Abstract:
In a micromechanical component having an inclined structure and a corresponding manufacturing method, the component includes a substrate having a surface; a first anchor, which is provided on the surface of the substrate and which extends away from the substrate; and at least one cantilever, which is provided on a lateral surface of the anchor, and which points at an inclination away from the anchor.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a micromechanical component having an inclined structure. The present invention also relates to a corresponding manufacturing method. 
     BACKGROUND INFORMATION 
     Modern semiconductor technology is largely based on the application and structuring of layers. Highly complex structures are possible using clever process sequences. 
     The degree of complexity of micromechanical components, such as sensors and actuators, has increased significantly in recent years. The recurring problem in this context is to cost-effectively and reliably manufacture components having inclined structures or round structures. 
     The introduction of inclined planes or round structures (“bumps” or “dents”) on or in micromechanical layers is not a high volume method, however. Such structures may be manufactured using grayscale lithography, but the processes are very sensitively dependent on the process parameters and are not suitable for high volumes. Anisotropic etching (e.g., silicon in KOH, TMAH) does not allow design freedom, because only very specific angles are possible. 
     SUMMARY 
     The micromechanical component having an inclined structure according to example embodiments of the present invention having the features described herein and the corresponding manufacturing method described herein have the advantage that they allow simple manufacturing of a micromechanical component having an inclined structure. An inclined structure according to example embodiments of the present invention is not restricted to a completely linear inclination, but rather also includes a partially linear inclination and a rounded inclination. In other words, inclined means that the cantilever has a tangent at least one point on its surface which does not form a right angle to the lateral surface of the first anchor. 
     Starting from an anchor structure having at least one cantilever located thereon, an aspect hereof is to induce bending of the cantilever such that it points at an inclination away from the anchor. Connection in the inclined position may be achieved either by a connection procedure, such as bonding or gluing, or by irreversible freezing of an internal stress in the cantilever, e.g., by quenching. 
     Example embodiments of the present invention provide a combination of methods via which inclined bars or planes may be permanently manufactured. Applications may be seen, for example, in microfluidics, actuators, or sensors. The manufacturing is performed using standard processes and may therefore also be modeled so that it is suitable for high volume. Example embodiments of present invention allow a structure manufactured in one layer, such as a bar, to be bent in a targeted manner using suitable steps (for example, using a stress induced by further layers or inherent stress, pressure, or electrostatic attraction, or by combination of various methods) and subsequently, or preferably in the bending process step, to be connected directly or via an anchor to a suitable substrate. The structure is thus connected out of the plane and may supplement the mode of operation of the further micromechanics. 
     Example embodiments of the present invention allow the structuring of a plane having an effect in various planes. It requires less structuring effort than conventional techniques, which allows a cost savings, a yield advantage, and better functionality due to less adjustment offset. Therefore, higher signals and/or forces may be achieved by better arrangement of the structures, better functionality, and more flexible overall sizes. An example is improved fluidic functionality due to smoother transitions between various levels. 
     According to example embodiments, the cantilever points at an inclination downward toward the surface of the substrate. 
     The cantilever may be connected directly to the surface of the substrate or indirectly, for example, via a second anchor or another connection structure. 
     The anchor and the cantilever may be implemented in one piece, for example, from a micromechanical silicon structure. 
     In example embodiments, a first anchor and a second anchor are provided spaced apart from one another by an intermediate space on the surface of the substrate, the anchors being connected to the surface of the substrate via a particular cantilever, a suspension for a rotational axis of a rotating bar being attached to the anchors in the intermediate space. 
     The cantilever may assume various forms, and may be bar-shaped or planar in particular (for example, shield-like, in the form of a circular segment, triangular, etc.). 
     Exemplary embodiments of the present invention are shown in the drawings and are explained in greater detail in the following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1   a - c  show schematic cross-sectional views of a micromechanical component according to an example embodiment of the present invention. 
         FIG. 2  shows a schematic cross-sectional view of a micromechanical component according to an example embodiment of the present invention. 
         FIGS. 3   a, b  show schematic cross-sectional views of a micromechanical component according to an example embodiment of the present invention. 
         FIG. 4  shows a schematic cross-sectional view of a micromechanical component according to an example embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Identical reference numerals refer to identical or functionally identical components in the figures. 
       FIGS. 1   a - c  are schematic cross-sectional views of a micromechanical component according to an example embodiment of the present invention. 
     In  FIGS. 1   a - c , reference numeral  1  refers to a borofloat substrate. A first anchor  3   e  is provided on a surface O of substrate  1 , the anchor extending away in a column from substrate  1 . Two thin cantilevers  3   c  are provided in one piece with anchor  3   e  on its side walls S 1 , S 2 , a second anchor  3   a  and  3   b  being provided at each end of the cantilevers. A particular metal coating area  3   d , for example, made of aluminum, is additionally provided on cantilevers  3   c . In the present example, first anchor  3   e , cantilevers  3   c , and second anchors  3   a  and  3   b  are produced in one piece from silicon, for example, by a corresponding etching process employing a corresponding sacrificial layer. Metal layer areas  3   d  are provided, for example, by deposition and back-etching on cantilevers  3   c . First anchor  3   e , cantilevers  3   c  having metal layer areas  3   d , and second anchors  3   a  and  3   b  thus form a T-structure in the present example. 
     By suitably selecting the relevant coefficients of thermal expansion of cantilevers  3   c  and metal layer areas  3   d , the cantilevers may be provided with a semiconductor/metal bimorphic characteristic, i.e., the possibility of bending by application of temperature. 
     Starting from the structure described with reference to  FIG. 1   a , according to  FIG. 1   b , heat is discharged to the T-structure using a heating unit HE, metal layer areas  3   d  on cantilevers  3   c  expanding to a greater extent than cantilevers  3   c  by appropriate selection of the coefficient of thermal expansion. 
     Finally, with reference to  FIG. 1   c , second anchors  3   a ,  3   b  touch surface O of substrate  1 , and in a manner which may be predefined by the geometry of second anchors  3   a ,  3   b  and the design of cantilevers  3   c  and metal layer areas  3   d . In their structuring, it is to be ensured that the movement occurs in a controlled manner from the starting position and bending in undesired directions is not possible. 
     After second anchors  3   a ,  3   b  rest positively on substrate  1  according to  FIG. 1   c , these anchors may be connected to substrate  1  using suitable measures. It is shown as an example in  FIG. 1   c  that this connection is performed by anodic bonding with the aid of a voltage source SP, which applies a voltage U on the one hand at point U 1  to substrate  1  and on the other hand at point U 2  to first anchor  3   e . A suitable material combination for this purpose is the described material combination of silicon anchor and borofloat substrate. The fact that both the temperature action of heating unit HE and the electrostatic attraction by applied voltage U support the bending of cantilever  3   c  may additionally be advantageously employed. 
     It is to be noted that other types of measures, such as seal glass bonding, gluing, etc., are also possible, as is local activation, for example, by electrical heating elements on second anchors  3   a ,  3   b.    
       FIG. 2  is a schematic cross-sectional view of a micromechanical component according to an example embodiment of the present invention. 
     In the example embodiment according to  FIG. 2 , metal layer areas  3   d  from  FIG. 1  are omitted. In this example, the heating of cantilevers  3   c  provided by heating unit HE only causes material softening, and the bending occurs under the influence of gravity and under the influence of the electrostatic attractive force between substrate  1  and second anchors  3   a ,  3   b , which is caused by applied voltage U. 
       FIGS. 3   a, b  are schematic cross-sectional views of a micromechanical component according to an example embodiment of the present invention. 
     In contrast to the above-described example embodiments, the example embodiment according to  FIGS. 3   a, b  does not start from a T-shaped basic structure, but rather from two gallows-shaped basic structures, which are provided on substrate  1  spaced apart from one another by an intermediate space Z. In particular, reference numeral  3   e ′ refers to the two first anchors, on whose side walls S 1 ′ and S 1   2 ′ a cantilever  3   c ′ is provided in each case. Associated second anchors  3   a ′ and  3   b ′ are located at each end of cantilevers  3   c′.    
     Second anchors  3   a ′ and  3   b ′ are brought into contact with surface O of substrate  1  and fixedly connected thereto by a method which has already been described in connection with  FIGS. 1 and 2 . 
     A suspension  5  for a rotational axis A of a rotating bar  10  is subsequently implemented in intermediate space Z. This suspension may be detached from anchors  3   e ′, in order to apply different potentials to rotational axis A and inclined structures  3   e ′,  3   c ′,  3   a ′ or  3   e ′,  3   c ′,  3   b ′, but may also be attached to anchors  3   e ′. Inclined structure  3   e ′,  3   c ′,  3   a ′ or  3   e ′,  3   c ′,  3   b ′ thus ensures solid support of suspension  5  for rotating bar  10 , which is rotatable along rotational direction D like a windmill vane. 
       FIG. 4  is a schematic cross-sectional view of a micromechanical component according to an example embodiment of the present invention. 
     In contrast to the example embodiment according to  FIG. 1 , second anchors  3   a ,  3   b  are omitted in the example embodiment according to  FIG. 4 . In this example embodiment, the outer ends of cantilevers  3   c  are connected directly to surface O of the substrate by anodic bonding employing voltage source SP. 
     Although the present invention was described above on the basis of exemplary embodiments, it is not restricted thereto, but rather is modifiable in a plurality of manners. 
     Although specific T-shaped or gallows-shaped micromechanical components are produced as starting structures for the bending in the above exemplary embodiments, in principle any starting structure having an extension in different directions is possible, so that any component having an inclined structure may be manufactured in a simple manner. In particular, fingers or isolated structures may be manufactured and then deflected by suitable measures. In particular, planar diaphragms may also be deflected and connected if the cantilevers are not bar-shaped but rather planar, for example, structuring being able to be performed after the deflection and connecting as necessary. A part of the curved structure may also be detached from the substrate again by structuring and then relax back into the starting plane. 
     Although the deflection of the cantilevers is achieved thermally and electrically in the above examples, it may also be additionally or alternatively achieved by further measures, for example, by overpressure or partial vacuum, current, etc., or any combination thereof. 
     In addition to the described sensors and actuators, inter alia, a possible field of use for the components according to example embodiments of the present invention is head-up displays in the automotive field or mini-projectors in the consumer field. In sensors, there are interesting areas of application in particular in the area of inertial sensors. In microfluidics, in which products for the new markets of life science and medical technology are being evaluated, favorable structures may also be manufactured using the method according to example embodiments of the present invention.