NONVOLATILE SEMICONDUCTOR MEMORY DEVICE AND FABRICATION METHOD THEREOF

摘要

PURPOSE: A nonvolatile semiconductor memory device and a fabrication method thereof are provided to decrease cell size and simplify fabrication process. CONSTITUTION: A memory device comprises a cell transistor having a memory transistor(101), a select transistor(102a), and a periphery transistor(102b). A field oxide layer(104) is formed on a semiconductor substrate(100) to define an active region and an inactive region. The field oxide layer(104) includes an isolated active region(T4) having a tunnel oxide layer(107). A floating gate(108) is formed on the tunnel oxide layer(107), overlapped with the field oxide layer(104). An insulating layer(109) covers the floating gate(108) and a sense gate(111a) is then formed on the insulating layer. A source(112a) and a drain(112b) of the memory transistor(101) are formed apart from both sides of the isolated active region(T4). A doped region(106) is formed below the isolated active region(T4) and the drain(112b). The select transistor(102a) includes a gate oxide layer(110a) formed on the substrate(100) and a select gate(111b) formed on the gate oxide layer(110a). A source(112b) and a drain(112c) of the select transistor(102a) are formed at both sides of the select gate(111b). The source(112b) of the select transistor(102a) and the drain(112b) of the memory transistor(101) have common region. The periphery transistor(102b) includes a gate oxide layer(110b) on the substrate(100) and a periphery gate(111c) on the gate oxide layer(110b). A source(112d) and a drain(112e) are formed at both sides of the periphery gate(111c).