Uncooled infrared focal plane array having 128 x 128 thermopile detector elements

Abstract

A 128 X 128 element thermopile infrared image sensor has been developed. This device has a monolithically integrated structure to increase fill factor. The CCD for signal charge accumulation and signal charge read-out is fabricated on the silicon surface. Over the CCD, silicon dioxide diaphragms for thermal isolation are made by using micromachining technology. On each diaphragm, 32 pairs of p-type polysilicon and n-type polysilicon thermopile are formed. The noise equivalent temperature difference obtained, by the device, is 0.5°C with an f/i lens. Since the materials used are the same as those for silicon IC 's, and since the whole fabrication process is earned out at the silicon IC plant, it can be said that a low cost uncooled infrared image sensor is realized by this technology.

Thermal Imaging Device using Infrared-to-Visible Converter Made of Temperature Sensitive Phosphor

“…The captured image contains large noise, mainly comes from the photon shot noise of the CCD due to the low luminescence intensity from Eu(TTA) 3 . To obtain a high quality thermal image, noise reduction method is required.…”

“…The thermal type device detects the temperature change of a thermally-isolated microstructure induced by an incoming IR. The conventional thermal type devices use electrical ways to detect the temperature change of the microstructure such as using a thermistor [1], a PN diode [2], a thermo-pile [3] and pyroelectric effect [4]. However, these devices should be fabricated on a read out integrated circuit (ROIC), which makes a fabrication difficult and thus the fabrication cost increases.…”

“…The phosphor (Eu(TTA) 3 ) was excited by LEDs and the luminescence from them were captured by a CCD camera through an optical band-pass filter.…”

“…a temperature sensitive film was suspended by narrow polymer beams. The temperature sensitive film was made of Europium(III) thenoyltrifluoroacetonate (Eu(TTA) 3 ), which emits the visible luminescence under excitation of ultraviolet (UV) light. The intensity of the luminescence reduces with the temperature [9], thus the temperature can be measured as the intensity of visible light [10].…”

Colloidal quantum dot photodetectors

“…Ideally, these materials should be integrable with silicon electronics [3], or with flexible substrates such as those based on organic and polymer materials [4]. Ink-jet printing, solution-casting, low-temperature evaporation, and layer-bylayer techniques are thus very attractive alternatives to hightemperature epitaxy [5].…”