FURNACE SYSTEM AND METHOD FOR SELECTIVELY OXIDIZING SIDEWALL SURFACE OF GATE CONDUCTOR BY OXIDIZING SILICON SIDEWALL IN LIEU OF REFRACTORY METAL SIDEWALL

摘要

PROBLEM TO BE SOLVED: To provide an improved furnace system and a method for substantially minimizing ambient air from entering a heated chamber of the furnace system during a critical processing step.;SOLUTION: The furnace system can be used in, for example, an oxidation step where ambient air containing oxygen is prevented from entering an atmospheric pressure tube by essentially purging potential leak areas with an inert gas, such as nitrogen, at the critical moment during temperature ramp up and ramp down, and prior to temperature stabilization and the introduction of an oxidizing gas. If oxygen is not present within the tube, then a tungsten sidewall surface of a gate conductor, for example, will not inadvertently oxidize at the critical pre- and post-oxidation moments. However, if steam is present where hydrogen is available with oxygen, the underlying polysilicon sidewall surface will selectively oxidize instead of the overlying tungsten. The inert gas-filled containers are retrofitted to potential leak areas of not only the tube, but also a torch that is used to forward heated gas into the tube.;COPYRIGHT: (C)2005,JPO&NCIPI