| 摘要 |
PURPOSE:To accurately control the thickness of a wafer without being affected by the concentration, temperature and the like of an etchant by a method wherein a recessed part of the prescribed depth is formed on a wafer in advance, the wafer is thinned off and the thinning work is stopped upon confirmation of penetration of the recessed part. CONSTITUTION:A recessed part of the prescribed depth is formed on one main surface of a wafer in advance, the wafer is thinned off, and the thickness of the wafer is detected by detecting the penetration of the recessed part. For example, a film such as a silicon oxide film (SiO2 film) is formed on the surface (110) of a silicon single crystal wafer 1 as a mask for an etchant, the silicon oxide film 2 is selectively removed using a glass mask 5 as a photomask, and recessed parts 31-35, having the cross-section becoming V-shape, for example, are formed on the part where the film 2 is removed in the silicon single crystal wafer 1. The parts where the recesses are formed are penetrated. At that time, when the thinning-off of the wafer 1 is stopped, the thickness of the wafer is made equal to the depth of the recesses.
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