Optical disk and method for producing the same
View Patent ↗An optical disk is constructed such that a thin film including a reflective layer is formed on a substrate, or on a thermoplastic resin layer on the substrate. A stamper having an asperity pattern corresponding to information signals is directly pressed against the thin film to transfer the asperity pattern on the thin film. Heat-pressing the stamper against the thin film makes it possible to further accurately transfer the asperity of the stamper to the reflective layer with less pressing force, in the case where the reflective layer is formed on the thermoplastic resin layer.
1. A method for producing optical disks constructed such that laser light is irradiated on a side of the disk opposite to a substrate in information reading, the method comprising:
forming reflective metal layer directly on a flat surface of a substrate; and
directly pressing a stamper having an asperity pattern on a side thereof facing the reflective metal layer against the reflective metal layer, so as to transfer the asperity pattern to the reflective metal layer while the flat surface of the substrate remains flat.
2. The method according to claim 1 , wherein the reflective metal layer includes a metal film containing at least one selected from Au, Ag, Cu, Pt, and Al in the content of 95 wt % or more.
3. The method according to claim 1 , wherein the reflective metal layer has a thickness substantially three times as high as a height or a depth of the asperity pattern of the stamper.
4. The method according to claim 1 , wherein the reflective metal layer is attracted toward the stamper by vacuum attraction when the stamper is pressed against the reflective metal layer.
5. The method according to claim 1 , wherein the substrate comprises a thermoplastic resin layer, the reflective metal layer is formed on the thermoplastic resin layer of the stamper is heated.
6. The method according to claim 1 , wherein a transparent sheet or a light transmissive layer made of a UV curing resin is formed on the reflective metal layer.