Optical sensitivity non-uniformity analysis and optimization of a tilt optical readout focal plane array

An optical readout focal plane array (FPA) usually has a differently tilted reflector/absorber at the initial state due to the micromachining technique. The angular deviation of the reflector/absorber has a strong impact on the optical sensitivity non-uniformity, which is a key factor which affects the imaging uniformity. In this study, a theoretical analysis has been developed, and it is found that the stress matching in SiO₂-Aluminum (Al) bilayer leg could make a contribution towards reducing the optical sensitivity non-uniformity. Ion implantation of phosphorus (P) has been utilized to control the stress in SiO₂ film. By controlling the implantation energy and dose, the stress and stress stability are modified. The optical readout FPA has been successfully fabricated with the stress-control technique based on P⁺ implantation. It is demonstrated that the gray response non-uniformity of optical readout FPA has decreased from 25.69% to 10.7%. (paper)