According to {TAIL ~ the aspect} of 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 {HEAD ~ the wet etching process} 
According to { TAIL ~ the aspect } of 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 { HEAD ~ the wet etching process }
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