| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor memory device for preventing degradation of a cell current by elevation of resistance because of decrease of impurity concentration of a diffusion layer or a semiconductor layer. SOLUTION: A plurality of cell gates 2 are formed at intervals on a principal surface of an n-type silicon substrate 1, and n-type diffusion layers 7 are formed in the principal surface of the silicon substrate 1 between the cell gates 2. Inter-cell insulating films 9 comprising a gate insulating film 3 and a buried insulating film 8 are provided at each part between the cell gates 2, and carbon accumulation regions 10 containing carbon elements are provided in the inter-cell insulating films 9. The maximum of carbon element concentration in the carbon accumulation region 10 is provided in a region of 2 nm from an interface between the n-type diffusion layer 7 and the inter-cell insulating film 9. The carbon element is bonded to Si to be positive fixed charge, and the positive charge increases carrier concentration of the n-type diffusion layer 7, thereby the cell current is increased without varying a threshold of a transistor. COPYRIGHT: (C)2009,JPO&INPIT
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