Fabrication of a vertical reflow microlens with silylation technology

The fabrication of a vertical reflow microlens (VRM) has been demonstrated by the thermal reflow method and succeeding silylative treatment on the lens surface, which can provide an appropriate stability and control of the lens curvature, and therefore can be applied to the micro optical/optoelectronic bench. By virtue of the strong adhesive force and cohesion, the VRM is formed by hanging the photoresist on a standing wall and then reflowing the photoresist. In order to enhance the thermal stability and reliability, the reflowed VRM is exposed to a silylative reagent (hexamethyl cyclotrisilazane, HMCTS) to form a hard shell.To characterize the VRM, we use a 1.31-μm-wavelength optical beam emerging from a single-mode fiber as light source and utilize the beam scanner, BeamScope P5, to observe the far-field angle. A simulation model based on the wave optics is constructed to compare with the measurement results. According to the comparison, the modeling result agrees well with the measured data and proves the effectiveness of the VRM in beam focusing.