Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Etching of SiO(2) in Presence of Light

IP.com Disclosure Number: IPCOM000080454D
Original Publication Date: 1973-Dec-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Verkuil, RL: AUTHOR

Abstract

This technique prevents the formation of undesired insulating film on the surface of N+ diffused regions during etching.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 100% of the total text.

Page 1 of 1

Etching of SiO(2) in Presence of Light

This technique prevents the formation of undesired insulating film on the surface of N+ diffused regions during etching.

During contact opening etching prior to metallization, it was noted that an unwanted insulating film is formed on the exposed N+ contact regions when exposed to the HF solution. This film increases contact resistance and is undesirable.

The reaction which forms the unwanted film can be suppressed by the junction photocell potential, on the order of several hundred millivolts, of the N+ diffusion-P- substrate junction by shining a light on the front of the wafer during contact etching. Pre-aluminum sinter contact resistance is lowered from 300 ohms to six ohms through the use of this technique.

Reasonably strong light is required. A normal household flashlight is adequate.

The same technique is useful for preventing the unwanted formation of film on N+ subcollectors. The light is applied to the wafer during removal of the SiO(2) mask used to form the subcollector regions.

1