Patent ID: 6429073
Filing Date: 2002-08-06
Classification: H01L,Y10S

Abstract:
A method for manufacturing a semiconductor device comprising a memory region, first, second and third transistor regions including field effect transistors that operate at different voltage level, whereinthe memory region includes a split-gate non-volatile memory transistor, the first transistor region includes a first voltage-type transistor that operates at a first voltage level, the second transistor region includes a second voltage-type transistor that operates at a second voltage level, and the third transistor region includes a third voltage-type transistor that operates at a third voltage level, the method for manufacturing the semiconductor device comprising the steps of: (a) forming a gate insulation layer and a floating gate that compose a portion of the non-volatile memory transistor on a silicon substrate in the memory region; (b) forming a first silicon oxide layer on the silicon substrate by a thermal oxidation method, and a second silicon oxide layer by a CVD method; (c) forming a mask layer defining an opening in the first transistor region, and removing the first and the second silicon oxide layers in the first transistor region; (d) forming a silicon oxide layer on the wafer by a thermal oxidation method for gate insulation layers of at least the first voltage-type transistor and the second voltage-type transistor; (e) forming a conductive layer and thereafter conducting a patterning to form an intermediate insulation layer and a control gate of the non-volatile memory transistor and a gate insulation layer and a gate electrode for each of the transistors in the transistor regions; and (f) forming an impurity diffusion region that forms a source or a drain by doping an N-type impurity or a P-type impurity in a predetermined region of the silicon substrate, wherein the silicon oxide layer formed in the step (d) forms at least part of a gate insulation layer of the first voltage-type transistor and a gate insulation layer of the second voltage-type transistor.