Study of Super-Resolution Read-Only-Memory Disk with a Semiconducting or Chalcogenide Mask Layer

Super-resolution read-only-memory (ROM) disks were manufactured with a semiconductor material (InSb) or a phase change material (AgInSbTe, AIST). A reasonable carrier-to-noise ratio (CNR) of 40 dBm was measured on a single-tone pattern with 80 nm pits for both materials. On a random pattern with RLL(1,9) (RLL: run-length limited) encoding and a channel bit length of 40 nm, a bit error rate (bER) of 10-3 was found for the InSb-based disk. However, the pattern was impossible to be decoded for the AIST-based disk. This is due to the unexpected reflectivity modulation that occurs when 2T marks are read out.