Interferometer arrangement and method for producing an interferometer arrangement
阅读说明：本技术 干涉仪装置和用于制造干涉仪装置的方法 (Interferometer arrangement and method for producing an interferometer arrangement ) 是由 R.雷德尔 C.D.克雷默 M.施密德 于 2020-03-20 设计创作，主要内容包括：本发明涉及一种干涉仪装置,包括：第一反射镜装置和第二反射镜装置；边缘结构,其中,第一反射镜装置和第二反射镜装置分别固定在所述边缘结构上并且所述边缘结构至少部分在横向在它的边缘区域上围绕第一反射镜装置和第二反射镜装置；其中,第一反射镜装置和第二反射镜装置彼此间隔第一间距布置,并且第一和/或第二反射镜装置在分别在横向处在边缘结构中的横向的内部区域中跨越空置的区域并且在这个空置的区域中能关于另一个反射镜装置运动,因此第一间距尤其能通过驱动改变；和多个刻蚀入口,刻蚀入口延伸穿过第一反射镜装置和/或穿过第二反射镜装置地进入空置的区域。(The invention relates to an interferometer arrangement comprising: a first mirror arrangement and a second mirror arrangement; an edge structure, wherein the first mirror device and the second mirror device are each fastened to the edge structure and the edge structure surrounds the first mirror device and the second mirror device at least partially in the lateral direction over its edge region; wherein the first mirror device and the second mirror device are arranged at a first distance from one another, and the first and/or second mirror device spans an empty region in the transverse inner region in the edge structure in the transverse direction and is movable relative to the other mirror device in this empty region, in each case in the transverse direction, so that the first distance can be varied, in particular, by means of driving; and a plurality of etching inlets extending through the first mirror arrangement and/or through the second mirror arrangement into the vacant region.)
1. An interferometer device (10), comprising:
-a first mirror arrangement (SP 1) and a second mirror arrangement (SP 2);
-an edge structure (RS), wherein the first mirror arrangement (SP 1) and the second mirror arrangement (SP 2) are each fixed to the edge structure (RS) and the edge structure (RS) surrounds the first mirror arrangement (SP 1) and the second mirror arrangement (SP 2) at least partially in the lateral direction over its edge region; wherein the first mirror device (SP 1) and the second mirror device (SP 2) are arranged at a first distance (d 12) from one another, and the first and/or second mirror device (SP 1; SP 2) spans the free region (FB) in a transverse inner region (IB) and is movable in said free region (FB) in relation to the other mirror device (SP 1, SP 2) in each case, so that the first distance (d 12) can be varied in particular by means of driving, wherein the transverse inner region is in each case in the lateral direction in the edge structure (RS); and
-a plurality of etching inlets (a) extending through the first mirror arrangement (SP 1) and/or through the second mirror arrangement (SP 2) into the free region (FB), wherein an edge density (RD) of the arrangement of the etching inlets (a) on the respective edge region of the first and/or second mirror arrangement (SP 1, SP 2) is changed with respect to an Internal Density (ID) of the arrangement of the etching inlets (a) on the lateral internal region (IB) of the first and/or second mirror arrangement (SP 1, SP 2).
2. Interferometer arrangement (10) according to claim 1, in which the edge density (RD) is greater than the Inner Density (ID).
3. The interferometer arrangement (10) as claimed in claim 1 or 2, in which the first mirror arrangement (SP 1) spans a first free region (FB 1) in the inner region (IB) and the second mirror arrangement (SP 2) spans a second free region (FB 2) in the inner region (IB).
4. Interferometer arrangement (10) according to claim 3, in which said second free region (FB 2) extends at least partially in a transverse direction beyond said first free region (FB 1).
5. Interferometer device (10) according to claim 3 or 4, in which said first mirror device (SP 1) comprises a first edge density (RD 1) of said etch inlet (A) and said second mirror device (SP 2) comprises a second edge density (RD 2) of said etch inlet (A), wherein the second edge density (RD 2) is greater or smaller than the first edge density (RD 1).
6. An interferometer arrangement (10) as claimed in claim 5, in which the first and/or second edge density (RD 1; RD 2) describes a closed curve in a plan view of the flat run of the mirror arrangement (SP 1; SP 2), which closed curve laterally encloses the inner region (IB).
7. Interferometer arrangement (10) according to any one of claims 1 to 6, in which the Internal Density (ID) in the first and/or second mirror arrangement (SP 1; SP 2) describes a grating arrangement in a top view of a flat, extended part of the mirror arrangement (SP 1; SP 2).
8. Interferometer device (10) according to any one of claims 1 to 7, in which said Internal Density (ID) and/or said edge density (RD) of the arrangement of said etch entrances (A) in said first and/or second mirror device (SP 1; SP 2) comprises a constant spacing (d) between etch entrances (A) within said edge density (RD) and/or said Internal Density (ID), respectively.
9. Interferometer arrangement (10) according to claim 7 or 8, in which the arrangement of said etch entrances (A) in said Inner Density (ID) describes a first grating arrangement and/or the arrangement of said etch entrances (A) in said edge density (RD) describes a second grating arrangement.
10. Interferometer arrangement (10) according to any one of claims 1 to 9, in which said edge density and said Inner Density (ID) comprise, respectively, adjacent to each other, transition regions in which said etch entrances (a) are moved from the pattern of said edge density or said inner density to the respectively nearest etch entrance (a) of the adjoining pattern of said edge density or said inner density.
11. Method for manufacturing an interferometer arrangement (10), comprising the steps of:
-providing (S1) a substrate (2);
-arranging (S2) a first sacrificial layer (O1) on the substrate (2);
-arranging (S3) the first mirror arrangement (SP 1) and the second mirror arrangement (SP 2) parallel above one another at a first distance (d 12) and on a first sacrificial layer (O1) with a second sacrificial layer (O2) between the first mirror arrangement (SP 1) and the second mirror arrangement (SP 2), wherein a plurality of etching inlets (a) are formed in the first mirror arrangement (SP 1) and/or in the second mirror arrangement (SP 2) in a lateral inner region (IB), which etching inlets extend through the first mirror arrangement (SP 1) and/or the second mirror arrangement (SP 2), respectively, and wherein an edge density (RD) of the arrangement of the etching inlets (a) on the respective edge region of the first and/or second mirror arrangement (SP 1, SP 2) is such that, with regard to the etching inlets (a), the edge density (RD) on the first and/or second mirror arrangement (SP 1 ) of the etching inlets (a), SP 2) is changed in the Internal Density (ID) of the arrangement on the transverse inner region (IB); and is
-removing (S4) the first sacrificial layer (OS) and/or the second sacrificial layer (O2) in the inner region (IB) by means of an etching process through an etching access (A), thereby creating an edge structure (RS) in which the first and second mirror arrangements (SP 1; SP 2) are fixed and which at least partially laterally surrounds the first and second mirror arrangements (SP 1; SP 2) over their edge regions, and wherein by means of said removing an empty region (FB) is created below the first and/or second mirror arrangements (SP 1; SP 2).
12. Method according to claim 11, in which method an etching inlet (a) is formed in said first mirror arrangement (SP 1) and in said second mirror arrangement (SP 2), whereby a second free region (FB 2) under said second mirror arrangement (SP 2) extends at least partially laterally beyond a first free region (FB 1) under said first mirror arrangement (SP 1).
Technical Field
The present invention relates to an interferometer arrangement and a method for manufacturing an interferometer arrangement.
Background
For spectral filters that are variable (tunable) in terms of wavelength and that are only transparent to specific wavelengths, miniaturization can be achieved, for example, by means of microelectromechanical structures (MEMS technology), for example, using Fabry Perot Interferometers (FPIs).
A cavity with two substantially plane-parallel, highly reflective mirrors with a spacing of the order of the number of optical wavelengths (cavity length) may have a strong transmission only for wavelengths which correspond to an integer multiple of half a wavelength by the cavity length. The mirror spacing can be varied by, for example, electrostatic or piezoelectric actuation, and a filter element can thus be produced which is spectrally tunable.
A fabry-perot interferometer is described in US 2012/05075 a1, which is manufactured by etching a sacrificial layer between two mirrors.
In a conventional interferometer, the mirrors can be driven electrostatically and the spacing of the mirrors from one another can be varied. The mirror can be produced as a thin film and by means of surface micromechanical processes. The mirrors may be left empty (freestellen) by removing the sacrificial layer between the mirrors. In general, in order to make the mirrors in the interferometer hollow, a large area can be made free by means of a regular arrangement of etching holes in such a way that the most circular shape possible can be produced in accordance with the etching process. For a pattern of etch entrances, such as a hexagonal grid of dots, the shape condition x 2+ y 2 r 2 can be used, for example, to tailor the pattern of etch entrances such that the etch entrances remain unchanged at position (x, y) in a circle of radius r, while etch entrances outside the circle can be removed. The empty regions under the mirror resulting from this pattern and the etching performed describe rather a polygon with vertices and corners as a smooth edge contour (seen in top view). The angle can serve as a nominal breaking point when the mirror or the entire interferometer arrangement is subjected to mechanical loading, for example in the event of a fall.
Disclosure of Invention
The invention creates an interferometer arrangement according to
Preferred embodiments are the subject matter of the dependent claims.
The present invention is based on the idea of specifying an interferometer arrangement and a method for producing an interferometer arrangement which is distinguished by an improved arrangement of etching access openings by means of which the edge profile can be defined more precisely by means of an etching process when the mirror layer in the interferometer arrangement is empty and underetched. The more precisely shaped edge contour advantageously leads to a better clamping of the mirror layer in the interferometer arrangement and thus to an increased stability of the mirror layer and a more precise symmetry of the recess, which is thus distinguished by a more symmetrical mechanical stress on the mirror layer via the clamped region on the edge in terms of higher optical quality, improved mirror parallelism and by a higher degree of durability resulting from the minimization of the edges or tips that occur on the edge of the recess region.
According to the invention, the interferometer arrangement comprises a first mirror arrangement and a second mirror arrangement; an edge structure, wherein the first mirror device and the second mirror device are each fastened to the edge structure and the edge structure surrounds the first mirror device and the second mirror device at least partially in the lateral direction over its edge region; in this case, the first mirror device and the second mirror device are arranged at a first distance from one another, and the first and/or second mirror device in each case spans an empty region in the transverse inner region in the edge structure in the transverse direction and can be moved in each case relative to the other mirror device in this empty region, so that the first distance can be varied, in particular by means of driving, advantageously by means of electrostatic driving. Furthermore, the interferometer arrangement may itself be composed of a plurality of layers and likewise comprise one or more sacrificial layers at least during the manufacturing process. Furthermore, the interferometer arrangement comprises a plurality of etching inlets which extend through the first mirror arrangement and/or through the second mirror arrangement into the vacant region, wherein the edge density of the arrangement of the etching inlets on the respective edge region of the first and/or second mirror arrangement changes with respect to the internal density of the arrangement of the etching inlets on the laterally inner region of the first and/or second mirror arrangement. That is to say, in other words, in the lateral boundary region of the free region, the edge density of the arrangement of etching inlets changes laterally within the boundary region with respect to the internal density of the arrangement of etching inlets.
In the laterally delimited regions of the free region, the arrangement of the etching inlets according to the defined shape of the free region (in plan view) can be shifted from the inner region to the edge region, in other words the edge density can differ from the inner density.
The interferometer arrangement can be designed as a (surface) microelectromechanical component (MEMS), advantageously as a micro spectrometer, since the interferometer arrangement with the first pitch as a condition for transmitting a specific wavelength can function as a filter.
The mechanically movable region of the mirror arrangement can advantageously be left free by the applied etching access and etching process, for example after a material, for example a sacrificial layer, is removed by the etching process below and/or above and/or inside the mirror arrangement or its process-engineering prototype structure. The placement and density of etch portals may define the vacant areas and their profile on the edge. The etch inlet may be shaped as an opening, which may extend completely through the mirror arrangement. In a top view of the flat, extended part of the mirror arrangement, the etch inlet can be shaped as a hole or hole-like structure with an angular cross section or a circular cross section.
In a preferred embodiment of the interferometer arrangement, the edge density is greater than the inner density.
In a preferred embodiment of the interferometer arrangement, the first mirror arrangement spans a first free region in the interior region and the second mirror arrangement spans a second free region in the interior region.
In a preferred embodiment of the interferometer arrangement, the second free region extends at least partially in the transverse direction beyond the first free region.
In accordance with a preferred embodiment of the interferometer arrangement, the first mirror arrangement comprises a first edge density of the etch inlet and the second mirror arrangement comprises a second edge density of the etch inlet, wherein the second edge density is greater or less than the first edge density.
According to a preferred embodiment of the interferometer arrangement, the first and/or the second edge density describe a closed curve in a plan view of the flat extension of the mirror arrangement, which curve laterally encloses the inner region.
According to a preferred embodiment of the interferometer arrangement, the internal density in the first and/or second mirror arrangement describes a grid arrangement in a plan view of the flat extension of the mirror arrangement.
The etch inlets may be arranged in a regular pattern in the inner region and/or in the bounded or edge regions. The internal density and/or the edge density can thus each comprise a plurality of etching inlets in a pattern, for example a hexagonal grid, or in a different pattern. By means of the regular spacing between the etching inlets, a uniform spacing below the respective mirror arrangement can be achieved at least in this region of the etching inlets. In order to be able to influence the edge region of the free region in terms of its shape better, the pattern of the edge density can be selected accordingly densely and likewise comprise regularly spaced etching entries. By a denser arrangement of the etching inlets, which is advantageously substantially similar to the shape of the edge contour (curve) to be defined, the shape of the edge contour of the free region can be better matched to the desired contour, for example to a circle. The higher the edge density, the better the approximation (flatness) to the desired edge profile is achieved. The arrangement with a grid produces, in plan view, vacant areas of polygonal shape without deviating from the own edge density of the internal density. The selected edge density may flatten the outline of this polygon depending on the density and approach the desired edge outline, e.g. circular or elliptical, as viewed in top plan view. By reducing the angle at the free structure (at its edges), mechanical stress peaks can be reduced and the robustness of the clamped mirror arrangement increased. For an etching process, a balancing of the etching duration in the undercutting of the mirror arrangement can be achieved by matching the pattern of the etch inlet to a defined profile, whereby process robustness can be improved.
During the sacrificial layer etching, the input of the etching medium is effected from above through the mirror arrangement and the layers of the mirror arrangement, the etching rate (or the etching duration for the same undercutting) being different in the layers laterally remote from the etch access. This can be balanced by different openings (etch inlets) in the upper and lower mirror arrangements.
In this case, a mechanical rotational symmetry can be achieved in a plan view of the plane of extension of the mirror arrangement, and the clamping properties in the edge structure can be designed more uniformly along the contour. The same or similar mechanical properties of the mirror arrangement along its lateral surround can be achieved by better symmetry. It is thus possible, for example, when the mirror arrangements are driven electrostatically, for example with ring electrodes below or above the mirror arrangements, to improve the irregular deflection towards one another in a more symmetrical spatial position and thus to achieve a better parallelism of the deflected mirror arrangements to one another, which can improve the optical properties (filter effect) of the interferometer arrangement.
According to a preferred embodiment of the interferometer arrangement, the internal density and/or the edge density of the arrangement of etching inlets in the first and/or second mirror arrangement comprises a constant spacing between the etching inlets within the edge density and/or the internal density, respectively.
According to a preferred embodiment of the interferometer arrangement, the arrangement of etch inlets in the inner density describes a first grating arrangement and/or the arrangement of etch inlets in the edge density describes a second grating arrangement.
According to a preferred embodiment of the interferometer arrangement, the edge density and the internal density each comprise, next to one another, a transition region in which the etching access moves from the pattern of the edge density or the internal density toward the respectively nearest etching access of the next pattern of the edge density or the internal density.
According to the invention, in a method for manufacturing an interferometer arrangement, a substrate is provided; disposing a first sacrificial layer on the substrate; the first mirror arrangement and the second mirror arrangement are arranged parallel above one another at a first distance and on a first sacrificial layer with a second sacrificial layer between the first mirror arrangement and the second mirror arrangement, wherein in the first mirror arrangement and/or the second mirror arrangement a plurality of etching inlets are formed in the lateral inner region, which etching inlets extend through the first mirror arrangement and/or the second mirror arrangement, respectively, and wherein the edge density of the arrangement of the etching inlets on the respective edge regions of the first and/or second mirror arrangement is changed with respect to the inner density of the arrangement of the etching inlets on the lateral inner region of the first and/or second mirror arrangement. That is to say, in other words, in the lateral bounding region of the inner region, the edge density of the arrangement of etching inlets changes laterally within the bounding region with respect to the inner density of the arrangement of etching inlets.
Here, the time lapse or repetition of the steps may be variable and possible. In case the etch access extends through one or the other mirror arrangement, the etch access may be generated in two separate steps.
Furthermore, the first sacrificial layer and/or the second sacrificial layer in the inner region are removed by means of an etching process by means of an etching access, so that an edge structure is produced in which the first and second mirror arrangements are fixed and which at least partially laterally surrounds the first and second mirror arrangements on their edge regions, and wherein, by means of said removal, a free region is produced below the first and/or second mirror arrangements.
The method may also be advantageously characterized by combining the features mentioned for the interferometer arrangement and the advantages thereof, and vice versa.
According to a preferred embodiment of the method, the etching access is formed in the first mirror arrangement and in the second mirror arrangement, so that the second free region below the second mirror arrangement extends at least partially laterally beyond the first free region below the first mirror arrangement.
The first and/or second sacrificial layer may for example comprise silicon dioxide (SiO 2). The removal can be carried out selectively, i.e. locally under the mirror arrangement, simultaneously or in succession.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings.
Drawings
The invention is explained in detail below with the aid of embodiments illustrated in the schematic drawings.
In the drawings:
FIG. 1 schematically shows an arrangement of etch inlets in an interferometer arrangement in a top view of a mirror arrangement according to an embodiment of the invention;
FIG. 2 schematically shows an arrangement of etch inlets in an interferometer arrangement in a top view of a mirror arrangement according to another embodiment of the invention;
FIG. 3 is a schematic side view of an interferometer apparatus according to another embodiment of the present invention; and is
Fig. 4 is a schematic block diagram of method steps of a method according to an embodiment of the invention.
Detailed Description
Identical or functionally identical elements are denoted by the same reference numerals in the figures.
Fig. 1 schematically shows the arrangement of etch inlets in a cut-out of an interferometer arrangement in a top view of a mirror arrangement according to an embodiment of the invention.
The interferometer arrangement may comprise a plurality of etching inlets a in the first and/or second mirror arrangement, which etching inlets can extend through the first mirror arrangement and/or the second mirror arrangement into an empty region, which can be shaped by removing the sacrificial layer below the respective mirror arrangement. Above the lateral delimited regions FBG of the free region, the edge density RD in an arrangement of etch inlets a can vary laterally within the delimited regions FBG, for example greater than the internal density ID in an arrangement of etch inlets a. In this way, the contour K for the region to be emptied on the edge can be defined more precisely and deviates from the polygonal structure formed by the exemplary grid arrangement of the etching inlets in the inner region IB. The contour K can be an imaginary (desired) target shape (of the region to be emptied) which can be approached by the arrangement of the etching inlets in an edge density. In other words, a plurality of additional etch inlets are provided in the edge region. In this case, certain edge conditions can be observed, for example a minimum spacing from adjacent etching access openings or other structures in the mirror arrangement, in order to maintain the stability of the mirror arrangement and thus of the interferometer arrangement. The etching inlets in the edge region can thus trim the pattern, such as a grid arrangement or polygons, in the inner region and approach the desired profile K in their position. The etching inlets can in particular be arranged themselves at the corners of the contour, for example of a grid or of a polygon.
With regard to the variation between the edge density and the internal density, it is possible that some etching inlets (not protruding significantly) present at specific locations in the pattern of the internal density can be removed in the region of the edge density. In this way, the transition region between the inner density and the edge density can be modified (created).
By defining the edge profile K more clearly by means of the increased edge density RD, the symmetry of the mechanical clamping around the mirror device can be improved and the inhomogeneity of the distribution of the mechanical clamping on the mirror device can be reduced. Additional etching inlets can be added in the edge region, for example, at a fixed radial distance from the mirror center (in plan view), for example, to approximately form a circular contour.
Asymmetric mirror deformation due to asymmetric clamping can be reduced or avoided. In the very uneven course of the edge profile K, a pure deletion of etching holes outside the desired edge profile K is brought about without increasing the edge density there and without producing mechanical stress inhomogeneities on the mirror arrangement.
The edge profile K may describe a closed curve which may laterally enclose the inner region IB.
The etching holes can in particular be arranged themselves on a hypothetical curve as profile K, i.e. on the edge profile, or on a tapered (radially shifted, advantageously inward) version of this curve, since the etching front can be shifted radially outward and can reach the initially assumed edge profile.
Fig. 2 schematically shows the arrangement of etch inlets in an interferometer arrangement in a top view of a mirror arrangement according to another embodiment of the invention.
In fig. 2, a similar arrangement of etch inlets to that of fig. 1 is shown, but with the difference being the edge density RD. In the inner region, the etch inlets may be arranged in a pattern, for example a hexagonal grid. In the edge region, the arrangement of etch inlets a may also comprise a pattern, advantageously also a grid arrangement, with a much higher edge density RD. The grid in the edge density can approach the desired contour K of the region to be emptied and be positioned accordingly. The pattern and the grid are periodic in one or more particular directions, respectively. Additional etch inlets may be arranged in the edge region of the original pattern relative to the inner region and may vary or be identical in position, shape and size. In order to transition the edge density RD more smoothly for the inner density ID, transition regions can be formed in the inner region and the edge region, respectively, and offset therefrom. Here, pairs of etched inlets on the edges of the exterior of the interior region and on the edges of the interior of the edge region (wherein, in pair a ', one etched inlet a ' may be in the interior region and the other etched inlet a ' in the edge region) are movable relative to each other from their original grid positions. In the inner region, the etching inlets are arranged at a fixed distance d from one another and in the edge region, the etching inlets are arranged at a fixed distance d' from one another. In the transition region, it may then be different from these spacings and the etch inlets are moved by a distance d', advantageously onto the other etch inlet of the respective pair (along the connecting line between the pair of etch inlets). In this way the patterns can be inverted with respect to each other. Instead of a grid structure in the edge region, the etch inlet can also draw other patterns there, for example concentric rings.
FIG. 3 is a schematic side view of an interferometer apparatus according to another embodiment of the present invention.
The
According to fig. 3, the free area FB below the first mirror arrangement SP1 differs from the free area below the second mirror arrangement SP2, for example with respect to the lateral extent or height of the mirror arrangement above the substrate 2 or respectively above the other mirror arrangement. The first mirror arrangement SP1 within the inner region IB therefore spans the first free region FB1 and the second mirror arrangement SP2 in the inner region IB spans the second free region FB 2. The second vacant area FB2 may extend at least partially in the lateral direction beyond the first
FIG. 4 is a schematic block diagram of method steps of a method according to one embodiment of the present invention.
In a method for manufacturing an interferometer device, a substrate is provided S1; disposing a first sacrificial layer S2 on the substrate; arranging S3 the first and second mirror arrangements parallel above one another at a first distance and on a first sacrificial layer with a second sacrificial layer between the first and second mirror arrangements, wherein a plurality of etching inlets are formed in the first and/or second mirror arrangement in a laterally inner region, which etching inlets extend through the first and/or second mirror arrangement, respectively, and wherein, in a laterally delimited region of the inner region, an edge density of the arrangement of etching inlets changes laterally within the delimited region with respect to an inner density of the arrangement of etching inlets; and removing S4 the first sacrificial layer and/or the second sacrificial layer in the inner region by means of an etching process through an etching access, thus creating an edge structure in which the first and second mirror arrangements are fixed and which at least partially laterally surrounds the first and second mirror arrangements on their edge regions, and wherein a free region is created under the first and/or second mirror arrangements by means of said removal. Both sacrificial layers can be removed simultaneously.
Although the present invention has been fully described above with reference to the preferred embodiments, it is not limited thereto but can be modified in various ways.