PREPARATION OF BRIDGE TYPE SILICON ACCELERATION SENSOR WITH EIGHT BEAMS AND ACCELERATION SENSOR TO BE MANUFACTURED BY THE PREPARATION

PURPOSE: To form an octagonal structure with improved directional selectivity by forming an n diffusion region on a substrate, growing an epitaxial layer, forming a porous silicon layer from the n diffusion region, mounting a mass to the epitaxial layer, etching the porous silicon layer, and forming an air gap on the substrate. CONSTITUTION: A silicon oxide film 2a is formed on a silicon substrate 1, a diffusion window 3 is opened, an n impurity is injected and is uniformed, and then an n diffusion region 4 is formed. After the silicon oxide film 2a is eliminated, an epitaxial layer 5 is grown, an oxide film 2c is grown on it, an impurity is injected, and then a plurality of pressure resistors 6 (R1 -R4 ) are formed on the epitaxial layer 5. After oxide films 2b and 2c are eliminated, an anode reaction is made in a fluoric acid solution, thus forming a porous silicon layer 7 in the n diffusion region. Then, after a mass 8 is formed by a mass loading technique such as dispensing, the porous silicon layer 7 is etched and an air gap 9 is formed, thus forming an octagonal structure with improved directional selectivity by utilizing porous silicon.