MANUFACTURE OF STOPPER IN SILICON FINE STRUCTURE

PURPOSE: To obtain through a two-step diffusion a stopper which acts as a buffer of a micromachining structure through a step for forming an n -layer consisting of a porous silicon layer by an anode reaction and a step for forming a micromachining structure by etching the porous silicon layer in an etching liquid. CONSTITUTION: An n -diffusion region 4, which is 0.5-5 μm deep is formed in a part for forming a stopper ST through a secondary diffusion. An oxide film 2 is removed and an n-type silicon epitaxial layer 5, exhibiting a resistivity of 9.5-10.5 Ω.cm is grown up to 5-15 μm in thickness on the whole surface. In order to limit the micromachining structure, the n-type epitaxial layer 5 is selectively etched by 5.5-15 μm to expose the n -layer and is subjected to an anode reaction in 10-30 minutes in an HF solution of 5-48 weight% at a reaction voltage of 2-5 V to form an n -layer with a porous silicon layer(PSL) 6. The PLS 6 is etched in an NaOH solution of 4.5-5.5 weight% to form a micromachining structure.