Method and apparatus incorporating nitrogen selectively for differential oxide growth

摘要

A method for forming an oxide on the surface of a semiconductor substrate. The method includes the steps of: placing the semiconductor substrate in an atmosphere containing an atmosphere of an oxide growth inhibiting compound; applying laser energy to at least a first portion of the substrate; and forming the oxide on the surface of the substrate by heating the substrate. In a further aspect of the invention, the method comprises applying laser energy through a patterned, reflective reticle. Alternatively, prior to the step of placing, a reflective mask layer may be applied to the surface of the semiconductor substrate. In addition, the invention comprises an EEPROM memory cell having a program junction region in a semiconductor substrate. The cell comprises at least a first program junction provided in the silicon substrate and a floating gate having a portion positioned over the program junction. In addition, an oxide layer is positioned between the program junction and the floating gate, the gate oxide formed by a single thermal oxidation step to have at least a first oxide thickness and a second oxide thickness due to gas immersion laser doped nitrogen underlying a region of the oxide having said at least first oxide thickness.