| 摘要 |
PROBLEM TO BE SOLVED: To control a diffusion of dopants in a polycrystalline silicon film into a substrate with high accuracy in a DRAM of a structure that the lower electrode of a capacitance element for storing information on a memory cell is constituted of this polycrystalline silicon film. SOLUTION: Connection holes 19, which respectively reach the N<-> semiconductor region 9A on one side of N<-> semiconductor regions 9A of each MISFET Qt for memory cell selection use, are formed and thereafter, a lightly doped (or non-doped) polycrystalline silicon film 16 is deposited on a semiconductor substrate 1 by a CVD method, then, N-type impurities (phosphorus or arsenic) are implanted in the surface layer part of this film 16 to heighten the impurity concentration in the surface layer part only. The substrate 1 is heat-treated and the N-type impuriites in the film 16 are diffused in a P-type well 2 through the holes 19, whereby N<+> semiconductor regions 9B are formed. |
