| 摘要 |
PURPOSE:To readily form a double N-type layer structure by bonding tungsten to the top and side of a silicon layer by CVD not to bond the tungsten to a silicon oxide film but to bond it only to the silicon by only the simple method of CVD. CONSTITUTION:A silicon oxide film 2 and a polysilicon layer 3a are formed on a P-type silicon substrate 1. Phosphorus or arsenic ions are implanted 1X10<13>cm<-2> in a direction of an arrow to form an N<-> type region of low density region layer. Then, a tungsten 5 is deposited by CVD. Since the tungsten 5 deposited by CVD has good bondability with polysilicon but has wrong bondability with the film 2, the tungsten is formed to extend on a gate region from a polysilicon layer 3a at the top and the side of the layer 3a. Then, phosphorus or arsenic ions are implanted 3X10<15>cm<-2> to form an N<+> type region 6 of deeper high density impurity region than the region 4, and to form source and drain regions made of the regions 4, 6.
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