JPS6466939A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To bury trenches flatly with an insulator, and to form an Si substrate with high accuracy by forming a plurality of the trenches being shaped onto the Si substrate to be treated and having a different size, coating the Si substrate coated with a low contrast pattern with a resist layer and flattening the Si substrate. CONSTITUTION:A wide recessed section 2 and narrow recessed sections 3 isolating elements by a trench process are shaped onto an Si substrate 1, and an SiO2 layer 4 is formed through CVD using SiH4 and O2 as a reaction gas. The recesses 9 and the flat recessed section 5 are buried with a resist by employing a photoetching technique on the SiO2 layer 4, but low contrast patterns 10 are shaped by displacing a focus and exposing the layer 4 by weak light at that time. The substrate is set to a plasma etching device, and plasma etching is performed, using the mixed gas of CHF3 and O2 as an etchant. The Si substrate 1, the trenches of which are buried flatly with the SiO2 layer 4, is acquired.