Plasma Technology  

Raman spectra after etching of
an 18nm thick MoS2 layer
17, 20 and 23 cycles

No defect induced peak at 227cm-1

Small shift in peaks per 3 ALE cycles

40 ALE cycles removed all material (starting thickness 18 nm)

(OPT Application lab)


ALE/ ICP schematic


ALE processes use self limiting process steps:
-exposing the surface with a very small
  controlled Cl2 dose
-removing only the top part from the surface
  by low energy ion bombardment

rate: 2 - 6 A/ cycle, at 6 sec cycle time
selectivity to SiO2 > 3 : 1

Advantages of ALE over conventional dry etching
- excellent depth control for nanoscale etching
- better selectivity to other layers
- very smooth surfaces
- excellent uniformity
- no or less ARDE effect (RIE lag)
- very low crystal damage

Atomic Layer etching of 2d MoS2

PlasmaPro 100


The OPT ALE systems include:

Very fast PLC: control time starting at 10 msec
with 1 msec steps
No delay between process steps
process step times reproducible to 1 msec

Dose control with very fast ALD valves

High precision ion energy control in the ALE range
Power damping (auto switch)
ALE requires low, well-controlled DC bias
and the RIE power typically <10W.
The ALE kit includes a low power mode.

helical ICP source
with electrostatic shield

system "fingerprinting" by optical emission (Option)





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