Metal working – Method of mechanical manufacture – Obtaining plural product pieces from unitary workpiece
Reexamination Certificate
1998-06-09
2002-05-28
Bueker, Richard (Department: 1763)
Metal working
Method of mechanical manufacture
Obtaining plural product pieces from unitary workpiece
C029S428000, C029S434000, C216S002000, C216S036000, C216S074000, C216S075000, C216S099000, C403S345000, C156S257000
Reexamination Certificate
active
06393685
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable
REFERENCE TO A MICROFICHE APPENDIX
Not Applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention pertains generally to devices and methods for interfacing, interconnecting and assembling a network of individual MEMS modules (i.e. microfluidic pumps and valves, miniature reaction chambers, optical detection schemes, CMOS control circuitry, etc.) for creating integrated miniature instruments, and more particularly to miniature devices and methods for constructing those devices in a microscopic environment which allows the manufacture of miniature high precision devices such as fiber optic switches, xyz translational optical benches and other devices on a microscopic scale.
2. Description of the Background Art
Microfabrication is a generic term for a rather large, eclectic, and sophisticated collection of different processing techniques. It is both a powerful and versatile technology which enjoys a well respected history in the fabrication of high density, high precision integrated electronics, LED's, solid state lasers, and optical detectors. The recent explosion in the field of optical communications, imaging, optical signal processing, and optical recording has fueled a focused search for reliable, compact, inexpensive, and low loss ancillary micro-accessories to augment functionality in expanding optical Microsystems. Foremost in the search for micro-accessories has been the application of surface micromachining to the fabrication of optical and mechanical microcomponents.
Surface micromachining was introduced in the late 1960s as a technology for the generation of elegant and moveable micromechanical components such as micro-gears, tongs, cams, and including a micromotor the diameter of a human hair. However, surface micromachining is inherently limited in its application because it provides only a limited range of motion for the mechanical components (a few hundred micrometers at best) as well as a particularly planar geometry which does not lend itself to three dimensional device construction. For example, fiber optic communication lines are approximately 125 micrometers in diameter, and therefore, physical fiber optic switches can require much more than microns of translation to effect switching between fiber optic lines.
Furthermore, systems integration of microfabricated components has recently blossomed into a critically emerging field of interest in today's microfabrication environment. Already, a literal zoo of revolutionary microdevices has appeared in the literature, generating such futuristic speculations as nano-robots and micro flying machines. Toyota has even fabricated a microcar powered by magnetic induction and Seiko has demonstrated a microlathe capable of turning a 40 micrometer needle tip. Although such interesting creations entice the imagination, practical Microsystems have yet to realize their full commercial potential, due mostly to stubborn technical limitations in present microfabrication technologies and techniques.
Despite the plethora of micromachined components reported in the literature to date, micromachines in general have recently come under strong criticism for promising much but delivering little. Generally, there is a growing sentiment that micromachining is more of an esoteric laboratory curiosity than a practical commercial commodity. For this reason, commercial and industrial concerns are backing off their initial excitement with the microworld and concentrating on more immediate products.
At least a portion of micromachining's perceived lackluster performance in microelectromechanical systems (MEMS) stems from a genuine limitation in the way the technology has developed. As it stands today, micromachining is a rather diverse collection of disjointed and inherently incompatible techniques. Although each particular micromachining technique is ideally suited to fabricate certain, very specific, types of microdevices, no one technology is capable of optimally fabricating all microstructures, nor can different micromachining techniques be ‘mixed and matched’ to fill in the missing components. Once a basic fabrication process is started, fundamental process incompatibilities dictate that it cannot be altered despite the fact that some of the required components may best be fabricated by other means. This translates into less than optimal performance for even the simplest microdevice, and a complete disaster for complex Microsystems requiring a broad spectrum of interconnected microdevices. For this reason the most successful micromachined devices on the market today are relatively simple straightforward projects focusing on one specific micromachining technique.
The problem is best illustrated by the recent attempts to create integrated free-space microphotonics systems: the so-called optical bench on a chip. Up to now, development of micro-optical systems has been divided between monolithic guided-wave approach, in which passive and/or electro-optic control networks route optical beams through planar waveguides and free-space microphotonic systems. Although the waveguide approach has enjoyed a modest degree of success, the method is rather limited in scope and potential application. Optical benches are now considerably more versatile, but require mechanical components to steer, align, scan, or otherwise manipulate optical beams. In the past, surface micromachining processes were the most widely used for construction of optical and mechanical microcomponents.
Ironically, integration, a touted advantage of surface micromachining, has also been a major impediment in its successful commercialization. Although surface micromachining is an extremely elegant method for the monolithic integration of many micro-opto-mechanical components, unless all necessary components in a microsystem are microfabricated with a virtual 100% yield, integration loses much, if not all, of its appeal. Unfortunately, surface micromachining's spectrum of available microstructures is insufficient to complete a truly functional microsystem. Input/output has been particularly troublesome for surface-micromachined optics and MEMS in general.
For example, most reports on surface-micromachined integrated optical systems usually show the optical source, III-V laser or LED, “hand glued” to an otherwise integrated silicon chip, the reason being that III-V semiconductor processing is inherently incompatible with silicon surface micromachining. Such crude and inaccurate hand assembly/alignment does little justice to the elegant precision available to micromachining.
A significant problem in the microfabrication of complicated systems is that different system components are process incompatible, i.e. the fabrication of one device destroys or impedes the fabrication of another critical component. Therefore, it is advantageous to microfabricate each component separately, using proven techniques and processes best suited for each component, then assemble them in the end to form the completed microsystem. This is a module, or hybrid, approach, and eliminates the issue of process incompatibility. However, to accomplish this, a means to interconnect modules and/or components is required.
Although each micromachining technology by itself may be limited in its range of performance, all micromachining technologies, when considered as a collective unit, generally span the entire spectrum of requisite microdevices. What is desperately needed to make commercially viable microsystems is a unifying micromachining technology which marries this already existing, but rather eclectic, collection of microdevices and micromachining technologies. The concept is not unlike the complimentary synergism between hybrid and integrated electronics, i.e., even though integrated electronic circuits are fast, powerful, and small, without the means to interconnect them to each other, discrete components, and the external world through the use of PC boards, thick-film technology, etc., they ar
Bueker Richard
O'Banion John P.
The Regents of the University of California
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