Noise Improvement of a-Si Microbolometers by the Post-Metal Annealing Process

Abstract

To realize high-resolution thermal images with high quality, it is essential to improve the noise characteristics of the widely adopted uncooled microbolometers. In this work, we applied the post-metal annealing (PMA) process under the condition of deuterium forming gas, at 10 atm and 300 °C for 30 min, to reduce the noise level of amorphous-Si microbolometers. Here, the DC and temperature coefficient of resistance (TCR) measurements of the devices as well as 1/f noise analysis were performed before and after the PMA treatment, while changing the width of the resistance layer of the microbolometers with 35 μm or 12 μm pixel. As a result, the microbolometers treated by the PMA process show the decrease in resistance by about 60% and the increase in TCR value up to 48.2% at 10 Hz, as compared to the reference device. Moreover, it is observed that the noise characteristics are improved in inverse proportion to the width of the resistance layer. This improvement is attributed to the cured poly-silicon grain boundary through the hydrogen passivation by heat and deuterium atoms applied during the PMA, which leads to the uniform current path inside the pixel.

A Low Power ROIC with Extended Counting ADC Based on Circuit Noise Analysis for Sensor Arrays in IoT System

“…These applications are often size constrained, while requiring high energy efficiency and stability [1][2][3][4]. With the advantages of low cost, small size, and good uniformity, uncooled infrared focal plane arrays (IRFPA) can be applied in IoT applications, such as composition analysis, smart monitoring, and spectral analysis [5][6][7][8][9][10][11][12].…”

“…Currently, the mainstream IRFPAs adopt vanadium oxide (VO X ) [5,6] or amorphous silicon (α-Si) microbolometers [7,8], or silicon diodes as the thermosensitive sensors [9,10]. Compared with VO X /α-Si microbolometers, silicon diodes are fabricated with monocrystalline silicon and have the advantages of CMOS process compatibility, low noise, high uniformity, and huge potential for pixel size reduction [11].…”