Browse Prior Art Database

Controlled Anisotropic Etching of Single Crystal Silicon

IP.com Disclosure Number: IPCOM000087658D
Original Publication Date: 1977-Feb-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Bassous, E: AUTHOR

Abstract

Many chemical compositions are known for the anisotropic etching of single crystal silicon. After prolonged etching most of these compositions tend to etch nonuniformly and uncontrollably. A particularly serious problem is the development of slow-etching multifaceted crystallite residues which occur on etched surfaces despite precautions to eliminate surface contaminants and maintain clean conditions.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 62% of the total text.

Page 1 of 1

Controlled Anisotropic Etching of Single Crystal Silicon

Many chemical compositions are known for the anisotropic etching of single crystal silicon. After prolonged etching most of these compositions tend to etch nonuniformly and uncontrollably. A particularly serious problem is the development of slow-etching multifaceted crystallite residues which occur on etched surfaces despite precautions to eliminate surface contaminants and maintain clean conditions.

A composition which gives consistently good results in etching silicon is as follows: pyrocatechol 4 gm. ethylenediamine 25 ml. water 8 ml.

The etching solution is heated in a flask fitted with a water-cooled reflux condenser and a magnetic stirrer. Etching is carried out at the boiling point 118 plus or minus 1 degree C with nitrogen gas bubbling through the stirred solution to prevent oxidation. Etching Procedure.

The following is a detailed sequence of steps which gives consistently satisfactory results on wafers which are processed by conventional photolithographic methods: 1. The wafers are cleaned to ensure that all photoresist residues are removed. 2. The wafers are placed in a quartz boat. 3. The loaded boat is dipped into buffered HF for 5 seconds. 4. The loaded boat is immersed in running DI water for 1 minute. 5. Without drying the wafers, the loaded boat is directly introduced into the boiling anisotropic etching solution.

Step 3 is extremely important and must always be carried out. Bare silicon i...