| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem that a silicon substrate cracks to cause incomplete bonding of substrates. SOLUTION: Heavily doped p-type impurity layers are formed on the opposite sides of a silicon substrate 21 such that the dosage of impurities in a heavily doped p-type impurity layer 21b on the surface where a diaphragm 10 is not formed is lower than the dosage of impurities in a heavily doped p-type impurity layer 21a on the surface where the diaphragm 10 is formed.
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