Master information carrier for magnetic transfer and a method for producing the carrier
View Patent ↗A method of producing a master information carrier by scanning a track a number of times. The method produces a master information carrier has a pattern of a magnetic layer representing information to be transferred to a high-density recording slave medium where the track width is not larger than 0.3 μm. The pattern is drawn by scanning a given track a plurality of times with an electron beam whose drawing diameter is smaller than the track width.
1. A method for producing a master information carrier equipped with a substrate having an irregular pattern corresponding to information to be transferred to high density slave media and a magnetic layer which is coated on the substrate, in which the track width is 0.3 μm or less, comprising:
coating a disk with resist;
drawing a pattern that corresponds to each recess or protrusion of the irregular pattern, by scanning an electron beam having a drawing diameter which is smaller than the track width a plurality of times along a single direction on the resist while rotating the disk;
producing the substrate having the irregular pattern based on the drawing performed by the electron beam; and
coating the substrate with the magnetic layer;
wherein irradiation position of the electron beam is being shifted for each scanning operation among the plurality of scanning operations; and
wherein the irradiation position is being shifted such that k is 0 or greater and 0.8 or less within a formula W=[n−(n−1)k]*d, wherein W is the track width in μm, n is the number of scanning operations, d is the drawing diameter of the electron beam in μm, and k is a coefficient that represents the degree of overlap of the electron beam.
2. The method according to claim 1 , wherein the value of n is not smaller than 2.
3. The method according to claim 2 , wherein as the value of n increases or as the value of d decreases, and as the value of k increases, the shape of the protruding potions of the irregular pattern becomes more rectangular.
4. The method according to claim 1 wherein the roundness of the protruding portions of the irregular pattern is governed by the drawing diameter d of the electron beam.
5. The method as defined in claim 1 , wherein the direction along which scanning is performed is the track direction.
6. The method as defined in claim 1 , wherein the direction along which scanning is performed is the track width direction.
7. The method as defined in claim 6 , wherein the orientation of the scanning movement of the electron beam is reversed at each scanning operation.
8. The method as defined in claim 1 , wherein k=0 is no overlap.
9. The method as defined in claim 1 , wherein k=0.8 is a partial overlap.