Hello, I'm developing a recipe for deep Si etch using a Cl2 based ICP process. After some time the surface of the exposed parts of the silicon wafer that I'm etching, becomes black. Has anyone had the same problem? I'm trying to avoid it but I can't since I don't know what it's due to. Before etching I make a short HF dip to clear off the native oxide and I use only Cl2 gas. The surface doesn't look very much rough, so it is not a black silicon type of thing. Thank you for the attention Best Regards Matteo