DE102008003242B4 - Micromechanical component and method for producing a micromechanical component - Google Patents

Abstract

Micromechanical component (1), comprising a homogeneous substrate (2) having a main extension plane (11) and a further layer (3) formed parallel to the main extension plane (11), characterized in that the substrate (2) is structured such that the substrate (2) has a micromechanical functional layer (2 ') which is arranged in a plane (11') arranged parallel to the main extension plane (11 ') in the substrate (2) and which at least in a direction (10') perpendicular to the main extension plane (11) partially overlapping the further layer (3), the micromechanical component (1) has a capping layer (4), wherein the capping layer (4) on a first side (5) of the substrate (2) and the further layer (3) on a second Side (6) of the substrate (2) is arranged, the further layer (3) has trenches (9) perpendicular to the main extension plane (11) and the further layer (3) contact pads (12).

Description

State of the art

The invention is based on a micromechanical component according to the preamble of claim 1.

Such base elements are well known. For example, from the document DE 43 15 012 B4 a sensor with a movable monocrystalline sensor element is known, wherein the movable sensor element is mounted on a plate-shaped substrate made of monocrystalline silicon and wherein the attachment of the sensor element on the substrate by means of an insulating layer, disposed between the sensor element and the substrate is provided.

The publication US 5 243 861 A discloses a semiconductor accelerometer consisting of three superimposed silicon substrates. Micromechanical functional elements are formed from the middle substrate. The publication US Pat. No. 5,846,849 and the publication US Pat. No. 6,239,473 B1 each discloses a micromechanical device having a substrate and a plurality of further layers, in which the substrate is also patterned. The publication DE 103 22 988 A1 discloses an electron beam mask substrate having a substrate layer for backside etching a membrane layer carrier, an etch stop layer formed on the substrate layer, and a membrane layer formed on the etch stop layer. The publication DE 196 32 060 A1 discloses a yaw rate sensor constructed from a three-layer system. The rotation rate sensor and conductor tracks are structured out of the third layer and electrically insulated against a first layer via a second electrical insulating layer. The publication DE 195 26 903 A1 discloses a yaw rate sensor made of a multilayer substrate in which an acceleration sensor is arranged on a rocker. The publication DE 100 55 081 A1 discloses a surface micromechanical device. Here is a micromechanical functional layer 14 over a substrate 10 arranged. From the micromechanical functional layer 14 is a microstructure 18 structured out. The publication DE 10 2007 001 290 A1 discloses a semiconductor module of three stacked substrates, the middle substrate of which is formed by a patterned semiconductor chip. The publication DE 10 2006 023 701 A1 discloses a micromechanical component having a substrate, a structured micromechanical functional layer arranged above it and a cap arranged above the functional layer.

Disclosure of the invention

The micromechanical component according to the invention and the method according to the invention for producing a micromechanical component according to the independent claims have the advantage over a comparatively small number of production steps that a micromechanical component can be produced which has a comparatively thick functional layer perpendicular to the main extension plane. Thus, for example, an increase in the aspect ratio of capacitive sensors is achieved, whereby the required chip area of the capacitive sensors is reduced compared to the prior art. The manufacturing cost of the micromechanical device are therefore significantly reduced. The functional layer is formed from the material of the substrate, which preferably comprises a monocrystalline silicon, and overlaps with the substrate in a direction perpendicular to the surface normal of the main extension plane.

A further subject matter of the present invention is a micromechanical component having a substrate having a main extension plane and a further layer formed parallel to the main extension plane, the substrate being structured such that the substrate has a micromechanical functional layer which is in a plane parallel to the main extension plane in the substrate is arranged and which at least partially overlaps the further layer in a direction perpendicular to the main extension plane. In an advantageous manner, the micromechanical functional layer is thus formed by a corresponding structuring of the substrate, so that the structures of the micromechanical functional layer are formed in particular by the material of the substrate. The micromechanical functional view is particularly advantageously covered by the further layer, which preferably comprises an epitaxial layer applied to the substrate, so that movable elements of the micromechanical functional layer are electrically contacted by the further layer, mechanically fixed and / or protected from mechanical and / or chemical influences become. In particular, it is advantageously possible in accordance with the invention in this way for the functional layer of the micromechanical component to be hermetically sealed on the side of the further layer through which the overlapping or continuous further layer is made, thus assuming the function of a capping by the further layer ,

Advantageous embodiments and further developments of the invention are the subclaims, and the description with reference to the drawings.

According to a preferred embodiment, it is provided that the micromechanical functional layer extends perpendicular to the main extension plane at least over 50%, preferably at least over 75% and particularly preferably at least over 90% of the substrate thickness. Such an increase in the functional layer thickness particularly advantageously further increases the aspect ratio of the micromechanical component, as a result of which the chip area is reduced and thus the production costs decrease.

According to a further preferred development, it is provided that the micromechanical functional layer has movable elements and / or that the substrate has a further layer. In an advantageous manner, in particular electrodes can be realized by the movable elements, which are preferably provided for the capacitive measurement of inertial forces acting on the movable elements. Particularly preferably, the further layer and / or parts of the further layer allow the electrical contacting of the movable elements and / or the formation of conductor tracks. Most preferably, the substrate and / or the functional layer comprise counterelectrodes with respect to the electrodes formed by the movable elements.

In accordance with a further preferred development, it is provided that the micromechanical component has a capping layer, the capping layer preferably being arranged on a first side of the substrate and the further layer being arranged on a second side of the substrate. The capping layer functions particularly advantageously for the protection of the micromechanical functional layer, with the oscillation capabilities of the movable elements preferably being adjusted by the inclusion of a special atmosphere in the micromechanical functional layer. The micromechanical functional layer is particularly advantageously protected and / or atmospherically sealed by the further layer on a side opposite the capping layer perpendicular to the main extension plane.

According to a further preferred development, it is provided that the substrate has a cavern, wherein the cavern is preferably formed in the region of the movable elements and / or on the first side. The formation of the cavern advantageously allows a comparatively precise definition of the functional layer thickness perpendicular to the main extension plane.

According to a further preferred development, it is provided that at least partially an insulation layer is arranged between the substrate and the further layer and / or that the further layer has trenches perpendicular to the main extension plane and / or that the further layer has contact pads. Advantageously, contact pads allow the electrical contacting of the micromechanical device, while an electrical insulation of parts of the further layer is realized by the trenches. The insulating layer preferably functions for electrically insulating the functional layer and / or the substrate from the further layer and / or for fastening the further layer to the functional layer and / or the substrate. Particularly preferably, the insulating layer is arranged in the trenches, while the insulating layer is at least partially etched away in the functional layer.

According to a further preferred development, it is provided that the micromechanical component is an inertial sensor. Advantageously, an inertial sensor with a comparatively high aspect ratio is realized by the micromechanical component.

Another object of the present invention is a method for producing a micromechanical device according to the invention, wherein in a first process step, a substrate is provided and wherein in a second process step on the substrate, a further layer is applied and further wherein in a third process step, the substrate is patterned , Due to the structuring of the substrate itself, the functional layer of the material of the substrate is particularly advantageously formed in the substrate. Due to the comparatively large substrate thicknesses perpendicular to the main extension plane, functional layers which have a significantly greater aspect ratio are thus made possible in comparison to the prior art. The further layer is preferably used for electrical contacting of the substrate and / or the functional layer.

According to a preferred development, it is provided that, in a fourth method step, the substrate is coated at least on one side with an insulating layer before the second method step and / or before the third method step, the further. Layer is coated in a fifth process step with a further insulating layer. Thus, part of the substrate, the functional layer and / or the further layer are particularly electrically insulated from one another.

According to a further preferred development, it is provided that before the third method step, the further layer in a sixth Process step structured and / or the substrate is etched in a seventh process step. The structuring of the further layer particularly advantageously allows the electrical insulation of parts of the further layer for electrical contacting of the functional layer and / or of the substrate and / or for the formation of conductor tracks.

The etching of the substrate allows a comparatively precise definition of the substrate or functional layer thickness.

According to a further preferred development, it is provided that, after the fourth method step, the insulation layer is patterned in an eighth method step and / or that after the fifth method step the further insulation layer is patterned in a ninth method step and / or that the insulation layer is etched in a twelfth method step , Particularly advantageously, the structuring of the insulation layer and / or the further insulation layer allows both the definition of mechanically strong connections between the insulation layers and the substrate and / or the further layer, and the definition of wegätzbaren insulation layers, for example, in the region of the functional layer by an etching process allow the formation of the moving elements.

According to a further preferred development, it is provided that, after the third method step, the substrate is at least partially covered by a capping layer in a tenth method step and / or at least one contact pad is arranged on the further layer in an eleventh method step. Particularly advantageously, the arrangement of at least one contact pad allows the electrical contacting of the micromechanical device, while the capping layer acts to protect and / or to atmospheric sealing of the micromechanical functional layer.

Embodiments of the present invention are illustrated in the drawings and explained in more detail in the following description.

Brief description of the drawings

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1a 1 is a schematic side view of a first precursor structure for producing a micromechanical device according to a first embodiment,

1b 1 is a schematic side view of a second precursor structure for producing a micromechanical device according to the first embodiment,

1c FIG. 2 shows a schematic side view of a third precursor structure for producing a micromechanical device according to the first embodiment, FIG.

1d FIG. 2 shows a schematic side view of a fourth precursor structure for producing a micromechanical component according to the first embodiment, FIG.

1e FIG. 2 shows a schematic side view of a fifth precursor structure for producing a micromechanical device according to the first embodiment, FIG.

1f FIG. 2 shows a schematic side view of a sixth precursor structure for producing a micromechanical component according to the first embodiment, FIG.

1g a schematic side view of a micromechanical device according to the first embodiment and.

2 a schematic perspective view of a micromechanical device according to a second embodiment.

Embodiment (s) of the invention

In the various figures, the same parts are always provided with the same reference numerals and are therefore usually named only once in each case.

In 1a is a schematic side view of a first precursor structure for producing a micromechanical device to illustrate a first, fourth and eighth process step 1 according to a first embodiment, wherein in the first method step, the substrate 2 provided. The substrate 2 is in the fourth step on both sides, each with an insulating layer 8th coated, wherein one of the insulating layers 8th is structured in the eighth process step. The substrate 2 preferably comprises a monocrystalline silicon wafer. At the insulation layer 8th it is preferably a thermal oxide, which is structured in a standard method, such as Tegal, LAM. The substrate 2 has a main extension plane 11 on.

In 1b is a schematic side view of a second precursor structure for producing a micromechanical device to illustrate a second and sixth method step 1 according to the first embodiment, wherein in the second method step on the substrate 2 or the structured insulation layer 8th another layer 3 is applied, which preferably comprises a polycrystalline silicon, which is particularly preferably deposited by an epitaxial process. In a sixth method step, the further layer 3 structured, in particular trenches 9 in the further layer 3 be formed by trench method. The further layer is preferred 3 planarized by a standard method.

In 1c is a schematic side view of a third precursor structure for producing a micromechanical device to illustrate a fifth and ninth method step 1 according to the first embodiment, wherein in the fifth method step, the further layer 3 with another insulation layer 8th' is covered, which is structured in a subsequent ninth step. The trenches are preferred 9 through further insulation layer 8th' completely filled, with the further insulation layer 8th' particularly preferably comprises a thermal oxide, which very particularly preferably by means of a MORI method for producing conductive structures in the further insulating layer 8th' is structured.

In 1d is an illustration of an eleventh process step, a schematic side view of a fourth precursor structure for producing a micromechanical device 1 illustrated in the first embodiment, wherein in the eleventh step on the further insulating layer 8th' contact pads 12 are arranged, which for electrical contacting of the micromechanical device 1 serve. The contact pad 12 preferably comprises a metal surface and / or a metallic conductor track.

In 1e is a schematic side view of a fifth precursor structure for producing a micromechanical device to illustrate a seventh process step 1 according to the first embodiment, wherein in the seventh process step, the substrate 2 is etched. Before the seventh process step, the fifth precursor structure is preferably rotated 180 degrees, with the axis of rotation in the main plane of extension 11 lies. Particularly preferred is a cavern 7 in the substrate 2 etched, so that a desired residual thickness of the substrate perpendicular to the main plane of extension between the substrate surface and the insulating layer 8th is set. The etching process is especially on a first page 5 of the substrate 2 performed, which is perpendicular to the main plane of extension 11 on the opposite side of a second page 6 with the further layer 3 with respect to the substrate 2 is arranged.

In 1f FIG. 3 is a schematic side view of a sixth precursor structure for producing a micromechanical device, to illustrate a third and a twelfth process step. FIG 1 according to the first embodiment, wherein in the sixth method step, the substrate 2 is structured and in a subsequent twelfth process step, the insulation layer 8th is etched, preferably by means of a gas phase etching process. Particularly preferred is the substrate 2 in the area of the cavern 7 trimmed, so that after the twelfth process step in the substrate 2 movable elements 2 ' from the material of the substrate 2 be formed

In 1g is a schematic side view of the micromechanical device 1 illustrated in the first embodiment, wherein in a tenth method step, the micromechanical device 1 with a capping layer 4 is covered. Preferably, the capping layer comprises 4 a thin-film cap, which is on the first page 5 of the substrate is arranged. The cap wafer 4 is particularly preferably by means of a seal-glass connection or by means of an anodic bonding process to the substrate 2 attached.

In 2 is a schematic perspective view of a micromechanical device 1 according to a second embodiment, wherein exemplified a comb structure 20 from moving electrodes 21 and fixed counterelectrodes 22 is shown, wherein the movable electrodes 21 fixed to each other and spring structures 23 with the substrate 24 are elastically connected.

Claims (11)

Micromechanical device ( 1 ), with a main extension plane ( 11 ) homogeneous substrate ( 2 ) and one parallel to the main extension plane ( 11 ) formed further layer ( 3 ), characterized in that the substrate ( 2 ) is structured such that the substrate ( 2 ) a micromechanical functional layer ( 2 ' ), which in one to the main extension plane ( 11 ) parallel plane ( 11 ' ) in the substrate ( 2 ) is arranged and which in a to the main extension plane ( 11 ) vertical direction ( 10 ' ) at least partially the further layer ( 3 ) overlaps the micromechanical device ( 1 ) a capping layer ( 4 ), wherein the capping layer ( 4 ) on a first page ( 5 ) of the substrate ( 2 ) and the further layer ( 3 ) on a second page ( 6 ) of the substrate ( 2 ), the further layer ( 3 ) Trenches ( 9 ) perpendicular to Main extension level ( 11 ) and the further layer ( 3 ) Contact Pads ( 12 ) having. Micromechanical device ( 1 ) according to claim 1, characterized in that the micromechanical functional layer ( 2 ' ) perpendicular to the main plane of extension ( 11 ) at least over 50%, preferably at least over 75%, and more preferably at least over 90% of the substrate thickness ( 10 ). Micromechanical device ( 1 ) according to one of the preceding claims, characterized in that the micromechanical functional layer ( 2 ' ) has movable elements. Micromechanical device ( 1 ) according to one of the preceding claims, characterized in that the substrate ( 2 ) a cavern ( 7 ), wherein the cavern ( 7 ) preferably in the region of the movable elements ( 2 ' ) and / or on the first page ( 5 ) is trained. Micromechanical device ( 1 ) according to one of the preceding claims, characterized in that between the substrate ( 2 ) and the further layer ( 3 ) at least partially an insulating layer ( 8th ) is arranged. Micromechanical device ( 1 ) according to one of the preceding claims, characterized in that the micromechanical component ( 1 ) is an inertial sensor. Method for producing a micromechanical component ( 1 ) according to one of the preceding claims, characterized in that in a first process step, a substrate ( 2 ), wherein in a second process step on the substrate ( 2 ) another layer ( 3 ) and wherein in a third process step the substrate ( 2 ), on the further layer ( 3 ) in an eleventh method step at least one contact pad ( 12 ) is arranged. Method according to claim 7, characterized in that, before the second method step, the substrate ( 2 ) in a fourth method step at least on one side with an insulating layer ( 8th ) and / or before the third process step, the further layer ( 3 ) in a fifth method step with a further insulation layer ( 8th' ) is coated. Method according to claim 8, characterized in that before the third method step the further layer ( 3 ) structured in a sixth method step and / or the substrate ( 2 ) is etched in a seventh process step. Method according to one of claims 8 or 9, characterized in that after the fourth process step, the insulating layer ( 8th ) is structured in an eighth method step and / or that after the fifth method step the further insulation layer ( 8th' ) is structured in a ninth method step and / or that in a twelfth method step the isolation layer ( 8th ) is etched. Method according to one of claims 7 to 10, characterized in that after the third method step, the substrate ( 2 ) in a tenth process step at least partially from a capping layer ( 4 ) is covered.

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