DE102018201965A1 - Micromechanical mirror device, mirror system and method for producing a micromechanical mirror device - Google Patents

Abstract

The invention provides a micromechanical mirror device, a mirror system and a method for producing a micromechanical mirror device. The mirror device is formed with: a first mirror element (10) which is planar;
a second mirror element (20) which is planar;
wherein the first and the second mirror element (10, 20) are arranged substantially plane-parallel;
wherein a gap (40) between the first and the second mirror element (10, 20) has a lower refractive index than the first and / or the second mirror element (10, 20);
wherein the first and second mirror elements (10, 20) are locally spaced from each other by at least one support structure (130); and
wherein the at least one support structure (130) is in an axial direction (A),
which is arranged perpendicular to the first and the second mirror element (10, 20), the first and the second mirror element (10, 20) overlaps; and
wherein the at least one support structure (130) comprises a material or is formed from a material which differs from a material,
from which the first and / or the second mirror element (10, 20) is formed.

Description

The present invention relates to a micromechanical mirror device, a mirror system and a method for producing a micromechanical mirror device. Furthermore, an interferometer according to the Fabry-Perot principle is provided which uses the mirror device according to the invention and / or the mirror system according to the invention.

State of the art

Tunable spectral filters with the possibility of miniaturization can be implemented using MEMS technology, for example as a Fabry-Perot interferometer (FPI). It is exploited that a cavity consisting of two plane-parallel, highly reflective mirror devices with a distance (cavity length) in the range of optical wavelengths shows a strong transmission only for wavelengths in which the cavity length corresponds to an integer multiple of half the wavelength. The cavity length can be changed, for example, by means of electrostatic or piezoelectric actuation, resulting in a spectrally tunable filter element. An important influencing factor on a performance of such a spectrometer is the parallelism of the two mirror devices, which should be as high as possible so that a defined cavity with the highest possible finesse arises between the two mirror devices.

In order to realize a Fabry-Perot interferometer that can address the widest possible wavelength range, several conditions must be met. A fundamental criterion is that the two mirror elements of the interferometer are highly reflective over the entire wavelength range to be measured. One frequently used design of mirror devices in miniaturized interferometers are dielectric layer systems comprising alternating layers of high and low refractive index materials, in particular Bragg reflectors (DBR), in which an optical thickness of these layers is ideally one quarter of the central wavelength of the area to be addressed.

A maximum reflectivity of the mirror layers is achieved by the highest possible refractive index jump of the DBR mirror layers. Very high refractive index jumps can be achieved, for example, with silicon-air multilayer mirror stacks. In order to ensure mutual parallelism of mirror layers within a mirror device, support structures that keep the distance between the surrounding high-index layers, which are referred to herein as mirror elements, constant.

In the US 2014/0111811 A1 For example, there is shown a tunable Fabry-Perot interferometer that includes anchor structures that space two mirror devices, ie, reflective elements. About the density of the support elements, a stiffness of the mirror devices can be adjusted. Both mirror devices are connected to one and the same substrate. So far, parts of the high-index layer, that is, the mirror elements, or intermediate layers have been used as support structures.

Disclosure of the invention

The present invention discloses a mirror device having the features of claim 1, a mirror system having the features of claim 8 and a method according to claim 9.

Accordingly, there is provided a micromechanical mirror device, comprising: a first mirror element which is planar; a second mirror element which is planar; wherein the first and the second mirror element are arranged substantially plane-parallel; wherein a gap between the first and the second mirror element has a lower refractive index than the first and / or the second mirror element; wherein the first and second mirror elements are locally spaced from each other by at least one support structure; wherein the at least one support structure in an axial direction, which is arranged perpendicular to the first and the second mirror element, overlaps the first and the second mirror element; and wherein the at least one support structure comprises a material, or is formed from a material which differs from a material from which the first and / or the second mirror element is formed.

A mirror device is understood in particular to mean a device which reflects a light beam in a Fabry-Perot interferometer.

Furthermore, a mirror system is provided, which has at least one mirror device according to the invention, and a contacting device which is designed to apply different electrical potentials to at least two mutually electrically insulated subsections of the first and / or the second mirror element of the at least one mirror device.

• Bereitstellen eines Schichtstapels mit:
  • - einer dielektrischen Schicht;
  • - einer an der dielektrischen Schicht angeordneten ersten lichtbrechenden Schicht;
  • - einer an der ersten lichtbrechenden Schicht angeordneten Opferschicht;
  • - einer an der Opferschicht angeordneten zweiten lichtbrechenden Schicht;
• Entfernen jeweils eines Teils der ersten lichtbrechenden Schicht, der zweiten Opferschicht und der zweiten lichtbrechenden Schicht, sodass eine zusammenhängende Ausnehmung in dem Schichtstapel derart entsteht, dass die Ausnehmung die erste und die zweite lichtbrechende Schicht in einer axialen Richtung, welche senkrecht zu der ersten und der zweiten lichtbrechenden Schicht angeordnet ist, überlappt;
• Abscheiden einer Füllschicht auf eine Seite des Schichtstapels, zu welcher sich die Ausnehmung öffnet;
• wobei die Füllschicht aus einem Material besteht, welches sich von dem Material der ersten und/oder der zweiten lichtbrechenden Schicht unterscheidet; Entfernen eines Teils der Füllschicht, welcher außerhalb einer ursprünglichen Außenschicht des Schichtstapels liegt; und
• Entfernen der dielektrischen Schicht und der Opferschicht zum Bereitstellen, insbesondere Freistellen, der ersten und der zweiten lichtbrechenden Schicht als zueinander planparallele Spiegelelemente.

Furthermore, a method for producing a micromechanical mirror device is provided, with the steps:

• Providing a layer stack with:
  • a dielectric layer;
  • a first refractive layer disposed on the dielectric layer;
  • a sacrificial layer disposed on the first refractive layer;
  • a second refractive layer disposed on the sacrificial layer;
• Removing each of a portion of the first refractive layer, the second sacrificial layer and the second refractive layer, so that a contiguous recess in the layer stack is formed such that the recess, the first and the second refractive layer in an axial direction which is perpendicular to the first and second refractive layer is arranged overlaps;
• Depositing a filling layer on one side of the layer stack to which the recess opens;
• wherein the filling layer is made of a material different from the material of the first and / or the second refractive layer; Removing a portion of the fill layer which is outside of an original outer layer of the layer stack; and
• Removing the dielectric layer and the sacrificial layer to provide, in particular, exposing, the first and the second refractive layer as mutually plane-parallel mirror elements.

The sacrificial layer is also denominatable as a dielectric layer and may for example consist of silicon dioxide.

Particularly preferably, a distance between the first and the second mirror element corresponds to a quarter of a central wavelength, for which the mirror device is to serve as an optical filter.

Advantages of the invention

The at least one support structure may consist of one or more separate support elements, or have one or more separate support elements. Because the at least one support structure overlaps both the first and the second mirror element in the axial direction, a mechanically particularly good connection is realized, wherein the at least one support structure simultaneously reduces deformation of the mirror elements under load.

Preferably, the first and the second mirror element are formed of the same material, while the at least one support structure is formed exclusively of materials or of exactly one material which differs from the material from which the mirror elements are formed.

The use of different materials for the at least one support structure on the one hand and the mirror elements on the other hand enables a separate optimization of the electrical and mechanical properties of the support structure on the one hand and the optical properties of the mirror elements on the other. It is particularly preferred if the at least one support structure is formed from one or more electrically insulating materials, while the first and / or the second mirror element is or are formed from an electrically conductive or a semiconducting material, so that the sections of the mirror elements as separate electrodes can act. In addition, the material of the support structure may have a different thickness and / or a different mechanical strain than the material of the mirror elements, whereby the robustness of the entire mirror device can be increased.

Advantageous embodiments and further developments emerge from the dependent claims and from the description with reference to the figures.

According to a preferred development, the material of the support structure has a different thickness and / or mechanical stress than a material of the first mirror element and / or the second mirror element. In this way, for example, the rigidity and thus the robustness of the entire mirror device can be positively influenced.

According to an advantageous development, the at least one support structure divides the first mirror element and the second mirror element into at least two subsections, which are electrically insulated from one another by the at least one support structure.

The electrical separation of the at least two subsections of the first and the second mirror element opens up a multiplicity of application and design options for the micromechanical mirror device. For example, the different, electrically isolated subsections can be used as separate electrodes, which can be placed on different electrical potentials and / or can be applied to different currents and voltages.

For example, a partial section can be subjected to a voltage which can be used to actuate the mirror device, that is to say, for example, to align the mirror device. In this way, the distance between the actuated mirror device to, for example, a further mirror device can be changed within one and the same interferometer, whereby the interferometer is spectrally tunable.

A further subsection of the first and the second mirror element can, for example, be subjected to a voltage which is used to detect the deflection of the mirror device. In a further section, a field-free space or a largely field-free space can be achieved, for example, to avoid deformation of the mirror device in the field-free space.

According to a preferred development, the support structure has at least one section which protrudes from an outer surface of the first and / or the second mirror element. This section is thus as a stopper or as an anti-static friction bump (short for "anti-static-friction bump"). It is particularly advantageous if the at least one support structure has a plurality of such stops or if a plurality of support structures are provided which each have at least one such stop.

Such stops can prevent or reduce a likelihood of gluing mirror devices or gluing mirror devices to a substrate. It is particularly advantageous if at least the respective section of the at least one support structure, which acts as a stop, is formed from an electrically insulating material (insulator). In this case, welding of electrodes with the mirror elements can be prevented during use of the mirror device, for example, within an interferometer.

An outer surface of a mirror element is understood in particular to mean a surface of the respective mirror element which faces away from the intermediate space between the first and the second mirror element. The outer surface of at least one mirror element also represents the surface on which light impinges, which is to be mirrored by the mirror device.

According to a further preferred development, a lateral extent of the at least one support structure overlaps with a lateral extent of the first and / or the second mirror element. In this way, a better mechanical connection between the at least one support structure and the first and / or the second mirror element can be achieved. A lateral, or transversal, expansion is understood in particular to mean an expansion in a direction which lies in a plane which can be thought of parallel to the first and the second mirror element. Thus, the direction is arranged perpendicular to an axial direction, which in turn is arranged perpendicular to the mirror elements.

According to a further preferred development, the at least one support structure is formed from at least two different materials. For example, a first material of the at least one support structure may be in contact with the mirror elements while a second material of the support structure is formed and arranged as a stabilizing core of the support structure to increase rigidity of the support structure and thus a distance between the first and second Mirror element to improve the optical properties of the mirror device to keep constant.

According to a further preferred development, the at least one support structure has a fluid passageway through which a fluid can pass through the support structure, the first and the second mirror element. In this way, a thermal and / or atmospheric balance between two different sides of the mirror device can be improved, whereby external tensile, compressive and deforming forces can be reduced to the mirror device.

According to a further preferred development, a gas or a vacuum is arranged in the intermediate space between the first and the second mirror element. A material with a low refractive index is preferably arranged in the intermediate space, which is particularly preferably close to one, as is the case, for example, with air (ie a gas or gas mixture) and under vacuum. A high refractive index contrast between a refractive index of the gap between the mirror elements on the one hand and a refractive index of the first and / or the second mirror element on the other hand increases the wavelength range in which the mirror device has a high reflection and increases the maximum achievable reflection with a constant number of layers in the mirror. A mirror system, in particular an interferometer, with a mirror device designed in this way is therefore even more versatile.

According to a preferred embodiment, the mirror system is an interferometer, in particular a Fabry-Perot interferometer, wherein at least one of the mirror devices of the interferometer is a mirror device according to the invention.

According to an advantageous embodiment of the method according to the invention, each removal of a portion of the first refractive layer, the sacrificial layer and the second refractive layer, such that the contiguous recess is formed such that the recess, the first and the second refractive layer (ie, the later mirror elements ) divided into at least two spaced apart sections. This has the advantages described above in connection with electrically insulating the sections.

According to a preferred development of the method according to the invention, the layer stack is provided with a protective layer arranged on the second refractive layer, which forms the original outer layer of the layer stack on one side of the layer stack. In this case, a part of the protective layer is removed to form the recess. In the removal of the part of the filling layer, the protective layer can function as an etching stop and / or as a polishing stop, that is, more resistant than the filling layer to an etching method and / or a polishing device used. The protective layer can be removed after removal of the part of the filling layer.

list of figures

• 1 eine schematische Querschnittsdarstellung einer mikromechanischen Spiegelvorrichtung gemäß einer Ausführungsform in einer Detailansicht;
• 2 eine schematische Querschnittsdarstellung einer mikromechanischen Spiegelvorrichtung gemäß einer weiteren Ausführungsform in einer Detailansicht;
• 3 eine schematische Querschnittsdarstellung einer mikromechanischen Spiegelvorrichtung gemäß noch einer weiteren Ausführungsform in einer Detailansicht;
• 4 eine schematische Querschnittsdarstellung einer mikromechanischen Spiegelvorrichtung gemäß noch einer weiteren Ausführungsform in einer Detailansicht;
• 5 eine schematische Querschnittsdarstellung einer mikromechanischen Spiegelvorrichtung gemäß noch einer weiteren Ausführungsform in einer Detailansicht;
• 6 eine schematische Querschnittsdarstellung einer mikromechanischen Spiegelvorrichtung gemäß noch einer weiteren Ausführungsform in einer Detailansicht;
• 7 eine schematische Draufsicht auf einen Ausschnitt aus einer mikromechanischen Spiegelvorrichtung gemäß einer der 1 bis 6;
• 8 ein schematisches Blockdiagramm zum Erläutern eines Spiegelsystems gemäß einer weiteren Ausführungsform;
• 9 ein schematisches Flussdiagramm zum Erläutern eines Verfahrens zum Herstellen einer mikromechanischen Spiegelvorrichtung; und
• 10 bis 15 schematische Detailansichten im Querschnitt durch Zwischenprodukte des erfindungsgemäßen Verfahrens zum Herstellen der mikromechanischen Spiegelvorrichtung.

The present invention will be explained in more detail with reference to the embodiments illustrated in the schematic figures of the drawings. Show it:

• 1 a schematic cross-sectional view of a micromechanical mirror device according to an embodiment in a detailed view;
• 2 a schematic cross-sectional view of a micromechanical mirror device according to another embodiment in a detailed view;
• 3 a schematic cross-sectional view of a micromechanical mirror device according to yet another embodiment in a detailed view;
• 4 a schematic cross-sectional view of a micromechanical mirror device according to yet another embodiment in a detailed view;
• 5 a schematic cross-sectional view of a micromechanical mirror device according to yet another embodiment in a detailed view;
• 6 a schematic cross-sectional view of a micromechanical mirror device according to yet another embodiment in a detailed view;
• 7 a schematic plan view of a section of a micromechanical mirror device according to one of 1 to 6 ;
• 8th a schematic block diagram for explaining a mirror system according to another embodiment;
• 9 a schematic flow diagram for explaining a method for producing a micromechanical mirror device; and
• 10 to 15 schematic detailed views in cross section through intermediates of the inventive method for producing the micromechanical mirror device.

In all figures, the same or functionally identical elements and devices - unless otherwise stated - provided with the same reference numerals. The numbering of method steps is for the sake of clarity and, in particular, should not, unless otherwise indicated, imply a particular chronological order. In particular, several method steps can be carried out simultaneously.

Description of the embodiments

1 shows a schematic cross-sectional view of a micromechanical mirror device 100 in a detailed view. The mirror device 100 has a first, plan trained mirror element 10 and a second, plan trained mirror element 20 on, which are arranged to each other substantially, or completely, plane-parallel. A gap 40 between the first and the second mirror element 10 . 20 has a lower refractive index than the first mirror element 10 and / or as the second mirror element 20 itself. This is how the mirror device works 100 as a micromechanical Bragg mirror.

The mirror device 100 For example, may be formed such that the gap 40 is open to the atmosphere and thus filled with air in operation, which has a close to 1 refractive index. Alternatively, the mirror device 100 also be designed such that the gap 40 gas-tight is completed. In this case, the gap 40 be filled with a gas or a gas mixture, eg air. Alternatively, in the gap 40 Also be formed a vacuum whose refractive index is also close to 1.

The mirror elements 10 . 20 , relative to a refractive index of the gap 40 , a higher refractive index. Advantageously, both the first and the second mirror element 10 . 20 be formed of the same, high-refractive material. As a high refractive index material is to be understood, for example, a material whose refractive index is greater than 3. The mirror elements 10 . 20 may for example be formed of silicon, which has a refractive index of about 3.5, or silicon. However, other materials such as germanium or silicon carbide are also materials for the first and / or the second mirror element 10 . 20 conceivable.

The micromechanical mirror device 100 also has a support structure 130 on, through which the first and the second mirror element 10 . 20 at least locally spaced from each other. In other words, it is at least one support structure 130 arranged at its position a defined and desired distance between the first mirror element 10 and the second mirror element 20 to secure.

The at least one support structure 130 is optionally formed such that through them the first mirror element 10 in a first section 11 and a second subsection 12 is divided, and further such that by the at least one support structure 130 the second mirror element 20 in a first section 21 and a second subsection 22 is divided. The at least one support structure 130 is optionally further configured such that the first and the second section 11 . 12 of the first mirror element 10 are electrically insulated from each other and that the first section 21 and the second subsection 22 of the second mirror element 20 are electrically isolated from each other.

For example, the at least one support structure 130 completely formed of an electrically insulating material, for example, silicon-rich nitride, silicon carbide (SiC), silicon carbonitride (SiCN) and the like.

The following is the mirror device 100 according to the assumption that the subsections 11 . 12 . 21 . 22 the mirror elements 10 . 20 from each other through the at least one support structure 130 are electrically isolated. It is understood, however, that the at least one support structure 130 , or at least one of several support structures 130 , may also be electrically conductive or semiconducting, so that no, or only a partial, electrical insulation of the sections 11 . 12 . 21 . 22 is present.

Electrically isolated sections of the mirror elements allow, for example, a direct capacitive detection of the distance of the mirror device from a reference object or a segmentation of electrodes on the mirror device itself.

It can be provided that the first section 11 of the first mirror element 10 and the first section 21 of the second mirror element 20 electrically connected to each other, for example, on an edge, not shown, of the mirror device 100 , Additionally or alternatively it can be provided that the second section 12 of the first mirror element 10 and the second subsection 22 of the second mirror element 20 electrically connected to each other, for example, on an edge, not shown, of the mirror device 100 ,

The at least one support structure 130 overlaps in an axial direction A, which is perpendicular to the first and the mirror element 10 . 20 is arranged, both the first mirror element 10 as well as the second mirror element 20 , In other words, the at least one support structure traverses 130 both the first mirror element 10 as well as the second mirror element 20 , In other words, the at least one support structure extends at least from an outer side of the first mirror element 10 that of the second mirror element 20 is remote, at least up to an outer side of the second mirror element 20 that of the first mirror element 10 turned away. The axial direction A is so designated because it can be used as an optical axis for the mirror device.

The at least one support structure 130 in the mirror device 100 in 1 is formed laterally continuous, that is, in particular, it has no voids between the first section 11 and the second subsection 12 of the first mirror element 10 and no voids between the first section 21 and the second subsection 22 of the second mirror element 20 on. Thus, the support structure 130 particularly stiff, causing deformation of the mirror elements 10 . 20 prevent or reduce it.

Furthermore, the at least one support structure 130 in 1 also formed axially continuous. The support structure 130 is both on an outer surface of the first mirror element 10 as well as on an outer surface of the second mirror element 20 each surface equal to the respective mirror element 10 . 20 formed, with deviations are also possible.

2 shows a schematic cross-sectional view of a micromechanical mirror device 200 according to another embodiment in a detailed view. The mirror device 200 represents a variant of the mirror device 100 dar. The mirror device 200 is designed as well as in the preceding with respect to the mirror device 100 described, with the difference that at least one support structure 230 the mirror device 200 on an outer surface 24 of the second mirror element 20 a section 232 which, from the outer surface 24 protrudes.

this section 232 Also referred to as a stopper or as an anti-static friction bump ("anti-static bump") and has the advantages described in the foregoing.

3 shows a schematic cross-sectional view of a micromechanical mirror device 300 according to yet another embodiment in a detailed view. Also with the mirror device 300 it is a variant of the mirror device 100 , The mirror device 300 is different from the mirror device 100 again in the design of at least one support structure 330 the mirror device 300 instead of the at least one support structure 130 the mirror device 100 ,

The at least one support structure 330 is formed such that it is both the first mirror element 10 as well as the second mirror element 20 overlapped laterally or transversely to ensure a better mechanical connection. Regardless, and optional, that is at least one support structure 330 additionally formed to form a section 332 having, which from the second outer surface 24 of the second mirror element 20 protrudes and thus not only very well the second mirror element 20 but at the same time as the section 332 again provides a stop or an anti-static friction survey.

4 shows a schematic cross-sectional view of a micromechanical mirror device 400 according to yet another embodiment in a detailed view. Also the mirror device 400 is a variant of the mirror device 100 is different from the mirror device 100 in the embodiment of a support structure 430 which in the mirror device 400 instead of the support structure 130 the mirror device 100 occurs.

The support structure 430 is formed of two different materials, wherein at least one of the two materials is an electrically insulating material. The electrically insulating material 434 stands with the first and the second mirror element 10 . 20 in direct contact, while the second material only with the first material 434 is in direct contact and, except on an outer surface 14 of the first mirror element 10 completely from the first material 434 is surrounded. The second material 436 can thus be considered a core of the support structure 430 may be designated and may for example be stiffer than the first material 434 to the support structure 430 to give greater overall rigidity.

The second material 436 may be electrically insulating, but need not be electrically insulated. Thus, the electrical properties of the support structure 430 on the one hand, which on the first material 434 go back, and the mechanically stabilizing properties of the support structure 430 on the other hand, which refers to the combination of the first material 434 with the second material 436 go back, largely optimized separately.

Even with the at least one support structure 430 can a section 432 be provided, which from the outer surface 24 of the second mirror element 20 protrudes or protruding and which, for example, as a kind of stop or anti-static survey is usable.

5 shows a schematic cross-sectional view of a micromechanical mirror device 500 according to yet another embodiment in a detailed view. The mirror device 500 is as a variant of the mirror device 100 signable, wherein the mirror device 500 through a support structure 530 which instead of the support structure 130 occurs from the mirror device 100 different.

The at least one support structure 530 has a blind hole or a recess 538 which extends to an outside of the mirror device 500 opens, for example, on the outer surface 14 of the first mirror element 10 , Advantageously, the at least one support structure 530 a section 534 on the outside surface 14 of the first mirror element 10 on which over the outer surface 14 of the mirror element 10 protrudes and in the lateral direction, the first and the second mirror element 10 . 20 overlaps. In this way, the mechanical connection of the at least one support structure 530 to the first and the second mirror element 10 . 20 be further improved. Furthermore, the at least one support structure can also be used 530 a section 532 which, from the outer surface 24 of the second mirror element 20 protrudes.

Furthermore, the support structure 530 be formed such that they both the first mirror element 10 as well as the second mirror element 20 overlapped laterally or transversely to ensure a better mechanical connection.

6 shows a schematic cross-sectional view of a micromechanical mirror device 600 according to yet another embodiment. The mirror device 600 is a variant of the mirror device 500 and differs from this in that a support structure 630 in place of the support structure 530 the mirror device 500 occurs. The at least one support structure 630 is formed as well as the at least one support structure 530 the mirror device 500 except for the difference that the at least one support structure 630 no blind hole 538 has, but instead a fluid passage channel 638 which the support structure 630 completely crossed.

The at least one support structure 630 may be configured to have at least one localized fluid passageway 638 having. Alternatively, the at least one support structure 630 Also be designed such that the fluid passageway 638 along the entire support structure 630 extends.

Various elements of the mirror devices described in the foregoing 100 - 600 Of course they can be combined with each other. For example, the mirror devices 100 . 200 . 300 and 400 one from the outside surface 14 of the first mirror element 10 protruding section 534 have to allow a better mechanical connection. Furthermore, the support structures 130 . 230 . 330 . 430 the mirror devices 100 to 400 a blind hole 538 or a fluid passageway 638 have, as in the 5 and 6 shown and described in the relevant text passages.

In addition, the support structures can also 130 . 230 . 330 . 530 and 630 be formed of more than two materials, as in 4 is shown and how this is related to 4 has been explained in the foregoing.

It is understood that also a lateral overlapping of the support structures 130 . 230 . 430 . 530 . 630 with the first and / or the second mirror element 10 . 20 , especially in the area of the gap 40 , can be provided as in 3 is shown and as mentioned above with reference to 3 has been described.

7 shows a schematic plan view of a section of a possible advantageous embodiment of the micromechanical mirror device 100 - 600 on the outside surface 14 of the first mirror element 10 , In 7 is clarified that the first subsection 11 of the first mirror element 10 , the support structure 130 to 630 and the second subsection 12 of the first mirror element 10 (and according to the sections 21 . 22 of the second mirror element 20 which is in 7 is not visible) are formed such that the first section 11 in lateral directions almost completely from the second section 12 surrounded, being a bridge 13 of the first mirror element 10 electrically with the first section 11 connected and electrically from the second section 12 is isolated, so that both the first section 11 as well as the second section 12 advantageous at an edge of the mirror device 100 - 600 can be contacted electrically.

Preferably, the at least one support structure 130 to 630 in the first mirror element 10 essentially in plan view (in particular except for the web 13 ) on a circular shape, so that the first section 11 within the second subsection 12 is formed substantially circular. In this way, in the area of the first subsection 11 a particularly homogeneous electric field or be formed, whereby unwanted electrical effects, for example, during actuation and / or detection can be reduced or avoided.

Indicates a mirror system (see also 8th ) For example, two of the mirror devices of the invention 100 - 600 can be due to the annular electrodes, as in 7 shown, the two mirror devices bidirectionally actuated and moved towards each other. Otherwise, in the case of flat electrodes, an attractive force would otherwise act between the two mirror devices, which would behave like a two-dimensional pressure load and thus lead to sagging of the mirror devices and a reduction in parallelism. This could increase a spectral transmission width of the mirror device and thus the resolution of one through the two mirror devices 100 - 600 reduce the formed interferometer.

Something similar also applies to capacitive detection if a voltage is applied between two mirror devices of an interferometer. In this case, surface electrons attract and, as described above, reduce the parallelism of the interferometer mirrors in the optically relevant region 7 the first section 11 equivalent. The embodiments described herein thus allow capacitive detection, in particular a direct measurement of an optical gap between two mirror devices of an interferometer, without thereby reducing the mirror parallelism between the mirror devices of the interferometer.

Of course, a further segmentation is conceivable, for example, a segmentation in more than two substantially mutually concentric sections 11 . 12 , This can be used, for example, in the optically relevant innermost subsection 11 to create a completely or largely field-free space. This can be achieved, for example, in that in a middle section 12 , which is the innermost subsection 11 largely encloses, as in 7 shown, a first electrical potential is applied and at a third portion, which both the first portion 11 as well as the second subsection 12 encloses substantially circular (in 7 not shown), a second electrical potential is applied, which has a reverse sign in comparison to the first electrical potential.

It can be provided that the mirror device according to the invention 100 -600 additionally or alternatively to the at least one electrically insulating support structure 130 - 630 also has at least one further support structure, which does not provide electrical insulation of subsections of mirror elements 10 . 20 performs. This can be accomplished, for example, by the fact that these additional support structures do not completely separate any subsections and / or in that the support structures themselves are electrically conductive or semiconductive, in particular formed from the same material as the first and / or the second mirror element 10 . 20 ,

These further support structures, which do not electrically isolate sections, may also be referred to as auxiliary support structures. The auxiliary support structures can be arranged, for example, in the form of regular or irregular lattices. For example, an auxiliary support structure in the form of a hexagonal honeycomb pattern may be formed, which is preferably completely over one of the subsections of the mirror elements 10 . 20 extends. For example, at the in 7 a first such auxiliary support structure shown covering the first part of the area 11 can be arranged, and / or a second auxiliary support structure can cover the second part of the area 12 of the first mirror element 10 and the second subsection 22 of the second mirror element 20.

A major advantage of the support structures and auxiliary support structures described herein is the mechanical stiffness against tension-induced deformation. Previously known supporting structures ("anchor structures") often have the intrinsic disadvantage that tensile biasing of the mirror devices causes the anchor structures to deform to partially degrade the bias. In a region around a respective anchor structure, this deformation leads to the spacing of the sublayers (corresponding to the mirror elements) no longer corresponding to the wavelength to which the Bragg mirror is set, which results in the optical properties of the Bragg mirror the mirror device, deteriorate. In contrast, the support structures and auxiliary support structures described herein have the distinct advantage of having greater rigidity over such deformations, thereby reducing optical surface loss due to misaligned mirror elements 10 . 20 is minimized.

The auxiliary support structures can be realized as wall structures which are at least partially or completely continuous and / or can be realized as pillar structures which are separate from one another and spaced apart from one another. Hexagonal lattice arrangements offer a particularly high mechanical stability. The support structures and / or the auxiliary support structures may be configured as filled or hollow / folded structures. The support structures and / or the auxiliary support structures can also be designed such that a layer stress of a membrane is adapted.

8th shows a schematic block diagram for explaining a mirror system 1000 according to a further embodiment. The mirror system 1000 For example, it can be an interferometer, in particular a Fabry-Perot interferometer. The mirror system 1000 is formed with at least two dielectric or semiconducting mirror devices, of which at least one mirror device according to the invention 100 - 600 is.

At least one of the mirror devices, in particular a mirror device according to the invention 100 - 600 , is movable relative to the at least one other mirror device.

8th does not imply a geometrical arrangement of the mirror devices. The mirror devices are preferably disposed on, or on, a common substrate and substantially (or completely) aligned parallel to one another to form a Fabry-Perot interferometer, as is already known in the art.

By changing a distance between the two mirror devices (in particular by moving the movable mirror device), the mirror system 1000 for example as a tunable spectral filter operate. To change the distance between the mirror devices may be to the at least one mirror device according to the invention 100 - 600 by means of a contacting device 1050 of the mirror system 1000 a first electrical potential to a first portion 11 this mirror device 100 - 600 be applied and a second electrical potential to a second portion of this mirror device 100 - 600 be created, for example as described above 7 described in more detail.

The contacting device 1050 may also be adapted to the at least one further mirror device of the mirror system 1000 to apply at least one electrical potential. All mirror devices in the mirror system are preferred 1000 Mirror devices according to the invention 100 - 600 and the contacting device 1050 is designed for the different sections 11 . 12 . 21 . 22 the at least two mirror devices 100 - 600 of the mirror system 1000 create different electrical potentials.

9 shows a schematic flow diagram for explaining a method for producing a micromechanical mirror device, in particular a micromechanical mirror device according to the invention 100 - 600 , The method according to 9 will be described below on the basis of 10 to 15 and with reference to reference numerals in these figures explained in more detail. The method according to 9 is in accordance with all with respect to the mirror device according to the invention 100 - 600 customizable variants and developments customizable and vice versa.

10 to 15 show schematic detailed views in cross section through intermediates of the inventive method for producing the micromechanical mirror device.

In a step SOI becomes a layer stack 70 provided, comprising: a dielectric layer 71 , one at the dielectric layer 71 arranged first refractive layer 72 , one at the first refractive layer 72 arranged sacrificial layer 73 , one at the sacrificial layer 73 arranged second refractive layer 74 , Optionally, the layer stack 70a also with a second refractive layer 74 arranged protective layer 75 to be provided. The dielectric layer 71 may also serve as a sacrificial layer depending on the design.

In other words, the layer stack comprises 70 arranged in the following order, the first dielectric layer 71 , the first refractive layer 72 , the sacrificial layer 73 , the second refractive layer 74 and, optionally, the protective layer 75 , The refractive layers 72 . 74 are in particular high-index layers, ie layers with a higher refractive index than air.

The dielectric layer 71 and / or the sacrificial layer 73 are layers which are easily removable in the later course of the process and can for example consist of silicon dioxide, SiO ₂ . The first and / or the second refractive layer 72 . 74 , from which below the mirror elements are made, for example, consist of a material such as silicon, in particular polysilicon, although other materials such as germanium or silicon carbide are conceivable, which are compatible with the sacrificial layer etching process, in which later the sacrificial layer 73 and optionally also the dielectric layer 71 be removed.

The optional protective layer 75 may be advantageous in the further processing and, for example, consist of silicon dioxide (SiO 2).

10 shows an intermediate product of the process after performing the process step S01 ,

The following is based on the 11 to 15 be explained as a single support structure 130 - 630 (always in cross-sectional representation) can be produced, it being understood that, in plan view, the at least one support structure 130 - 630 for example, may be formed as in 7 shown and / or as related to 7 was explained in more detail. Furthermore, it is understood that in the same way a plurality of support structures 130 -630, for example, for simultaneously forming a plurality of mutually electrically isolated sections 11 . 12 . 21 . 22 , can be trained simultaneously.

In one step S02 each becomes a part of the first refractive layer 72 , the sacrificial shift 73 and the second refractive layer 74 removed, leaving a coherent recess 76 such arises that the recess 76 the first and the second refractive layer 72 . 74 in each case at least two spaced-apart sections 11 . 12 . 21 . 22 divided.

Removing the layers 72 - 74 is performed such that the recess 76 the first and the second refractive layer 72 . 74 in an axial direction A perpendicular to the first and second refractive layers 72 . 74 is arranged, overlaps, as well as in too 1 with respect to the support structure 130 was explained.

The formation of the recess 76 can be done for example by lithography and / or etching. The recess may in particular, in plan view, be formed as a round hole or as a trench.

The dielectric layer 71 and the sacrificial layer 73 , and optionally also the optional protective layer 75 , can be etched isotropically or partially isotropically, after a conformal deposition of a filling layer to form the later support structure, a better mechanical connection of the later support structure to the first and the second refractive layer 72 . 74 (Later mirror elements) to allow by a larger contact area. One possible end result is for example in 3 presented and was referring to 3 explained in more detail.

Optionally, after, or at, the basic forming S02 the recess 76 , eg in a further process step, the dielectric layer 71 from the recess 76 are etched out, so that the later support structure is formed with stops, such as a stop 232 as in 2 shown and related to 2 described.

Was in the step S01 a layer stack 70 with a protective layer 75 provided accordingly, the recess to be collected by the protective layer 75 formed through. An intermediate of the method after performing the step S02 is in 11 shown. It can be seen that the recess 76 is shown in cross section as a blind bore.

For electrical separation of spaced apart sections 11 . 12 . 21 . 22 the mirror elements 10 . 20 can the recess 76 , which partially dictates the shape of the later support structure, may be formed as an elongate structure, for example, as an elongated channel.

The recess is preferred 76 be formed in the plan view as in relation to 7 with respect to the at least one support structure 130 to 630 between the first section 11 and the second subsection 12 has been described. Alternatively, the recess 76 , or a plurality of recesses 76 be formed also columnar or in any other form.

In one step S03 gets on one side of the layer stack 70 , in which respect the recess 76 opens, and which one in 11 denoted by 77, a filling layer 78 delivered, for example by means of a vapor deposition process or other known processes for depositing layers on substrates. Due to the existing recess 76 is the filling layer 78 not just flat on the layer stack 70 arrange, but the recess 76 fill in whole or in part, as in 12 shown. 12 represents an intermediate product of the process according to the invention after the process step S03 schematically. The filling layer 78 is made of a material or comprises a material which differs from the material (or materials) of the refractive layers 72 . 74 different.

In the foregoing it has been explained in detail that it is advantageous if the at least one support structure different subsections 11 . 12 . 21 . 22 the mirror elements electrically isolated from each other. For the filling layer 78 as an electrically insulating layer 78 be formed, ie consist of an electrically insulating material or material mixture.

In the deposition S03 the filling layer 78 If possible, a preferred deposition is preferred. The deposited layer thickness of the filling layer is preferably at least half the width of the recess 76 in order to produce as little topography as possible, that is to say as homogeneous a filling of the recess as possible 76 to effect. The filling layer 78 advantageously consists of a silicon or an aluminum-based insulator, for example silicon nitride, silicon carbide, silicon carbonitride or aluminum oxide.

In one step S04 becomes at least that part of the additional layer 78 which is outside of an original outer surface of the layer stack is removed. In particular, over the entire surface material can be removed. Was in the step S01 a layer stack 70 with the optional protective layer 75 provided, that part of the filling layer becomes 78 removed, which over the protective layer 75 protrudes, as in 13 shown.

The removal S04 the protruding part of the filling layer 78 is preferably carried out by etching and / or polishing. The protective layer 75 if it has been formed, can act as an etch stop or polishing stop. On the formation of the protective layer 75 can be omitted, in particular, if the selected processes have sufficient selectivity, that is, sufficiently well on the filling layer 78 act and at the same time the second refractive layer 74 not, or only to a small extent, attack.

13 shows a schematic detail view in cross-sectional representation of an intermediate product of the method according to the invention for producing the micromechanical mirror device after performing the step S04 ,

Was not an optional protective layer 75 provided, and became the original outer surface of the layer stack 70 for example through the second refractive layer 74 provided, accordingly, that part of the filling layer 78 which is outside of this original outer surface, that is, the second refractive layer 74 lies, that is protruding from this.

In an optional step S05 becomes the protective layer 75 after the process step S04 away.

13 shows a schematic cross-sectional representation of an intermediate product of the method for producing the micromechanical mirror device after performing the optional step S05 ,

In one step S06 Finally, for example, not shown here sacrificial layer Ätzzugänge by a sacrificial layer etching process, the dielectric layer and / or the sacrificial layer 73 away. Thus, the refractive layers become 72 . 74 as mirror elements 10 . 20 with spaced apart (and optionally electrically isolated from each other) sections 11 . 12 . 21 . 22 provided. In some embodiments, the photorefractive layers 72 . 74 as mirror elements 10 . 20 with spaced apart (and optionally electrically isolated from each other) sections 11 . 12 . 21 . 22 be released.

The remaining filling layer 78 thus acts as a support structure 30 , as in 15 shown.

For producing the mirror device 100 according to 1 can, for example, via the respective outer surfaces 14 . 24 the first and second mirror elements 10 . 20 protruding portions of the filling layer 78 be removed.

Although the present invention has been described above with reference to preferred embodiments, it is not limited thereto, but modifiable in a variety of ways. In particular, the invention can be varied or modified in many ways without deviating from the gist of the invention.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 2014/0111811 A1 [0005]

Claims (12)

Micromechanical mirror device (100-600), comprising: a first mirror element (10) which is planar; a second mirror element (20) which is planar; wherein the first and the second mirror element (10, 20) are arranged substantially plane-parallel; wherein a gap (40) between the first and the second mirror element (10, 20) has a lower refractive index than the first and / or the second mirror element (10, 20); wherein the first and second mirror elements (10, 20) are locally spaced from each other by at least one support structure (130-630); wherein the at least one support structure (130-630) is in an axial direction (A), which is arranged perpendicular to the first and the second mirror element (10, 20), the first and the second mirror element (10, 20) overlaps; and wherein the at least one support structure (130-630) comprises a material, or is formed of a material which differs from a material of which the first and / or the second mirror element (10, 20) is formed. Mirror device (100-600) after Claim 1 wherein the material of the at least one support structure (130-630) has a different thickness and / or mechanical strain than a material of the first mirror element (10) and / or the second mirror element (20). Mirror device (200-600) after one of Claims 1 or 2 wherein the at least one support structure (130-630) subdivides the first mirror element (10) and the second mirror element (20) into at least two subsections (11, 12, 21, 22) which are defined by the at least one support structure (130-630 ) are electrically isolated from each other. Mirror device (200-600) after one of Claims 1 to 3 wherein the support structure (230-630) has at least one portion (232; 332; 432; 532) protruding from an outer surface (14, 24) of the first and / or second mirror element (10, 20). Mirror device (300; 500; 600) according to one of Claims 1 to 3 wherein a lateral extent of the at least one support structure (330; 530; 630) overlaps a lateral extent of the first and / or the second mirror element (10, 20). Mirror device (400) according to one of Claims 1 to 5 wherein the at least one support structure (430) is formed of at least two different materials (434, 436). Mirror device (600) according to one of Claims 1 to 6 wherein the at least one support structure (630) has a fluid passage opening (638) through which fluid can traverse the support structure (630), the first and second mirror elements (10). Mirror device (100-600) according to one of Claims 1 to 7 , wherein in the intermediate space (40) between the first and the second mirror element (10, 20), a gas or a vacuum is arranged. Mirror system (1000) comprising: a mirror device (100-600) according to any one of Claims 1 to 7 ; and a contacting device (1050) which is designed to apply different electrical potentials to at least two subsections (11, 12, 21, 22) of the first and / or the second mirror element (10) which are electrically insulated from one another. Method for producing a micromechanical mirror device, comprising the steps: Providing (S01) a layer stack (70) with: a dielectric layer (71); a first refractive layer (72) disposed on the dielectric layer (71); a sacrificial layer (73) disposed on the first refractive layer (72); and a second refractive layer (74) disposed on the sacrificial layer (73); Removing (S02) in each case a part of the first refractive layer (72), the sacrificial layer (73) and the second refractive layer (74) so that a continuous recess (76) is formed in the layer stack (70) such that the recess (76 ) overlapping the first and second refractive layers (72, 74) in an axial direction (A) disposed perpendicular to the first and second refractive layers (72, 74); wherein the filling layer (78) is made of a material different from the material of the first and / or the second refractive layer (72, 74); Depositing (S03) a filling layer (78) on one side of the layer stack (70) to which the recess (76) opens; Removing (S04) a portion of the fill layer (78) that is outside of an original outer layer of the layer stack (70); and Removing (S06) the sacrificial layer (73) to provide the first and second refractive layers (72, 74) as mutually plane parallel mirror elements (10, 20). Method according to Claim 10 wherein the removal (S02) takes place in such a way that the continuous recess (76) is formed in such a way that the recess (76) divides the first and the second refractive layer (72, 74) into at least two mutually spaced partial sections (11, 12, 21, 22). Method according to Claim 10 or 11 wherein the layer stack (70) is provided with a protective layer (75) disposed on the second refractive layer (74) forming the original outer layer of the layer stack (70) on one side of the layer stack (70); wherein also a part of the protective layer (75) for forming the recess (76) is removed; wherein the protective layer (75) acts as an etch stop and / or a polishing stop in removing (S04) the portion of the filler layer (78); and wherein the method comprises the step of: removing (S05) the protective layer (75) after removing (S04) the part of the filling layer (78).

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