Browse Prior Art Database

METHOD OF REMOVING RIE SIDEWALL VEILS FOR GOLD INTERCONNECT

IP.com Disclosure Number: IPCOM000008174D
Original Publication Date: 1997-Jun-01
Included in the Prior Art Database: 2002-May-23
Document File: 1 page(s) / 59K

Publishing Venue

Motorola

Related People

Richard Burton: AUTHOR [+2]

Abstract

A gold interconnect layer serves as the mask during reactive ion etching (RIE) of a TiWN, refractory gate or diffusion barrier. Since gold has a very high sputter yield, gold is sputtered and redeposited during the RIE step, resulting in gold/polymer veils that form on the sidewalls of the gold metallization (see Figure 1). After subsequent standard wet cleans, residues am observed when the gold veils conglomerate and are m-deposited on the wafer surface. These gold residues are not removable with available cleaning processes.

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m MDLA Technical Developments

METHOD OF REMOVING RIE SIDEWALL VEILS FOR GOLD INTERCONNECT

by Richard Burton and Janet Hill Tinkler

BACKGROUND AND PROBLEM

  A gold interconnect layer serves as the mask during reactive ion etching (RIE) of a TiWN, refractory gate or diffusion barrier. Since gold has a very high sputter yield, gold is sputtered and redeposited during the RIE step, resulting in gold/polymer veils that form on the sidewalls of the gold metallization (see Figure 1). After subsequent standard wet cleans, residues am observed when the gold veils conglomerate and are m-deposited on the wafer surface. These gold residues are not removable with available cleaning processes.

SOLUTION

To prevent the gold residues from conglomerat- ing and re-depositing onto the wafer, a wet gold

GOLD VEILS

etch was found to remove the gold veils formed during the refractory RlE. The gold etch developed consists of potassium iodide and iodine diluted with water. After the RIE step, the wafers are etched in the dilute gold etch and thoroughly rinsed in DI water, resulting in residue free wafers.

  The critical part of this idea is to use a dilute gold etch solution to remove the gold veils resulting from the RIE process. The gold etch eliminates the gold veils while removing only minimal gold from the gold interconnect layer (<300 A removed from
2.5 pm of plated gold). The dilute gold etch does not degrade gold reflectivity and does not interfere with subsequent processing steps (i...