Self-align method for improving sensitivity and resolution of infrared focal plane array

In this Letter, it is discussed whether a non-self-align process based on microelectronics technology causes the alignment error (AE) between two material layers in a gold-silicon nitride (Au-SiN) bi-material uncooled optic readout infrared focal plane array (UOR IR FPA). That the AE reduces sensitivity of the FPA and causes extra noise to the FPA is analysed. A self-align method including both process and pattern design, related to an aluminium-silicon nitride (Al-SiN) bi-material UOR IR FPA, is proposed. The method effectively eliminates the AE. As a result, the measured value of thermomechanical response of an Al-SiN pixel is closer to the design value in comparison with the Au-SiN FPA fabricated by the non-self-align process. The measured value of the thermomechanical response of an Al-SiN pixel is 3.73 × 10^-3 rad/°C and is 3.3 times as large as that of the Au-SiN FPA. Thus, the sensitivity of the FPA is improved. There is also no the extra noise. In addition, without the AE, a certain amount of alignment distance is not required while designing the FPA patterns. Therefore it is possible to improve the resolution of the FPA through increasing the quantity of pixels for a given FPA size.