Explain what happens to the ion energy as the pressure is increased in a plasma etching system, and how does the etching profile of the etched structures change if the material is etched at a high pressure versus at a low pressure. Answer: Question 13 (10): You have only a high-pressure plasma etch and an ion mill at your disposal. Select which one to use in the following applications. Justify your answer. (a) Etching a 5000 polysilicon layer that serves as the upper electrode of a large square capacitor. The capacitor dielectric is 50 of SiO2. (b) Anisotropic patterning of a thin layer of Yba2Cu3O7 on a thick insulating film. (c) Recessing the channel of a GaAs FET. For this application the residual etch damage must be minimized