The advent of optical communications has resulted in the use of various means to effect optical coupling with high efficiency with the hope of reduced cost of integration. One way in which those charged with this task have chosen to effect the desired end is by the use of silicon waferboard technology. To this end, the use of silicon in substantially monocrystalline form allows the skilled artisan to selectively etch the silicon to reveal well defined crystalline planes with precise orientations. The use of silicon waferboard technology has enabled various and sundry desired alignment techniques of devices to passive elements and fiber to fiber alignment, to mention a few. An example of the tools used to effect the selective etching is found in U.S. Pat. No. 4,210,923, to North, et al., the disclosure of which is specifically incorporated herein by reference. North, et al. discloses the selective masking of a silicon substrate having major surfaces lying in the (110) crystalline plane. An etch resistant mask of SiO.sub.2 is selectively grown and etching is effected by the use of an anisotropic etchant such as KOH. The '923 patent also discloses how the depth of the etch is directly proportional to the width of the etch in this self-limiting process. This particular orientation of substrate will allow for etching of v-grooves having sidewalls and an endwall in the (111) family of planes. This structure allows for the orientation of devices via, as well as the placement of fibers in, the etched grooves. The use of the well-defined crystalline planes of monocrystalline materials has played a fundamental role in the alignment of optical components in optical interconnects. One field of use deals with mechanical alignment via alignment spheres and spherical lenses. For example, U.S. Pat. No. 5,123,073 to Pimpinella teaches the technique of etching wells for spherical lenses and troughs for cylinders. The reference discloses the use of metal or glass cylinders in v-grooves or troughs for rough positioning of lens-spheres of an upper fiber holder with respect to receiving grooves in a lower fiber holder. The optical fibers are held in etched v-grooves. Misalignment of the upper and lower fiber holders is rectified by tapered surfaces on the upper holder engaging the cylinders on the lower holder. Finally, the reference discloses the use of a tripod structure of spherical supports to retain the opposing groove surfaces of the upper and lower fiber holders in predetermined parallel planes while preventing rotation of the fiber holders.
Blind assembly of elements has been utilized in the mating of chip carriers in the electrical assemblies. For example, U.S. Pat. No. 4,565,314 discloses the use of alignment indents having alignment balls mounted therein. This enables the connection of the electrical traces without visual means. Finally, U.S. Pat. No. 5,329,423 the use of raised bumps to effect interconnection of electrical components with the use of a bump-and-socket arrangement. The disclosures of these patents are specifically incorporated herein by reference.
The major drawback with the inventions heretofore mentioned is that there is little if any tolerance in the various degrees of freedom, making precision of alignment of the alignment components critical. What is needed is an alignment scheme that allows for inaccuracies and tolerances in alignment of the devices.