| 摘要 |
PURPOSE:To reduce the area of a capacitor with improvement in the degree of integration of a DRAM by easily controlling the density of crystal grains and crystal grain size and forming a polycrystalline silicon film having finer grain size by conducting the generation of a crystal nucleus and the growth of the crystal nucleus under different conditions when an amorphous silicon film is changed into a polycrystal. CONSTITUTION:An amorphous silicon film 103 is heated at a fixed temperature and crystal nuclei 104 are generated, and a temperature is lowered and crystal nuclei 105 are grown. The means grain size of a polycrystalline silicon film depends upon a nucleus generation rate and the growth rate of the crystal nuclei. The nucleus generation rate is increased with the elevation of a heating temperature, and the growth rate of the crystal nuclei is also accelerated simultaneously. The density of the crystal nuclei is augmented with time at the nucleus generation rate, but the generation of a novel crystal nucleus is prevented by the growth of the previously existing crystal nuclei when the growth rate of the crystal nuclei is made larger than the nucleus generation rate. Accordingly, the heating temperature for the growth of the crystal nuclei is elevated and the heating time is shortened, and the temperature for the growth of the crystal nuclei is lowered, thus easily controlling crystal grain size. |
