Method of manufacturing an optical data storage medium, optical data storage medium and apparatus for performing said method

Abstract

A method of manufacturing an optical data storage medium, comprising at least one substrate ( 11 ) and a plurality of layers deposited on the substrate ( 11 ) is described. The medium includes at least one of a transparent spacer layer and transparent cover layer ( 12 ). The layer ( 12 ) is provided by applying a liquid onto the rotating substrate ( 11 ) and rotating the substrate ( 11 ) further in order to spread out the liquid into a layer substantially uniformly between an inner radius r i and an outer radius r o , and solidifying the liquid layer ( 12 ) by means of exposure to UV radiation. After applying the liquid onto the rotating substrate the liquid layer ( 12 ) is heated by heating means ( 14 ) in such a way that the temperature rise of the liquid layer ( 12 ) at r i has a value δT ri , while the temperature rise of the liquid layer ( 12 ) between r i and r o gradually increases, and the temperature rise of the liquid layer ( 12 ) at r o has a value δT ro >δT ri . In this way the spacer layer or cover layer has a variation in thickness smaller than +/−1 μm, measured over the information storage area. Further a medium manufactured using said method and an apparatus for performing the method are described.

1 - 8 . (canceled) 
     
     
         9 . An optical data storage medium manufactured using the method of claim  8 , wherein additionally:
 a stamper is pressed into the unsolidified top portion of the liquid layer,   subsequently the top portion is solidified by exposure to radiation,   the stamper is separated from the top portion of the completely solidified liquid layer,   further layers are provided for finalization of the optical data storage medium.   
     
     
         10 . An optical data storage medium according to  claim 9 , wherein the stamper is transparent to UV radiation and the top portion is solidified by UV radiation which is projected through the transparent stamper. 
     
     
         11 . An apparatus for performing the method of claim  1  comprising
 means for receiving a substrate and a plurality of layers deposited on the substrate, 
 means for rotating the substrate, 
 means for providing at least one of a transparent spacer layer and transparent cover layer, by applying a liquid onto the rotating substrate and rotating the substrate further in order to spread out the liquid into a layer substantially uniformly between an inner radius r i  and an outer radius r o , and 
 means for heating the liquid layer after applying the liquid onto the rotating substrate in such a way that, 
 the temperature rise of the liquid layer at r i  has a value δT ri  while, 
 the temperature rise of the liquid layer between r i  and r o  gradually increases, 
 the temperature rise of the liquid layer at r, has a value δT ro >δT ri , and 
 means for solidifying the liquid layer by exposure to UV radiation directly after the heating step. 
 
     
     
         12 . An apparatus as claimed in  claim 11 , wherein the means for heating comprise an infrared heating device projecting IR radiation onto the substrate in an area with a radius larger than r i  for causing a desired radial temperature profile in the liquid layer. 
     
     
         13 . An apparatus as claimed in  claim 11 , wherein the means for heating comprise a heated chuck on which the substrate is mounted during rotation, said chuck having a heated surface for causing a desired radial temperature profile in the liquid layer. 
     
     
         14 . An apparatus as claimed in  claim 11 , wherein the means for heating comprise a directed flow of heated gas emanating from a nozzle for causing a desired radial temperature profile in the liquid layer. 
     
     
         15 . An apparatus as claimed in  claim 11 , wherein a mask for shielding a few mm wide outer peripherical zone of the substrate is present in order to prevent exposure of the liquid layer in this zone to UV radiation.