Direct measurement of the etching rates on Si(111) and silicon dioxide surfaces in 40% ammonium fluoride aqueous solution via atomic force microscopy

The etching process on micropatterned Si (111) and silicon dioxide surfaces in 40% ammonium fluoride aqueous solution has been studied with atomic force microscopy. The etching rates of silicon and silicon dioxide are obtained from air-saturated and oxygen-free solutions. From the measurements at different temperatures (20-40 degreesC), the apparent activation energies are deduced. It is found that the etching rates are substantially different in silicon and silicon dioxide and that the dissolved oxygen in the solution facilitates the etching of silicon but obstructs it for silicon dioxide. It is also demonstrated that the thickness of the silicon dioxide film on the silicon substrate can be determined accurately from the jump of the etching rate at the SiO(2)/Si interface. (C) 2003 American Institute of Physics.Physics, AppliedSCI(E)EI12ARTICLE74315-43209