According to {HEAD ~ the aspect} of {TAIL ~ the invention}, it is preferable that the wet etching be performed to a front surface of the substrate provided with the dry etching mask in the wet etching process 
According to { HEAD ~ the aspect } of { TAIL ~ the invention } , it is preferable that the wet etching be performed to a front surface of the substrate provided with the dry etching mask in the wet etching process
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