High frequency apparatus for transmitting or processing high frequency signal, and method for manufactruing the high frequency apparatus

A method for manufacturing a high frequency apparatus, including the following:

• a first step of etching a surface of a substrate to a predetermined depth, and forming a recessed portion in the surface of said substrate;
• a second step of forming one of a first interconnecting conductor and a third interconnecting conductor on said substrate including at least the recessed portion of said substrate;
• a third step of filling a material of a sacrificial layer into the recessed portion of said substrate, and removing the material of said sacrificial layer formed on said substrate excluding at least the recessed portion of said substrate and an area in the vicinity of the recessed portion of said substrate;
• a fourth step of forming a sacrificial layer by performing planarization in such a manner that the surface of said sacrificial layer and one of the surface of said substrate and said first interconnecting conductor become substantially an identical horizontal surface to each other;
• a fifth step of forming a dielectric support film on at least said planarized surface of said sacrificial layer and said substrate;
• a sixth step of forming a second interconnecting conductor on a surface of said dielectric support film;
• a seventh step of forming at least one opening portion above said sacrificial layer so as to pass through said dielectric support film;
• and
• an eighth step of removing said sacrificial layer via said opening portion.

A high frequency apparatus comprising:

• a first substrate having a recessed portion formed in a surface of said first substrate;
• a first grounding conductor formed on said first substrate including at least the recessed portion of said first substrate;
• a dielectric support film formed on said first substrate above the recessed portion of said first substrate with an air space sandwiched between said first substrate and said dielectric support film;
• an interconnecting conductor for transmission use formed on a part of a surface of said dielectric support film;
• and
• second grounding conductors formed on the surface of said dielectric support film located on both sides of said interconnecting conductor film for transmission use with a spacing between said interconnecting conductor and each of said second grounding conductors.