 This study examined an isotropic etching process for silicon dioxide selective to silicon nitride using a NF3H2 methanol chemistry. The process involved forming hydrogen fluoride HF radicals with a remote plasma of NF3 and H2 followed by injection of methanol to remove the F radicals and prevent spontaneous etching of silicon based materials. This resulted in the formation of etch products on the surface of silicon dioxide which could then be removed by heating. The process was optimized to achieve high etch selectivity between silicon dioxide and silicon nitride resulting in etch rates of 13 nanometers per cycle and etch selectivities of greater than 50 and 20 for silicon dioxide and polysilicon respectively. This article was offered by Hong Songil, Dusan Kim, Yun Jong Jang and others.