Now, let’s continue to explore how to create tapered holes.
This process uses the Bosch Process, achieved through the alternating cycles of SF6, C4F8, and Ar gases. SF6 is primarily responsible for the etching action, while C4F8 mainly serves to passivate. The hole walls produced by this process exhibit a scallop pattern, with rougher sidewalls.
After this step, a non-Bosch etching process will follow, typically using gases such as SF6, O2, and Ar. By adjusting the ratio of SF6 to O2, the taper of the through-hole can be precisely controlled.
However, after this process, the top of the hole will form very sharp corners, which will require the next step of rounding treatment, which we will introduce in detail in subsequent articles.
