Abstract: The invention provides a process to form on a certain conductive type semiconductor substrate 1 insulation layer 9 having openings 11, which regions will become source and drain; a process to form diffusion layer 8 of the same conductive type as semiconductor substrate 1 in to-be-drain space, with insulation layer 9 and photoresist 10 as masks; a process to form side wall layer 13 alongside openings of insulation layer 9; a process to form diffusion layers 4 and 5, conductive type of which layers is opposite to that of semiconductor substrate 1, in to-be-source and to-be-drain regions, with insulation layer 9 and side wall layer 13 as masks; a process to remove insulation layer 9 and side wall layer 13; and a process to form insulation layer 2 on semiconductor substrate in channel region distinguished by, and including part of, diffusion layers 4 and 5, and to form floating-gate electrode 3 on insulation layer 2, and control-gate electrode 7 with insulation layer 6 in between.

Abstract: A diffraction element includes a diffraction grating for dividing a light beam, emitted from a light source along a predetermined path, into a principal light beam and at least two auxiliary light beams, and a hologram for separating the beam, which has been reflected from an optical information recording medium, from the predetermined path. The diffraction grating and the hologram are integrated together by being formed in alignment with each other in opposite portions of a block of glass or plastics. A slide is provided at at least a portion of the diffraction element and includes a peripheral wall in sliding engagement with a cylindrical surface coaxial with an optical axis of the diffraction element to permit the diffraction element to be rotatable about the optical axis.