Preferential Silicon Etchants

Anisotropic etching of silicon on the < 100 > and < 110 > crystal orientation planes.

PREFERENTIAL SILICON ETCHANT – PSE-200

Alkali based – for < 110 > crystal orientation – etches with vertical walls.

PREFERENTIAL SILICON ETCHANT – PSE-300, PSE-300F

Ethylenediamine based – for < 100 > crystal orientation.

PREFERENTIAL SILICON ETCHANTS
DESCRIPTION

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.

PROPERTIES OF PREFERENTIAL SILICON ETCHANTS

PSE-200 PSE-300
Appearance Odorless, colorless liquid Clear liquid
Composition Alkali-based Ethylenediamine-based
Boiling Point > 100 °C 118 °C
Oper. Temp 75-100 °C 100 °C
Preferred Operation < 110 > direction < 100 > direction
Other Common Orientations
< 111 > Plane
—- < 110 > can be used
< 111 > negligible
Etch Rate 25 m/3 min. @ 100 °C 25 m /hr. < 100 >
Etch Rinse Water Water
Metallization


SiO2
Attacks Al; does not attack Au; mild attack on Ag
Will not attack–use as mask
No attack on Au, Ta; Attacks Al, Cu; mild attack on Ag
Negligible

APPLICATION

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.

Reagent Semiconductor Etchants

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 Silicon and Germanium Etchants

Product No: Etchant Room Temp Etch Rate:
RSE-100 Slow Silicon Etch 12-15Å/sec
RSE-200 Mesa Etch 100Å/sec
RSE-563 Germanium Etchant 250Å/sec
Standard Nitric-HF-Acid Etch
Product No: Etchant Ratio
RSE-101 10:1
RSE-41 4:1
RSE-31 3:1
RSE-12 1:2
Standard Nitric-HF-Acetic Etch
Product No: Etchant Ratio
RSE-533 5:3:3
RSE-511 5:1:1
RSE-111 1:1:1
RSE-322 3:2:2
RSE-1155 11:5:5
RSE-563 5:6:3

SPECIAL PROPRIETARY FORMULATIONS IN ANY RATIO CAN BE PROVIDED.