Patent ID: 7227829

Claim:
A method for erasing data recorded in a data storage device in which a data bit is originally written onto a polymeric surface carried by a silicon substrate by applying a first combination of heat energy and mechanical force to the polymeric surface via a tip to form a pit in the surface representative of the data bit by local deformation of the polymeric surface, the method comprising applying a write current to the tip to heat the tip to a temperature of the order of 700 degrees centigrade level sufficient to locally deform the polymer layer thereby causing the tip to indent the surface of the polymer layer and leave a pit of a diameter of about 40 nm and surrounded by a ring of polymer substrate material raised above the polymer layer and applying a second combination of energy and mechanical force via the tip to prerecorded pits of the polymeric surface to be erased, the second combination being different to the first combination, and forming new pits overlapping pits representative of prerecorded data to be erased to substantially level the polymeric surface by performing the write operation to overwrite pits to be erased with a greater density of new pits overlapping each other so that each new pit erases the immediately preceding pit, the overlapping new pits merging with each other and the pre-recorded pit to be erased to substantially level the polymer surface to a level where the erased, pre-recorded bit is not detected as a data bit during a read operation.