DE102020214792A1 - micromechanical component - Google Patents

Abstract

Micromechanical component (100), having: - a cover element (10); - a cavity (20) arranged below the cover element (10); - at least one vertical etching channel (11) arranged outside an anchoring structure of the cover element (10); - at least one lateral etching channel (12a...12n) starting from the at least one vertical etching channel (11), provided below an etching stop layer (3) and below the cavern (20) and arranged between the etching stop layer (3) and the silicon substrate (1); and- at least one access etching channel (3a1...3an) formed between the at least one lateral etching channel (12a...12n) and the cavern (20).

Description

The present invention relates to a micromechanical component. The present invention also relates to a method for producing a micromechanical component.

State of the art

In the production of surface micromechanical sensors such as inertial sensors or pressure sensors, it is necessary to remove sacrificial layers from cavern areas using etching accesses in order to be able to produce freely movable structures such as movable masses or membranes. As a rule, these etching accesses must be closed again after removal in order to be able to achieve a defined internal cavern pressure.

However, etching access from the top of the layer system directly into the cavern area can lead to reduced membrane stability, e.g. in pressure sensors. In the variant with at least one etching access outside the cavity area, care must be taken to ensure that the lateral etching channel cross-section is sufficiently large or that there are a sufficiently large number of etching channels to ensure rapid, homogeneous and complete removal of sacrificial layers within the functional layer system. However, when producing large etching channel cross sections within a functional layer system, there is often a limitation due to the existing layer thicknesses and lateral layer dimensions required for the realization of the sensor element.

Due to the progressing miniaturization, however, the geometric dimensions available for the production of etching channels in a functional layer system are decreasing. In order to avoid undercutting of e.g. poly-Si conductor tracks when etching the sacrificial layer, these and the other layers of the functional layer system are ideally deposited on an electrically insulating layer, which is also etch-resistant to the medium with which the sacrificial layer(s) in the etching channels and/or be removed in the cavern area. Further layers can be located under this etch stop layer, which form the substructure of the sensor element.

In both of the etching access variants described, electrical conductor tracks must be led out of the cavern area in order to produce the functionality of the sensor element. For this purpose, a lateral etching boundary surrounding the cavern area must be interrupted. If the electrical insulation layer surrounding the electrical conductor tracks also consists of the material of the sacrificial layer(s), e.g. SiO2, the electrical insulation layer is also etched/removed along conductor track structures. If long etching times are required to remove sacrificial layers in the cavern area, large-area removals of sacrificial layer material can also occur outside of the cavern area. Due to increasing miniaturization and the associated short distances between neighboring components/sensors, this can result in unwanted etching in neighboring components or unwanted ventilation access to the cavern.

Disclosure of Invention

It is an object of the present invention to provide an improved micromechanical component relating in particular to the aspects mentioned above.

• - ein Abdeckelement;
• - eine unterhalb des Abdeckelements angeordnete Kaverne;
• - wenigstens einen außerhalb einer Verankerungsstruktur des Abdeckelements angeordneten vertikalen Ätzkanal;
• - wenigstens einen von dem wenigsten einen vertikalen Ätzkanal ausgehenden, unterhalb einer Ätzstoppschicht und unterhalb der Kaverne vorgesehenen und zwischen der Ätzstoppschicht und dem Siliziumsubstrat angeordneten lateralen Ätzkanal; und
• - wenigstens ein zwischen dem wenigstens einen lateralen Ätzkanal und der Kaverne ausgebildeter Zugangsätzkanal.

According to a first aspect, the object is achieved with a micromechanical component having:

• - a covering element;
• - a cavity arranged below the cover element;
• - at least one vertical etching channel arranged outside of an anchoring structure of the covering element;
• at least one lateral etching channel starting from the at least one vertical etching channel, provided below an etching stop layer and below the cavern and arranged between the etching stop layer and the silicon substrate; and
• at least one access etching channel formed between the at least one lateral etching channel and the cavern.

• - Ausbilden einer Kaverne unterhalb eines Abdeckelements;
• - Ausbilden wenigstens eines außerhalb einer Verankerungsstruktur des Abdeckelements angeordneten vertikalen Ätzkanals; wobei das Ausbilden der Kaverne mittels wenigstens eines vom vertikalen Ätzkanal ausgehenden, unterhalb einer Ätzstoppschicht und unterhalb der Kaverne vorgesehenen und zwischen der Ätzstoppschicht und dem Siliziumsubstrat angeordneten lateralen Ätzkanals und wenigstens eines Zugangsätzkanals in die Kaverne durchgeführt wird.

According to a second aspect, the object is achieved with a method for producing a micromechanical component, having the steps:

• - Forming a cavern below a covering element;
• - forming at least one vertical etching channel arranged outside of an anchoring structure of the covering element; wherein the formation of the cavity by means of at least one lateral etching channel starting from the vertical etching channel, provided below an etching stop layer and below the cavity and arranged between the etching stop layer and the silicon substrate and at least an access etching channel is carried out in the cavern.

In this way, a cavern area below the cover element can advantageously be cleared from below by a single vertical etching access, which extends into a lateral etching access. In this way, the covering element and electrical conductor tracks are advantageously largely unaffected by the lateral etching channel. Starting from the vertical etching channel, a network of lateral etching channels can advantageously be created, as a result of which etching accesses from below into the cavern area can be formed in a simple manner.

This advantageously supports the fact that at least one lateral etching channel can be provided at defined points below the cavity area and below an etch stop layer, from which at least one access etching channel can be provided through the etch stop layer for etching the cavity area from below.

As a result, gaseous etching medium for clearing out a cavern area can be distributed in an efficient manner. In this way, the cavern area can advantageously be cleared out from below in a comparatively short time and not just coming from the side, as is conventionally provided, due to the principle, with a comparatively long etching time.

In this way, an etching medium can advantageously be distributed very efficiently within the cavern area, with the etching fronts starting from at least one access etching channel through the etching stop layer and at least one lateral etching channel between etching stop layer and substrate being able to start from below into the cavern area. As a result, a large cavern area can be quickly and efficiently cleared from below over a large area.

Preferred developments of the micromechanical component are the subject of dependent claims.

An advantageous development of the micromechanical component is characterized in that the vertical etching channel is designed in the form of a column or tube. This advantageously results in different geometric configurations of the vertical etching channel.

Further advantageous developments of the micromechanical component are characterized in that at least one electrically conductive delimiting element laterally delimiting at least one lateral etching channel and/or an electrically insulating delimiting element is formed in a first silicon dioxide layer.

In this way, electrically conductive “Si plugs” can be formed, by means of which there are advantageously diverse possibilities for electrically contacting various elements of the micromechanical component. In this way, an electrical substrate contact, for example, can also be realized via the vertical etching channel. In addition, the at least one delimiting element can be provided as a lateral etching stop structure during the production of the at least one lateral etching channel. The advantages described can also be realized in the variant with the non-electrically conductive delimiting element. In both variants, it is essential that the delimiting elements are resistant to etching or have a low etching rate compared to the etching medium for removing the sacrificial layer(s) in the cavern area.

A further advantageous development of the micromechanical component is characterized in that the vertical etching channel is electrically conductively connected to the covering element or is designed to be electrically insulated from the covering element. In this way, different options for making electrical contact with the cover element can be implemented.

A further advantageous development of the micromechanical component is characterized in that the at least one lateral etching channel in a first silicon dioxide layer is delimited by at least one electrically conductive or electrically insulating delimiting element which is etch-resistant to a sacrificial layer etching medium. In this way, the vertical etching channel can be electrically conductively connected to the remaining layer system or insulated from it.

A further advantageous development of the micromechanical component is characterized in that the at least one lateral etching channel is formed at least partially within the substrate or at least partially above the substrate. As a result, even larger cross sections can advantageously be formed for the at least one lateral etching channel.

Further advantageous developments of the micromechanical component are characterized in that a plurality of lateral etching channels are formed starting from the at least one vertical etching channel and/or starting from the at least one lateral etching channel, the plurality of lateral etching channels being formed in a network and/or in parallel. Beneficial can in this way a dimensioning of an entirety of lateral etching channels can be realized.

The invention is described in detail below with further features and advantages on the basis of several figures. Elements that are the same or have the same function have the same reference numbers therein. The figures are intended in particular to clarify the principles which are essential to the invention and are not necessarily drawn to scale. For the sake of better clarity, it can be provided that not all of the reference symbols are drawn in in all of the figures.

• 1-3 Querschnittsansichten eines konventionellen mikromechanischen Bauelements;
• 4 eine Querschnittsansicht einer Ausführungsform eines vorgeschlagenen mikromechanischen Bauelements;
• 5-7 alternative Varianten zur Bereitstellung von Ätzkanälen des vorgeschlagenen mikromechanischen Bauelements;
• 8 eine Querschnittsansicht einer Ausführungsform eines vorgeschlagenen mikromechanischen Bauelements;
• 9 eine Querschnittsansicht einer weiteren Ausführungsform eines vorgeschlagenen mikromechanischen Bauelements;
• 10-14 Querschnittsansichten durch laterale Ätzkanäle eines vorgeschlagenen mikromechanischen Bauelements;
• 15-18 Querschnittsansichten durch laterale Ätzkanäle eines vorgeschlagenen mikromechanischen Bauelements;
• 19-23 Querschnittsansichten durch laterale Ätzkanäle eines vorgeschlagenen mikromechanischen Bauelements;
• 24-28 Querschnittsansichten durch laterale Ätzkanäle eines vorgeschlagenen mikromechanischen Bauelements;
• 29-31 Draufsichten auf Ausführungsformen des vorgeschlagenen mikromechanischen Bauelements; und
• 32 einen prinzipiellen Ablauf zum Herstellen eines vorgeschlagenen mikromechanischen Bauelements.

In the figures shows:

• 1-3 Cross-sectional views of a conventional micromechanical component;
• 4 a cross-sectional view of an embodiment of a proposed micromechanical component;
• 5-7 alternative variants for providing etching channels of the proposed micromechanical component;
• 8th a cross-sectional view of an embodiment of a proposed micromechanical component;
• 9 a cross-sectional view of a further embodiment of a proposed micromechanical component;
• 10-14 Cross-sectional views through lateral etching channels of a proposed micromechanical component;
• 15-18 Cross-sectional views through lateral etching channels of a proposed micromechanical component;
• 19-23 Cross-sectional views through lateral etching channels of a proposed micromechanical component;
• 24-28 Cross-sectional views through lateral etching channels of a proposed micromechanical component;
• 29-31 Top views of embodiments of the proposed micromechanical component; and
• 32 a basic process for producing a proposed micromechanical component.

Description of Embodiments

A core idea of the invention consists in particular in realizing etching channel structures that are independent of layers and layer thicknesses that are used to produce a functional layer system of a sensor element, and that make it possible, for example, to implement only small etchings of SiO2 layers along conductor track structures outside of a cavern area.

For this purpose, provision is made for etching channels not to be provided in layers within a functional layer system that are required for the realization of the mechanical and electrical function of a sensor element, but rather in their substructure. In this context, a “substructure” is understood to mean a layer system that is located between an etch stop layer (e.g. silicon-rich silicon nitride, SiRiN) and the silicon substrate.

Essentially two types of etching accesses are known in the prior art. For example, an etching access within a cavern area is known, which opens directly into the cavern area from the upper side of the layer system. Also known is an etching access which opens into the cavity region from the top side of the layer system, but from outside the cavity region, via a lateral etching channel within the layer system. In this variant, the lateral etching channel is usually routed orthogonally within the functional layer system through a cavern wall.

1 1 shows a cross section through a conventional micromechanical component 100 in the form of a sensor element with an Si substrate 1 (silicon substrate) and a first silicon dioxide layer 2 arranged thereon. An etch stop layer 3 is arranged on the first silicon dioxide layer 2. FIG. A first functional layer 4 is located on the etch stop layer 3. A second silicon dioxide layer 5 is arranged on the first functional layer 4, on which a second functional layer 6 is arranged. A third silicon dioxide layer 7 is arranged on the second functional layer 6, on which a third functional layer 8 is arranged, from which the covering element 10, for example in the form of a membrane or a cap element, is later formed. The material used for the functional layers 4, 6, 8 can be polysilicon, for example, preferably a polysilicon provided with a dopant.

At least one vertical etching channel 11 is guided through the cover element 10 and ends in a cavern area 7a (later cavern 20) on the third silicon dioxide layer 7. FIG. Silicon dioxide material is removed from the cavern region 7a via the at least one vertical etching channel 11 with the aid of a liquid or gaseous etching medium which, for example, has HF. As in 2 implied the cavern 20 under the cover element 10 is created in the process or as a result. The vertical etching channel 11 is then closed with a closure element 11a. The problem can be that when the cavity area 7a is cleared using an etching medium along electrical conductor tracks 4a of the first functional layer 4 which lead out of the cavity area 7a, uncontrolled etching X can take place along conductor tracks 4a and within the functional layer system. This occurs in particular when the electrical conductor tracks 4a of the first functional layer 4 are also at least partially surrounded by silicon dioxide for the purpose of electrical insulation.

An improvement of the above situation can be as in 3 indicated to arrange the at least one vertical etching channel 11 at a lateral distance from an anchoring structure of the cover element 10 in a region outside of the cavern 20, as a result of which the cover element 10 is no longer impaired. However, in this case the problem can still exist that electrical conductor tracks 4a formed in the first functional layer 4, which are located in the surrounding area of the lateral etching channel 12a formed in the functional layer system, are unfavorably etched.

In the prior art, etching channels from outside the cavity area end at the cavity walls and from there can remove the sacrificial layer(s) in the cavity area 7a. Since etching times can be long depending on the size of the cavern area 7a, insulation layers around conductor tracks 4a, which lead out of the cavern 20 and which are located in the vicinity or in the region of etching channels penetrating cavern walls, are exposed to an etching attack for a particularly long time.

For improvement, at least one lateral etching channel 12a is proposed, which is provided in the substructure of a proposed component 100 produced, for example, surface micromechanically, which can end at any desired point below a cavern area 7a and along the course of which at least one access etching channel 3a1 starting from the lateral etching channel 12a through the Etch stop layer 3 is guided to or into the cavern area 7a, from there sacrificial layers can be removed within the cavern area 7a, as is shown in 4 with an embodiment of a proposed micromechanical component 100 is indicated. Similar to etching accesses, which are guided from the surface via at least one vertical etching access 11, at least one access etching channel 3a1, 3b through the etch stop layer 3 and at least one lateral etching channel 12a directly into a cavern area 7a and can be arranged arbitrarily, one or several access etching channels 3a ... 3n are positioned in the substructure in such a way that a rapid, homogeneous and complete removal of sacrificial layers can be guaranteed without making a perforation, for example of the cover element 10 and thereby accepting mechanical restrictions and/or major design restrictions in the functional layer system have to.

Compared to conventional micromechanical components, the proposed formation of one or more lateral etching channels 12a...12n in the substructure also offers the possibility of placing an etching channel network, e.g. under the cavern area 7a, which only requires a single vertical etching access 11 on the upper side of the functional layer system. By positioning the one or more access etching channels 3a1...3an more centrally below the cavern area 7a, the removal of sacrificial layers, starting from the cavern center, can result in insulation or sacrificial layer material being removed along conductor tracks 4a, 4b outside of the cavern area 7a can be avoided, or at least greatly minimized.

In the variants shown of the proposed micromechanical component 100, the walls of the cavern area 7a and those of the etching channels 11, 12a . . . 12n are made of silicon, for example, due to the functional layer system. Here, Poly-Si layers within the functional layer system are used to implement both lateral etching limiting structures and electrical connections between Poly-Si levels within electrically insulating layers, e.g. made of SiO2. In principle, however, it is also possible to use electrically insulating materials for lateral etch protection boundaries if they have a high etch resistance to the etching medium used to remove the sacrificial layer(s), such as SiRiN when using HF vapor as the etching medium.

The production of etch channels in a functional layer system substructure consisting of a first silicon dioxide layer 2, which is located between an etch stop layer 3 consisting of SiRiN and a silicon substrate 1, can be carried out as follows, for example:

At least one first silicon dioxide layer 2 is deposited or thermally grown on the substrate 1 and structured using standard methods in such a way that the first silicon dioxide layer 2 is removed down to the substrate 1 in a defined area. This can be done with the help of a plasma etching process or by wet chemical etching (eg in BOE). With the subsequent deposition of the etch stop layer 3, these structures can then be filled. If these structures are designed appropriately, they can form the walls of an etching channel and serve as lateral etching stop structures in a later etching process to remove SiO2 sacrificial layers in the cavern area.

Furthermore, it is also conceivable to fill these structures with silicon, e.g. with the help of LPCVD deposition. Etch stop layer 3 can then be deposited on this silicon layer, or the poly-Si layer is removed from first silicon dioxide layer 2, e.g. using a CMP method, so that poly-Si only remains in the exposed structures of first silicon dioxide layer 2. The superficial removal of the poly-Si layer on the oxide can then be necessary if the smallest possible parasitic capacitance is to be formed between the electrically active layers of the functional layer system of the component 100 and the substrate 1 .

Compared to filling the exposed structures in the first silicon dioxide layer 2 with the aid of an electrically insulating material (e.g. SiRiN), filling the structures with electrically conductive poly-Si (polysilicon) has the advantage that the substrate 1 is also electrically connected or contacted in a targeted manner can be used to place it on a defined electrical potential. In order to increase the conductivity of the polysilicon structures through the first silicon dioxide layer 2, the poly-Si can also be doped in a targeted manner during the deposition or else in a subsequent step. Thus, with the help of a poly-Si filling, lateral etching delimitations as well as one or more electrical contacts of the substrate 1 can be realized.

4 shows a sketch of a cross section through a micromechanical component 100 produced in this way, in which at least one vertical etching channel 11 was provided in a functional layer system outside of a cavity region 7a, which is connected via an access etching channel 3b in the first functional layer 4 and the etching stop layer 3 to a lateral etching channel 12a.. 12n in the substructure of the micromechanical component 100, which in turn is connected to the cavity region 7a via an access etching channel 3a1 in the first functional layer 4 and the etching stop layer 3. The at least one vertical etching channel 11 can be designed in the form of a column or in the form of a tube.

By removing oxide material in vertical etching channel 11 within the functional layer system, the walls of which advantageously consist of silicon, for example, and the oxide material within lateral etching channel 12a...12n in the substructure of micromechanical component 100, access etching channels 3a1...3an, 3b can provide at least one Access to the cavern area 7a of the micromechanical component 100 can be created, via which the at least one sacrificial layer made of e.g. SiO2 in the cavern area 7a can be removed. Due to the position of the lateral etching channel 12a... 12n in the substructure of the sensor element 100, access etching channels 3a1...3an can be created at any defined positions within the cavity area 7a, via which the at least one sacrificial layer is removed from the cavity area 7a can be. In this way, when laying out the sensor design, no measures, or no measures that significantly limit the design, have to be taken into account for the realization of etching channels within the functional layer system.

The silicon dioxides in the etching channels 11, 3a1...3an, 3b, 12a...12n and in the cavern area 7a can be removed by means of an HF gas phase etching process or by means of a wet-chemical etching process (e.g. BOE) that includes HF.

the 5-7 show several possibilities for the formation of access etch channels 3a1...3an and 3b from the functional layer area to the substructure through the etch stop layer 3.

5 shows, for example, how an etch access 3a1, 3b can be etched through the first functional layer 4 and the etch stop layer 3 with the aid of a mask level, and the resulting depressions can then be filled with the second silicon dioxide layer 5.

6 indicates a further possibility, with the aid of two mask levels first the etch stop layer 3 and then the first functional layer 4 being structured in such a way that in the area of access etch channel structures 3a1, 3b the channel structures are formed through the etch stop layer 3 within the opening area of the channel structures through the first functional layer 4 and then the resulting depressions/channel structures are filled with silicon oxide material of the second silicon dioxide layer 5 .

7 shows a further variant in which the etch stop layer 3 is structured first, then the first functional layer 4 is deposited and structured in such a way that channel structures through the first functional layer 4 are located within the opening area of access etch channel structures 3a1, 3b through the etch stop layer 3 and then the resulting depressions / etching access channel structures 3a1, 3b are filled with silicon dioxide material of the second silicon dioxide layer 5.

By using the electrically insulating etch stop layer 3, it can be achieved that the vertical etching channel 11 is formed electrically insulated from the substructure of the functional layer system by the functional layer system, as shown in FIG 8th implied.

This can be used to be able to electrically contact at least one electrical conductor track 4a of the functional layer system via the at least one vertical etch channel 11 with its conductive walls made of poly-Si and/or by providing one or more corresponding contacts through the etch stop layer 3 one or more to be able to contact electrically conductive delimiting elements 13a ... 13n in the form of Si structures in the first silicon dioxide layer 2, via which the substrate 1 can also be electrically contacted, as in 9 implied. In this way, the substrate 1 can also be electrically contacted at the same time via the vertical etching channel 11 through the functional layer system. On the other hand, if electrically insulating layers such as SiRiN are used for the lateral etching delimitation of etching channels in the first silicon dioxide layer 2, a substrate contact must be produced with the aid of further process steps, which can cause additional costs.

As an alternative to the described production of electrically conductive limiting elements 13a ... 13n in the first silicon dioxide layer 2, the procedure can also be such that the Si structures, which are used, for example, for lateral etching limitation at least one lateral etching channel 12a ... 12n and/or for electrical Contacting of the substrate 1 in the first silicon dioxide layer 2 in the substructure of the sensor element 100 are intended to serve, are first structured out of the substrate 1 with the aid of a mask level, as in 10 indicated and then covered by depositing a SiO2 layer, as in 11 recognizable.

If a CMP process is then carried out to planarize the wafer surface, the raised electrical delimiting elements 13a... 13n can be uncovered again and an SiO2 layer can be left between them, as in 12 implied. With the help of electrically conductive _delimiting elements 13a . In this way, lateral etching channels 12a...12n that are not completely filled or a lateral etching channel system that is not completely filled are obtained in the first silicon dioxide layer 2 of the substructure, through which an etching medium, such as HF vapor, can flow through the lateral etching channels 12a... 12n to the access etching channels 3a1...3an in the cavern area 7a.

As a result, it is possible in this way to implement a rapid etching attack on sacrificial oxide layers in the cavern area 7a even when using longer, lateral etching channels 12a . . . 12n. Furthermore, with this method, the poly-Si deposition step for filling the exposed structures in the first silicon dioxide layer 2 and also a possibly subsequent doping step can be saved.

13 shows the in 12 described substructure with part of the subsequently deposited functional layer system. 14 shows the lateral etching channels 12a-12c through the functional layer system after the etching of the oxide sacrificial layers in the cavern area 7a. In this variant, the at least one vertical etch channel 11 within the functional layer system can be implemented in such a way that the vertical etch channel 11 is split into a plurality of etch channel structures, which open into the lateral etch channels 12a-12c.

So how in the 10-14 can be seen, with a corresponding design of the vertical etch channel 11 in the functional layer system, several lateral etch channel structures 12a . . . 12n in the first silicon dioxide layer 2 can be connected to only one vertical etch channel 11 in the functional layer system. This can advantageously be used to enlarge the effective cross section of a lateral etching channel 12a...12n. Furthermore, starting from the at least one vertical etching channel 11 through the functional layer system, several lateral etching channels 12a . . . For this purpose, the splitting of the at least one vertical etching channel 11 does not necessarily have to take place in the functional layer system. Rather, the at least one vertical etching channel 11 can also open into at least one lateral etching channel 12a . . . 12n and from there the distribution to a plurality of lateral etching channels 12a .

As an alternative to the procedure described in the 10-14 An enlargement of a lateral etching channel cross section can also be achieved by first etching trenches in the substrate 1 in the area of a lateral etching channel 12a...12n and sealing them with the aid of the first silicon dioxide layer 2 in such a way that a cavity 2a... .2n is formed, as in the 15 and 16 implied.

Using the already associated with 4 described manufacturing steps can now the lateral etch stops in the first silicon dioxid layer 2 are generated and the further functional layer structure can be realized. During the removal of the sacrificial oxide layers in the cavern area 7a, the etching medium can be distributed quickly along the cavities 2a...2n in the trenches, even in long, lateral etching channels 12a...12n, thereby advantageously achieving a significant reduction in the sacrificial oxide layer etching time compared to completely filled trenches .

Plays the formation of parasitic capacitances between the functional layer system and the substrate 1 does not matter, so, referring to the 15-18 the layer system of the substructure and thus the first silicon dioxide layer 2 mentioned in the examples shown can also be dispensed with.

As in the 19-23 shown, the deposited first silicon dioxide layer 2 can be removed, for example using a CMP process (chemical mechanical polishing), in such a way that the cavities created in the lateral trench channels 12a...12n remain sealed with material from the first silicon dioxide layer 2 , while on the remaining substrate 1, the first silicon dioxide layer 2 is completely removed. After the partial removal of the first silicon dioxide layer 2, the manufacturing process already described for realizing the functional layer system with optional electrical contacting of the substrate 1 then takes place.

Another variant for the production of the lateral etching channels 12a ... 12n is in the 24-28 shown. In this case, a first silicon dioxide layer 2 is first produced on the substrate 1 and this is structured in such a way that silicon can be removed from the substrate 1 through the openings produced, as in FIGS 24 and 25 implied. After the substrate 1 has been etched, the openings in the first silicon dioxide layer 2 are closed with the aid of a second silicon dioxide layer 5 in such a way that cavities 1a...1n are formed in the substrate 1, as shown in FIG 26 recognizable.

Depending on the choice of etching process (isotropic, anisotropic, combination of both), individual lateral channel structures 12a... 12n (as in 24 indicated) and/or lateral canal structures with a large canal cross-section (as in 25 indicated) are generated. If the openings in the first silicon dioxide layer 2 are small or narrow, they can be closed quickly. As a result, only slight topographical differences arise on the upper side of the sealing layer, in this case the second silicon dioxide layer 5, which makes an additional CMP step for the production of a planar surface unnecessary.

Compared to the related to the 10-14 explained variant, this variant has the advantage that under the first silicon dioxide layer 2, the channel structures in the substrate 1 can have almost any shape and do not have to be designed in such a way that they can be closed quickly in order to be able to create cavities.

If, as explained above, the channel structures described are also provided below lateral channel structures running in the substructure (as in 27 indicated), a e.g 28 recognizable. As a result, a further increase in the cross-section of the channel can advantageously also be provided.

In all variants shown, the electrically insulating etch stop layer 3, which is etch-resistant to the etching medium used to remove sacrificial layers, and the lateral etch stop boundaries 13a...13n in the substructure serve to guide etching channels for removing sacrificial layers to any desired location within a cavern area.

The proposed micromechanical component 100 produced using the proposed method can be a capacitive pressure sensor, for example. However, other forms of implementation are also conceivable, such as a microphone, piezoresistive pressure sensor, etc.

the 29-31 12 show plan views of various embodiments of the proposed micromechanical component 100. It can be seen that, starting from a vertical etch channel 11, a plurality of lateral etch channels 12a...12n can be formed in their area or course at defined positions access etch channels 3a1...3an through the etch stop layer 3 can be provided in the cavern area 7a, through which a sacrificial layer etching can take place within the cavern area 7a from below.

32 shows a basic sequence of a method for producing a proposed micromechanical component 100.

In a step 200, a cavity 20 is formed below a cover element 10.

In a step 210, at least one vertical etching channel 11 arranged outside of an anchoring structure of the covering element 10 is formed, the cavity 20 being formed by means of at least one of the vertical Etching channel 11 outgoing, provided below an etch stop layer 3 and below the cavern 20 and arranged between the etch stop layer 3 and the silicon substrate 1 lateral etching channel 12a ... 12n and at least one access etching channel 3a1 ... 3an in the cavern 20 is performed.

Claims (10)

Micromechanical component (100), comprising: - a cover element (10); - A cavity (20) arranged below the cover element (10); - at least one vertical etching channel (11) arranged outside of an anchoring structure of the covering element (10); - at least one lateral etching channel (12a...12n) starting from the at least one vertical etching channel (11), provided below an etching stop layer (3) and below the cavity (20) and arranged between the etching stop layer (3) and the silicon substrate (1). ); and - at least one access etching channel (3a1...3an) formed between the at least one lateral etching channel (12a...12n) and the cavern (20). Micromechanical component (100) after claim 1 , characterized in that the at least one vertical etching channel (11) is column-shaped or tubular. Micromechanical component (100) after claim 1 or 2 , characterized in that in a first silicon dioxide layer (2) there is at least one electrically conductive delimiting element (13a... 13n) laterally delimiting the at least one lateral etching channel (12a...12n) and/or an electrically insulating delimiting element (13a... 13n) is formed. Micromechanical component (100) according to one of the preceding claims, characterized in that the at least one vertical etching channel (11) is electrically conductively connected to the covering element (10) or is electrically insulated from the covering element (10). Micromechanical component (100) according to one of the preceding claims, characterized in that the at least one vertical etching channel (11) is electrically conductively connected to the at least one electrically conductive delimiting element (13a... 13n) or is separated from the at least one electrically conductive delimiting element (13a ... 13n) is designed to be electrically insulated. Micromechanical component (100) after claim 4 or 5 , characterized in that the at least one lateral etching channel (12a... 12n) is delimited in a first silicon dioxide layer (2) by at least one electrically conductive and/or electrically insulating delimiting element (13a... 13n). Micromechanical component (100) according to one of the preceding claims, characterized in that the at least one lateral etching channel (12a...12n) is formed at least partially within the substrate (1) or at least partially above the substrate (1). Micromechanical component (100) according to one of the preceding claims, characterized in that a plurality of etching channels (12a...12n) are formed starting from the at least one vertical etching channel (11). Micromechanical component (100) after claim 8 , characterized in that the plurality of lateral etching channels (12a... 12n) are formed like a network and/or in parallel. Method for producing a micromechanical component (100), having the steps: - Forming a cavern (20) below a cover element (10); - forming at least one vertical etching channel (11) arranged outside of an anchoring structure of the covering element (10); wherein the formation of the cavern (20) by means of at least one lateral etching channel ( 12a... 12n) and at least one access etching channel (3a1...3an) into the cavern (20).

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