Light modulator, especially for laser beam modulation in high speed fiber-optical communications, has a thickened insulation layer portion directly above a bond island section to reduce parasitic static capacitance

摘要

A light modulator has a thickened insulation layer portion directly above a bond island section. A light modulator comprises a semiconductor substrate (2) having a back face earthing conductor and, on its front face: (a) a layered mesa structure including a light absorption layer (1); (b) an insulation layer (4) which covers the mesa and an adjacent bond island formation section and which has an opening directly above the mesa (9); and (c) an electrode (6a) formed above the bond island formation section (6) and electrically connected to the mesa via the opening. The insulation layer portion, directly above the bond island formation section, has an increased thickness to reduce parasitic static capacitance of the remaining portion of the insulation layer. An Independent claim is also included for production of the above light modulator. Preferred Features: The insulation layer comprises a SiO2 and/or Si3N4 layer formed by CVD, sputtering or vacuum vapor deposition.