ATOMIC LAYER DEPOSITION BENEQ TFS200 (ALD 2) ‒ Center of MicroNanoTechnology CMi ‐ EPFL

To be read first:

This tool is NOT MICRO-ELECTRONIC compatible tool
- Organic layers (Photoresist, Kapton, polyimide etc …) allowed
- Gold and copper allowed

BUT NO GLUE or QUICKSTICK

RESERVATIONS RULES AND BILLING POLICY :

Booking : No restriction
Reservation names must be correspond to operators
Billing : Processing time + pulse number
No penalty fees in case of user’s no show
Below 200°C : Booking before 1 am
Below 300°C : Booking after 1 am
Long time deposition : Night job

I. Equipment description

The tool Beneq TFS200 is an ALD (Atomic Layer Deposition) system dedicated to the deposition of thin dielectric or metallic layers on wafers from 100 mm up to 200 mm as well as on piece of wafers. This second ALD system has also the capability to deposit dielectric layers on powder larger than 100 nm thanks to a Fluidized Bed Reactor (FBR).

The Atomic Layer Deposition (ALD) technique is recommended for thin layers (30 nm or lower) and/or for layers requesting a high level of conformality. The deposition is done under vacuum (between 7 to 12 mbar) by pulsing alternatively 2 chemically activ precursors.

The equipment is composed of :

a chamber with inside :
- a reactor for wafer (Temperature : 450°C Max)
- or a reactor for powder (Temperature : 350°C Max)
a load lock system
4 liquid sources and 3 hot sources
5 gas lines (O₂, O₃, N₂ and NH₃ and purge with N₂)
an ozone generator
a plasma generator
a primary pump

The equipment is driven by a software interface but some manual operations are requested for each deposition:

Chamber and/or precursors heat up
Loading and unloading the samples
Opening of the liquid precursors at the beginning of the process
Closing of the liquid precursor at the end of the process

II. Deposition mechanism

The mechanism of deposition for the Atomic Layer Deposition (ALD) is composed of 4 steps as described below whatever the reactor:

The first precursor (precursor 1) is pulsed into the reactor and reacts at the surface of the sample by chemisorption to form a monolayer.
The reaction chamber is purged with inert gas (N₂) and the excess of precursor 1 is removed.
The second precursor (precursor 2) is pulsed into the reactor and reacts with the precursor 1 already present at the surface of the sample. The reaction generates the desired monolayer and a byproduct.

The byproduct and the excess of precursor are then purged from the reactor with inert gas (N₂) (step 4).

The 4 steps represent the elementary loop which is repeated until we get the requested thickness of the layer. An illustration of these 4 steps is done with the deposition of Al₂O₃ from the Tri-Methyl Aluminum (TMA) and water (H₂O).

III. Layers available at CMi

On the ALD II system, we have 2 categories of layers available :

Layers for wafers
Layers for powders

Layers for wafers

For TiO₂ layer, the layer’s phase changes at around 200°C. Below 200°C, the layer has a low roughness. Above 200°C, the layer is very rough.

“Under development” recipes means that the pulsing sequence is not fixed and can be changed as well as the pressures and the temperatures. The recipes are available for CMi users but are not optimized. The up to date process conditions are summarized in the table below:

For Ni deposition, the cycle time is very long and to have the lowest resistivity an annealing time of 120 min at 300°C is included in the recipe. For these reasons, the Ni deposition has to be run in night job only. It takes one hour to heat up the NiCp₂ hot source for Ni and NiO_x deposition.

Layers for powders

Layer

Precursor

Chamber temperature

(°C)

Deposition rate

(A/cy)

Al₂O₃

TMAl – RT

H₂O

200

TiO₂