Patent Application
20240359975
The present application claims the benefit under 35 U.S.C. § 119 of German Patent Application No. DE 10 2023 203 847.1 filed on Apr. 26, 2023, which is expressly incorporated herein by reference in its entirety.
The present invention relates to a method for producing a particle protection element, in particular a particle filter, for a membrane of a pressure sensor and to a corresponding particle protection element. The present invention also relates to a method for producing a pressure sensor and to a corresponding pressure sensor.
A pressure sensor and a particle protection element, in particular a particle filter, are described in U.S. Pat. No. 10,640,367 B2. However, details regarding the production of the particle protection element are not specified in this patent.
It is an object of the present invention to specify both an improved production method for a particle protection element, in particular a particle filter, and also a pressure sensor. In addition, it is an object of the present invention to specify both an improved particle protection element, in particular a particle filter, and also an improved pressure sensor.
This object may be achieved by features of the present invention. Advantageous example embodiments of the present invention are disclosed herein.
Provided according to the present invention is a method for producing a particle protection element, in particular a particle filter, for a membrane of a pressure sensor. According to an example embodiment of the present invention, the method comprises the following steps:
Further provided according to the present invention is a particle protection element, in particular a particle filter, which has been produced according to the aforementioned method of the present invention.
Structuring the individual aforementioned layers can in this case mean the purposeful local or regional removal of material by means of an etching process, wherein the etching process can be designed as a wet-chemical, plasma-based and/or gaseous etching process or gas-phase etching process. Conventional etching media and etching methods from semiconductor technology can be used as etching media and etching methods, wherein, for removing silicon dioxide, for example from sacrificial layer regions, wet-chemical and/or gaseous etching media containing hydrofluoric acid can preferably be used in corresponding etching processes.
According to an example embodiment of the present invention, applying the second silicon dioxide layer to the structured first silicon dioxide layer in the second step may include the second silicon dioxide layer also being applied to the surface of the substrate that has been exposed during the structuring of the first silicon dioxide layer.
According to an example embodiment of the present invention, the connectable design of the at least one first channel structure and/or of the later plurality of media passage structures and/or of the later at least one second channel structure with regard to a media flow comprises the at least one first channel structure and the later plurality of media passage structures forming a contiguous structure, i.e., a contiguous zone of material of the first silicon dioxide layer and/or of the second silicon dioxide layer, and the at least one second channel structure stops/ends directly at the first silicon dioxide layer in the region of the at least one first channel structure.
The later at least one first channel structure and/or the later plurality of media passage structures can each be arranged on the front side of the substrate, i.e., on the surface thereof or on the layers applied to or deposited onto the surface of the substrate. This can correspond to the front side of the particle protection element, while the at least one second channel structure can be arranged on the rear side of the particle protection element, i.e., on the side of the substrate that is opposite the front side. If the substrate or the particle protection element is rotated, it is understood that the mentioned front side of the substrate or the surface of the substrate or the front side of the particle protection element together with the first channel structure and/or with the plurality of media passage structures as well as the rear side of the substrate or of the particle protection element together with the second channel structure are then likewise rotated.
The first channel structure and/or the second channel structure as well as the plurality of media passage structures can each be regarded as channels or openings or structures.
According to an example embodiment of the present invention, during the production of the later plurality of media passage structures (preferably gas passage structures) of the particle protection element or of the cap, the use of a first silicon dioxide layer (SiO2), for example of a defined thickness, and/or of a second silicon dioxide layer of a defined thickness, in each case as a sacrificial layer, can advantageously be used to define the height, i.e., the cross section, of the plurality of media passage structures/media passage channels. The plurality of media passage structures thus act as filter structures. The media passage structures can be used not only when using gaseous media, but also when using liquid media. Via the choice of the number of the respective channel structures and the channel cross sections thereof, it is possible to exert almost any influence on a filter effect with respect to particles and influence on the flow resistance of a medium through the particle protection element.
In contrast to the production of media passage structures/channel structures by means of conventional photolithographic exposure methods, significantly smaller cross sections of media passage structures can thereby be achieved. By purposefully arranging a plurality of media passage structures in the walls of at least one first channel structure, it is furthermore possible to influence the damping-dependent behavior of a pressure signal. This approach also offers the possibility of being able to use standard packaging methods and thus to achieve a cost advantage over packaging-based particle protection, for example integrated in a housing.
However, a plurality of second channel structures, starting from the rear side of the substrate, does not necessarily have to be provided. Via the number and the geometric properties of the first channel structures and of the second channel structures through the substrate, it is also possible to influence the speed of a gas exchange between the front side and rear side as well as the mechanical stability of the gas-permeable region of a particle protection element.
By means of the connectable design of the later at least one first channel structure and/or of the later plurality of media passage structures and/or of the later at least one second channel structure with regard to a media flow, a bilateral media exchange (e.g., gas exchange) between the front side (top side) and the rear side (bottom side) of the particle protection element can advantageously be made possible, and a membrane of a pressure sensor element can be protected from penetrating particles (e.g., dust, dirt, etc.).
According to an example embodiment of the present invention, the particle protection element or the media-permeable, in particular gas-permeable, cap is preferably produced in a separate production process. The particle protection element on the basis of a substrate which is in particular designed as a silicon wafer offers the advantage that particle protection of a membrane of the pressure sensor can already take place during the production of a pressure sensor or pressure sensor element.
The particle protection element is subsequently connected to a further substrate, which is designed as a pressure sensor element or forms a pressure sensor wafer, by means of conventional connection techniques/bonding methods, such as eutectic bonding, e.g., Al/Ge bonding, thermocompression bonding, e.g., Au/Au bonding, seal glass bonding, adhesive methods, etc.
In a further example embodiment of the present invention, depositing and structuring the first polysilicon layer (poly-Si) and/or the second polysilicon layer in the third step comprises forming silicon dioxide regions covered with the first polysilicon layer, and/or silicon-dioxide-free regions.
The silicon dioxide regions covered with the first polysilicon layer and/or the second polysilicon layer can later be used to form the at least one first channel structure and the plurality of media passage structures. In the silicon-dioxide-free regions, material of the first polysilicon layer and/or of the second polysilicon layer is deposited, for forming a later plurality of structure-fastening anchoring structures, which serve to anchor a later cover spanning the at least one first channel structure and to form the plurality of media passage structures. A width of the later at least one first channel structure and/or a width of the later plurality of media passage structures can be set on the basis of a distance of adjacent anchoring structures of the later plurality of anchoring structures.
The lateral dimensions and the shape of the plurality of anchoring structures can in this case advantageously be selected as desired. The height of the anchoring structures results from the thickness of the first and/or of the second silicon dioxide layer. The shape of a cover (of the front side of the particle protection element) which is fastened to the front side of the substrate by means of anchoring structures can be selected as desired. Alternatively, the cover can also be understood to mean a covering region or a silicon cover or a polysilicon cover or a channel cover of the at least one first channel structure. The anchoring structures can be formed at least in regions circumferentially around the contour of the at least one first channel structure and can respectively be mechanically and optionally also electrically connected on one side to the cover of the at least one first channel structure and on one side to the substrate.
Long etching times and different etching rates over the substrate or Si substrate in combination with a thin first silicon dioxide layer can lead to the first silicon dioxide layer being through-etched locally, i.e., in regions, on the substrate during the production of the at least one second channel structure. In this case, through-etching of the first polysilicon layer on the front side of the substrate can furthermore also occur, which would result in a filter function with respect to particles of a certain size in consequence of the plurality of media passage structures or media passage channels no longer being present. In order to avoid this, a first silicon dioxide layer of any thickness can be provided on the front side of the substrate or top side, said silicon dioxide layer being structured in such a way that the oxide of the first silicon dioxide layer is removed only in a region of the later media passage structures. Following this, a second silicon dioxide layer produced by means of conventional methods, such as by thermal oxidation or by CVD deposition, is provided at least in this region. The thickness of the second silicon dioxide layer later defines the height of a media passage structure.
Following this, silicon dioxide is removed in the regions in which anchoring structures are to be produced later. The further procedure can here take place analogously to what has already been described above. By providing a thicker first silicon dioxide layer, it is advantageously possible to purposefully provide a thicker silicon dioxide layer in the regions in which an etching process is to stop safely on the silicon dioxide layer. A further advantage when using a thicker first silicon dioxide layer is that due to the thicker first silicon dioxide layer the first channel structures on the front side of the substrate receive a larger channel cross section at least in regions and the flow resistance of a medium, e.g., a gas, through the filter system can thus be further reduced.
In a further example embodiment of the present invention, for forming the later at least one second channel structure through the substrate, a mask for structuring, in particular a photoresist mask and/or a silicon dioxide hard mask, is applied to the rear side of the substrate in the fourth step, and the structuring of the substrate is carried out. The at least one second channel structure is advantageously formed such that the structuring, i.e., the etching process, stops at the first silicon dioxide layer within a first channel structure provided with gas-permeable boundaries/walls.
In a further example embodiment of the present invention, the first silicon dioxide layer and/or the second silicon dioxide layer can be used as a silicon dioxide hard mask. Advantageously, the first silicon dioxide layer and/or the second silicon dioxide layer can serve as buried etching masks. In an exemplary embodiment in which the second silicon dioxide layer and the second polysilicon layer are applied to the first polysilicon layer and in each case structured, the second silicon dioxide layer can be used as a silicon dioxide hard mask/etching mask. During the structuring of the second polysilicon layer, this etching mask can also be used to etch the first polysilicon layer in such a way that, in regions outside of first channel structures, the first silicon dioxide layer is exposed between media-permeable, i.e., gas-permeable, boundaries/walls. Here, too, the etching process after the etching of the first polysilicon layer stops at the first silicon dioxide layer. By means of the procedure described here, the particle protection element or the Si covers over first channel structures can be designed to be spaced apart from the surface of the substrate delimiting the first channel structures. During the production of further, e.g., second channel structures through the substrate, a mechanical contact between channel covers and chucks or trays in processing systems and/or handling systems in the production process can thus be prevented. Here, too, all silicon dioxide layers in the region of the media passage structures or filter structures and of first channel structures on the front side of the substrate can be removed by means of BOE or by an HF gas-phase etching step.
In a further example embodiment of the present invention, substrate material on the rear side of the substrate can be removed or the substrate on the rear side can be thinned before the formation of the later at least one second channel structure, starting from the rear side of the substrate. The removal or purposeful thinning of the substrate to a target thickness can advantageously take place by means of a grinding process and/or polishing process. Advantageously, the overall height of the particle protection element can thereby be reduced so that the particle protection element can be produced to be very compact, i.e., very thin.
In a further example embodiment of the present invention, regions of silicon dioxide can be embedded in the first polysilicon layer and/or in the second polysilicon layer, which regions serve as etch stop structures when forming the later at least one first channel structure in the third step and/or when forming the later at least one second channel structure from the rear side of the substrate through the substrate in the fourth step. Advantageously, slight etching of the first polysilicon layer and/or of the second polysilicon layer can thus be avoided, and the etch stop structures can optionally be removed again, for example after the production of the at least one second channel structure. Alternatively, through-etching of the first polysilicon layer and/or of the second polysilicon layer can be avoided by providing the mentioned layers of a sufficient thickness, which does, however, increase the overall height of the particle protection element. In the alternative described, it must however be ensured that providing the sufficiently thick first polysilicon layer and/or the sufficiently thick second polysilicon layer does not result in a pressure access to the membrane of the pressure sensor that has an undesirably large cross-sectional area.
In a further example embodiment of the present invention, the method furthermore comprises the step of removing the first silicon dioxide layer and/or the second silicon dioxide layer in a fifth step by means of an etching process via an access through the first and/or second polysilicon layer to the later at least one first channel structure and/or to the later plurality of media passage structures and/or of removing the first silicon dioxide layer and/or the second silicon dioxide layer in a fifth step by means of an etching process via the formed at least one second channel structure through the substrate.
Advantageously, after removing the first silicon dioxide layer and/or the second silicon dioxide layer by means of an etching process, which can preferably take the form of a BOE or HF gas-phase etching process, the plurality of media passage structures, which extend through boundaries/walls of first channel structures and whose height is defined by the thickness of the first and/or the second silicon dioxide layer and whose width is defined by the distance from adjacent anchoring structures, is produced at/on the front side of the substrate.
In a further example embodiment of the present invention, the at least one first channel structure, which has been exposed in the fifth step, and/or the exposed plurality of media passage structures essentially has a meandering course. Advantageously, the number, the shape and the geometric dimensions of the at least one second channel structure can vary as desired, starting from the rear side of the substrate. This flexibility (number, shape, geometry) advantageously also applies to the at least one first channel structure and/or the plurality of media passage structures. It is advantageously possible in this way to produce structures/first channel structures with long gas-permeable boundaries/walls which make possible a rapid, bilateral, media exchange (preferably gas exchange) between a front side and a rear side of the particle protection element. Via the length of the gas-permeable boundaries/walls of structures/first channel structures, it can furthermore be ensured that even a greater number of media passage structures blocked/closed off with particles will not have any influence on a gas exchange through boundaries/walls of first channel structures.
Via the shape and the geometric dimensions of the at least one media passage channel structure of the plurality of media passage channel structures and/or of the at least one first channel structure and/or of the at least one segment and/or of the at least one connection channel structure, a large-area filter structure can advantageously be generated/produced on a relatively small area.
In a further example embodiment of the present invention, the at least one first channel structure, which has been exposed in the fifth step, and/or the exposed plurality of media passage structures can be arranged essentially in the form of a plurality of segments which can be connected by means of connection channels and/or comprise an access to the at least one second channel structure. Advantageously, segments or regions of the particle protection element can be connected to one another as desired via the aforementioned connection channels so that the particle protection element can be produced very flexibly. Advantageously, at least one segment or at least one region of the particle protection element can be connected to the at least one second channel structure via a separate access, wherein the at least one second channel structure can be arranged, for example, outside of the at least one segment and/or outside of the region of the particle protection element designed as a media passage structure. In this way, the second channel structure can, for example, end in a later cavity region of a pressure sensor and at least one portion/region of the plurality of media passage structures can be arranged outside of the cavity region.
In addition, according to an example embodiment of the present invention, the segments can comprise a cover comprising, for example, the material of the first polysilicon layer, wherein the cover is connected to the surface of the substrate via the plurality of anchoring structures. The plurality of anchoring structures can be provided at least in regions circumferentially around the contour of a segment between the cover associated with the segment and the surface of the substrate.
Via the shape and the geometric dimensions of the at least one media passage channel structure of the plurality of media passage channel structures and/or of the at least one first channel structure and/or of the at least one segment and/or of the at least one connection channel structure, a large-area filter structure can advantageously be generated/produced on a relatively small area.
In a further example embodiment of the present invention, when structuring the substrate, i.e., when forming the later at least one second channel structure and/or when forming the at least one first channel structure and/or the plurality of media passage structures when structuring the first polysilicon layer and/or the second polysilicon layer, stiffening structures contiguous at least in portions can in each case be formed. This can advantageously improve the mechanical stability or the robustness of the particle protection element. The stiffening structures can be designed to be contiguous at least in portions and optionally separated from the surrounding substrate and/or optionally separated from the surrounding polysilicon layer. Contiguous at least in portions can in this case be understood as being connected to one another via certain regions. In this case, the stiffening structures can also be connected to the surrounding substrate and/or to the surrounding polysilicon layer
In a further example embodiment of the present invention, the later plurality of media passage structures and/or the later at least one first channel structure and/or the later at least one second channel structure are designed to be coatable, in particular coatable hydrophobically or hydrophilically. The hydrophobic or hydrophilic coating provided can, for example, be a non-stick layer (AHS), which prevents a liquid medium from passing through the plurality of media passage structures, i.e., the filter structures, due to the edge angle forming on the non-stick layer, or a coating which makes possible better wetting of at least one of the surfaces of the plurality of media passage structures, i.e., of the filter structures, in order to achieve a better flow of a liquid medium. Through the height, width and length of the at least one first channel structure, of the plurality of media passage structures and of the at least one second channel structure and through the edge angle of the medium on the surface of the at least one first channel structure, of the plurality of media passage structures and of the at least one second channel structure, it is thus possible, for example in the case of a hydrophobic layer to set a watertightness down to a particular water depth.
Furthermore, according to an example embodiment of the present invention, a method for producing a pressure sensor is proposed, comprising the following steps:
Also proposed is a pressure sensor which has been produced according to the aforementioned method.
According to an example embodiment of the present invention, after the removal of the first and second silicon dioxide layers or further silicon dioxide layers in the production method of the particle protection element, the substrate forming/constituting the particle protection element is connected as a cap wafer to a further substrate (likewise a Si substrate), which is designed as a pressure sensor element, in such a way that, after the processing has been fully completed, a gaseous medium can be conducted to the membrane of the pressure sensor via the first channel structures and the trench structures produced in the first and/or second polysilicon layer and the second channel structures, and a pressure of the gaseous medium can be measured. In this way, a pressure sensor having the aforementioned features, whose membrane can already be protected during the production process by using the particle protection element, can advantageously and simply be provided.
In a further example embodiment of the present invention, the further substrate and the particle protection element are connected by means of the bonding method, in particular the wafer bonding method, and/or by means of the adhesive method in the third step in such a way that bond structures and/or adhesive joints are arranged on the rear side of the substrate of the particle protection element and/or bond structures and/or adhesive joints are arranged on a front side of the particle protection element.
If corresponding bond areas or bond structures and/or adhesive areas or adhesive structures are provided on the layer system on the front side of the substrate or on the rear side of the substrate, a previously described substrate (Si wafer), which forms/constitutes a particle protection element, or the gas-permeable cap wafer can be connected in a simple manner to a further substrate, for example designed as a pressure sensor element (or pressure sensor wafer). A possible bond connection, in particular a wafer bond connection, can, for example, be a eutectic Al/Ge bond connection, a seal-glass bond connection, an Au/Au thermocompression bond connection, a solder connection or an at least punctiform laser-assisted bond connection. Alternatively, a substrate (Si wafer) forming/constituting a particle protection element, or a gas-permeable cap wafer, can be connected by an adhesive connection to a further substrate designed, for example, as a pressure sensor element (or pressure sensor wafer). Advantageously, the substrate and/or the further substrate can also be brought to a desired target thickness by a grinding process and/or polishing process, as mentioned above.
In a further example embodiment of the present invention, the further substrate and the substrate forming/constituting the particle protection element are first connected in the third step, before forming the later at least one second channel structure through the substrate from the rear side of the substrate forming/constituting the particle protection element in the fourth step. Advantageously, in this way, the substrate forming/constituting the particle protection element and/or the further substrate can first be brought to a desired target thickness as mentioned above, and the at least one second channel structure can only be formed thereafter. This can advantageously prevent the at least one second channel structure from being blocked/closed by removed material during removal/thinning of the substrate, forming/constituting the particle protection element, or of the further substrate.
The above-described properties, features, and advantages of the present invention and the way in which they are achieved become clearer and more readily comprehensible in connection with the following description of exemplary embodiments, which are explained in more detail in connection with the schematic figures.
The figures are merely schematic and are not true to scale. In this sense, components and elements shown in the figures may be shown exaggeratedly large or reduced in size for better understanding. It is also pointed out that the reference signs in the figures have been selected to be unchanged or similar for elements and/or components that are designed identically or similarly.
Structuring 137 the first silicon dioxide layer 135 in the second step 110 further comprises forming silicon dioxide-free regions for the production of a later plurality of structure-fastening anchoring structures 175. In other words, the plurality of anchoring structures can be formed where the first silicon dioxide layer 135 has been removed. The plurality of anchoring structures 175 are inter alia designed for structure-fastening purposes. A height 183 of the later plurality of anchoring structures 175 can be set on the basis of a thickness 143 of the first silicon dioxide layer 135 (comparably to the aforementioned adjustable height 141 of the later plurality of media passage structures 140, based on the thickness 143 of the first silicon dioxide layer 135). A width 185 of the later plurality of media passage structures 140 can be set on the basis of a distance 176 from adjacent anchoring structures 175 of the later plurality of anchoring structures 175 (cf., for example,
Furthermore, boundaries 127 of a later at least one first channel structure 167 and a region between the boundaries of the later at least one first channel structure 167 are shown in
For forming the later at least one second channel structure 170 starting from the rear side 173 of the substrate 130 in the fourth step 120, a mask, for example a photoresist mask 177 and/or a silicon dioxide hard mask, is applied to the rear side 173 of the substrate 130.
The later at least one first channel structure 167 and/or the later plurality of media passage structures 140 and/or the later at least one second channel structure 170 are designed to be connectable with regard to a media flow. This comprises the at least one first channel structure 167 and the later plurality of media passage structures 140 forming a contiguous structure, i.e., a contiguous zone made of material of the first silicon dioxide layer 135, and the at least one second channel structure 170 stopping/ending in the region of the at least one first channel structure 167, and at least one etching access or media access 188 through the first polysilicon layer 160 stopping/ending in the region outside of the at least one channel structure 167 directly on the first silicon dioxide layer 135.
In addition, a region 129 between the boundaries of adjacent channel structures is shown in
In
In the upper figure region of
In contrast to the previous
By providing a plurality of media passage structures 140 in at least one partial region of a wall/of a lateral boundary of at least one first channel structure 167 provided with a cover made of material of the first polysilicon layer 160, it can advantageously be achieved that a medium 15 can flow through at least one media passage structure 140 of the plurality of media passage structures 140 and through at least one channel structure 167 and/or through at least one connection channel structure 126 in the direction of at least one second channel structure 170 until all media passage structures are closed in a media-tight manner by foreign substances, such as particles.
Via the shape of the at least one media passage channel structure 140 of the plurality of media passage channel structures 140 and/or of the at least one first channel structure 167 and/or of the at least one segment 194 and/or of the at least one connection channel structure 126, a large-area filter structure can advantageously be generated/produced on a relatively small area.
A second step 210 of the production method according to the second embodiment 200 comprises applying a second silicon dioxide layer 147 to the structured first silicon dioxide layer 135 and to the at least one exposed surface 133 of the substrate 130 in addition to applying the first silicon dioxide layer 135 to a surface of the substrate 133 and structuring or locally removing the first silicon dioxide layer 137. If, in the second step 210, the second silicon dioxide layer 147 is applied to the structured first silicon dioxide layer 135 and to the at least one exposed surface 133 of the substrate 130, the first silicon dioxide layer 135 will have a second settable thickness 145, which is designed to be greater than the first settable thickness 143 of the first silicon dioxide layer 135 without the applied second silicon dioxide layer 147. The second silicon dioxide layer 147 deposited onto the at least one exposed surface 133 of the substrate can be used to produce at least one media passage channel structure 140 of the plurality of media passage channel structures 140. In the method 200, the height of the later at least one media passage channel structure 140 of the plurality of media passage structures 140 can, for example, be set on the basis of a thickness 153 of the second silicon dioxide layer 147.
When the second silicon dioxide layer 147 is applied to the structured first silicon dioxide layer 135 in the second step 210, the first silicon dioxide layer 135 is only structured in regions in which the later plurality of media passage structures 140 and/or the later plurality of anchoring structures 175 are formed.
Before the deposition of the first polysilicon layer 160 in a third step 215 of the production method according to the second embodiment 200, the first silicon dioxide layer 135 and the second silicon dioxide layer 147 are structured in such a way that they are completely removed at least in one region of an anchoring structure 175 of the later plurality of anchoring structures 175. After the subsequent full-area deposition of the first polysilicon layer 160, the first polysilicon layer 160 is structured 157 in the third step 215 in such a way that, due to polysilicon-free regions in the first polysilicon layer 160, the first and second silicon dioxide layers 135, 147 can be removed for forming a later at least one first channel structure 167 and an at least one media passage channel structure 140 of the plurality of media passage channel structures 140. A fourth step 220 of the production method according to the second embodiment 200, i.e., the formation of the at least one second channel structure 170, can be designed similarly to the above-explained fourth step 120 of the production method according to the first embodiment 100.
In a fifth step 225 of the production method according to the second embodiment 200, by means of an etching process 192 (as explained above) via an access through the first polysilicon layer 160 outside of the cover of the at least one channel structure 167 consisting of material of the first polysilicon layer 160, the first silicon dioxide layer 135 and/or the second silicon dioxide layer 147 can be removed outside of the at least one channel structure 167 and/or within the at least one channel structure 167 and/or in the region of at least one media passage structure 140 of the plurality of media passage structures 140. Additionally or alternatively, the fifth step 225 may also comprise removing the first silicon dioxide layer 135 and the second silicon dioxide layer 147 by means of an etching process 192 via the formed at least one second channel structure 170 through the substrate 130 starting from the rear side 173 of the substrate 130. The structure of the particle protection element 20 can thus vary in consequence of the slightly modified production process 200 in comparison to the particle protection element 10 according to the first embodiment and can advantageously, for example, provide a larger channel cross section which is independent of the choice of a thickness of a silicon dioxide layer 135, 147 which determines the height of a later at least one media passage structure 140 of the plurality of media passage structures 140.
In contrast to the preceding methods 100, 200, a third step 315 of the production method 300 may comprise applying a second polysilicon layer 163 to the surface 156 of the second silicon dioxide layer 147 in addition to depositing the first polysilicon layer 160 onto the surface 155 of the first silicon dioxide layer 135 and the surface 133 of the substrate 130 and applying the second silicon dioxide layer 147 to the surface 161 of the first polysilicon layer 160 and structuring 150 it. Furthermore, the third step 315 of the production method 300 may comprise structuring the first polysilicon layer 160 and/or structuring 166 the second polysilicon layer 163, wherein the structured second silicon oxide layer 147 can be used at least in regions as an etching mask for the first polysilicon layer 160 and for forming the cover of the at least one first channel structure 167 from material of the first polysilicon layer 160, and wherein the etching process used for structuring the first and/or second polysilicon layer 160, 163 preferably stops at the first and/or second silicon dioxide layer 135, 147. Additionally, the third step 315 may also comprise removing the first silicon dioxide layer 135 for forming a later at least one first channel structure 167 and/or for forming at least one media passage structure 140 of the plurality of media passage structures 140, and removing the etching mask comprising the material of the second silicon dioxide layer 147.
A fourth step 320 of the production method according to the third embodiment 300, i.e., the formation of the at least one second channel structure 170, can be designed similarly to the above-explained fourth step 120, 220 of the production method according to the first embodiment 100 or according to the second embodiment 200 but is not shown in
The fifth step 325 of the production method 300 is not shown in
In the following,
In both figures, regions/structures made of, e.g., silicon dioxide are embedded in the first polysilicon layer 160 and, during the formation of the at least one second channel structure 170 from the rear side 173 of the substrate 130 through the substrate 130, serve as etch stop structures 191 and can reliably prevent through-etching of the first polysilicon layer 160.
In the following,
As shown in
The etching process during the structuring of the second polysilicon layer 163 stops at the second silicon dioxide layer 147, and the second silicon dioxide layer 147 is removed in the fifth method step 1225 in
For all of the aforementioned embodiments of the proposed particle protection element 10, 20, 30, 35, 37 and of the proposed pressure sensor 40, 50, 55, 57, 59, 60, 63, 65, 67, 70, 73, 75, 80, it is true without restriction that the later plurality of media passage structures 140 and/or the later at least one first channel structure 167 and/or the later at least one second channel structure 170 are in each case designed to be coatable, in particular coatable hydrophobically or hydrophilically.
It is to be understood without restriction for all explained embodiments of the figures shown that further layers can be applied to the substrate 130 and structured, and that the formation of the proposed at least one first channel structure 167 and/or the plurality of media passage structures 140 is not restricted to the explained layers or the structuring thereof. The same can apply to the formation of the at least one second channel structure 170, provided that the substrate 130 comprises embedded structures and/or materials.
It is to be understood that, for producing a planar, i.e., flat, surface, all deposited/applied layers, i.e., the first and second silicon dioxide layers 135, 147 and the first and second polysilicon layers 160, 163, as well as, where applicable, further layers for all figures can optionally be planarized by means of a polishing process/polishing step after the deposition.
The first and second polysilicon layers 160, 163 can optionally be doped without restriction, for all explained figures, in order to influence the layer stress and/or the electrical conductivity.
In addition, it is also true, without restriction, that all channels/openings/structures through the first and second silicon dioxide layers 135, 147 and/or the first and second polysilicon layers 160, 163 and/or the substrate 130 can have any geometric shape/structure.
It is furthermore to be understood that at least one opening that completely penetrates the particle protection element can be provided in the particle protection element, which opening makes possible an electrical contacting of the pressure sensor outside of the particle-protected membrane region, for example by means of a wire bonding process.
The present invention has been described in detail by means of preferred exemplary embodiments. Instead of the described exemplary embodiments, further exemplary embodiments are conceivable, which can have further modifications or combinations of described features. For this reason, the present invention is not limited by the disclosed examples since other variations can be derived therefrom by a person skilled in the art without departing from the scope of protection of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2023 203 847.1 | Apr 2023 | DE | national |
