Takanori Tanaka

Infrared focal plane array incorporating silicon IC process compatible bolometer

A 128/spl times/128 element bolometer infrared image sensor using thin film titanium is proposed. The device is a monolithically integrated structure with a titanium bolometer detector located over a CMOS circuit that reads out the bolometers signals. By employing a metallic material like titanium and refining the CMOS readout circuit, it is possible to minimize 1/f noise. It is demonstrated that the use of low 1/f noise material will help increase bias current and improve the S/N ratio. Since the fabrication process is silicon-process compatible, costs can be kept low.

Silicon IC Process Compatible Bolometer Infrared Focal Plane Array

A 128 x 128 element bolometer infrared image sensor using thin film titanium is proposed. The device is a monolithically integrated structure having a titanium bolometer detector and a CMOS circuit underneath it for reading out the bolometers signals. By employing a metallic material like titanium and refining the CMOS readout circuit, l/f noise can be minimized. It was demonstrated that by using small l/f noise material, a bias current is increased and S/N ratio can be subsequently improved. Since the fabrication process is silicon-process compatible, low-cost inkared image senson can be realized by using this technology.

Influence of bias heating on a titanium bolometer infrared sensor

A 128 by 128 pixel bolometer infrared focal plane array using thin film titanium has been developed. The device is a monolithically integrated structure with a titanium bolometer detector located over a CMOS circuit that reads out the bolometers signals. Since the thermal conductance of the bolometer detector is minimized, the temperature of the detector itself is increased by applying the bias current. Under the present operating conditions of the titanium bolometer, this temperature increase becomes about 30 degrees Celsius. The influence of this bias heating on device destruction and degradation was experimentally investigated and is discussed. The noise equivalent temperature difference obtained with the device is 0.07 degrees Celsius. Since the fabrication process is silicon-process compatible, costs can be kept low.

A 2/3-inch 2 M-pixel IT-CCD image sensor with individual p-wells for separate V-CCD and H-CCD formation

This 2/3-inch optical-lens-format, 2 M-pixel interline-transfer (IT) CCD image sensor achieves large charge handling capability in the vertical CCD (V-CCD), and at the same time ensures sufficient transfer efficiency in the horizontal CCD (H-CCD). A V-CCD/H-CCD connection eliminates the potential barrier caused by separate V-CCD/H-CCD formation. Image sensor performance includes a 40 k-electron charge-handling capability in the V-CCD, leading to a 71 dB dynamic range, and sufficient transfer efficiency in the H-CCD, with no deterioration in V-CCD to H-CCD transfer efficiency. The power consumption is 0.49 W, just 22% of that previously achieved in a 1-inch 2 M pixel frame interline transfer (FIT) CCD. This is possible because the p-well reduces the driving pulse amplitude in the V-CCD and the IT scheme decreases electrode capacitance and driving frequency.<<ETX>>

A 1920(H)*1035(V) pixel high-definition CCD image sensor

A 1920(H) × 1035(V) pixel high definition CCD image sensor has been developed. In order to follow up 74.25 MHz high sampling frequency, as well as to avoid the necessity for ultra fine patterning work for horizontal CCD register electrode formation, the device adopts a dual channel configuration for the horizontal CCD register. To accomplish both vertical signal charge transfer in the V-CCD register and signal charge distribution from the V-CCD registers into the dual channel horizontal CCD registers simultaneously within a 3.77 ¿s short horizontal blanking period, the 1H memory electrode between the V-CCD and H-CCD is introduced. The device operates successfully and a 1000 TV line limiting resolution has been obtained.

324*487 Schottky-barrier infrared imager

A standard TV-compatible PtSi Schottky-barrier infrared imager is described. The imager is a 324*487 element area array and has an electronic shutter function. Although the pixel is 42*21 mu m, a large fill factor of 42% is obtained, using a 1.5- mu m minimum design rule and a two-level polysilicon layer, and two-level aluminum layer structure. Using face-down bonding technology, it was possible to reduce the package size to 60% of the conventional ceramic package size. Due to optimization of the Schottky-barrier diode process and the diode structure, the noise equivalent temperature difference is as small as 0.1 K at f/1. >

1/2-in 768(H)*492(V) pixel CCD image sensor

A sensor with unit cell dimensions as small as 8.4(H)*9.8(V) mu has been developed. In order to realize such a high-density device, the following technologies have been developed: (1) dual-channel horizontal CCD registers, (2) single p-well vertical overflow drain, (3) high-capacitance p-well structure, and (4) inverted-LOCOS channel isolation process. A horizontal resolution of more than 500 TV lines has been obtained. Maximum signal charge for the vertical CCD register is as much as 1.5*10/sup 5/ electrons, corresponding to 270-nA output current, in spite of a narrow-channel vertical CCD register with a mask width of only 1.8 mu m. The total random noise is less than 20 electrons after correlated double sampling. The dynamic range reaches 77 dB, and the photosensitivity is 0.092 mu A/ mu W. Experimental results also show that the technologies used here are effective for realizing a high-definition CCD image sensor for future use. >

HDTV single-chip CCD color camera

An HDTV (high-definition television) color camera has been developed by using a novel color-coding method, the field sequential color-coding method, to suppress spurious color signals. This camera has realized a high resolution of more than 850 TV lines without color moire and spurious color signals. Since the size and weight are 1/5 that of an HDTV 3-CCD color camera, it is suitable for both industrial and home use. >

A 1280 &#215; 980 pixel CCD image sensor

An interline-transfer CCD image sensor with 1280(H)× 970(V) pixels that has been developed for a TV camera will be presented. The device, designed for high definition TV, has a 48dB SNR.

Estimating temperature and emissivity for infrared measurements using a PtSi Schottky-barrier infrared CCD image sensor

A new analytical method to estimate temperature and emissivity for infrared measurements is described. There are four steps in the method. First, in calculating the output voltage, the dependence of temperature and emissivity of the object was evaluated. The result was the output voltage increased in proportion to the second power of the object temperature and the dependence of the emissivity was linear for the 250 K to 400 K temperature range. Second, in the fitting of these polynomial equations, the orders of six coefficients were also evaluated. Third, in measuring the output voltage of the standard imaging area, the unit transfer coefficient from digital unit (LSB) to voltage (V) was computed. Finally, an inversion problem for estimating temperature and emissivity of the object was proposed. We have developed a new kind of 3 approximately 5 micrometers band Schottky-barrier infrared CCD image sensor, which we call SCAT648, to verify the validity of the estimating method. The SCAT648 image sensor is composed of the different types of pixels. These pixels have different spectral responsivities and capabilities of measuring target temperature and target emissivity. Four standard temperature-controlled samples were imaged with the newly developed SCAT648 camera system. We estimate the error of the temperature and emissivity measurements to be a low +/- 0.5 K and +/- 5%, respectively.