A novel solution is presented for dielectric and silicon etching when using FIB for circuit edit. In contrast to commonly used XeF2, the new solution has a significantly higher activation threshold that allows it to be used for etching new sensitive low-k dielectrics and even thin silicon without the risk of damaging these materials spontaneously. Examples of operations presented are: etching through ultra low-k dielectrics on a front side device, exposure of a conductor through shallow trench isolation (STI), and trimming active silicon when performing circuit edit on a back side device. The advantages in comparison to XeF2 applications are discussed.