| 摘要 |
PURPOSE:To decrease leaks between memory cells, by forming a groove-shaped capacitor in a well region having a uniform impurity concentration in the direction of the depth and the specified value of the impurity concentration. CONSTITUTION:Impurities are diffused from a first epitaxial layer 10 into a second epitaxial layer 11 by outward diffusion. Then, the impurity concentration profile in the direction of the depth from the surface of a well region becomes uniform. The impurity concentration becomes 2-3X10<16>/cm<3>. Thus, a well region 2 wherein the impurity concentration profile is uniform is formed in the second epitaxial layer 11. Thereafter, capacitor for a memory cell is formed through the following steps: formation of an oxide film 6, digging of grooves in a substrate, doping of impurities into the inner walls of the grooves 3 and 31, formation of an insulating film 4 that is to become the dielectric of a capacitor, formation of a cell plate electrode 5 with polycrystalline silicon, filling of the grooves and the like. Thus, the memory cell is formed. When the impurity concentration of the well region is in the range of 1-5X10<16>/cm<3>, it is more effective. |
