Method for manufacturing recording original disc for optical information recording media

Abstract

A recording original disc (,) for optical discs is manufactured by the following steps: a first step for forming a lower layer (,), an intermediate layer (,) and an upper layer (,) of photoresist on the surface of a substrate (,), a second step for exposing the upper layer (,) to light to form a pattern corresponding to recording information on the upper layer (,) and developing the upper layer (,), a third step for etching the intermediate layer (,) while using the upper layer (,) which has been exposed to light and developed in the second step, a fourth step for etching the lower layer (,) while using as a mask the intermediate layer (,) etched in the third step, and a fifth step for removing the residual intermediate layer. An intermediate step for applying far ultraviolet radiation to the upper layer (,) and then subjecting the upper layer (,) to a heat treatment. Representing the thickness of the intermediate layer (,) and the thickness of the upper layer (,) formed in the first step by D and d respectively, and representing the etching ratio of the intermediate layer (,) to the upper layer (,) by n, the relationship: D≦ is achieved. The etching ratio of the lower layer (,) to the intermediate layer (,) in the fourth step is set to 10 or more.