Method of manufacturing a stamper for producing optical discs, a stamper thus obtained and an optical disc obtained by using such a stamper

Abstract

The invention relates to a method of manufacturing a stamper for producing optical disks, comprising the application of a photoresist to a stamper plate and the structuring of the applied photoresist film. The structuring comprises the successive exposure, development and heating of the photoresist film. The developed photoresist film is subjected to an additional exposure in the deep UV range prior to the final heat treatment. The invention also relates to a stamper and to an optical disk obtained using the stamper.

1. A method of manufacturing a stamper for producing optical discs, comprising:
 applying a photoresist to a stamper plate to form a photoresist film; and  
 structuring the photoresist film, the structuring including, in order, 
 exposing the photoresist film;  
 developing the photoresist film;  
 heating the photoresist film; 
 additionally exposing the developed photoresist film to a light having a wavelength in the deep UV range; and  
 heat treating the additionally exposed photoresist film;  
 
 wherein said additional exposing is performed using a light wavelength of 200-320 nm and an energy level between 4·10 −4  and 5·10 −2  J/cm.  
 
     
     
       2. A method according to  claim 1 , wherein the energy level of said additional exposing ranges between 8·10 −4  and 1.2·10 −2  J/cm 2 . 
     
     
       3. A method according to  claim 1 , wherein an exposure time of said additional exposing ranges between 1 and 125 seconds. 
     
     
       4. A method according to  claim 3 , wherein the exposure time of said additional exposing ranges between 2 and 30 seconds. 
     
     
       5. A method according to  claim 1 , wherein the light wavelength is in the range of 240-260 nm. 
     
     
       6. A method according to  claim 5 , wherein said additional exposing is carried out under rotation. 
     
     
       7. A method according to  claim 5 , wherein said additional exposing is carried out under heating. 
     
     
       8. A method according to  claim 1 , wherein a negative photoresist is used for said applying. 
     
     
       9. A stamper for producing optical discs obtained by using the method according to  claim 1 . 
     
     
       10. An optical disc, obtained by using the stamper according to  claim 9 . 
     
     
       11. A method according to  claim 1 , wherein said exposing is carried out in two stages, comprising a first selective exposure stage and a second integral exposure stage, wherein the selectively exposed photoresist is heated prior to carrying out said second integral exposure stage.