I am asking this question because I want to make sure my understanding is correct.
I'm learning about the etching process, but I'm having difficulty with bond strength and etching mechanism. I'm studying on my own, so I'd like to check if what I've studied is correct.
1) When selecting an etching gas to remove Si-O, it must have a higher bond strength than Si-O to break the bond and react. Additionally, these by-products must evaporate for etching to proceed.
2) If the bonding strength is greater than that of the target material, the bonding strength between such etching materials is low, and the higher the increase pressure, the more advantageous it is for etching.
3) If the energy required for the reaction can be supplied sufficiently, the one with the higher bond strength will proceed first and produce by-products.
I feel very honored to be able to ask this question even though I have no one to ask it to. Please feel free to answer and I will study it. thank you
Are you talking about etching by (a) unenhanced chemical reaction or (b) with plasma, e.g. in an ICP setup?
Case (a):
Your argumentation is kind of correct, but usually people use enthalpies or Gibbs free energies of entire moieties for such discussions which is also the kind of data you find in thermochemical databases. Using bond energy increments also leads to correct trends, but the overall sum may result to be different because those binding energy increments that you find are more sort of "mean values" and not globally accurate. When you etch Ni with CO as it's done in the Mond process, you won't end up with a proper result. So, preferably use Gibbs free energies for discussion.
Case (b):
If there is a plasma involved, eventually you will etch everything if it's just harsh enough. In an Ar plasma, you will etch despite the fact that no "chemical product" is formed that would include the Ar. Of course, in this case sputtered byproducts become very important since these are usually deposited on the chamber wall and are not pumped away with the gas flow.