MFDigital CD DVD Information Library
Tuesday, June 15, 2004
CD Manufacturing - Mastering - Development and Metallisation
Development and Metallisation
The exposed photoresist surface is developed to remove the photoresist exposed by the laser, creating pits in the surface. These pits should extend right through the photoresist to the glass underneath to achieve good pit geometries as specified in the Red Book. The glass itself is unaffected by this process and acts merely as a carrier for the photoresist.
The active surface (ie containing pits) of the developed glass master is then metallised either with nickel or nickel alloy created by sputtering or with silver by evaporation. If nickel or nickel alloy is used this becomes part of the Father which is created by electroforming so the pit geometry is maintained. If silver is used, the nickel Father is grown on top of the silver resulting in some distortion of the pit shapes, but (for CDs) this is not usually enough seriously to impair the resultant pits.