Self-centering arrangement of microstructured elements

Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package

Reexamination Certificate

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Details

C257S797000, C257S432000, C438S106000, C438S121000

Reexamination Certificate

active

06255724

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to an arrangement of microstructured elements according to the preamble of claim
1
.
In microtechnology, there is the problem of precisely positioning individual, already existing components with respect to each other before securing them. Frequently, for example in microoptics, the permissible tolerances fall within the micrometer or even the submicrometer range. Currently, primarily active adjusting processes are typically used. Active in this connection means that the individual components are brought into their final position during the active operation of the system or subsystem. An example for this is the coupling of a semiconductor laser to an optical fiber. The fiber is shifted until the intensity of the light guided in the fiber reaches a maximum. Active adjustment processes are difficult to automate and therefore expensive. This impedes the continued expansion of microtechnology systems.
In many cases, active adjustment is not possible, or extremely difficult, for technical reasons. Particularly if many components are to be arranged on a small area, there is frequently no space to accommodate adjusting tools in this area to shift the components with micrometer precision. Attempts have therefore been made for some time to use passive adjustment for the individual components. In passively adjusted systems, the outside dimensions of the individual components or subsystems are so exact, or the limit stop edges so precisely executed, that the components can be positioned next to each other, or inserted into each other, to permit immediate optimal operation of the system, i.e., without requiring any further adjustment steps.
Passive adjustment in microtechnology has thus far primarily failed because the components to be positioned are not manufactured with the requisite exactness. As a result, simple positioning together or insertion of components has been successful in only a few special cases. For example, for laser-fiber coupling, spherical lenses on silicon substrates can be inserted in pyramidal recesses produced by anisotropic etching processes. The spherical lenses touch the etched recesses at only four points. Due to their simple geometric shape, spherical lenses can be manufactured very precisely at low cost. Optimizing the etching process has meanwhile also made it possible to produce recesses in silicon, which have the requisite tolerances of a few tenths of a micrometer to make such passive adjustment possible.
Optical fibers, too, can be very precisely positioned on silicon substrates if they are placed in V-shaped etched channels. The optical fibers touch these channels only along two lines and not along an area.
EP 0 638 829 A1 discloses a concept for positioning optical components on a (silicon) substrate. As indicated in
FIG. 74
, for example, terrace shaped shoulders, onto which the component to be positioned is placed, are etched out of the substrate. As a result, the height of the component In relation to the substrate surface is precisely defined. The lateral alignment of the component is achieved by limit stops on both sides of the component The limit stops are made as surfaces arranged perpendicularly to the substrate surface. Between the limit stops and the component to be inserted, there must be a clearance fit so that the component can still be Inserted. Since It is difficult to insert the component into the gap between the two limit stops, an alternative is proposed where the component is laterally adjusted by means of flip chip bonds. Flip chip bonding, however, requires additional process steps. Furthermore, this technique cannot be used for all components.
SUMMARY OF THE INVENTION
The object of the invention is to define an arrangement by means of which components produced by microtechnology can be mutually aligned in any manner. The arrangement is to be self-centering, i.e., if one component is placed on the other, the two components are automatically to assume their ultimate position. Adjustments of the two components with respect to each other, which do not affect the function of the subassembly, or affect it only to a minor extent, are to be possible if necessary. The arrangement is to eliminate, or at least minimize, active adjustment steps during the positioning of the components.
The invention attains this object in that it provides the components with projections and corresponding recesses. The important thing is that the projections or recesses, or also the connection between the two, are designed in such a way that an (elastic or plastic) deformation occurs when the projections are inserted into the recesses. In one exemplary embodiment of the invention according to claim
2
, the projections and for recesses themselves are deformed when the projections are inserted into the recesses. In another embodiment of the invention according to claim
5
, a molding material, for example, an adhesive, inserted between projection and recess is deformed. On the one hand this deformation has a self-centering effect. On the other hand minor imperfections in fit, inevitable depending on the manufacturing process, may be compensated.
In a further advantageous concrete embodiment of the Invention according to claim
9
, the element is a silicon substrate into which pyramidal or V-shaped recesses are etched. The other element is a plastic component fabricated by a LIGA process, which is essentially provided with wedge shaped projections on its underside. These wedge shaped projections fit Into the corresponding recesses In the silicon substrate. The plastic component has retaining structures on its upper side to receive additional components such as lenses, optical fibers, laser interlocking devices, or guide pins for connector systems. In this case, the plastic component acts as an intermediate carrier, which permits the precise positioning on a silicon carrier of those components whose insertion into the recesses producible by etching is impossible, or very difficult, due to their geometry.
Additional exemplary embodiments of the invention are given in the subclaims.


REFERENCES:
patent: 5227663 (1993-07-01), Patil et al.
patent: 5574628 (1996-11-01), Persia et al.
patent: 5889323 (1999-03-01), Tachibana
patent: 6046498 (2000-04-01), Yoshikawa

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