Method for trench etching

Abstract

The invention relates to a method for trench etching, in particular a method for anisotropic deep trench (DT) etching in an Si substrate by plasma dry etching, such as reactive ion etching (RIE), magnetically enhanced RIE or inductively coupled plasma etching (ICP), and sidewall passivation of the etched trenches in the Si substrate, the Si substrate being provided with an etching mask before the beginning of the etching operation. The invention is intended to provide a method for depth etching which, with a low outlay, makes it possible to achieve a significantly larger etching depth at higher speed and which enables a further reduction of the structure widths without any difficulty. This is achieved by virtue of the fact that a DT etching step into the Si substrate (2) as far as a predetermined etching depth is performed, in that the redeposit (4) produced during the DT etching step is replaced by a protective layer for the sidewall passivation, and in that the sequence of these steps is repeated until the envisaged target depth of the trench (3) is reached, a break-through (6) being etched through the protective layer at the bottom of the trench (3) before each further DT etching step.

Dependencies are inferred from the claim text.