JPS5529179A - Semiconductor device - Google Patents

Abstract

PURPOSE: To reduce the leakage current of a device by employing a procedure that in forming an impurity ion injuction layer inside a semiconductor substrate by use of a selective mask, a surface layer which is knock-on by the mask and in which the impurity concentration increase is removed by etching.

CONSTITUTION: Impurity ions are injected into a Si substrate 1 by the use of a selective mask of SiO₂, and then a stained layer of SiC and the like formed on the surface of an injection layer 3 is removed with a mixed boil solution of NH₄OH, H₂O₂ and H₂O. Then, a knock-on layer 4 formed at the same time is removed, but this removal is effected by slight etching utilizing a mixed solution of HF and HNO₃ having a slow etching speed since the knock-on layer 4 is as thin as 100 to 300Å. In this way, the layer 4 is removed and at the same tine the thicknesses of masking layers 2 and 3 are slightly reduced. By so arranging, the leakage current of an element is markedly reduced in providing the element in the layer 3.

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