Gas-phase etching with ClF3 gas at atmospheric pressure and at room temperature – anisotropic etching

We find that single crystal Si (c-Si) is etched anisotropically in the gas phase with ClF3 gas at atmospheric pressure and at room temperature (RT). The etching of Si with ClF3 gas at low temperatures results in congested steps for Si(100) surface and pyramidal pits for Si(111) surface, which means that the etch proceeds anisotropically. On the other hand, the etch of Si with ClF3 gas at high temperatures results in macroscopic-roughening on the Si surface, which means that etching proceeds isotropically. The formation of anisotropic etch pits will be a very promising technology for c-Si solar cells, which is used to reduce the surface reflectance.