Deep reactive ion etching

Abstract

In a method of performing an anisotropic etch on a substrate in an inductively coupled plasma etch chamber, at least three cycles of a procedure consisting essentially of the four following steps are performed: a. depositing a protective polymer on a patterned substrate; b. performing a first low pressure etch to partially remove the deposited protective polymer at a pressure less than 40 mTorr; c. performing a high pressure etch at a pressure between between 40 mT and 1000 mT to form a portion of a trench in the substrate; and d. performing a second low pressure etch at a pressure less than 40 MTorr to reduce surface roughness. This method permits the fabrication of deep trenches with reduced surface roughness.

Dependencies are inferred from the claim text.