The partnership between RVS, Seek Thermal and Freescale Semiconductor continues on the path to bring the latest technology and innovation to both military and commercial customers. The partnership has matured the 17μm pixel for volume production on the Thermal Weapon Sight (TWS) program in efforts to bring advanced production capability to produce a low cost, high performance product. The partnership has developed the 12μm pixel and has demonstrated performance across a family of detector sizes ranging from formats as small as 206 x 156 to full high definition formats. Detector pixel sensitivities have been achieved using the RVS double level advanced pixel structure. Transition of the packaging of microbolometers from a traditional die level package to a wafer level package (WLP) in a high volume commercial environment is complete. Innovations in wafer fabrication techniques have been incorporated into this product line to assist in the high yield required for volume production. The WLP seal yield is currently > 95%. Simulated package vacuum lives >> 20 years have been demonstrated through accelerated life testing where the package has been shown to have no degradation after 2,500 hours at 150°C. Additionally the rugged assembly has shown no degradation after mechanical shock and vibration and thermal shock testing. The transition to production effort was successfully completed in 2014 and the WLP design has been integrated into multiple new production products including the TWS and the innovative Seek Thermal commercial product that interfaces directly to an iPhone or android device.
Indigo’s emergence as a production source of uncooled microbolometers was reported in the SPIE proceeding in 2003. With now over a year of modest volume production history on the small-format FPAs, the details of the production experiences are reported. Progress on the mid-format arrays is discussed as are the efforts towards large-format, small pixel devices. Also discussed is the status of the production ramp that will lead to the supply of uncooled FPAs into the automotive market.
While microbolometers have been in production for several years, the number of companies producing them is quite small. Indigo Systems has entered into the development and production of VOx based microbolometers, at its Goleta facility. Through the investment of significant capital, Indigo has established a high volume production facility based on the silicon industry model. The 6-inch, cassette-to-cassette, highly automated facility is capable of yielding hundreds of thousands of die per year. Discussed in the paper will be the design and layout of the facility, performance of the devices, as well as yield, trend and throughput data.
This paper describes two camera systems based on the advanced 160 X 128 uncooled micro-bolometer FPAs. The UL3 ALPHA camera is in production and takes advantage of the patented bias equalization FPA performance to produce the world's smallest IR production camera. UL3 ALPHA weighs less than 195 grams, uses 1.5 W of power (nominal) and has a overall dimensions of 4.3 cm X 4.3 cm X 7.5 cm. ULS ALPHA production cameras have demonstrated 62 mK NEdT operation with over 99% operability.
The IR detector array, which is the heart of any imaging system or missile seeker, continues to evolve toward larger size, smaller pixels, and higher sensitivity. Any scene projector that is intended to test one of these advanced devices must keep pace. As IR scene projection evolves to 1024 X 1024 and 1024 X 2048 arrays, both the emitter array and drive electronics must overcome numerous technological challenges. This paper discusses the approach taken to provide the same 200 Hz frame rate, 16-bit accuracy, and high operability already demonstrated with 512 X 512 MIRAGE arrays in a larger format. In addition to current capabilities that are to be preserved in the design of larger devices, scalability of the architecture to allow growth to even larger formats is desired. Other features such as windowing and even higher frame rates are critical for future applications.
This paper describes the UL3 camera system based on the advanced 160 X 128 uncooled micro-bolometer FPA. The UL3 camera takes advantage of the patented bias equalization FPA performance techniques to produce the world's smallest IR camera. The UL3 camera weights less than 2.3 ounces, uses less than 600 mW of power, and has overall dimensions of 3 cm X 3 cm X 6 cm. The architectures feature an approach that integrates the required system functions on ASICs and FPGAs rather than including discrete components and microprocessors.
This paper describes a new approach for the control of microbolometer detector array uniformity as a function of substrate temperature change. This approach, called the bias equalization method, uses an electronic means of controlling the microbolometer array uniformity. For this method a three stage non-uniformity correction algorithm is employed. The first stage corrects for substrate temperature non- uniformity effects on the microbolometer detector elements followed by traditional offset and gain non-uniformity correction stages. To correct for substrate temperature non- uniformity effects, bias equalization coefficients are supplied to the readout integrated circuit (ROIC) to allow the control of a unique operating bias or temperature delta for each microbolometer detector element in the array. The bias equalization method circuitry allows microbolometer array non-uniformity control over a wider range of ROIC substrate temperatures while maintaining better than 80 mK NEdT using f/1.8 optics. This approach is expected to allow removal of the thermoelectric cooler from uncooled systems, thus making it ideally suited for high-volume, low-cost, low-power and low-weight production applications.
This paper describes a high performance 320 by 256 readout integrated circuit (ROIC) designed for P-on-N short wave IR (SWIR) detectors including InGaAs and HgCdTe, which also has the ability to operate at low input current levels with N- on-P detectors. The ROIC/FPA will support a wide range of system requirements from very low background applications to daytime high illumination conditions. To accommodate the wide scene dynamic range requirements, two selectable integration capacitors are used to control the input circuit transimpedance gain. A 10fF integration capacitor is used for low noise and low flux levels down to 10-5 ft Lambert, corresponding to approximately 2 X 1010 ph/cm2-sec for 0.9 micrometers to 1.7 micrometers spectral band using f/1.5 optics, assuming a 2856 Kelvin blackbody distribution. For higher flux levels, a 0.21pF integration capacitor can be selected, thus providing over a factor of 20 dynamic range. A capacitive feedback transimpendance amplifier provides a low noise detector interface circuit capable of operating at low input currents without frame-to- frame image lag. A sample and hold capacitor is also part of the input unit cell architecture, which allows the FPA to be operated in full frame snapshot mode and provides the maximum integration time available. The integration time is electronically controlled by an external clock pulse, and is adjustable form 0.5microsecond(s) ec to approximately the frame time of 33.3 msec for 30Hz operation. This produces an additional factor of 66,000 to the total nine orders of magnitude in scene dynamic range.
This paper presents background and measured performance data on a novel, low cost, high performance readout integrated circuit (ROIC) for microbolometer uncooled detector applications. The array is designed to offer better than 80mK NEdT performance using f/1.8 optics. The design incorporates advanced on-ROIC signal processing electronics that allow bolometer element non-uniformity control over a wide range of ROIC substrate temperatures. The small format array is ideally suited for high volume low-cost production applications.
This paper describes a standardized high performance 640 by 512 readout integrated circuit (ROIC) for p-on-n detectors such as InSb, Heterojunction HgCdTe, QWIP, and InGaAs. The array is intended to support a wide range of system through flexibility and advanced modes of operation. The ISC9803 uses a flexible, programmable, multistage pipelined architecture to achieve a state-of-the-art ROIC suitable for applications ranging from hand-held IR viewers to high-speed industrial imaging system. A simplified default mode directly supports single output NTSC or PAL operation. Using the programmable mode, the ISC9803 supports such advanced features as dynamic image transportation, dynamic windowing, multiple high-speed multi tout configurations, and signal 'skimming'. Both default and programmed modes support integrate-while-read and integrate-then-read snapshot operation, and variable gain. This array is part of the Indigo Systems family of standard ROICs that use a common architecture and electrical interface.
This paper describes Boeing's next-generation 320 X 320 uncooled IR focal plane product. The basic objectives have ben to at least double focal plane performance, improve focal pane operating stability, and significantly enhance the control interface between the focal pane and the camera. All of these basic objectives have been achieved. Focal plane temporal NETD equals 0.028 degrees C has been demonstrated at a frame rate of 60 Hz on the first lot of UFPAs produced, as well as a worst-case spatial NETD < 0.016 degrees C measured over 10 degrees C temperature calibration range. Operating stability improvement has been successfully demonstrated. The design has validated a 'smart sensor' UFPA/camera control interface that provides externally programmability of on-chip signal gain, on-chip pixel offset compensation, on-chip detector bias regulation, precision on-chip temperature measurement, and a 16 test- point Built In Test function. Based on Lot-1 test results, the next lot, which is now in wafer processing, is expected to achieve NETD < 0.02 degrees C at a 60 Hz frame rate. With an improved microbolometer Thermal Isolation Structure, currently in development at Boeing, NETD < 0.010 degrees C can be demonstrated before the end of this year.
The MIRAGE Dynamic IR Scene Projector is a standard product being developed jointly by Santa Barbara Infrared, Inc. and Indigo Systems Corporation. MIRAGE is a complete IR scene projection system, accepting digital or analog scene data as the input and providing all other electronics, optics and mechanics to project high fidelity dynamic IR scenes to the unit under test. At the heart of the MIRAGE system is the 512 X 512 microemitter array that incorporates many state-of-the-art features previously not available. The Read-In-Integrated-Circuit (RIIC) leverages technology from IR Focal Plane electronics to provide a system with advanced capability with low risk. The RIIC incorporates on chip DACs, snap-shot frame updating, constant current mode, voltage drive emitters and substrate ground plane providing high resolution and low noise performance in a very small package. The first 512 X 512 microemitter assembly has been received and was imaged on 2 APR 99. The complete MIRAGE system is currently in integration with the first deliverable unit scheduled for June 1999.
This paper present a novel low cost, high performance readout integrated circuit (ROIC) for bolometer uncooled detector applications. The array is designed to offer better than 80mK NEdT using f/1.8 optics. The design incorporates advanced on-ROIC signal processing electronics that allows bolometer element non-uniformity control over a wide range of ROIC substrate temperatures. The small format array is ideally suited for high volume low-cost production applications.
This paper describes a standardized high performance 320 by 256 readout integrated circuit for p-on-n detectors such as InSb, heterojunction HgCdTe, QWIP, and InGaAs. The array is intended to support a wide range of systems through flexibility and advanced modes of operation. The ISC9705 uses a flexible, programmable, multistage pipelined architecture to achieve a state-of-the-art ROIC suitable for applications ranging from hand-held IR viewers to high-speed industrial imaging systems. A simplified 'hands-off' default mode directly supports single output NTSSC or PAL operation. Using the programmable mode, the ISC9705 supports such advanced features as dynamic image transposition, dynamic windowing, multiple high-speed multiple output configurations, and signal 'skimming'. Both default and programmed modes support integrate-while-read and integrate- then-read snap shot operation, and variable gain.
The current advances in density and performance of 2-D staring IR FPAs are now enabling the development of solid state non-scanning imagers of TV quality. Significant cost reductions with performance improvements are accomplished using these new high density staring arrays. This paper reports on the development of an IR imager using a new system oriented 256 X 256 InSb hybrid FPA. Two-dimensional InSb hybrid FPAs were first reported on in 1978 at the IEDM with papers describing 32 X 32 arrays using indium bumps and CCD multiplexers. This basic technology has progressed to 256 X 256 and large arrays using HgCdTe and InSb detectors. The arrays are still interconnected with indium bumps but rely on improved MOS switched readouts using the latest in CMOS process technology. Significant improvements in performance and operability as well as system implementation have also been made.
The need for increased resolution and sensitivity in IR systems applications has provided the impetus for the development of high-performance second-generation staring focal plane array technology. Previously, the availability of these focal plane array components has been limited and the costs associated with delivery of useful hardware have been high. Utilizing proven InSb detector technology and foundry silicon CMOS processes, a high performance, affordable hybrid focal plane array and support electronics system has been developed. The 128 X 128 array of photovoltac InSb detectors on 50 micrometers centers is interfaced with the silicon readout by aligning and cold welding indium bumps on each detector with the corresponding indium bump on the silicon readout. The detector is then thinned so that it can be illuminated through the backside. The 128 X 128 channel signal processing integrated circuit performs the function of interfacing with the detectors, integrating the detector current, and multiplexing the signals. It is fabricated using a standard double poly, single metal, p-well CMOS process. The detector elements achieve a high quantum efficiency response from less than 1 micrometers to greater than 5 micrometers with an optical fill factor of 90%. The hybrid focal plane array can operate to a maximum frame rate of 1,000 Hz. D* values at 1.7 X 1014 photons/cm2/sec illumination conditions approach the BLIP value of 9.4 X 1011 cm(root)Hz/W with a capacity of 4 X 107 carriers and a dynamic range of greater than 60,000. A NE(Delta) T value of .018 C and a MRT value of .020 C have been measured. The devices operate with only 3 biases and 3 clocks.
This paper discusses the development and measured performance of a high-density infrared staring camera operating with outstanding performance over the entire 3-5 micrometers band. The camera has demonstrated excellent night and thermal vision in a multitude of conditions including penetration through weather and over water. Hybrid focal plane technology was used to construct the 256 X 256 area array. Backside illuminated Indium Antimonide detectors are interconnected using Indium bumps to an advanced CMOS readout integrated circuit. The hybrid format yields high detector fill factor (>90%) and quantum efficiency (>50%). This approach has resulted in an infrared focal plane which has greater than 95dB dynamic range and is background limited (BLIP) for most applications. The paper also covers the integration of the device into a small low power cryogenic dewar as well as the interface and video electronics used to provide remarkable infrared image quality.