Exploring the impact of aspect ratio and O2 flow rate on the etch rate ratio of SiO2 at the bottom and top of the trench

In the field of semiconductor manufacturing and microelectronics processing, precisely controlling the etching process of SiO2 is crucial for enhancing device performance. For the present study, C4F8/Ar/O2 plasma dry etching technology was adopted. First, trenches with different aspect ratios were etched, and then, SiO2 was deposited on them. Through this process, experimental SiO2 structures featuring different aspect ratios were successfully fabricated. Subsequently, a systematic study was done to examine the influence of the O2 flow rate, trench depth, and trench width on the ratio of SiO2 etching rates between the bottom and top of the trench (B/T ratio). The findings revealed that an augmentation in the O2 flow rate resulted in a discernible increase in the B/T ratio. Moreover, an expansion in the trench width generally led to an elevation of the B/T ratio, whereas intensification in trench depth substantially decreased the B/T ratio. The three parameters independently and precisely regulate the changes in the etching rate ratio, providing essential theoretical support and practical guidance for optimizing etching processes and improving product quality in actual production.