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

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

RIE1 (part of cluster1)

RIE2 (part of cluster2)

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 (is discussed under III-V processing). 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 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 PECVD thin films 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 pressure	~20-200 mTorr
.	Gas flows	SF$_{6}$: sccm O$_{2}$O: sccm CHF$_{3}$: sccm CF$_{4}$: sccm H$_{2}$: sccm C$_{2}$F$_{6}$: 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	Silicon/PolySi Silicon oxide or silicon (oxy)nitride Aluminium Other metals if the coverage is <5% of the wafer area (ONLY PECVD3!)
.	Material allowed on the substrate	Aluminium All metals < 5% of the substrate coverage (ONLY PECVD3!)