Infrared collecting microlens integrated with Si photo cell

Infrared collecting microlens is prepared at the backside of Si photo cell. The preform technique based on the stacked resist layers can give the shape variation of the lens. Not only the simple convex spherical shape but also the combination of the flat center plane and the spherical surrounding ring can be realized. This is for the shorter focus length to combine with IR detector. The Si photo cell realizes the power generation from the visible light.