[labnetwork] Mixing Fluorine and Chlorine Chemistries

[James P McVittie]

Ron,

1. F in an etch chamber from previous etch runs can slow down a Cl2 etching process. This is of most concern to III-V users. So for a well-controlled Cl2 etch process you want to get all the F based polymers out of the chamber.

2. In Poly Si etching C2F6, CF4 or NF3 are often used to remove surface oxides before start the HBr / Cl2 Si etch.

3. " Small amounts of CF4 (5-10 sccm) are added to the standard BCl3/Cl2/N2 process for residue removal.  In some cases (particularly for copper residue), CF4 appears to widen the process window for residue control.CF4 typically helps to eliminate open field residue, but there have been cases where CF4 helped with dense area residue as well.  Since the addition of another gas introduces more variables to the process, the use ofCF4 should be minimized."  From old AMT Metal (Al)  Etch Process Manual

 In the Stanford Nanofabrication Facility (SNF) we have F containing gases in all our Cl2 etchers. Our Cl2 Si etchers have CF4 and C2F6. Our ICP metal etcher has CF4, and Our III-V etcher has SF6.


James (Jim) McVittie, Ph.D.

Senior Research Engineer

Electrical Engineering

Stanford University

336x Paul G. Allen Bldg

420 Via Palou Mall

Stanford, CA 94305

mcvittie at stanford.edu

650-725-3640


________________________________
From: labnetwork-bounces at mtl.mit.edu <labnetwork-bounces at mtl.mit.edu> on behalf of Reger, Ronald K <rreger at purdue.edu>
Sent: Thursday, November 8, 2018 10:45 AM
To: labnetwork at mtl.mit.edu
Subject: [labnetwork] Mixing Fluorine and Chlorine Chemistries


Dear Colleagues,



Here at the Birck Nanotechnology Center we have a Panasonic E620 RIE ICP etcher that uses a variety of gases for etching of various materials.  It has capability to do both chlorine-based and fluorine-based processes.  This has given us a lot of versatility for a wide variety of materials.  We’re now exploring the implications of using both chemistries in the same etcher, particularly when it comes to making electron devices.



We had done a small survey of a few other facilities and are finding a mixed response….. some facilities use dedicated etchers to keep these chemistries separated while others have both gases in the same etcher and use one type of recipe or the other.  Particularly for electron devices are there cross-contamination issues/models with using both gases in the same chamber?  What would be the failure physics/mechanisms from this?  If both chemistries are used in the same system are there standard protocols between switching etch chemistries that we need to follow?



Any advice would be greatly appreciated as we’re getting into more electron device processing!



Thanks,
Ron





Ron Reger

Engineering Manager

Birck Nanotechnology Center | Room 2289 |

Office:  765.494.6667 | Email: rreger at purdue.edu<mailto:rreger at purdue.edu>

Wiki:  https://wiki.itap.purdue.edu/display/BNCWiki

iLabs:  https://purdue.ilabsolutions.com/homepage/

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