| 摘要 |
PURPOSE: To prevent the latch-up phenomenon by adjusting the anisotropic etching time of a silicon oxide layer to desired position and width of insulation isolated trenches along the dish-like region end edges and adjusting the isotropic etching time for desired depth thereof. CONSTITUTION: After masking a double layer of silicon nitride 3/oxide layer 2 on the surface of an Si substrate 1 with a mask 6, it is implanted with P-ions. The isotropic undercut etching 7 of the SiO2 layer 2 determines the position of insulation isolated trenches 13 along the edges of p-type dish-like regions 12. The width of the trench 13 is adjustable over the etching time. After removing the mask 6, it is thermally oxidized to form a second silicon oxide layer 8. Using a second silicon nitride layer 9 and nitride layer 3 formed thereon as a mask, a third silicon oxide layer 10 is formed. After removing the nitride layers 3, 9, it is implanted with B-ions 11 to form p-type dish-like regions 12. After removing the oxide layer 8, the trench etching is executed by anisotropic etching.
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