| 摘要 |
PURPOSE:To improve SiO2 etching in the stage of forming through-holes by using an SiO2 film for an insulating film and maintaining the surface temp. of a substrate during the formation at <=300 deg.C. CONSTITUTION:The SiO2 film is formed on the substrate kept at 300 deg.C and is heat-treated at 400 deg.C in a vacuum then the SiO2 film further laminated thereon is etched. The stopping degree of etching is so strong that the etching stops at the surface of the SiO2 film subjected to the heat treatment with the formation of substantially no ruggedness. More specifically, the SiO2 film is formed while the surface temp. of the substrate is maintained at <=300 deg.C, then even if many of such SiO2 films are laminated, the thorough etching can be executed without having the unetched layers in the same manner as in the stage of etching the single layer or the relatively thin SiO2 films laminated with about 2 layers. The good magnetic coupling at the rear ends of the substrate for a lower core and the magnetic layer for an upper core and the parallel gap-butt faces at the front end are thus obtd. |
