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IMPROVEMENT OF THE ALUMINUM ETCH PROCESS, ON SUB-MICRON TECHNOLOGY, IN THE AME 8330 UTILIZING N2 AS A PASSIVATING GAS

IP.com Disclosure Number: IPCOM000009140D
Original Publication Date: 1999-Jun-01
Included in the Prior Art Database: 2002-Aug-09
Document File: 2 page(s) / 128K

Publishing Venue

Motorola

Related People

Robert J. Wilson: AUTHOR

Abstract

The transfer of a 0.5~ MMBiCMOS technology necessitated developing a Nitrogen passivation process on Applied 8330 Metal Etch systems in order to be able to etch sub-micron Aluminum lines. The resultant etched metal lines had to meet speci- fied criteria which were comparable to the results of those obtained from a process which utilized a Lam 9600 (variable gap) Metal Etch system.

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m MOTOROLA Technical Developments

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IMPROVEMENT OF THE ALUMINUM ETCH PROCESS, ON SUB-MICRON TECHNOLOGY, IN THE A,ME 8330

UTILIZING N2 AS A PASSIVATING G/k

by Robert J. Wilson

ABSTRACT

  The transfer of a 0.5~ MMBiCMOS technology necessitated developing a Nitrogen passivation process on Applied 8330 Metal Etch systems in order to be able to etch sub-micron Aluminum lines. The resultant etched metal lines had to meet speci- fied criteria which were comparable to the results of those obtained from a process which utilized a Lam 9600 (variable gap) Metal Etch system.

  The multilevel metalisation scheme, to be etched, consists of a low temperature planar oxide di-electric which is compatible with the Salicide (TiSi2) regions within the CMOS process. 'CMP' planarisation is then used to achieve planar oxide ILD layers between metals 1 & 2. The metal layers consist of Al/Cu (1%) with an underlying Ti/TiN layer and capped with a TiN ARC layer and are sub- micron in geometry.

INTRODUCTION

  In the production of integrated circuits, the etch- ing of aluminum interconnects is a critical step in the manufacturing process. New designs dictate the development of highly capable and cost effective aluminum etch processes. The process must pro- duce:

  In the case of metali,etch, this match, which included all of the above requirements, was success- ful except for the repeatability of the line profile which showed a degree of undercutting on the mate- rial etched on the Applied 8330's; more so from a repeatability perspective; i.e. sometimes the lines were good and at other times there was undercutting seen.

  From this issue, was born the idea of investigat- ing the use of nitrogen (N2) as a passivating gas, in order to reduce the degree of undercut and to devel- op a more manufacturable metal etch process for sub-micron lines.

AME 8330 PROCESS OVERVIEW (CHF3 CHEMISTRY) '

  The AME 8330 etch process, currently used for UDR-1 BiCMOS technology consists of five (5) steps:

Breakthrough
. BulkEtch

Over Etch

Passivation I

Passivation II

where:

  Step 1 (breakthrough) removes the native A1203 on the wafer surface as well as clearing the TiN ARC (anti-reflective coating) layer. It is a low pressure, high DC bias: step resulting in a very 'physical' etch.

l

l

l

l

l

high photoresist selectivity

satisfactory etchrates

low uniformity (o/o)

no corrosion

good line profiles

l

l

l

l

l

no metal shorts

  One of the aims of the transfer was for to 'match' processes, both physically and electrically, to within 5%.

' AppliedMaterialsRecisionEfch83WRocess Notea.Ch4 March 1991).

OMrMmla,loc. 1599 96 Jum? 1999

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0 M

MOTOROLA Technical Developments

  Step 2 (main etch) is a 'timed' etch that clears all aluminum from the surface of the wafer. There are primarily three (3) gases used during this step, namely:

  Chlorine (Cl*)-primary etchant of aluminum. Aluminum etchrate is primarily depend...