High-density optical disk and method of producing the same

Abstract

A high-density optical disk includes reflective layers respectively formed at both information-recorded surfaces of a first substrate, and semitransparent layers respectively formed at one information-recorded surface of each of second and third substrates. The second and third substrates are respectively bonded at both sides of the first substrate.

What is claimed is:  
     
       1. A high-density optical disk comprising: 
       reflective layers respectively formed at both information-recorded surfaces of a first substrate; and  
       semitransparent layers respectively formed at one information-recorded surfaces of each of second and third substrates;  
       wherein said second and third substrates are respectively bonded at both sides of said first substrate.  
     
     
       2. A high-density optical disk as claimed in  claim 1 , wherein said second and third substrates are bonded at said first substrate by a UV bonding method. 
     
     
       3. A high-density optical disk as claimed in  claim 1 , further comprising 
       a first bonding layer formed between a first one of said semitransparent layers and a first one of said reflective layers; and  
       a second bonded  bonding layer formed between a second one of said semitransparent layers and a second one of said reflective layers;  
       wherein each of said first and second bonding layers is 30-40 μm.  
     
     
       4. A high-density optical disk as claimed in  claim 2 , further comprising 
       a first bonding layer formed between a first one of said semitransparent layers and a first one of said reflective layers; and  
       a second bonded  bonding layer formed between a second one of said semitransparent layers and a second one of said reflective layers;  
       wherein each of said first and second bonding layers is 30-40 μm.  
     
     
       5. A high-density optical disk as claimed in  claim 3 , wherein of each of said semitransparent layers is SiC or SiN. 
     
     
       6. A high-density optical disk as claimed in  claim 3 , wherein of each of said reflective layers is aluminum. 
     
     
       7. A high-density optical disk as claimed in  claim 3 , wherein of each of said reflective layers is aluminum-titanium. 
     
     
       8. A high-density optical disk as claimed in  claim 1 , wherein said first substrate is molded after fixing two stampers each for forming the information-recorded surfaces of said first substrate to two respective surfaces of a molding machine. 
     
     
       9. An optical disk comprising: 
       a first substrate having first and second information-recorded surfaces which are opposite each other;  
       a second substrate having a third information-recorded surface; and  
       a third substrate having a fourth information-recorded surface.  
     
     
       10. The optical disk as claimed in  claim 9 , wherein said first through fourth information-recorded surfaces are substantially parallel to one another. 
     
     
       11. The optical disk as claimed in  claim 9 , wherein said second, first and third substrates are formed substantially parallel to one another in that order, such that said first through fourth information-recorded surfaces are parallel to one another. 
     
     
       12. The optical disk as claimed in  claim 9 , further comprising: 
       a first reflective layer formed on said first information-recorded surface;  
       a second reflective layer formed on said second information-recorded surface;  
       a first semitransparent layer formed on said third information-recorded surface; and  
       a second semitransparent layer formed on said fourth information-recorded surface.  
     
     
       13. The optical disk as claimed in  claim 11 , further comprising: 
       a first reflective layer formed on said first information-recorded surface;  
       a second reflective layer formed on said second information-recorded surface;  
       a first semitransparent layer formed on said third information-recorded surface; and  
       a second semitransparent layer formed on said fourth information-recorded surface.  
     
     
       14. The optical disk as claimed in  claim 13 , further comprising: 
       a first bonding layer to bond with said first reflective layer and said first semitransparent layer; and  
       a second bonding layer to bond with said second reflective layer and said second semitransparent layer.  
     
     
       15. The optical disk as claimed in  claim 12 , further comprising: 
       a first bonding layer to bond with said first reflective layer and said first semitransparent layer; and  
       a second bonding layer to bond with said second reflective layer and said second semitransparent layer.  
     
     
       16. The optical disk as claimed in  claim 12 , wherein each of said second and third substrates have a thickness of 0.6 mm and said first substrate has a thickness of 0.6 or 1.2 mm. 
     
     
       17. The optical disk as claimed in  claim 14 , wherein each of said second and third substrates have a thickness of 0.6 mm and said first substrate has a thickness of 0.6 or 1.2 mm. 
     
     
       18. The optical disk as claimed in  claim 14 , wherein each of said first and second semitransparent layers is SiC or SiN. 
     
     
       19. The optical disk as claimed in  claim 14 , wherein each of said first and second semitransparent layers is aluminum. 
     
     
       20. The optical disk as claimed in  claim 14 , wherein each of said first and second semitransparent layers is aluminum-titanium. 
     
     
       21. The optical disk as claimed in  claim 14 , wherein each of said first and second bonding layers is 30-40 μm. 
     
     
       22. The optical disk as claimed in  claim 13 , wherein said first and second semitransparent layers have a reflectance of approximately 30% for respective lights irradiated through said first and second semitransparent layers from a surface opposite to that of said respective third and fourth information-recorded surfaces, said first and second reflective layers have a reflectance of approximately 90% for said respective lights, said third and fourth information-recorded surfaces have reflectances of approximately 30% for said respective lights, and said first and second information-recorded surfaces have reflectances of approximately 44% for said respective lights. 
     
     
       23. An optical disk comprising: 
       a first side having first and second information-recorded surfaces to contain first data to be reproduced by a first light irradiated toward said first side;  
       a second side having third and fourth information-recorded surfaces to contain second data to be reproduced by a second light irradiated toward said second side; and  
       a first substrate having said second and third information-recorded surfaces on opposite sides thereof.  
     
     
       24. The optical disk as claimed in  claim 23 , further comprising: 
       a second substrate formed to face said second information-recorded surface, wherein said second substrate has a first surface facing away from said second information-recorded surface and said first information-recorded surface facing said second information-recorded surface; and  
       a third substrate formed to face said third information-recorded surface, wherein said third substrate has a first surface facing away from said third information-recorded surface and said fourth information-recorded surface facing said third information-recorded surface.  
     
     
       25. The optical disk as claimed in  claim 24 , further comprising: 
       a first semitransparent layer having a first surface contacting said first information recorded surface, and a second surface;  
       a first bonding layer having a first surface contacting said second surface of said first semitransparent layer opposite that of said first surface of said first semitransparent layer, and a second surface;  
       a first reflective surface a first surface contacting said second surface of said first bonding layer, and a second surface contacting said second information-recorded surface;  
       a second semitransparent layer having a first surface contacting said fourth information-recorded surface, and a second surface;  
       a second bonding layer having a first surface contacting said second surface of said second semitransparent layer opposite that of said first surface of said second semitransparent layer, and a second surface; and  
       a second reflective surface having a first surface contacting said second surface of said second bonding layer, and a second surface contacting said third information-recorded surface.  
     
     
       26. The optical disk as claimed in  claim 9 , wherein said first and second information-recorded surfaces contain information to be reproduced by a first light irradiated onto a first side of the optical disk, and said third and fourth information-recorded surfaces contain information to be reproduced by a second light irradiated onto a second side of the optical disk opposite the first side. 
     
     
       27. The optical disk as claimed in  claim 9 , wherein said first and third information-recorded surfaces contain information to be reproduced by a first light irradiated onto a first side of the optical disk, and said second and fourth information-recorded surfaces contain information to be reproduced by a second light irradiated onto a second side of the optical disk opposite the first side. 
     
     
       28. A method of producing an optical disk, comprising the steps of: 
       forming pits of the  first and second information-recorded surfaces onto first and second surfaces of a first substrate, respectively;  
       forming first and second reflective layers on said first and second information-recorded surfaces;  
       producing pits of third and fourth information-recorded surfaces onto first surfaces of second and third substrates, respectively;  
       forming first and second semitransparent layers on said third and fourth information-recorded surfaces, respectively; and  
       bonding said first semitransparent to said first reflective layer using a first bonding layer therebetween, and bonding said second semitransparent layer to said second reflective layer using a second bonding layer therebetween.  
     
     
       29. The method as claimed in  claim 28 , wherein said step of forming first and second reflective layers comprises the steps of: 
       placing targets at first and second surfaces, respectively, of a chamber of a sputter device; and  
       simultaneously forming said first and second reflective layers on said first and second information-recorded surfaces.  
     
     
       30. The method as claimed in  claim 29 , wherein said step of bonding comprises the step of performing a UV bonding method. 
     
     
       31. A method of producing an optical disk, comprising the steps of: 
       fixing first and second stampers form  for making pits of respective first and second information-recorded surfaces to a molding machine;  
       simultaneously forming the pits of the first and second information-recorded surfaces onto first and second surfaces of a first substrate, respectively;  
       simultaneously forming first and second reflective layers on said first and second information-recorded surfaces;  
       producing pits of third and fourth information-recorded surfaces onto first surfaces of second and third substrates, respectively;  
       forming first and second semitransparent layers on said third and fourth information-recorded surfaces, respectively; and  
       bonding said first semitransparent layer to said first reflective layer using a first bonding layer therebetween, and bonding said second semitransparent layer to said second reflective layer using a second bonding layer therebetween.  
     
     
       32. The method as claimed in  claim 31 , wherein said step of simultaneously forming first and second reflective layers comprises the steps of: 
       placing targets at first and second surfaces, respectively, of a chamber of a sputter device; and  
       simultaneously forming said first and second reflective layers on said first and second information-recorded surfaces.  
     
     
       33. The method as claimed in  claim 32 , wherein said step of bonding comprises the step of performing a UV bonding method. 
     
     
       34. An optical disk comprising: 
         a first substrate having first and second information - recorded surfaces which are opposite each other; and    
         a second substrate having a third information - recorded surface and formed at a side of said first substrate.   
     
     
       35. An optical disk comprising: 
         a first side having first and second information - recorded surfaces to contain first data to be reproduced by a first light irradiated toward said first side;    
         a second side having a third information - recorded surface to contain second data to be reproduced by a second light toward said second side;    
         a first substrate having said second and third information - recorded surfaces on opposite sides thereof; and    
         a second substrate having said first information - recorded surface.   
     
     
       36. A method of producing an optical disk, comprising: 
         forming pits of first and second information - recorded surfaces onto first and second surfaces of a first substrate, respectively;    
         forming first and second reflective layers on said first and second information - recorded surfaces;    
         producing pits of a third information - recorded surface on a first surface of a second substrate;    
         forming a first semitransparent layer on said third information - recorded surface; and    
         bonding said first semi - transparent layer to said first reflective layer using a first bonding layer therebetween.   
     
     
       37. A method of producing an optical disk, comprising: 
         fixing first and second stampers for making pits of respective first and second information - recorded surfaces to a molding machine;    
         simultaneously forming the pits of the first and second information - recorded surfaces onto first and second surfaces of a first substrate;    
         producing pits of a third information - recorded surface onto a first surface of a second substrate; and    
       
         bonding said first substrate with said second substrate. 
       
     
     
       38. The method as claimed in  claim 37 , wherein said bonding comprises: 
         simultaneously forming first and second reflective layers on said first and second information - recorded surfaces;    
         forming a semitransparent layer on said third information - recorded surface; and    
       
         bonding said semitransparent layer to said first reflective layer using a bonding layer therebetween. 
       
     
     
       39. An optical disk comprising: 
         a first substrate having first and second information - recorded surfaces which are opposite each other;    
         a second substrate having a third information - recorded surface and formed at a first side of said first substrate; and    
         a third substrate having a fourth information - recorded surface and formed at a second side of said first substrate opposite said first side.   
     
     
       40. A method of producing an optical disk, comprising: 
         fixing first and second stampers for making pits of respective first and second information - recorded surfaces to a molding machine;    
         simultaneously forming the pits of the first and second information - recorded surfaces onto first and second surfaces of a first substrate;    
         producing pits of third and fourth information - recorded surfaces onto first surfaces of second and third substrates, respectively; and    
       
         bonding said second substrate at a first side of said first substrate and bonding said third substrate at a second side of said first substrate opposite to said first side. 
       
     
     
       41. An optical disk comprising: 
       
         a first substrate;  
       
         a second substrate having an information - recorded surface and formed at a first side of said first substrate; and    
       
         a third substrate formed at a second side of said first substrate opposite said first side. 
       
     
     
       42. A method of producing an optical disk, comprising: 
         producing pits of an information - recorded surface onto a surface at a first side of a first substrate; and    
       
         bonding a second substrate at said first side of said first substrate and bonding a third substrate at a second side of said first substrate opposite said first side. 
       
     
     
       43. An optical disk comprising: 
         a first substrate having a first information - recorded surface at a side thereof; and    
         a second substrate having a second information - recorded surface formed at a side of thereof and facing the first information - recorded surface;    
         wherein said first and second - information - recorded surfaces are both in a same half of the optical disk.   
     
     
       44. An optical disk comprising: 
         a side having first and second information - recorded surfaces to contain data to be reproduced by a light irradiated toward said side;    
         a first substrate having said first information - recorded surface; and    
         a second substrate having said second - information - recorded surface facing said first information - recorded surface.   
     
     
       45. A method of producing an optical disk, comprising: 
         forming pits of a first information - recorded surface onto a surface of a first substrate;    
         forming a reflective layer on said first information - recorded surface;    
         producing pits of a second information - recorded surface on a surface of a second substrate;    
         forming a semitransparent layer on said second information - recorded surface; and    
         bonding said semi - transparent layer to said reflective layer using a bonding layer therebetween.   
     
     
       46. A method of producing an optical disk, comprising: 
         forming pits of a first information - recorded surface onto a surface of a first substrate;    
         forming a reflective layer on said first information - recorded surface;    
         producing pits of a second information - recorded surface on a surface of a second substrate; and    
         bonding said first substrate to said second substrate so that said first and second - information - recorded surfaces face each other and are on a same half of the optical disk.   
     
     
       47. An optical disk comprising: 
       
         a first substrate;  
       
       
         a second substrate at a first side of said first substrate and having a first information recorded surface facing said first substrate; and  
       
         a third substrate at a second side of said first substrate opposite said first side and having a second information - recorded surface facing said first substrate.   
     
     
       48. An optical disk comprising: 
         a first side having a first information - recorded surface to contain first data to be reproduced by a first light irradiated toward said first side;    
         a second side having a second information - recorded surface to contain second data to be reproduced by a second light toward said second side;    
       
         a first substrate formed in a middle of the optical disk and extending through to both said first and second sides;  
       
         a second substrate having said first information - recorded surface which faces said first substrate; and    
         a third substrate having said second information - recorded surface which faces said first substrate.   
     
     
       49. A method of producing an optical disk, comprising: 
         producing pits of a first information - recorded surface onto a surface of a first substrate;    
         producing pits of a second information - recorded surface onto a surface of a second substrate;    
       
         bonding said first and second substrates to opposite sides of a third substrate. 
       
     
     
       50. The method as claimed in  claim 49 , wherein the third substrate is positioned in a middle of the optical disk and extending through both halves of the optical disk. 
     
     
       51. An optical disk comprising: 
         a first substrate having a first information - recorded surface;    
         a second substrate having a second information - recorded surface; and    
         a third substrate having a third information - recording surface.   
     
     
       52. The optical disk as claimed in  claim 51 , wherein said first information- recorded surface is formed on surface of said first substrate, said second information - recorded surface is formed on a surface of said second substrate facing said first information - recorded surface, and said second and third substrates are on opposite sides of said first substrate.   
     
     
       53. The optical disk as claimed in  claim 52 , wherein said first and second information- recorded surface are to be reproduced by a first light irradiated toward a first side of the optical disk and said third information - recorded surface is to be reproduced by a second light irradiated toward a second side of the optical disk.   
     
     
       54. An optical disk comprising: 
         a first side having first and second information - recorded surfaces to contain first data to be reproduced by a first light irradiated toward said first side;    
         a second side having a third information - recorded surface to contain second data to be reproduced by a second light toward said second side; and    
         a first substrate having said first information - recorded surface;    
         a second substrate having said second - information - recorded surface; and    
         a third substrate having said third information - recorded surface.   
     
     
       55. A method of producing an optical disk, comprising: 
         forming pits of a first information - recorded surface onto a surface of a first substrate;    
         forming a reflective layer on said first information - recorded surface;    
         producing pits of a second information - recorded surface on a surface of a second substrate;    
         forming a first semitransparent layer on said second information - recorded surface;    
         bonding said first semi - transparent layer to said first reflective layer using a first bonding layer therebetween;    
         producing pits of a third information - recorded surface on a surface of a third substrate; and    
       
         bonding said third substrate to a side of said first substrate opposite to that of said second substrate. 
       
     
     
       56. An method of producing an optical disk, comprising: 
         producing pits of a first information - recorded surface onto a surface of a first substrate;    
         producing pits of a second information - recorded surface onto a surface of a second substrate;    
         producing pits of a third information - recorded surface onto a surface of a second substrate; and    
         bonding said second substrate with said first substrate at a first side of said first substrate with said first information - recorded surface and bonding said third substrate to a second side of said first substrate opposite said first side.   
     
     
       57. The method as claimed in  claim 56 , wherein said bonding comprises: 
         forming a reflective layer on said first information - recorded surface;    
         forming a semitransparent layer on said second information - recorded surface; and    
       
         bonding said semitransparent layer to said reflective layer using a bonding layer therebetween. 
       
     
     
       58. A method of producing an optical disk, comprising: 
         fixing first and second stampers for making pits of respective first and second information - recorded surfaces to a molding machine; and    
         simultaneously forming the pits of the first and second information - recorded surfaces onto first and second surfaces of a first substrate.