Chemical a may have a higher spontaneous chemical reaction rate with the film and etch the film isotropically Chemical B may photoresist erosion during the etching. Another possibility is that chemical b itself byproduct of its reaction with the film may be deposited on the sidewall as inhibi leads to non-vertical slope of sidewall with zero bias 5.(Plummer 10.8) It is observed that the sidewall slope in an etch process becomes more sloped as the temperature is reduced Why? Answer This observation of more sloped sidewall at lower temperatures can be explained by the negative net temperature dependence of inhibitor deposition. In a plasma etching, the removal rate of substrate is limited by bond breaking and forming, which is sensitive to the incident ions energy, while insensitive to temperature. However, the desorption rate of the deposited inhibitor layer is strongly temperature dependent. When the temperature is reduced, the desorption of inhibitor is slower, which will cause relatively faster deposition of inhibitor on the sidewall and eventually lead to more sloped etch profile.Chemical A may have a higher spontaneous chemical reaction rate with the film and etch the film isotropically. Chemical B may cause photoresist erosion during the etching. Another possibility is that chemical B itself or the byproduct of its reaction with the film may be deposited on the sidewall as inhibitor that leads to non-vertical slope of sidewall with zero bias. 5. (Plummer 10.8) It is observed that the sidewall slope in an etch process becomes more sloped as the temperature is reduced. Why? Answer: This observation of more sloped sidewall at lower temperatures can be explained by the negative net temperature dependence of inhibitor deposition. In a plasma etching, the removal rate of substrate is limited by bond breaking and forming, which is sensitive to the incident ion’s energy, while insensitive to temperature. However, the desorption rate of the deposited inhibitor layer is strongly temperature dependent. When the temperature is reduced, the desorption of inhibitor is slower, which will cause relatively faster deposition of inhibitor on the sidewall and eventually lead to more sloped etch profile. 3