| 摘要 |
PURPOSE:To form a low density diffusion layer structure MOS transistor in a self-matching manner by a method wherein the drain consisting of a low density diffusion layer and a high density diffusion layer is formed simultaneously by implanting impurities using a gate and a dummy pattern as a mask. CONSTITUTION:After a gate oxide film 22 has been formed on a silicon substrate 21, poly silicon 23 is deposited thereon, and a gate 24 and a dummy pattern 26 are formed by performing an etching operation. Then, a layer 28 is formed by ion-implanting phosphorus, and a drain 210 consisting of a low density diffusion layer LDD 29 and a high density layer is formed by performing an annealing. As the impurities implanted from between the gate 24 and the dummy pattern 26 spreads over the lower part of the gate 24 and the dummy 26, the impurity density of the layer 28 is made lower than that of the region 210 whereon the drain consisting of the high density diffusion layer, and an LDD 29 can be formed.
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