| 摘要 |
PURPOSE: To eliminate a gate offset region on the side of a source and reduce on-resistance of a transistor by a method wherein a thin film region of a gate oxide film forming a heavily doped source and drain layer is self-alizningly formed for a gate electrode of a high breakdown strength MOS transistor. CONSTITUTION: A gate electrode 26B of a normal breakdown strength MOS transistor is formed on a thin gate oxide film 24 and a gate electrode 26A of a high breakdown strength MOS transistor is formed on a thick gate oxide film 22. With the use of these gate electrodes 26A, 26B as a mask, gate oxide films 24, 25 are dry-etched up to substantially 300Åor less. Thereafter,<31> P<+> ions are ion-implanted on one side of the gate electrode 26A, whereby a lightly doped drain layer 28 is formed. Next<75> As<+> ions are ion-implanted, whereby heavily doped source and drain layers 30, 31 of a normal breakdown strength MOS transistor and heavily doped source and drain layers 32, 33 of a high breakdown strength MOS transistor are formed.
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