| 摘要 |
PROBLEM TO BE SOLVED: To increase the capacitance of a capacitor by using a silicon film having minute unevenness caused by grains at least in a part of the surface as an electrode. SOLUTION: Phosphorus diffusion is performed at 820 deg.C for 60 minutes to a silicon film 54 deposited on an Si substrate 50 on which a thick SiO2 , film 52 is formed using a of SiH4 +He under a pressure of 1 Torr, thereby forming a capacitor insulating film 56. A polysilicon film 58 serving as an upper layer electrode is formed on the film 56. The surface of the silicon film deposited at 510 deg.C is very smooth, no growth of grains is seen, an the surface area is as small as 1mm<2> . When a deposition temperature is set to 550 deg.C, however, hemispherical grains each having the diameter of about 700Å are formed at high density and the surface area is largely increased by fine unevenness. That is, when the grains are grown in a transition temperature at which a crystal state of the deposition film is changed from an amorphous phase to polycrystal, fine unevenness due to the grain growth of silicon occurs on the surface at high density and the surface area of the film can be increased. |
