Specific Process Knowledge/Etch/RIE (Reactive Ion Etch)

Etching using the dry etch technique RIE (Reactive Ion Etch)

RIE1 (part of cluster1) - positioned in cleanroom2

RIE2 (part of cluster2)- positioned in cleanroom3

At Danchip we have three RIE's. Two (RIE1 and RIE2) for etching silicon based materials (silicon, silicon oxide, sillicon nitride) and one (III-V RIE) for etching III-V materials. The hardware of RIE1 and RIE2 is very similar but you cannot count on that identical recipes on RIE1 and RIE2 perform exactly the same. In addition to that the main difference between RIE1 and RIE2 is the cleanness of the two equipment. In rough terms RIE1 is the clean system and the RIE2 is the dirty system. This means that in RIE2 opposed to RIE1 it is allowed to have small amounts of metals exposed to the plasma. Look in the manuals for RIE1 and RIE2 to read the details for this difference (you can find the manuals in LabManager [1]).

Process information

• Etch of Silicon using RIE
• Etch of Silicon Oxide using RIE
• Etch of Silicon Nitride using RIE

A rough overview of the performance of the RIE´s and some process related parameters

Purpose	Dry etch of	Silicon Silicon oxide Silicon (oxy)nitride
Performance	Etch rates	Silicon: ~0.04-0.8 µm/min Silicon oxide:~0.02-0.15 µm/min Silicon (oxy)nitride:~0.02-? µm/min
	Anisotropy	Can vary from isotropic to anisotropic with vertical sidewalls and on to a physical etch were the sidewalls are angled but without etching under the mask.
Process parameter range	Process pressure	~20-200 mTorr
	Gas flows	SF$_{6}$: 0-130 sccm O$_{2}$: 0-100 sccm CHF$_{3}$: 0-100 sccm CF$_{4}$: 0-84 sccm H$_{2}$: ?sccm Ar: 0-145 sccm N$_{2}$: 0-100 sccm C$_{2}$F$_{6}$: 0-24 sccm
Substrates	Batch size	1 4" wafer per run 1 2" wafer per run Or several smaller pieces
	Substrate material allowed	Silicon wafers with layers of silicon oxide or silicon (oxy)nitride Quartz wafers
	Possible masking material	Photoresist/e-beam resist Silicon/PolySi Silicon oxide or silicon (oxy)nitride Aluminium Other metals if the coverage is <5% of the wafer area (ONLY RIE2!)