P. Böttger 16 November 2017 SEMICON Europa Munich, Germany Ion Beam Etching Technologies for Sensor Manufacturing
P. Böttger16 November 2017
SEMICON EuropaMunich, Germany
Ion Beam Etching Technologies for Sensor Manufacturing
2Ion Beam Etching Technologies for Sensor Manufacturing
Provide vacuum processing equipment for MEMS/sensor and optics industry
Coating
Etching/structuring
Special/customised equipment
Founded in 2013
Located in Chemnitz
(300 km north of Munich)
Private company with 50.1 % shares
of VON ARDENNE GmbH, Dresden
Ca. 100 employees
20 … 30 Mio. EUR annual revenue
scia Systems Company
Aerial photograph of Technologie Centrum Chemnitz (TCC)
3Ion Beam Etching Technologies for Sensor Manufacturing
Technological Background
Principles of ion beam etching
4Ion Beam Etching Technologies for Sensor Manufacturing
Ion Beam Etching Principles
Atoms of target material can be ejected by bombardment of high-energy ions
Momentum exchange between incident ions and atoms of the target material in
collision cascades
Material removal with Angstrom accuracy (Ion Beam Etching)
Implantation of ions (Ion Implantation)
Any material with a sufficient high melting point can be etched
Low process pressure (10-4 mbar) and temperature (< 100 °C)
Process with resolution
on atomic scale
5Ion Beam Etching Technologies for Sensor Manufacturing
Basic components of ion beam milling arrangement
Ion Beam Milling Principles
Generation of ion beam by broad
beam ion source
Ionization of process gas by electric
discharge (RF or DC)
Multi aperture extraction grid systems
for ion extraction and beam shape
formation
Separate electron neutralizer for ion
charge neutralization
High vacuum conditions for sufficient
ion mean free path larger than
substrate distance
Substrate sage for positioning and
cooling of substrate
6Ion Beam Etching Technologies for Sensor Manufacturing
scia Mill 150
Ion beam milling for
wafers up to 150 mm or
irregular samples
Flexible tool for R&D and
small scale production
Ion Beam Etching Equipment
scia Mill 200
Ion beam milling for
wafers up to 200 mm
Production tool meeting
industry standards,
cluster compatible
scia Coat 200
Upgrade to dual ion
beam deposition for
wafers up to 200 mm or
irregular samples
R&D or production layout
in cluster configuration
> 15 ion beam etching chambers shipped or in order backlog since 2014
7Ion Beam Etching Technologies for Sensor Manufacturing
scia Mill 200 - Process Arrangement
Substrate Holder
200 mm
Ion Beam Source
RF350-e
Argon
50 … 600 eV
800 mA
8Ion Beam Etching Technologies for Sensor Manufacturing
scia Coat 200 - Process Arrangement
Substrate Holder
200 mm
Assist Ion Source
RF350-e
Argon, Oxygen
50 … 600 eV
800 mA
Sputter
Ion Source
RF120-e
Argon
600 … 1800 eV
400 mA
Target Drum
4 or 6 Materials
9Ion Beam Etching Technologies for Sensor Manufacturing
Application
Structuring of Spintronic Sensors
10Ion Beam Etching Technologies for Sensor Manufacturing
Principle of MTJ-based Sensors
Use of electron‘s spin-degree in magnetic sensors
based on magnetic tunnel junctions (MTJ)
Thin non-magnetic, insulating tunnel barrier layer
sandwiched in between two ferromagnetic (FM) layers
Upper FM layer’s magnetization easily changeable by
applying an external magnetic field (free FM layer)
Lower FM layer‘s magnetization pinned by antiferro-
magnetic (AFM) layer below (pinned FM layer)
Relative magnetic orientation of both FM layers
defines electric resistivity of tunnel barrier layer
Magnitude of tunnel magnetoresistance (TMR)
expressed by ratio:
Schematic of a magnetic tunnel
junction (MTJ)
Low TMR High TMR
P
PAP
R
RR
R
R
RAP and RP are the respective resistances for the antiparallel (AP) and parallel (P) magnetic states
11Ion Beam Etching Technologies for Sensor Manufacturing
Deposition of Sensor Layer Stack
Layers of magnetic stack are deposited by
magnetron sputtering
Silicon substrate with silicon oxide on top
Ta (5 nm) / Ru (30 nm) / Ta (10 nm) /
Ru (10 nm) / MnIr (20 nm) / CoFe (3 nm) /
Ru (0.8 nm) / CoFeB (3 nm) /
MgO (1.7 nm) / CoFeB (3 nm) / Ta (5 nm) /
Ru (5 nm)
Annealing at 360 °C for 60 min in an external
field of ~ 5500 Oe, to induce pinning and
crystallize the MgO layer
Patterned by masks made of positive
photoresist for formation of upper contacts
Layer stack with hard mask
High resolution TEM cross section of a standard MTJ
12Ion Beam Etching Technologies for Sensor Manufacturing
Sensor Structuring using Ion Beam Etching
Removing of unmasked material by ion beam etching with argon as process gas
In situ deposition of insulating encapsulation using DIBD
Process controlled by Secondary Ion Mass Spectrometer (SIMS), to detect layer boundaries and determine angle change points and etch stops
SIMS is sensitive to layer thick-nesses in the single-digit nm range
Stack was etched at 30° down to the 10 nm Ta layer, all materials were detected by the SIMS
Creation of MTJs by ion beam etching
SIMS signal for different materials in layer stack
13Ion Beam Etching Technologies for Sensor Manufacturing
TMR Evaluation
TMR plotted versus the applied magnetic field
TMR value reaches 140 %
High value indicates lack of critical sidewall deposition
TMR versus applied magnetic field
Selecting a high enough field range, enables to switch the exchange biased
pinned layer and the free layer (left)
In a reduced field range, only the pinned layer changes its magnetization
(right)
14Ion Beam Etching Technologies for Sensor Manufacturing
Summary
Ion beam etching most suitable for structuring of multi-layered sensor stacks
Exact process control with SIMS down to single nm range
Prevention of side wall redeposition during etching by use of angled ion beam
incidence
In situ deposition of adhesion, intermediate or capping layers possible using
dual ion beam deposition process arrangement
scia Systems GmbH
Annaberger Straße 240
09125 Chemnitz
Germany
Phone: +49 371 5347-780
Fax: +49 371 5347-781
www.scia-systems.com
Chemnitz
Dresden
Thank you for your attention!