate has an area between 0.5 mm x 0.5 mm and 50 mm x 50 mm.

21. Composite cap element according to one of the preceding claims, wherein the cover substrate has a surface having a mean roughness value R a exhibits a thickness of less than or equal to 15 nm, preferably less than or equal to 10 nm, particularly preferably less than or equal to 5 nm, and / or wherein the covering substrate, in particular an optically relevant part of the window, has a flatness of less than 20 µm, and / or wherein the covering substrate has a thickness variation of less than 5%, in particular of the mean thickness over the area of ​​the window, and / or wherein the covering substrate has a transmission of at least 90% for a wavelength between 300 nm and 2500 nm. 22.Composite cap element according to one of the preceding claims, wherein the base substrate has a plurality of windows, each formed by an opening within the base substrate, and wherein the plurality of windows are preferably arranged in a regular grid, and wherein the transparent cover substrate covers the plurality of windows simultaneously, or wherein a plurality of transparent cover substrates are comprised, each covering one or more windows, and wherein preferably a hermetic connection between the base substrate and the cover substrate is comprised circumferentially around each of the windows, and wherein the base substrate preferably has a deformation (150) in a region around each window such that the cover substrates are positioned displaced relative to the base substrate.

23. Encapsulated MEMS component comprising: a carrier substrate with a MEMS component, e.g. a MEMS mirror, and a composite cap element according to one of the preceding claims, which is applied to the support substrate and hermetically connected, such that the MEMS component is hermetically enclosed between the support substrate and the composite cap element.

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