Patent ID: 6063645
Filing Date: 2000-05-16
Classification: G01F,G05D

Abstract:
A method of fabricating an integrated MFC module on a semiconductor substrate with front and back sides, wherein said MFC module comprises microvalve and mass flow sensing regions, comprising the steps of:(a) growing an oxide layer on the surface of both front and back sides of said semiconductor substrate;(b) partially etching said oxide layer on the front side of semiconductor substrate to define said microvalve and mass flow sensing regions;(c) forming a diffusion layer on the front side surface of semiconductor substrate, wherein said diffusion layer is served for microvalve of said microvalve region and microbridge of said mass flow sensing region;(d) removing the remaining of said oxide layer, and then forming a dielectric layer on the surface of both front and back sides of said semiconductor substrate;(e) forming a layer of piezoresistive material overlaying said dielectric layer on both front and back sides of said semiconductor substrate, wherein said piezoresistive layer is served for heater of said microvalve region and sensing element of said mass flow sensing region;(f) partially etching said piezoresistive layer to define heater area of said microvalve region and said microbridge of said mass flow sensing region;(g) depositing a passivation layer over the entire said semiconductor substrate, and then pattering said passivation layer to define mass flow channel of said microvalve region and sensing membrane of said mass flow sensing region;(h) depositing and patterning a metal layer overlaying said passivation and said piezoresistive layers on the front side of said semiconductor substrate to carry out signals;(i) partially etching said passivation, dielectric and diffusion layers to define microbridge structure on a mesa; and(j) partially etching said semiconductor substrate to define suspended heater structure of said microvalve region, suspended sensing structure of said mass flow sensing region, and at least one supporting bump.