| 摘要 |
PURPOSE:To enable a high-resistance section to have a selectively decreased thickness, by forming polysilicon on a semiconductor substrate, doping regions thereof destined for low- resistance sections with an impurity, covering the polysilicon with non-oxidizing mask layers except a region destined for the high-resistance section, then oxidizing the region destined for the high-resistance section to a predetermined depth and finally removing the oxide film and the mask layers. CONSTITUTION:A region of a polysilicon layer 13 destined for a high-resistance section 13a is oxidized to a predetermined depth. The oxide film 17 is then removed, whereby the thickness of the high-resistance section 13a is decreased. During said oxidation, regions of the polysilicon 13 destined for low-resistance sections 13b are not oxidized since they are covered with non-oxidizing mask layers 15 and 16. Accordingly, their thickness can be maintained at a predetermined level. On the other hand, the high-resistance section 13a is allowed to have a higher resistance value by decreasing its thickness. As a result, even if the high-resistance section 13a has a length as small as 4 mum or less, decrease in resistance value caused by diffusion of impurities from the low-resistance section 13b to the high-resistance section 13a can be compensated and the resistance is maintained at a high level. When dimensions of the high-resistance section 13a are the same as those of conventional ones, a substantially higher resistance value can be obtained in comparison with the conventional ones.
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