Anisotropic etching of silicon on the < 100 > and < 110 > crystal orientation planes.
Alkali based – for < 110 > crystal orientation – etches with vertical walls.
Ethylenediamine based – for < 100 > crystal orientation.
Preferential Silicon Etchants are preparations which have the greatest etch rate on a specific plane of orientation. These anisotropic etchants are used in lead beam technology to separate silicon chips and a technique to obtain electrical isolation within integrated circuit chips. The etching systems may also be used for chemical shaping of silicon and as etchants with photomask of Ag, Au, Ta, or SiO2 as these materials are not etched.
Two etching systems are offered: PSE-200 is alkali-based, is safe to use and has a fast etch rate. It is used to etch deep-wall patterns in silicon. PSE-300 is ethylenediamine-based and has a moderate etch rate. For faster etching, PSE-300F is available.
The etching process using PSE-300 is best carried out in a flask fitted with a reflux condenser. The flask should be heated gently so that the etchant is just at the boiling point. PSE-200 is commonly used with a thermally grown silica mask for etching mesas. It is employed at approximately the boiling point of the preparation. Oxides present on the silicon wafer may interfere with all etching; a preliminary dip in HF or buffered HF is desirable. Of the two etchants, PSE-300 is the safer product.
Pre-mixed and ready-to-use etchants containing electronic quality nitric-acid-HF-acid mixtures for silicon, germanium, gallium, arsenide and other semiconductor materials.
SPECIAL PROPRIETARY FORMULATIONS IN ANY RATIO CAN BE PROVIDED.