Process for forming an integrated circuit comprising non-volatile memory cells and side transistors of at least two different types, and corresponding IC

摘要

A process for forming an integrated circuit calls for the provision of at least one matrix of non-volatile memory cells (1) including an intermediate dielectric multilayer comprising a lower silicon oxide layer (7), an intermediate silicon nitride layer (8) and an upper silicon oxide layer (10) and the simultaneous provision in zones peripheral to the memory cells of at least one first (2) and one second (3) transistor type having gate dielectric of a first and a second thickness respectively. After formation of the floating gate of the cells with a gate oxide layer (5) and a polycrystalline silicon layer (6) and the formation of the lower silicon oxide layer (7) and of the intermediate silicon nitride layer (8), the process in accordance with the present invention includes: removal of said layers from the zones peripheral (R2,R3) to the matrix; formation of a first silicon oxide layer (9) over the substrate in the areas (R2,R3) of both types of transistor (2,3); removal of the preceding layer (9) from areas (R3) assigned only to the transistors (3) of the second type; deposition of said upper silicon oxide layer (10) over the memory cells (1), over the first silicon oxide layer (9) in the areas (R2) of the transistors (2) of the first type and over the substrate (4) in the areas (R3) of the transistors of the second type; and formation of a second silicon oxide layer (11) in the areas (R2,R3) of both types of peripheral transistors (2,3).