Semiconductor device and a manufacturing method thereof
A semiconductor device includes at least two adjacent memory cell blocks, each of the memory cell blocks having a plurality of memory cell units, each of memory cell units having a plurality of electrically reprogrammable and erasable memory cells connected in series, a plurality of cell gates for selecting the plurality of memory cells within the two adjacent memory cell blocks, each of the plurality of cell gates being formed with roughly rectangular closed loops or roughly U shaped open loops, each of the loops being connected to a corresponding cell of the memory cells in a corresponding memory cell unit of the plurality of memory cell units within one of the two adjacent memory cell blocks and being connected to a corresponding memory cell of the memory cells in a corresponding memory cell unit of the plurality of memory cell units within the other memory cell block of the two adjacent memory cell blocks and a plurality of pairs of first and second selection gates for selecting the memory cell block, the plurality of cell gates being located between one pair of the first and second selection gates within a corresponding block of the memory cell block.
1. A method of manufacturing a semiconductor device comprising:
depositing a first hard mask on a material to be processed;
forming a first resist pattern of a roughly rectangular closed loop on said first hard mask;
etching said first hard mask into a roughly rectangular closed loop using said first resist pattern as a mask;
depositing a second hard mask on said material and said first hard mask after removing said first resist pattern;
etching said second hard mask anisotropically into a roughly rectangular closed loop which encloses said first hard mask on both sides of said first hard mask;
etching said material using said second mask with a roughly rectangular closed loop as a mask after selectively removing said first hard mask;
forming a second resist pattern on said second hard mask before etching of said materials; and
etching said second hard mask so that said roughly rectangular closed loop converts into two roughly symmetrically U shaped open loops whose openings face each other using said second resist pattern as a mask.