Tapered etching of polysilicon films has been achieved by implanting phosphorus ions into the polysilicon film and using plasma etch in either $CF_4-O_2;or;SF_6$. A two-step plasma etching method is also proposed to control the taper angle of the etched edge without changing the implantion conditions. The taper angle is determined by the ratio of the etch rate of the undamaged region to that of the damaged top region of the polysilicon layer. The ratio is found to be dependent on the implantion dose, the implantion energy and the anisotropy of etching. The minimum angle in our experiments is about $10^{circ}$. When the two-step etching method is employed, the taper angles can be controlled from the minimum angle up to about $55^{circ}$.