NONVOLATILE SEMICONDUCTOR STORAGE DEVICE AND ITS MANUFACTURING METHOD

摘要

PROBLEM TO BE SOLVED: To provide a highly reliable nonvolatile semiconductor storage device by preventing change in configuration of a contact hole thereby suppressing bad contact, and its manufacturing method. SOLUTION: A memory cell transistor, a selecting transistor, and a peripheral transistor are formed on a semiconductor substrate 10, and then BPSG films 23 and 39 are made all over the surface. Contact holes 27 and 29 extending to the impurity diffusion layer 18 of the selecting transistor and the polycrystalline silicon film 15 of a select gate shunt part are made in the BPSG films 23 and 39. Then, the occurrence of abnormality of the form of contact holes caused by the reflow of the BPSG films 23 and 39 occurring at heat treatment is prevented by stopping these contact holes 27 and 29 with polycrystalline silicon films.