Micromirror array and method for the manufacture thereof

Abstract

A micromirror array is provided having a mirror membrane, including a first supporting element, including for each first supporting element, a first coupling element that is located between the mirror membrane and the particular first supporting element and is formed to mechanically couple the particular first supporting element to the mirror membrane; having at least one second supporting element that is mechanically coupled to the at least one first supporting element; and having a second coupling element for each second supporting element that is formed to be mechanically contacted. Also a method for manufacturing a micromirror array according to the present inventions described.

Claims

1. A micromirror array, comprising: a mirror membrane; at least one first supporting element, wherein for each first supporting element, a first coupling element that is located between the mirror membrane and the first supporting element is formed to mechanically couple the first supporting element to the mirror membrane; at least one second supporting element mechanically coupled to at least one first supporting element; and a second coupling element for each second supporting element, the second coupling element located on a side of the second supporting element facing away from the mirror membrane and formed to be mechanically contacted, wherein the first coupling element defines a first distance between the mirror membrane and the at least one first supporting element, and defines a second distance between the mirror membrane and the at least one second supporting element, wherein the first distance is equal to the second distance.

2. The micromirror array as recited in claim 1, further comprising: at least one web formed to mechanically intercouple the at least one first supporting element and the at least one second supporting element.

3. The micromirror array as recited in claim 2, wherein the at least one second supporting element is web-shaped, and the at least one web is disposed at a predefined angle of 90 or 45 to the at least one second supporting element.

4. The micromirror array as recited in claim 2, wherein at least one of: i) the first coupling elements are each configured at the ends of the at least one web, or ii) the first coupling elements are distributed over a length of the at least one web, the first coupling elements being symmetrically distributed relative to a central axis of the mirror membrane.

5. The micromirror array as recited in claim 1, wherein at least one of: i) the first coupling elements are at least one of punctiform and circular, and ii) the first coupling elements contact the mirror membrane at at least one edge region of the mirror membrane.

6. The micromirror array as recited in claim 1, wherein the first coupling elements couple the first supporting elements to the mirror membrane in a way that minimizes a dynamic deformation of the mirror membrane in response to a movement of the micromirror array.

7. The micromirror array as recited in claim 1, wherein at least one of: i) at least one of the at least one first supporting element, the at least one second supporting element, and the mirror membrane, is formed with silicon, ii) the first coupling elements are formed with oxide, and iii) the second coupling elements are formed with germanium.

8. A micromirror array, comprising: a mirror membrane; at least one first supporting element, wherein for each first supporting element, a first coupling element that is located between the mirror membrane and the first supporting element is formed to mechanically couple the first supporting element to the mirror membrane; at least one second supporting element mechanically coupled to at least one first supporting element; and a second coupling element for each second supporting element, the second coupling element formed to be mechanically contacted, wherein at least one of: i) at least one of the at least one first supporting element, the at least one second supporting element, and the mirror membrane, is formed with silicon, ii) the first coupling elements are formed with oxide, and iii) the second coupling elements are formed with germanium, wherein the at least one first supporting element is formed with silicon and is dimensioned in such a way that, in one etching process, the first coupling element that is formed with the corresponding oxide is not completely etched away between the mirror membrane and the first supporting element; and wherein the at least one second supporting element is formed with silicon and is dimensioned in such a way that, in one etching process, an oxide layer present between the corresponding second supporting element and the mirror membrane is completely etched away.

9. A method for manufacturing a micromirror array from an SOI wafer, that is formed with an oxide layer between a first silicon layer and a second silicon layer, the method comprising: patterning the second silicon layer to form a mirror membrane, and the first silicon layer to form at least one first supporting element of a first thickness; patterning the first silicon layer to form at least one second supporting element of a second thickness in a way that allows the at least one second supporting element to be mechanically coupled to the at least one first supporting, the first thickness being smaller than the second thickness; attaching a second coupling element for each of the second supporting elements on the side of the particular second supporting element facing away from oxide layer; and etching the oxide layer in a way that allows a first coupling element, in each instance formed with a first oxide, to remain only between mirror membrane (2) and the at least one first supporting element.

10. The method as recited in claim 9, wherein the patterning includes an anisotropic etching, and one of an etching with potassium hydroxide, KOH etching, or a trench etching.

11. The method as recited in claim 9, wherein the etching of the oxide layer includes an isotropic etching including a wet chemical isotropic etching or an isotropic etching with a gas phase.

12. The method as recited in claim 9, wherein the at least one first supporting element and the at least one second supporting element are dimensioned to allow the oxide between the at least one second supporting element and the mirror membrane to be completely etched away during etching of the oxide layer, and the first coupling element to at least partially remain in the oxide layer between the at least one first supporting element and the mirror membrane.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention is explained below on the basis of the exemplary embodiments shown in the schematic figures.

(2) FIG. 1 shows a schematic representation of a specific embodiment of a micromirror according to the present invention.

(3) FIG. 2 shows a flow chart of a specific embodiment of a method according to the present invention.

(4) FIG. 3 shows a schematic representation of a specific embodiment of a micromirror array according to the present invention.

(5) FIG. 4 shows a schematic representation of a specific embodiment of a micromirror array according to the present invention.

(6) FIG. 5 shows a schematic representation of a specific embodiment of a micromirror array according to the present invention.

(7) FIG. 6 shows a schematic representation of a specific embodiment of a micromirror array according to the present invention.

(8) FIG. 7 shows a schematic representation of a specific embodiment of a micromirror array according to the present invention.

(9) FIG. 8 shows a schematic representation of a specific embodiment of a micromirror array according to the present invention.

(10) FIG. 9 shows a schematic representation of a specific embodiment of a micromirror array according to the present invention.

(11) FIG. 10 shows a schematic representation of a specific embodiment of a micromirror array according to the present invention.

(12) FIG. 11 shows a schematic representation of a specific embodiment of a micromirror array according to the present invention.

(13) In all of the figures, like or functionally equivalent elements and devicesprovided that nothing else is indicatedare provided with the same reference numerals.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

(14) FIG. 1 shows a schematic representation of a specific embodiment of a micromirror array 1 according to the present invention in a side view.

(15) Micromirror array 1 has a mirror membrane 2, above which, two first supporting elements 3-1 and 3-2 and three second supporting elements 5-1-5-3 are configured at a defined distance. First supporting elements 3-1 and 3-2 are coupled via two first coupling elements 4-1, 4-2 to mirror membrane 2. The two first coupling elements 4-1, 4-2 thereby define the distance between mirror membrane 2 and the two first supporting elements 3-1 and 3-2 and the three second supporting elements 5-1-5-3. In addition, first supporting elements 3-1, 3-2 are coupled via a web 7 to the three second supporting elements 5-1-5-3, so that the three second supporting elements 5-1-5-3 are fixed relative to mirror membrane 2, even without a direct coupling to mirror membrane 2.

(16) On the side of the three second supporting elements 5-1-5-3 facing away from mirror membrane 2, a second coupling element 6-1-6-3 is configured in each case. Second coupling elements 6-1-6-3 are used for mechanically contacting micromirror array 1 and for fastening the same, for example, to a spring or the like that micromirror array 1 bears in operation.

(17) For illustration purposes, FIG. 1 shows a specific embodiment of micromirror array 1, that has two first supporting elements 3-1 and 3-2 and three second supporting elements 5-1-5-3. First supporting elements, second supporting elements, as well as first and second coupling elements may be more or less provided in further specific embodiments.

(18) In a specific embodiment, micromirror device 1 is fabricated from a single SOI wafer 10, thus from a wafer 10 that is formed from an oxide layer 11 between a first silicon layer 12 and a second silicon layer 13. This makes it possible to determine the thickness of mirror membrane 2 and, in particular, also the distance between mirror membrane 2 and first and second supporting elements 3-1, 3-2 and 5-1-5-3 by properly selecting SOI wafer 10. In addition, SOI wafer 10 makes possible a very simple manufacturing of micromirror array 1, as it may be fabricated from SOI wafer 10 using simple etching steps. Possible specific embodiments of the manufacturing method are explained in the context of FIG. 2.

(19) Also showns in FIG. 1 to the right and left of the described elements are housing sections 20-1, 20-2.

(20) FIG. 2 shows a flow chart of a specific embodiment of a method according to the present invention where a micromirror array 1 according to the present invention may be fabricated in an SOI wafer 10, that is formed with an oxide layer 11 between a first silicon layer 12 and a second silicon layer 13.

(21) The method provides for patterning S1 second silicon layer 13 to form a mirror membrane 2. In addition, the method provides for patterning first silicon layer 12 to form at least one supporting element 3-1-3-22 of a first thickness.

(22) In S2, the method provides for patterning first silicon layer 12 to form at least one second supporting element 5-1-5-3 of a second thickness in a way that allows the at least one second supporting element 5-1-5-3 to be mechanically coupled to the at least one first supporting element 3-1-3-22, the first thickness being smaller than the second thickness. Thus, in S2, in accordance with one specific embodiment, for example, webs 7, 7-1-7-21 may also be formed that mechanically couple the at least one second supporting element 5-1-5-3 to the at least one first supporting element 3-1-3-22.

(23) S3 provides for attaching a second coupling element 6-1-6-3 for each of the second supporting elements 5-1-5-3 on the side of the particular second supporting element 5-1-5-3 facing away from oxide layer 11. Finally, S4 provides for etching oxide layer 11 in a way that allows a first coupling element 4-1-4-22, in each instance formed with a first oxide, to remain only between mirror membrane 2 and the at least one first supporting element 3-1-3-22.

(24) The term thickness is understood here to refer to the thickness or width of the particular element in a side view. Thus, an element that is thicker than another has a larger surface area than the mirror membrane; respectively, from the edges thereof, features a larger distance to the center thereof. This is important in order to be able to completely remove the oxide layer underneath the thinner elements during etching, and at least partially leave the oxide layer under the thicker elements.

(25) In a specific embodiment, to manufacture first coupling elements 4-1-4-22, the at least one first supporting element 3-1-3-22, and the at least one second supporting element 5-1-5-3 are dimensioned to allow the oxide between the at least one second supporting element 5-1-5-3 and mirror membrane 2 to be completely etched away during etching S4 of oxide layer 11, and first coupling element 4-1-4-22 to at least partially remain in oxide layer 11 between the at least one first supporting element 3-1-3-22 and mirror membrane 2.

(26) Within the scope of the present invention and in a specific embodiment, the patterning may include an etching, in particular an anisotropic etching, in particular also an etching with potassium hydroxide, KOH etching, or a trench etching. In a specific embodiment, the etching of oxide layer 11 may include an isotropic etching, in particular, a wet chemical isotropic etching or an isotropic etching with a gas phase.

(27) The sequence of the individual manufacturing steps described above is merely exemplary and may deviate from that illustrated in further specific embodiments.

(28) FIG. 3 shows a schematic representation of a specific embodiment of an inventive micromirror array 1 of FIG. 1 prior to a processing of SOI wafer 10.

(29) FIG. 3 through 6 show micromirror array 1 in a side view, as in FIG. 1. It may be micromirror array of FIG. 7, for example. Therefore, FIGS. 1 and 3-6 show it in a side view along central axis 8 of mirror membrane 2, as illustrated in FIG. 7.

(30) FIG. 3 shows the SOI wafer in the initial state thereof in which a first silicon layer 12 resides above oxide layer 11, and a second silicon layer 13 underneath oxide layer 11.

(31) FIG. 4 shows a schematic representation of a specific embodiment of an inventive micromirror array 1 of FIG. 3, following a first manufacturing step.

(32) In FIG. 4, second supporting elements 5-1-5-3 are formed by a first patterning process, which may be an etching process, for example.

(33) FIG. 5 schematically shows a specific embodiment of an inventive micromirror array 1 of FIG. 4 in accordance with a further manufacturing step.

(34) In FIG. 5, a further etching process is shown which forms first supporting elements 3-1, 3-2, which only have approximately half of the height of second supporting elements 5-1-5-3. In addition, web 7 was also already formed by the etching process.

(35) FIG. 6 shows a schematic representation of a specific embodiment of an inventive micromirror array 1 of FIG. 5 in accordance with a further manufacturing step.

(36) FIG. 6 shows virtually complete micromirror array 1 following removal of oxide layer 11 by an etching process, beginning with micromirror array 1 of FIG. 5. The etching process is realized in such a way that oxide layer 11 remains merely underneath first supporting elements 3-1 and 3-2, and thus has formed first coupling elements 4-1, 4-2. The etching of oxide layer 11 may feature an isotropic etching, for example, in particular, a wet chemical isotropic etching or an isotropic etching with a gas phase.

(37) FIG. 7 schematically illustrates a specific embodiment of a micromirror array 1 according to the present invention.

(38) The micromirror array of FIG. 7 shows a plan view of micromirror array 1 of FIG. 1 from behind, thus on the side facing away from mirror membrane 2.

(39) Mirror membrane 2 is approximately rectangular; mirror membrane 2 being larger in the horizontal direction than in the vertical direction and having rounded corners. This shape of mirror membrane 2 is merely to be seen as an example and may also differ, for example, be elliptical in another variant. In the plan view, it is discernible that a first supporting element 3-3-3-6 is configured in each of the corners. Supporting elements 3-3-3-6 are circular in shape, but not limited to this shape.

(40) Configured underneath first supporting elements 3-3-3-6 are first coupling elements 4-3-4-6, which are likewise round in this specific embodiment. In principle, the shape of first coupling elements 4-3-4-6 is derived from the shape of first supporting elements 3-3 through 3-6, and the isotropic etching. Therefore, a multiplicity of shapes is possible. In FIG. 7-11, first coupling elements 4-3-4-6 are discernible, even if they are disposed underneath first supporting elements 3-3-3-6. This is merely to illustrate the present invention.

(41) First supporting elements 3-3 and 3-6, which are configured at the bottom corners of mirror membrane 2, and first supporting elements 3-4 and 3-5, which are configured at the top corners of mirror membrane 2, are each intercoupled by a web 7-3, 7-4 and also coupled by webs 7-3, 7-4 to second supporting elements 5-1-5-3, that are not shown separately in FIG. 7, since second coupling elements 6-1-6-3 cover the same. Second supporting elements 5-1-5-3 and second coupling elements 6-1-6-3 each extend vertically between the two webs 7-3 and 7-4. Also disposed around mirror membrane 2 is a housing 20 that was left during the manufacturing process that had been described in connection with FIG. 2. This may be accomplished, for example, by properly carrying out the etching processes.

(42) FIG. 8 schematically shows another specific embodiment of a micromirror array 1 according to the present invention.

(43) Micromirror array 1 of FIG. 8 is based on micromirror array 1 of FIG. 7 and differs therefrom in that, in each case, a web 7-20 and 7-21 interconnects the two left first supporting elements 3-3 and 3-4 and the two right first supporting elements 3-5 and 3-6. In addition, three webs 7-5-7-7 are provided that connect the two webs 7-20 and 7-21 to the second coupling elements 6-1-6-3.

(44) Thus, FIG. 8 shows an alternative specific embodiment of micromirror device 1, where mirror membrane 2 is contacted at the same sites as in FIG. 7, but the connections to second coupling elements 6-1-6-3 are differently configured.

(45) FIG. 9 schematically shows a specific embodiment of a micromirror array 1 according to the present invention that is based on micromirror array 1 of FIG. 7.

(46) In FIG. 9, micromirror array 1 has four further first supporting elements 4-7-4-10. The two first supporting elements 3-7-3-8 and the two first supporting elements 3-9-3-10 are each disposed to the right and left of second supporting elements 5-1-5-3, respectively second coupling elements 6-1-6-3. In the vertical direction, first supporting elements 3-7 and 3-10 reside below central axis 8 of mirror membrane 2, and first supporting elements 3-8 and 3-9 above central axis 8 of mirror membrane 2.

(47) FIG. 10 schematically shows a specific embodiment of an inventive micromirror array 1 where the array resembles first supporting elements 3-3-3-6 and 3-7-3-10 of the array of FIG. 9.

(48) In contrast to FIG. 9, the four first supporting elements 3-3-3-6 are intercoupled in each case by webs 7-3, 7-4 and 7-12-7-13, so that webs 7-3, 7-4 and 7-12-7-13 form a frame whose corners are the four first supporting elements 3-3-3-6. In addition, first supporting elements 3-7 and 3-10 and first supporting elements 3-8 and 3-9 are coupled in each case by a horizontally extending web 7-8-7-10 to corresponding second supporting elements 5-1, 5-3, as in FIG. 9.

(49) FIG. 11 schematically illustrates a specific embodiment of a micromirror array 1 according to the present invention.

(50) In contrast to the previous specific embodiments, micromirror array 1 of FIG. 11 has twelve first supporting elements 3-11-3-22 that are arrayed in an X shape on mirror membrane 2. First supporting elements 3-11, 3-15 and 3-19 on the left, lower diagonal of the X shape are coupled by web 7-19 to second supporting element 5-1. First supporting elements 3-11, 3-16 and 3-20 on the left upper diagonal of the X shape are coupled by web 7-16 to second supporting element 5-1. First supporting elements 3-13, 3-17 and 3-21 on the right upper diagonal of the X shape are coupled by web 7-17 to second supporting element 5-3. Finally, first supporting elements 3-13, 3-17 and 3-21 on the right lower diagonal of the X shape are coupled by web 7-18 to second supporting element 5-3. The outermost, two left, first supporting elements 3-11 and 3-12 are intercoupled by a web 7-14, and the two right, outermost supporting elements 3-13 and 3-14 likewise by a web 7-15.

(51) The arrays of first supporting elements 3-1-3-22 and of second supporting elements 5-1-5-3 described in the figures are merely exemplary and serve merely to illustrate the present invention. The number and array of the elements of micromirror array 1 according to the present invention may vary in other specific embodiments. The positions of first supporting elements 3-1-3-22 or of second supporting elements 5-1-5-3, for example, may be determined using a simulation that makes it possible to minimize the deformation of mirror membrane 2 used for the particular application in response to a movement thereof.

(52) Although the present invention is described above on the basis of preferred exemplary embodiments, it is not limited thereto, but rather may be modified in numerous ways. In particular, the present invention may be modified in various ways without departing from the spirit and scope thereof.