Basic concept of PillarHall thin film conformality analysis explained. http://www.pillarhall.com

1. 1
By Riikka Puurunen, Copyright VTT 2017
PillarHall®
09/05/2017 1
PillarHall® silicon wafers and chips enable easy analysis
of thin film conformality using well-defined, record-
demanding microscopic 3-D structures.
Typical usage areas are atomic layer deposition and
chemical vapor deposition R&D.
pillarhall.com
#TestedWithPillarHall
PillarHall® — accelerating thin film R&D
”What you can’t measure, you can’t improve”

2. 2
By Riikka Puurunen, Copyright VTT 2017
PillarHall®
09/05/2017 2
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.

3. 3
By Riikka Puurunen, Copyright VTT 2017
PillarHall®
09/05/2017 3
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%

4. 4
By Riikka Puurunen, Copyright VTT 2017
PillarHall®
09/05/2017 4
Schematic:
uncoated structure
Structure after coating with
ALD, CVD, …
Structure after peeling off the
top membrane
PillarHall® lateral
high-aspect-ratio
(LHAR) all-silicon
chips and wafers
(current: 150 mm)

5. 5
By Riikka Puurunen, Copyright VTT 2017
PillarHall®
09/05/2017 5
Typical 500 nm
Max 5000 µm
Max
5000 µm
Top view
Side view
~1.5 µm
PillarHall® dimensions
(not in scale)
• Gap height typically 500 nm, can be
varied (e.g., 100 and 1000 nm)
• Membrane length up to 5000 µm
• Multiple aspect ratios (AR) in one chip,
e.g. 5:1 to 10 000:1

6. 6
By Riikka Puurunen, Copyright VTT 2017
PillarHall®
09/05/2017 6
PillarHall®: Multitude of analysis possibilities
Penetration depth
under membrane
~70 µm
AR ~140:1
Cross-section, SEM
(50 nm by 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
Top-view microscopy
(50 nm by ALD)
Quick semiquantitative
(nondestructive) analysis
Traditional electron
microscopy cross-sections
Uniform coating all around
the feature, AR ~40:1,
gap height 500 nm

7. 7
By Riikka Puurunen, Copyright VTT 2017
PillarHall®
09/05/2017 7
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

8. 8
By Riikka Puurunen, Copyright VTT 2017
PillarHall®
09/05/2017 8
distance, aspect ratio
thickness • Optimise reaction times/doses
(tA, tB, pA, pB)
• Extract kinetic parameters
• Optimise purge times (tA2, tB2)
• Understand reaction mechanisms
PillarHall® line scans: route to understanding
and optimising process fundamentals

9. 9
By Riikka Puurunen, Copyright VTT 2017
PillarHall®
09/05/2017 9
PillarHall®: Some 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 wafers. Potentially chips , too
 Applicable at temperatures up to ~800°C

10. 10
By Riikka Puurunen, Copyright VTT 2017
PillarHall®
09/05/2017 10
Scientific publications using
PillarHall 1st generation prototypes
1. 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.
2. 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
3. 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/

11. 11
By Riikka Puurunen, Copyright VTT 2017
PillarHall®
09/05/2017 11
Interested to know more on PillarHall®?
 Take the PillarHall Survey
 Contact
 Mikko Utriainen,
Tel: +358 40 753 7415,
pillarhall (at) vtt.fi
 Participate in PillarHall survey
 Proof-of-concept tests with
selected partners  interested
parties can contact
 Meet us at conferences:
 Joint EuroCVD 21 - Baltic ALD 15, June 11-14, 2017, Linköping, Sweden,
http://www.eurocvd-balticald2017.se/
 ALD 2017, 17th International Conference on Atomic Layer Deposition,
Denver, Colorado, USA, July 15-18, 2017. https://aldconference.avs.org/.
Dr. Mikko Utriainen Prof. Riikka Puurunen

12. 12
By Riikka Puurunen, Copyright VTT 2017
PillarHall®
09/05/2017 12
PillarHall® — Accelerating thin film R&D
http://www.pillarhall.com
Email: pillarhall (at) vtt.fi
Twitter: #TestedWithPillarHall