PillarHall® Test Chip is a special substrate for thin film deposition and related processes. The PillarHall® Test Chip consists of microscopic Lateral High-Aspect-Ratio (LHAR) test structures that offer an easy, fast and accurate way to characterize thin film processes in three dimensional substrate. PillarHall® approach is especially suitable for thin film conformality characterization by deposition methods such as ALD (Atomic Layer Deposition) and Chemical Vapor Deposition (CVD). PillarHall® Test Chips are useful for thin film R&D as well as their manufacturing process control and monitoring.
The core of the PillarHall® LHAR structures is the existence of a wide area lateral air gap under the thin silicon membrane with controlled 500 nm gap height. The name PillarHall comes from the microscopic silicon pillars that stabilize the thin silicon membrane roof. This lateral 3D approach is the core invention and benefit of the PillarHall® technology. The controlled lateral high aspect ratio structures enable fast analysis of thin film conformality without cross-sectioning and tedious sample preparation.
PillarHall® LHAR Test Chips are designed, developed and fabricated in VTT Technical Research Centre of Finland. The PillarHall® MEMS processes and manufacturing is carried out in Micronova Micro- and Nanomanufacturing Centre of VTT in Espoo, Finland.
More: http://www.pillarhall.com/
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PillarHall Test Chip introduction update 2018
1. Lateral High Aspect Ratio (LHAR) Test
Structures for Thin Film Conformality
Measurements
2. 27/06/2018 2
Why conformal thin films are important?
Moore’s law – vertical scaling trend
Core value proposition of ALD: conformal thin films
New opportunities in manufacturing and material
science
MSW 13.-15.5.2018 Espoo, Finland
3D NAND
Source: Applied Materials post
3D NAND
FinFETs
Mayer et al. APL 82 (2003) 2883.
3. 27/06/2018 3
Conformal film covers complex 3-D structures
uniformly with the same thickness and properties
Conformal film,
schematic example:
a. Optimized ALD
Same film top (1), sidewall (2),
bottom (3), deep within (4)
Partly conformal & non-conformal films,
schematic examples
b. Partly conformal, typical for CVD
c. Noncormal with overhang,
from line-of-sight deposition
d. ”Superconformal”, i.e., preferential
filling inside the 3-D feature
(a)
(c) (d)(b)
(Side view)
1.
2.
3.4.
4. 27/06/2018 4
Traditional way of measuring conformality:
Cross-sections of vertical trenches in silicon
• Measurement takes time & effort, accuracy operator-dependent
• Point-per-point analysis, wafer mapping quasi-impossible
Vertical HAR procedure:
Measure thickness
1. Top
2. Sidewall
3. Bottom
Calculate conformality:
• Bottom/top xx%
• Sidewall/top yy%
Aspect ratio
(height/width,
not in scale)
max ~50:1
1.
2.
3.
If thinner in trench
conformality <100%
5. 27/06/2018 5
Why chacterization of vertical microstructures is a
PROBLEM ?
Analysis needs cross-sectioning.
• Sample preparation (FIB) + special
analytical tools (HR-TEM) can take
weeks and cost 2000-3000 euros
for service
• Access to test structures is also a
headache.
• PillarHall enables to do all this
and much more without delay - in
a price point of a test chip
7. 27/06/2018 7
PillarHall® Innovative LHAR Test Structures:
Cross-section without cross-sectioning
1) Test chip as delivered – all silicon
2) Test chip after thin film deposition
PillarHall
+thin film (ALD,CVD)
9. 27/06/2018 9
LHAR3 PillarHall® Test Chip features:
9 different and 8 parallel LHARs in rectangular test
areas, AR from 2:1 to 10 000:1 (gap 500 nm)
Scale
100 µm
Vertical
trenches
Additional
directional
LHARs on edges Distance indicator markers
Cleavage
line
Chip size: 15x20 mm
31 HAR test structures in one chip
1 gap height (default 500 nm)
All silicon
11. 27/06/2018 11
PillarHall®: Remove top membrane to access
detailed, reproducible information of film on Si
Photo: Riikka Puurunen, VTT
Distance from LHAR opening (µm)
Reflectometry
Al2O3 ALD
For scientific publications, see: DOI
10.1116/1.4903941; DOI acs.langmuir.6b03007
More info to come: Puurunen et al., EuroCVD 2017,
accepted; ALD 2017, submitted
12. 27/06/2018 12
Compatible surface analysis tools
COMPATIBLE SURFACE
ANALYSIS TOOLS e.g.
•Optical microscopy image
analysis
•Optical reflectometry
spectrometry (VIS to SWIR)
•Line scans and spectral
imaging
•Small spot Ellipsometry
•AFM and other SPMs
•SEM/EDS plan-view
•High resolution confocal
microscopy
•XPS, ToF-SIMS
13. 27/06/2018 13
Saturation profile terminology for ALD
(as proposed by PillarHall)
Distance l (µm, mm, …)
Relative dimensionless distance (RDD) l / g [r.d.u.]
(RDD ~ aspect ratio AR)
Amount
grown
(nm,
# of atoms,
…)
(per cycle)
50%-thickness-
penetration-depth (PD50%)
Slope at PD50%
( Lumped sticking coefficient)
GPC just
inside + initial slope
Knee
GPC just
outside
x1. 2.
3.
4.
5. 6.
14. 27/06/2018 14
Predicting and modelling thermal ALD
Modeling growth kinetics of thin films made by atomic layer deposition
in lateral high-aspect-ratio structures M.Ylilammi, O. Ylivaara and R. L.
Puurunen, J.Appl.Phys. In press
15. 27/06/2018 15
PillarHall®: Benefits
Avoid the need for tedious cross-sections combined with
electron microscopy, needed for traditional vertical features
Record-high aspect ratios >10000:1, exposing a parameter
space beyond access with traditional vertical structures
Microscopic dimensions suitable for kinetic modelling
Wafer mapping possibility, even nondestructively
IC-compatible silicon test chips
Accuracy in 3 dimensions
Applicable at temperatures up to ~800°C
16. 27/06/2018 16
PillarHall Test Chip Offering
Test chips in VTT sales offering
Analysis guide manual
IC cleanliness proven certificate
Accompanying service options
Chip size: 15 x 15 mm (LHAR4),
15x20 mm (LHAR3, in picture)
Gap height: 500 nm + options
Test Chips delivered in vacuum
release trays (Gel-Pak)
17. 27/06/2018 17
Scientific publications using
PillarHall® test chips
1. Modeling growth kinetics of thin films made by atomic layer deposition in lateral high-aspect-
ratio structures, M. Ylilammi, O. M. E. Ylivaara, R. L. Puurunen, J. Appl. Phys. 123 (2018) art.
205301 (8 pages). https://doi.org/10.1063/1.5028178
2. Microscopic silicon-based lateral high-aspect-ratio structures for thin film conformality
analysis,
F. Gao, S. Arpiainen, R. L. Puurunen, J. Vac. Sci. Technol. A 33 (2015) 010601.
http://dx.doi.org/10.1116/1.4903941,
open access pdf.
3. Nucleation and Conformality of Iridium and Iridium Oxide Thin Films Grown by Atomic Layer
Deposition,
M. Mattinen, J. Hämäläinen, F. Gao, P. Jalkanen, K. Mizohata, J. Räisänen, R. L. Puurunen, M.
Ritala, M. Leskelä, Langmuir 32 (2016) 10559-10569. http://dx.doi.org/10.1021/acs.langmuir.6b03007
4. Influence of ALD temperature on thin film conformality: Investigation with microscopic lateral
high-aspect-ratio structures,
R. L. Puurunen, F. Gao, Proceedings of the International Baltic Conference on Atomic Layer
Deposition, 2-4 Oct 2016, St. Petersburg, Russia. Electronically published in IEEE Xplore,
http://ieeexplore.ieee.org/document/7886526/
18. CONTACT: Dr. Mikko Utriainen
Sales responsible of PillarHall @VTTFinland
Tel. +358 40 753 7415 mikko.utriainen@vtt.fi or pillarhall@vtt.fi
Editor's Notes
Value based pricing: Price point hundreds of euros. We have started at price point testing at 1000 euros per chip
To accelerate vertical scaling and development of thin film processes for 3D challenges
To accelerate vertical scaling and development of thin film processes for 3D challenges
Averaging large area= accuracy, parallel structures, Gap height variation requires another chip
Commercialization project has enabled to increase technical readiness level. Process dev has included