Patent ID: 7247542
Filing Date: 2007-07-24
Classification: C25D,H01F,H01L

Abstract:
1. A fabrication method of RF chip inductor, fabricating on porous glass substrate to give low k, low loss and high Q inductor, comprising the following steps: a P-type silicon wafer is used as the substrate; an N-type silicon film is formed on the back side of the substrate by implanting; a porous silicon layer, formed by electrochemical etching in hydrogen fluoride (HF) solution to a high degree of porosity; a porous glass layer, thermally oxidizing at high temperature to convert said porous silicon layer into porous glass texture; a thin layer of electrically conductive metal film is deposited on the porous glass to be the plating electrode of copper plating; a first layer of photo-resist is spun on the front side of said silicon wafer; a mask process is adopted for patterning to said first layer photo-resist and formed openings for the under layer of a spiral inductor; a layer of copper is electroplated on the wafer surface complementary to said openings; the photo-resist is stripped away; the electrically conductive metal film is etched out in hydrogen peroxide; a cover layer of polyimide is spun on the surface and a second mask process is taken for patterning the cover polyimide to define the contact via; another electrically conductive metal film is deposited on said cover layer of polyimide and said contact via to be the plating electrode of copper plating; a second layer of photo-resist is spun on the front side of the silicon wafer; a mask process is adopted for patterning said photo-resist and form opening for the second layer of the spiral inductor; a second layer of copper is electroplated on the top to a thickness of the inductor strip; the photo-resist is stripped away; the electrically conductive metal film is etched out in hydrogen peroxide; a thin layer of gold is plated to the exposed copper surface by electro-less plating to protect the inductor surface.