Structures for reducing and avoiding stress and strain during silicon processing by laser melting

Abstract

Method for producing a micromechanical component (1) with a substrate (3) and with a cap (7) connected to the substrate (3) and enclosing a first cavity (5) with the substrate (3), wherein a first pressure prevails in the first cavity (5) and a first gas mixture with a first chemical composition is enclosed, wherein -- in a first method step (101), an access opening (11) connecting the first cavity (5) to an environment (9) of the micromechanical component (1) is formed in the substrate (3) or in the cap (7), wherein -- in a second method step (102), the first pressure and / or the first chemical composition in the first cavern (5) is adjusted, wherein -- in a third method step (103), the access opening (11) is closed by introducing energy or heat into an absorbing part (21) of the substrate (3) or the cap (7) with the aid of a laser, characterized in that -- in a fourth method step (104), a recess (17) and a further recess (17) are formed in a surface (19) of the substrate (3) or of the cap (7) facing away from the first cavity (5) in the region of the access opening (11) in order to reduce local stresses occurring when the access opening (11) is closed, the fourth method step (104) being carried out before the second method step (102).

Description

State of the art

[0001] The invention is based on a method according to the preamble of claim 1.

[0002] Such a method is known from WO 2015 / 120939 A1. If a specific internal pressure is desired in a cavity of a micromechanical component or if a gas mixture with a specific chemical composition is to be enclosed in the cavity, the internal pressure or the chemical composition is often adjusted during the capping of the micromechanical component or during the bonding process between a substrate wafer and a cap wafer. During capping, for example, a cap is connected to a substrate, whereby the cap and the substrate together enclose the cavity. By adjusting the atmosphere or the pressure and / or the chemical composition of the gas mixture present in the environment during capping, the specific internal pressure and / or the specific chemical composition in the cavity can be adjusted.

[0003] The method known from WO 2015 / 120939 A1 allows for the targeted adjustment of an internal pressure in a cavity of a micromechanical component. This method makes it possible, in particular, to produce a micromechanical component with a first cavity, wherein a first pressure and a first chemical composition can be adjusted in the first cavity, which differ from a second pressure and a second chemical composition at the time of encapsulation.

[0004] In the method for the targeted adjustment of internal pressure in a cavity of a micromechanical component according to WO 2015 / 120939 A1, a narrow access channel to the cavity is created in the cap or cap wafer, or in the substrate or sensor wafer. The cavity is then flooded with the desired gas and the desired internal pressure via the access channel. Finally, the area around the access channel is locally heated using a laser; the substrate material liquefies locally and, upon solidification, hermetically seals the access channel. Further objects are known from the following publications: DE 10 2014 202 801 A1, US 2013 / 0 265 701 A1, US 2013 / 0 074 596 A1, DE 10 2014 210 006 A1, US 2014 / 0217 521 A1. Disclosure of the invention

[0005] It is an object of the present invention to provide a method for producing a micromechanical component that is mechanically robust and has a long service life compared to the prior art, in a simple and cost-effective manner compared to the prior art. Furthermore, it is an object of the present invention to provide a micromechanical component that is compact, mechanically robust and has a long service life compared to the prior art. According to the invention, this applies in particular to a micromechanical component with a (first) cavity. With the method according to the invention and the micromechanical component according to the invention, it is also possible to realize a micromechanical component in which a first pressure and a first chemical composition can be set in the first cavity and a second pressure and a second chemical composition can be set in a second cavity.For example, such a method is provided for the production of micromechanical components for which it is advantageous if a first pressure is enclosed in a first cavity and a second pressure is enclosed in a second cavity, whereby the first pressure should be different from the second pressure. This is the case, for example, if a first sensor unit for measuring angular rate and a second sensor unit for measuring acceleration are to be integrated into a micromechanical component.

[0006] The object is achieved by a method according to claim 1.

[0007] This provides a simple and cost-effective method for producing a micromechanical component with which local stresses occurring in the region of the access opening can be reduced and distributed. Furthermore, the method according to the invention makes it possible to significantly reduce or avoid stress peaks that conventionally occur. In particular, the recess makes it possible to reduce mechanical stresses through elastic deformation. Compared to a method without forming the recess, the method according to the invention has the advantage, for example, that a material region that has solidified after the third method step and / or the interfaces between the solidified material region and the remaining substrate or the remaining cap and / or the area around the interfaces are less susceptible to crack formation, since locally occurring stresses can be effectively reduced or distributed with the help of the recess.can be distributed over a larger area of ​​material. Thus, with the method according to the invention, it is less critical if the solidified material area is unintentionally touched, for example in the production flow, since the solidified material area is less of a cause and starting point for cracks due to reduced local stresses. Also, with the method according to the invention, it is less problematic if the substrate material is only heated locally and the heated material contracts relative to its surroundings both during solidification and cooling. The fact that very high tensile stress can therefore arise in the sealing area is also less of a problem, since the reduction of local mechanical stresses means that any additional mechanical stress required to occur, which leads to component failure, is significantly higher than with conventional methods. Thus, spontaneous crack formation, which can occur depending on the stress and material, is also less likely.Crack formation due to thermal or mechanical stress on the micromechanical component during further processing or in the field is also less likely, since the mechanical stress or prestress present in the micromechanical component is significantly lower than in micromechanical components manufactured using previously known methods. In particular, with the method according to the invention, it is less critical if, during solidification of the material region, a tip or a protrusion of the tip above the surface of the substrate or cap forms due to the recrystallization dynamics in the center of the molten zone or in the center of the solidified material region. The probability of damage to such a tip or negative effects due to unintentional contact with the tip, for example, during the further production flow, can be effectively reduced by using the recess.Thus, the method according to the invention is an effective way to reduce the probability that the solidified material region or tip is the cause or starting point of cracks. Thus, a method for producing a micromechanical component that is mechanically robust and has a long service life compared to the prior art is provided in a simple and cost-effective manner.

[0008] In the context of the present invention, the term “micromechanical component” is to be understood as encompassing both micromechanical components and microelectromechanical components.

[0009] The present invention is preferably intended for the production of a micromechanical component with one cavity. However, the present invention is also intended, for example, for a micromechanical component with two cavities or with more than two, ie, three, four, five, six, or more than six, cavities.

[0010] Preferably, the access opening is closed by introducing energy or heat into a part of the substrate or cap that absorbs this energy or heat, using a laser. In this case, energy or heat is preferably introduced sequentially into the absorbing part of the substrate or cap of several micromechanical components, which are manufactured jointly on a wafer, for example. Alternatively, however, a temporally parallel introduction of the energy or heat into the respective absorbing part of the substrate or cap of several micromechanical components is also provided, for example using several laser beams or laser devices.

[0011] Advantageous embodiments and further developments of the invention can be found in the dependent claims and the description with reference to the drawings.

[0012] According to a preferred development, it is provided that the cap with the substrate encloses a second cavity, wherein a second pressure prevails in the second cavity and a second gas mixture with a second chemical composition is enclosed.

[0013] A further subject of the present invention is a method for producing a micromechanical component having a substrate and a cap which is connected to the substrate and encloses a first cavity and a second cavity with the substrate, wherein a first pressure prevails in the first cavity and a first gas mixture having a first chemical composition is enclosed, wherein a second pressure prevails in the second cavity and a second gas mixture having a second chemical composition is enclosed, wherein -- in a first method step, an access opening connecting the first cavity with an environment of the micromechanical component is formed in the substrate or in the cap, wherein -- in a second process step, the first pressure and / or the first chemical composition in the first cavern is adjusted, wherein -- in a third process step, the access opening is closed by introducing energy or heat into an absorbing part of the substrate or the cap using a laser, whereby -- in a fourth method step, a recess is formed in a surface of the substrate or the cap facing away from the first cavity in the region of the access opening in order to reduce local stresses occurring when the access opening is closed.

[0014] According to a preferred development, the recess is formed such that a first surface of a projection of the recess onto a plane extending substantially parallel to the surface and a second surface of a projection of the absorbing part of the substrate or the cap onto the plane do not overlap or at least partially overlap. This advantageously ensures that - in the event that there is no overlap between the two surfaces - no molten material flows into the recess or recesses and thus the recess can be designed particularly precisely for the reduction of mechanical stresses. Alternatively, if the two surfaces overlap, it is advantageously possible for the recess to be provided not only for dissipating mechanical stresses but also for accommodating a material region that has transitioned into a liquid state in the third method step.Thus, for example, the solidified material area can be at least partially reduced relative to the surface compared to a conventional method without using a recess.

[0015] According to the invention, in the fourth method step, a further recess or a plurality of further recesses are formed in the surface in the area of ​​the access opening to relieve local stresses that occur when the access opening is closed. This advantageously allows the relief of occurring local mechanical stresses to be adjusted particularly precisely.

[0016] According to a preferred development, the recess and / or a further recess and / or a plurality of further recesses are formed in a plane extending substantially parallel to the surface, substantially rotationally symmetrical to the access channel or to the absorbent part of the substrate or cap, in particular to the center of mass of the absorbent part of the substrate or cap. This advantageously enables a particularly symmetrical reduction of mechanical stresses.

[0017] According to a preferred development, it is provided that the recess and / or the further recess and / or the plurality of further recesses are etched anisotropically into the surface, wherein in particular after the anisotropic etching, the recess and / or the further recess and / or the plurality of further recesses are etched isotropically. This advantageously makes it possible for the recess and / or the further recess and / or the plurality of further recesses to be provided anisotropic or elongated, in the sense of a larger extent of the recess substantially perpendicular to the surface than parallel to the surface or in the sense of a smaller extent of the recess substantially perpendicular to the surface than parallel to the surface. Furthermore, it is advantageously possible for the recess to comprise an isotropic and an anisotropic region.

[0018] According to a preferred development, the recess and / or the further recess and / or the plurality of further recesses are formed such that a first extension of the recess and / or the further recess and / or the plurality of further recesses substantially perpendicular to the surface essentially corresponds to a second extension of the absorbent part of the substrate or the cap. This advantageously enables mechanical stresses to be reduced, in particular over the entire area of ​​the absorbent part of the substrate or the cap or over the entire area of ​​the solidified material region.

[0019] According to a preferred development, the fourth method step is performed after the first method step. This advantageously allows the recess(es) or structures to be introduced into the cap surface after the access channel has been created.

[0020] According to a preferred development, the fourth method step is carried out, in particular, prior to the second method step. This advantageously allows the recess(es) or structures to be introduced before the first pressure and / or the first chemical composition are set.

[0021] According to a preferred development, the recess and / or the further recess and / or the plurality of further recesses are formed such that, after the third method step, the recess and / or the further recess and / or the plurality of further recesses comprise an annular cavity or a plurality of annular cavities. This advantageously enables mechanical stresses to be reduced, in particular also below the region of the absorbing part of the substrate or the cap or below the entire region of the solidified material region, below in the sense of in the direction away from the surface or in the direction toward the first cavity.

[0022] Furthermore, a further subject of the present invention is a micromechanical component according to claim 9.

[0023] According to a preferred development, it is provided that the cap with the substrate encloses a second cavity, wherein a second pressure prevails in the second cavity and a second gas mixture with a second chemical composition is enclosed.

[0024] Furthermore, a further subject matter of the present invention is a micromechanical component having a substrate and having a cap which is connected to the substrate and which, together with the substrate, encloses a first cavity and a second cavity, wherein a first pressure prevails in the first cavity and a first gas mixture having a first chemical composition is enclosed, wherein a second pressure prevails in the second cavity and a second gas mixture having a second chemical composition is enclosed, wherein the substrate or the cap comprises a closed access opening, wherein the substrate or the cap comprises a recess arranged in a surface of the substrate or the cap facing away from the first cavity and in the region of the access opening for reducing local stresses which occur when the access opening is closed.This advantageously provides a compact, mechanically robust, and cost-effective micromechanical component with a set first pressure and a second pressure. The aforementioned advantages of the method according to the invention also apply accordingly to the micromechanical component according to the invention.

[0025] According to the invention, the substrate or cap comprises a further recess, or preferably a plurality of further recesses, in the surface in the region of the access opening for relieving local stresses that occur when the access opening is closed. This provides a micromechanical component that advantageously allows the reduction of local mechanical stresses that occur to be adjusted particularly precisely.

[0026] According to a preferred embodiment, the substrate and / or the cap comprise silicon. This enables the micromechanical component to be manufactured using standardized layer technology methods.

[0027] According to a preferred development, the first pressure is lower than the second pressure, with a first sensor unit for measuring the yaw rate being arranged in the first cavity and a second sensor unit for measuring acceleration being arranged in the second cavity. This advantageously provides a mechanically robust micromechanical component for measuring yaw rate and acceleration with optimal operating conditions for both the first sensor unit and the second sensor unit. Short description of the drawings Fig. 1 shows a schematic representation of a micromechanical component with an open access opening according to an exemplary embodiment of the present invention. Fig. 2 shows a schematic representation of the micromechanical component according to Fig. 1 with closed access opening. Fig. 3 shows a schematic representation of a method for producing a micromechanical component according to an exemplary embodiment of the present invention. Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8 and Fig. 9 show schematic representations of partial regions of a micromechanical component according to exemplary embodiments of the present invention. Embodiments of the invention

[0028] In the various figures, identical parts are always provided with the same reference symbols and are therefore usually named or mentioned only once.

[0029] In Fig. 1 and Fig. 2 is a schematic representation of a micromechanical component 1 with open access opening 11 in Fig. 1 and with closed access opening 11 in Fig. 2 according to an exemplary embodiment of the present invention. Here, the micromechanical component 1 comprises a substrate 3 and a cap 7. The substrate 3 and the cap 7 are connected to each other, preferably hermetically, and together enclose a first cavity 5. For example, the micromechanical component 1 is designed such that the substrate 3 and the cap 7 additionally enclose a second cavity. The second cavity is in Fig. 1 and in Fig. 2 is not shown.

[0030] For example, in the first cavern 5, especially as in Fig. 2, a first pressure. In addition, a first gas mixture with a first chemical composition is enclosed in the first cavity 5. Furthermore, a second pressure prevails, for example, in the second cavity, and a second gas mixture with a second chemical composition is enclosed in the second cavity. Preferably, the access opening 11 is arranged in the substrate 3 or in the cap 7. In the present embodiment, the access opening 11 is arranged, for example, in the cap 7. According to the invention, however, it can also be provided alternatively that the access opening 11 is arranged in the substrate 3.

[0031] For example, it is provided that the first pressure in the first cavern 5 is lower than the second pressure in the second cavern. For example, it is also provided that in the first cavern 5 a Fig. 1 and Fig. 2 not shown first micromechanical sensor unit for angular rate measurement and in the second cavern a Fig. 1 and Fig. 2 not shown second micromechanical sensor unit for acceleration measurement are arranged.

[0032] In Fig. 3 shows a schematic representation of a method for producing the micromechanical component 1 according to an exemplary embodiment of the present invention. -- in a first method step 101, the access opening 11, in particular a narrow one, connecting the first cavity 5 with an environment 9 of the micromechanical component 1 is formed in the substrate 3 or in the cap 7. Fig. 1 shows an example of the micromechanical component 1 after the first method step 101. In addition, -- in a second method step 102, the first pressure and / or the first chemical composition in the first cavern 5 is adjusted or the first cavern 5 is flooded with the desired gas and the desired internal pressure via the access channel. Furthermore, for example, -- in a third method step 103, the access opening 11 is closed by introducing energy or heat into an absorbing part 21 of the substrate 3 or the cap 7 using a laser. Alternatively, it is also provided, for example, that -- in the third method step 103, the area around the access channel is only locally heated, preferably by a laser, and the access channel is hermetically sealed. Thus, it is advantageously possible to provide the method according to the invention with energy sources other than a laser for closing the access opening 11. Fig. 2 shows an example of the micromechanical component 1 after the third method step 103.

[0033] After the third method step 103, in a Fig. 2, mechanical stresses occur in the lateral region 15 shown by way of example on the surface 19 as well as in the depth perpendicular to a projection of the lateral region 15 onto the surface 19, i.e. along the access opening 11 and in the direction of the first cavity 5, of the micromechanical component 1. These mechanical stresses, in particular local mechanical stresses, prevail in particular at and in the vicinity of an interface between a material region 13 of the cap 7, which changes into a liquid aggregate state in the third method step 103 and, after the third method step 103, changes into a solid aggregate state and closes the access opening 11, and a residual region of the cap 7 remaining in a solid aggregate state during the third method step 103. In this case, Fig. 2 the material region 13 of the cap 7 closing the access opening 11 is to be regarded or shown schematically only, in particular with regard to its lateral extension or shape, in particular running parallel to the surface 19, and in particular with regard to its extension or configuration perpendicular to the lateral extension, in particular perpendicular to the surface 19.

[0034] In Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8 and Fig. 9 are schematic representations of partial regions of a micromechanical component 1 according to exemplary embodiments of the present invention. Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8 and Fig. 9 different recesses 17 or structures for reducing stresses are arranged in or around the absorbing part 21 of the substrate 3 or the cap 7 or the area that is melted. The structures are designed such that the material directly around the absorbing part 21 of the substrate 3 or the cap 7 or around the melting area 21 can reduce the stresses in the solidified melting area through elastic deformation. For this purpose, for example, a single structure or a plurality of structures are preferably arranged rotationally symmetrically to the center of the melting. Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8 and Fig. 9, exemplary recesses 17 or structures are proposed. However, differently shaped and differently extending recesses 17 are also provided, which fulfill the purpose of the invention. Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8 and Fig. 9 are preferably etched anisotropically into the surface 19. In addition, for example, a lower part of the Fig. The structures shown in Figure 9 are etched isotropically after the anisotropic etching. For example, the surface 19 comprises a silicon surface. For example, a first extension of the recesses 17 perpendicular to the surface 19 or the depth that the recesses 17 or structures extend into the surface 19 or into the silicon surface lies in the region of a second extension of the absorbing part 21 perpendicular to the surface 19 or the melting depth, for example of the silicon. Alternatively, however, it is also provided that the first extension is less than the second extension. Further alternatively, it is also provided that the second extension is less than the first extension.

[0035] In Fig. 3 shows by way of example that -- in a fourth method step 104, the recess 17 or a stress release structure is formed in a surface 19 of the substrate 3 or the cap 7 facing away from the first cavity 5 in the region of the access opening 11 in order to reduce local stresses occurring when the access opening 11 is closed.

[0036] In Fig. 4 and Fig. 5 shows different recesses 17 or structures or annular structures for stress relief. For example, the distance between a recess 17 and the outer edge of the absorbing part 21 of the substrate 3 or of the cap 7 corresponds at most to the radius of the absorbing part 21 or of the melting region 21. In particular, it is provided, for example, that the distance between the recess 17 and the outer edge of the absorbing part 21 of the substrate 3 or of the cap 7 corresponds to half the radius of the absorbing part 21 or of the melting region 21. Furthermore, it is provided, for example, that the recess 17 is formed as a circular ring, a square frame, or a polygon, in particular a quadrilateral, hexagon, octagon, decagon, and dodecagon, or as a polygon with more than twelve corners.For example, the square frame or the polygon can be arbitrarily aligned and / or formed as another polygon depending on the crystal orientation, in particular depending on the silicon crystal orientation.

[0037] In Fig. 6 shows two further possible designs of the recess 17. In particular, Fig. 6 shows a plurality of recesses 17. For example, the recess 17 or the plurality of recesses 17 or the stress release structure comprise one or more nested, interrupted ring structures for adapting the mechanical properties. These ring structures, for example, do not overlap, or at least partially overlap, with the melting region 21 or with the absorbing part 21, or extend into the melting region 21 or into the absorbing part 21.

[0038] In Fig. 7 shows two further possible embodiments of the recess 17 by way of example. For example, here the recess 17 comprises a ring structure extending around the melting region 21 or the absorbing part 21 as well as spoke-like or radially extending trenches to the center or center of mass of the melting region 21 and connected to the ring structure. In this case, the trenches extend, for example, only partially into the absorbing part 21 and are arranged at least partially outside the absorbing part 21. For example, it is also provided that the trenches are formed so as to be connected to one another in the region of the access opening 11. In other words, the trenches can meet in the middle or preferably end earlier. For example, it must also be ensured, taking all tolerances into account, that the ends lie within the melting region 21. Furthermore, in Fig. 7 shows another possible configuration of a plurality of additional recesses 17. Here, a plurality of individual structures 17 are arranged in and around the melting region 21, which make the material more elastic and, due to the matrix-like arrangement, are tolerant of alignment misalignments. For example, it is envisaged that the individual structures 17 are formed from squares, hexagons, or octagons, or a combination thereof.

[0039] Fig. 8 shows, by way of example, a further possible embodiment of the recess 17. In this case, the recess 17 comprises, for example, an annular structure or a plurality of individual structures shaped in a ring shape and arranged within the melting region 21 around the access channel 11. In this case, the depth of the recess 17 or structure or the extension of the recess 17 perpendicular to the surface 19 is greater than the extension of the absorbent part 21 or than the melting depth. It is thus possible that, after a material region which has solidified in the region of the absorbent part 21 and after the material region has melted, an annular cavity 301 or a plurality of cavities 301 arranged in a ring around the access channel 11 are formed or remain below the melting symmetrically around the access channel 11. Stress or mechanical tension can be exerted in the region of the underside of the access hole closure oron a side of the absorbing part 21 facing the first cavity 5. For example, the width or an extension of the recess 17 is designed such that, for example, the laser in the third method step 103 does not reach the etching base or an interface between the recess 17 and the cap 7 or that the laser does not irradiate the etching base or the interface. Alternatively, it is also provided that the angle of incidence of the laser beam in the third method step 103 is set such that the laser beam or laser pulse does not impinge perpendicularly on the recess surface or on the interface between the recess 17 and the cap 7.

[0040] According to the invention, it is provided that, for example, the recesses 17 or structures are optionally combined with stress release structures or further recesses 17 or structures outside the melting region 21 or the absorbing part 21. Different etching depths can be realized, for example, using the aspect ratio dependent etch (rate) (ARDE) effect.

[0041] Finally, Fig. 9 recesses 17, wherein the recesses 17 each comprise an isotropic region 303. In this case, it is provided, for example, that the isotropic region 303 is arranged in particular on a side of the recess 17 facing away from the surface 19. For example, the recesses 17 Fig.9 are etched in such a way that an isotropic etching step is performed at the end of the etching or on a side of the recess 17 facing the first cavity 5, whereby an undercut 305 is formed at the etching base. In particular, it is provided that the undercut 305 is designed such that the undercut 305 extends substantially parallel to the surface 19 or, in comparison to the remaining recess 17, protrudes at least partially into the cap 7 parallel to the surface.

Claims

[1] Method for producing a micromechanical component (1) with a substrate (3) and with a cap (7) connected to the substrate (3) and enclosing a first cavity (5) with the substrate (3), wherein a first pressure prevails in the first cavity (5) and a first gas mixture with a first chemical composition is enclosed, wherein -- in a first method step (101), an access opening (11) connecting the first cavity (5) to an environment (9) of the micromechanical component (1) is formed in the substrate (3) or in the cap (7), wherein -- in a second method step (102), the first pressure and / or the first chemical composition in the first cavern (5) is adjusted, wherein -- in a third method step (103), the access opening (11) is closed by introducing energy or heat into an absorbing part (21) of the substrate (3) or the cap (7) with the aid of a laser, characterized by , that -- in a fourth method step (104), a recess (17) and a further recess (17) are formed in a surface (19) of the substrate (3) or of the cap (7) facing away from the first cavity (5) in the region of the access opening (11) in order to reduce local stresses occurring when the access opening (11) is closed, the fourth method step (104) being carried out before the second method step (102). [2] Method according to claim 1, wherein the cap (7) with the substrate (3) encloses a second cavity, wherein a second pressure prevails in the second cavity and a second gas mixture with a second chemical composition is enclosed. [3] Method according to one of the preceding claims, wherein the recess (17) is formed such that a first surface of a projection of the recess (17) onto a plane extending substantially parallel to the surface (19) and a second surface of a projection of the absorbing part (21) of the substrate (3) or of the cap (7) onto the plane do not overlap or at least partially overlap. [4] Method according to one of the preceding claims, wherein in the fourth method step a plurality of further recesses (17) are formed in the surface (19) in the region of the access opening (11) in order to reduce local stresses occurring when the access opening (11) is closed. [5] Method according to one of the preceding claims, wherein the recess (17) and / or a further recess (17) and / or a plurality of further recesses (17) in a plane extending substantially parallel to the surface (19) is formed substantially rotationally symmetrically to the access channel (11) or to the absorbent part (21) of the substrate (3) or the cap (7), in particular to the center of mass of the absorbent part (21) of the substrate (3) or the cap (7). [6] Method according to one of the preceding claims, wherein the recess (17) and / or the further recess (17) and / or the plurality of further recesses (17) are etched anisotropically into the surface (19), wherein in particular after the anisotropic etching the recess (17) and / or the further recess (17) and / or the plurality of further recesses (17) are etched isotropically. [7] Method according to one of the preceding claims, wherein the recess (17) and / or the further recess (17) and / or the plurality of further recesses (17) are formed such that a first extension of the recess (17) and / or the further recess (17) and / or the plurality of further recesses (17) substantially perpendicular to the surface (19) substantially corresponds to a second extension of the absorbent part (21) of the substrate (3) or the cap (7). [8] Method according to one of the preceding claims, wherein the recess (17) and / or the further recess (17) and / or the plurality of further recesses (17) are formed in such a way that, after the third method step (103), the recess (17) and / or the further recess (17) and / or the plurality of further recesses (17) comprises an annular cavity (301) or a plurality of annular cavities (301). [9] Micromechanical component (1) with a substrate (3) and with a cap (7) connected to the substrate (3) and enclosing a first cavity (5) with the substrate (3), wherein a first pressure prevails in the first cavity (5) and a first gas mixture with a first chemical composition is enclosed, wherein the substrate (3) or the cap (7) comprises a closed access opening (11), characterized by in that the substrate (3) or the cap (7) comprises a recess (17) arranged in a surface (19) of the substrate (3) or the cap (7) facing away from the first cavity (5) and in the region of the access opening (11) for reducing local stresses occurring when the access opening (11) is closed, and a further recess (17) arranged in the region of the access opening (11) for reducing local stresses occurring when the access opening (11) is closed. [10] Micromechanical component (1) according to claim 9, wherein the cap (7) with the substrate (3) encloses a second cavity, wherein a second pressure prevails in the second cavity and a second gas mixture with a second chemical composition is enclosed.

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