Via hole forming method

Abstract

A method of forming a via hole reaching a bonding pad in a wafer, which have a plurality of devices on the front surface of a substrate and bonding pads on each of the devices, by applying a pulse laser beam from the rear surface of the substrate, comprising the steps of: affixing a protective member to the front surface of the substrate; grinding the rear surface of the substrate having the protective member affixed to the front surface to reduce the thickness of the wafer to a predetermined value; forming via holes in the substrate by applying a pulse laser beam from the rear surface of the substrate of the wafer having the predetermined thickness; and etching the wafer having the via holes in the substrate from the rear surface of the substrate.

Dependencies are inferred from the claim text.