PURPOSE:To improve the close adhesiveness of a biochemical substance, by forming a polycrystalline silicon layer to the surface of a substrate between the source and drain of said substrate through an insulating film and further applying anodic chemical forming treatment to said silicon layer to fill said silicon layer with chlorine to substitute a biochemical substance with chlorine. CONSTITUTION:After the diffusion region of a source 11 and a drain 12 was formed to the surface of a monocrystalline silicon substrate 10, an insulating film comprising silicon dioxide is formed to the surface of the substrate. Next, the insulating film 23 between the source 11 and the drain 12 is removed and a gate oxidized film 13 is formed by oxidation and a silicon nitride layer is further formed on said film 13. The part corresponding to a contact hole of the insulating film 23 is removed to form a polycrystalline silicon layer 25. After P-type impurities were diffused throughout the silicon layer 25, a P-type silicon layer 25' is exposed and the other part is converted with aluminum 27. Hereupon, said aluminum is subjected to anodic chemical forming treatment to form a porous silicon layer 16. Unnecessary aluminum 27 is removed to fill the silicon layer with chlorine. Then, chlorine is substituted with a biochemical substance to adhere said substance to said layer to make it possible to improve close adhesiveness.
