| 摘要 |
PURPOSE:To miniaturize a PROM by forming a floating gate and a control gate on a semiconductor substrate via an insulating film without overlapping with a source and drain and by preventing the floating gate from overlapping with a field insulating film. CONSTITUTION:Into thermally-oxidized film 23 on p-type Si substrate 21, B ions are injected through the mask of low-density doped poly-Si24 and Si3N425. Through a heat treatment, field oxidized film 22 and p<+> layer 33 are formed by self-matching with floating gate 24. Next, the 2nd poly-Si layer 26 is deposited and photoetched to remove layers 26 to 23 by the same mask, so that control gate 26 and floating gate 24 will be formed by self-matching. Next, phosphorus is diffused to provide n-type source and drain layers 30 and 29, which are covered with a PSG as usual and provided with a window, and Al wiring 28 is made. In this way, a n-type MOS type miniature PROM can be formed easily with good reproducibility. |
