| 摘要 |
PURPOSE: A formation method of double deep trenches of semiconductor devices is provided to prevent residues of a photoresist by previously etching to a step difference extent between a substrate and a B/L(Buried Layer). CONSTITUTION: After forming a number of n+ B/Ls(22) by heavily implanting doped dopants on a p-type substrate(21), an n-type epitaxial layer(23), an oxide(24), a nitride(25), and a masking oxide(26) are sequentially formed on the resultant structure. Then, first and second trench regions(A,B) are defined by selectively etching the masking oxide(26), the nitride(25), and the oxide(24) using a photoresist pattern as a mask. Only the second trench region(B) is etched to the step difference extent between the substrate(21) and the B/L(22) as a first trench etching. Then, first and second trench regions(A,B) are entirely etched to the thickness extent between the B/L(22) and the substrate(21) as a second trench etching, so that the surfaces of the B/Ls(22) are exposed in the first trench regions(A) and the surface of the substrate(21) is exposed in the second trench region(B) without residues of a photoresist.
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