| 摘要 |
PROBLEM TO BE SOLVED: To provide a anode-forming method of a silicon substrate, wherein effectively making selectively into porous quality is possible and a range of it is suppressed to a designed region by controlling a current flow for suppressing a voltage drop due to the presence of reactive current. SOLUTION: On a p-type single-crystal silicon substrate (silicon substrate), a p-type silicon layer 3 which is to be an embedded layer is formed, and an n-type silicon layer 4 is formed on the upper surface of the silicon substrate. On the n-type silicon layer 4, a p-type silicon layer 5 for forming an opening part, while a metal protective film 14 is formed on the upper surface of the n-type silicon layer 4. For the silicon substrate, an electrode layer 18 is formed on the rear surface side via an oxide film 17. At a part corresponding to the p-type silicon layer 3, the electrode layer 18 and the silicon substrate are electrically connected via a connection opening part 17a. At anode formation, the electrode layer 18 is connected to a DC current, while a counter electrode is connected to a negative terminal.
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