Abstract
The damascene process using chemical mechanical polishing was introduced to embed a super-resolution material in the pits of a read-only memory (ROM) substrate to fabricate discs using a next-generation large-capacity optical-disc technique called three-dimensional pit selection. GeSbTe was used as the super-resolution material. Experimental results using scanning electron microscopy and energy-dispersive X-ray spectroscopy revealed that GeSbTe remained only in the pits. The readout signal from a disc tester demonstrated that GeSbTe in the damascene disc changed its phases between amorphous and crystal. The polishing rate could be controlled by adjusting the conditions for the concentration of colloidal silica and the pH of the slurry. The test equipment we fabricated for mass producing the discs demonstrated that the degree of polishing could automatically be determined by detecting the distortion in the polishing arm caused by friction between the polishing head and the sample surface.