Presented is the Multiple Signal Classification (MUSIC) algorithm which uses the high frequency differences in sensed time signals to discriminate, count, and accurately locate closely spaced targets. Z technology focal planes allow the implementation of this algorithm and the trade-off between finer spatial resolution systems and systems with coarser resolution but higher sampling rates.
A low cost, light weight, highly repeatable alignment system was developed to support and automatically align the individual modules of a mosaic photo diode detector array. The system consists of hollow round metal alignment pins nested in the square holes formed by V-grooves in the face of adjacent modules, and threaded rods passing through the modules to draw the modules into contact with the alignment pins and one-another and to support the modules. V-grooves and thru-holes in support brackets along two sides of the array align the brackets to the array for mounting to the optical system.
The implications of implementing a Lightning Mapper Sensor (LMS) using Z-plane technology were compared with using CCDs. Comparisons were made in 1) signal-to-noise ratio, 2) field-of-view/pixel size, 3) modularity/flexibility, 4) data processing, 5) associated electrical power, and 6) development risk. The Z-plane was found to be superior in all six categories. It was shown that no CCD currently under development is capable of coming close to meeting the LMS requirements whereas the Z-plane approach meets them comfortably.
This paper describes a Hybrid Mosaic on a Silicon Sandwich (HYMOSS) module with the Dynamic Stare algorithm being investigated for possible application in an air-to-air missile. The demonstration program will consist of a Phase I study and a possible Phase II hardware development program. The programs will determine the guidance characteristics of an air-to-air missile seeker utilizing the HYMOSS module with Dynamic Stare. Dynamic Stare is a combination of a dithered scan mechanism and a staring FPA which can be used to separate moving targets and backgrounds. Increases in acquisition range and processing speed using this technology are illustrated.
Z-plane electronics packaging technology was initially developed to provide real estate for advanced analog signal processing infrared circuitry for focal plane applications. This paper will discuss the relevant qualities of Z-technology, review forecasting technology methodologies, and develop conclusions regarding the future of 3-dimensional electronics--both analog and digital.
It has been noted by many investigators that there is a desirability of using staring sensors for those applications where a weak target signal must be extracted from a heavily cluttered background. The earliest form of the focal plane array for these staring sensors evolved from the charge-coupled device (CCD) technology. The evolution and problem areas of the planar technology from its earliest form using monolithic structures to its current form of hybrid technology will be discussed. A comparison between these devices and the "Z" technology devices under development will be made, particularly in the areas of signal processing and dim target detection. For the "Z" technology devices, a comparison of various signal processing techniques will be presented using the results of an in-house developed digital simulation. These results will be compared with the signal processing requirements of the planar devices to produce comparable detection performance.
The use of charge-coupled device (CCD) circuits in Z-plane architectures for focal-plane image processing is discussed. The low-power, compact layout nature of CCDs makes them attractive for Z-plane application. Three application areas are addressed; non-uniformity compensation using CCD MDAC circuits, neighborhood image processing functions implemented with CCD circuits, and the use of CCDs for buffering multiple image frames. Such buffering enables spatial-temporal image transformation for lossless compression.
Hardware fabrication has been initiated on a test IC which has 32 channels of amplifiers, low pass anti-aliasing filters, 13-bit analog-to-digital (ND) converters per channel and a digital multiplexer. The single slope class of ND conversion is described, as are the unique variations required for incorporation on-focal plane. An IC architecture which contains an ND converter per detector channel operating at the sensor frame rate prior to digital multiplexing is described. Methods for achieving ultra low power dissipation (3 MicroWatts per channel at 1000 Hertz conversion rate) through the use of power strobing are also discussed.
Z-technology utilizes the process of stacking integrated circuits (ICs) to achieve a high degree of packaging density. This technique has been most commonly applied to packaging read out electronics for infrared (IR) focal plane arrays to achieve more signal processing at the detector interface. Irvine Sensor Corporation's (ISC's) standard packaging technology, called HYMOSS (HYbrid Mosaic On Stacked Silicon), has been tailored for stacking 0.004- inch thick silicon integrated circuits of custom designed read out electronics. New advances have been made which allow for stacking; non-silicon ICs, commercial (non-custom) circuits, and/or ICs which have been thinned to 0.002 inches.
This paper presents a system design for a target extraction engine capable of extracting point targets from clutter. The system is realized entirely on the focal plane using z-plane technology and a scanned image. System performance against clutter is analyzed in the spatial frequency domain. High performance, three dimensional bus architectures for high speed image motion compensation are derived, and misregistration in on-focal plane image motion compensation addressed.
LWIR photodiodes have been fabricated in (Hg,Cd)Te heterostructures grown liquid phase epitaxially from tellurium rich solutions. R°A values of up to 10 8 ohm-cm2 and quantum efficiencies in excess of 50 percent have been demonstrated at 40K for a cutoff wavelength of λco ≈ 10.0 μm. These diodes have also been found to be extremely hard to nuclear radiation with no perceivable deterioration in the device performance even upon irradiation of up to 0.85 Megarads. We believe that these R°A performance and the levels of tolerance to radiation are the highest anyone has reported in literature to date.
This paper discusses the hybridization,electrical interconnection via indium bump bonds, of Rockwell designed and fabricated infrared detector arrays onto three dimensional Grumman (Z-Plane) ceramic signal processing modules. The hybridization of detector arrays to the Z-Plane module provides the basic building block for large two dimensional focal plane arrays. This unique Z-Plane module provides on-focal plane data processing which decreases the requirement for interconnect wiring between the focal plane and data processing electronics. This effort implements a modified bonder mating station for use in hybridizing Grumman ceramic multi-layered Z-Plane modules and Rockwell HgCdTe photovoltaic detector arrays. The work involves the hybridization of large aspect ratio detector arrays (16:1). Two detector arrays are mounted end to end on a Z-Plane module for a total length of over one inch. The mating station features a visible viewing system which displays both the detector array and module indium bumps prior to mating. The detector array has electro-plated indium bumps with a typical height of 10-12 microns and the Z-Plane module has vacuum deposited indium pads typically 3 microns high. Hybrid mating tolerances on the order of two tenths of a mil accuracy are routinely held. The hybrid mating station will be reviewed through initial modification, engineering evaluation, semi-manual operation, optimization of mating parameters, resultant bond pull strength and effect on photodiodes. Current yield for this mating system will also be presented. The system will be further refined to increase ease of operation and throughput with the addition of software and microprocessor control. The commitment to achieving good mechanical and electrical indium bonds in this Z-Plane technology has resulted in successful hybrids using both short wave (SWIR) and medium wave (MWIR) infrared HgCdTe detector arrays.
Large area HgCdTe epitaxial films grown on CdTe substrates are routinely used to produce high quality devices. Scaleup of substrate and liquid phase epitaxial (LPE) film growth and characterization processes will give techniques capable of supplying the throughput of low cost, high quality material required for manufacturing of large area infrared focal plane arrays (IRFPA).
"Z" technology FPA architectures offer many advantages over planar technologies, stemming from the much larger electronics real estate available for signal conditioning and processing. 'ecause it is an unconventional architecture for FPAs, producibility of Z-plane technology has frequently been called into question. The HYMOSS® Z-plane technology is now used to package computer electronics and will soon enter high volume production for that family of applications. FPA applications will benefit as well as a result of lowered cost, higher reliability, and available productiAl capacity. In addition, new electronic capabilities will continue to accrue from the incorporation of digital processing and sophisticated interconnect technology. The transition to high volume production is described and the ramifications for FPA manufacturing are identified.
Production rates of low-noise, cryogenic readout devices have been demonstrated. These devices are being produced under a MIL-Q-9858A quality system and are processed per the requirements of MIL-STD-883C. Performance, testability, reliability and producibility of the design have been equally considered throughout the development cycle. All required processes, test methodologies, and quality assurance procedures have been implemented to support production requirements.
A plan to manufacture Z-Technology focal planes was validated by an approach that extends learning curve data from a module pilot line to intercept the planned rate-over-time of a modeled production factory. The pilot factory data are based on 87 Lot IV submodules produced at Grumman's Irvine, California facility. Detailed capital, material and labor costs were tracked for each operation in the manufacturing process. These data were analyzed with equipment manufacturer's data and program requirements to compute the cost of manufacturing for the model factory. The model can be tailored to fit various scenarios of focal plane configuration, resource availability and schedule.
A highly complex Z-Technology module, intended for use in a surveillance satellite, has been greatly simplified by using Tape Automated Bonding (TAB) processes. The module design is based on multiple layers of thin-film substrates as interconnections between active devices mounted on three surfaces and as packaging protection for the custom LSIC devices involved. Most of the TAB processes make an excellent fit with processes already on-line in a thin-film fabrication and assembly operation. A need to attach the TAB leads to ceramic substrates at various levels above the level of the substrate to which the dice are attached complicated the application, and the solution to this problem is detailed. The process development steps needed to apply TAB technology to the product are described, along with evaluation tests which were performed to assure that the thin and fragile ceramics are not broken during pressures encountered in the processing. Automation of the TAB processes and the production steps are also discussed. A cost trade-off study shows the extent to which automation is cost effective. Product design, production equipment design, and process and test changes needed to apply TAB technology to the product are presented, and anticipated payoff in terms of cost reduction and reliability improvement are given. In spite of difficult requirements imposed by space-rated specifications, the TAB processes have been adapted to provide cost and risk reductions as well as reliability improvements while enabling MIL specifications to be met.