Process for improving the thickness uniformity of a thin layer in semiconductor wafer fabrication

• Main Authors: SCHREMS MARTIN, TEWS HELMUT HORST
• Format: Patent
• Language: English
• Published: 22.05.2001
• Edition: 7
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; SEMICONDUCTOR DEVICES

A two-step progressive thermal oxidation process is provided to improve the thickness uniformity of a thin oxide layer in semiconductor wafer fabrication. A semiconductor wafer, e.g., of silicon, with a surface subject to formation of an oxide layer thereon but which is substantially oxide layer-free, is loaded, e.g., at room temperature, into an oxidation furnace maintained at a low loading temperature, e.g., of 400-600° C., and the wafer temperature is adjusted to a low oxidizing temperature, e.g., of 400-600° C., all while the wafer is under an inert, e.g., nitrogen, atmosphere. The wafer is then subjected to initial oxidation, e.g., in dry oxygen, at the low oxidizing temperature to form a uniform initial thickness oxide, e.g., silicon dioxide, layer, e.g., of up to 10 angstroms, on the surface, after which the furnace temperature is increased to a high oxidizing temperature, e.g., of 700-1200° C., while the wafer is under an inert atmosphere. The wafer is next subjected to final oxidation, e.g., in oxygen and/or water vapor, at the high oxidizing temperature to increase uniformly the oxide layer to a selective final thickness, e.g., of 20-100 angstroms, whereupon the resultant uniform final thickness oxide layer-containing wafer is recovered from the furnace.