OXFORD, Conn. A technique for micromachining very deep and narrow holes in silicon is being applied to increase the performance of a wide range of optical and magnetic sensors here at NanoSciences Corp. In a new development program, the micromachine technique will be applied to building compact magnetic sensors.
The small company, founded in 1997 by a group of materials scientists, recently announced a grant from the government's Small Business Innovative Research (SBIR) program to extend the technology into giant magnetoresistance (GMR) sensors.
The basic capability is simple: A dense array of holes about 6 microns in diameter can be drilled through a standard silicon wafer. The structure has immediate utility in such sensor applications as X-ray and gamma-ray detection. The company has built and marketed scintillation plates for converting X-rays into visible light and coupling the scintillation light into detector arrays. Arrays can also be used as collimators and focusing elements for X-rays.
The goal of the new development program is to build a self-contained position sensor for micromechanical devices. A film with a precisely graded magnetic field will be built by embedding nanorods of 600 angstroms to 2 microns in diameter into a matrix.
The nanorod structure orients the magnetization of the film to the plane.
The graded magnetic field operates as a positioning reference for a GMR magnetic read head, thus allowing for a reading of absolute position directly from the voltage drop through the read head. The positioning sensor can be directly integrated into micromachine designs. The sensor architecture uses local feedback to position the sensor at a point of motion, such as in automated test equipment.
OEMs in the medical, digital imaging, security surveillance and machine vision industries could benefit from an integrated circuit-sized photomultiplier tube technology that NanoScience engineers have developed.
Macroscopic photomultiplier tubes are used in advanced technology areas that require extreme speeds or sensitivity.
Typical photomultiplier tubes are large, bulky structures that are hand-assembled. The new micromachining capability has the potential to create IC-sized tubes in the form of imaging arrays. The resultant sensor array would put the speed and sensitivity of large-scale photomultipliers in a package smaller than a charge-coupled device array.
The company plans to attack some problem areas in VLSI design with through-wafer via etch processes for novel 3-D chips, chip-scale interconnects and chip-level heat sinks.
The vertical machining technology could enable high-density z-axis connections for direct die-to-die and direct die-to-board bonding, eliminating die packaging and wire bonding.