Patent ID: 7981798

Claim:
A method of manufacturing a substrate, the method comprising the successive steps of: (a) forming through holes by applying an anisotropic etching to a silicon substrate from a first surface of the silicon substrate; (b) forming a first insulating film to cover the first surface of the silicon substrate, surfaces of the silicon substrate exposed from the through holes, and a second surface of the silicon substrate opposite to the first surface; (c) forming an opening in a portion of the first insulating film provided on the second surface, the portion of the first insulating film corresponding to an area in which the through holes are formed; (d) etching the silicon substrate using the first insulating film provided on the second surface as a mask such that at least the first insulating film provided on bottom surfaces of the through holes is exposed, thereby forming a cavity in the silicon substrate, and forming the cavity such that a width of a cross-sectional shape of the cavity is widened gradually as a distance from the through holes is increased; and (e) removing the first insulating film.