| 摘要 |
PURPOSE:To precisely control a gate length and an offset length in order to improve reproducibility of characteristics of a semiconductor device, by forming an undercut region by the use of a difference in etching speed of an insulating film on a poly Si film. CONSTITUTION:After a silicon oxidizing film 11 is removed, a silicon substrate 1 is coated with a p-type poly Si film 4 as a low resistivity layer and an NSG film 12 and a BSG film 13 as insulating layers, and an opening 15 of a photoresist 14 is formed by photo-lithography or the like. Next, while the photoresist 14 is used as a mask, the BSG film 13 and the NSG film 12 are etched. Because the NSG film 12 is made several times higher in its etching grade than the BSG film 13 and because the NSG film 12 is formed much thinner than the BSG film 13, an opening 16 can be easily formed by undercutting the NSG film 12 without almost changing the size of the opening 15.
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