Laser-assisted thermally enhanced InP via etching for microwave device applications

A laser-based technique for thermally enhanced rapid etching of via holes through Fe-doped semi-insulating InP substrates is described. The process produces steep-walled closely-spaced via holes in etch times as short as 3-5 s/via in 100- mu m-thick substrates. This technique is key to the fabrication of low-inductance metallized via contacts critical for high-speed microwave and millimeter-wave devices and circuits. The laser-based technique is material selective, allowing both through-wafer and blind-hole etching which is terminated on metal circuit contacts. Via structures have been fabricated on semi-insulating InP substrates patterned with millimeter-wave device geometries.<
>