Monitoring Conformality in ALD Manufacturing

Comparing Lateral and Vertical High Aspect Ratio Test Structures

Mikko Utriainen, Feng Gao, Riikka L. Puurunen, Stefan Riedel, Alireza M. Kia

Research output: Contribution to conferenceConference AbstractScientificpeer-review

Abstract

Atomic Layer Deposition (ALD) technology enables manufacturing of
conformal thin films into such deep microscopic trenches and cavities that
the film characterization becomes a true challenge. In ALD applications
these 3D microstructured substrates are typically vertically oriented high
aspect ratio (HAR) structures. Monitoring and control of conformality relies
predominantly on cross-sectional sample preparation and SEM/TEM
characterization. This approach has several challenges, e.g. need to break
the wafer, seeing only thin slice, cleavage plane inaccuracy, multiple
repeated samples to get reliable data and long response times.
A potential approach to circumvent the challenges is a MEMS-based allsilicon lateral high aspect ratio (LHAR) test structure, PillarHall® developed
at VTT [1-2]. The LHAR test chip is IC cleanliness proven and thus
potentially compatible to any cleanroom environment. This study focuses
to research questions: How reliable and accurate is LHAR test in 300 mm
wafer manufacturing environment and, especially, how does it compare to
vertical HAR structures.
The LHAR Test Chip (LHAR3 -series, AR range 2:1 - 10000:1, 500nm gap
height) was employed for the first time on the carrier wafer in 300 mm
wafer ALD process (Jusung Eureka 3000) in Fraunhofer IPMS. The ALD
process was foundry’s default ZrO2/Al2O3 laminate process, 22 nm, carried
out in two process variation runs (A=optimized for 3D, B=planar) at same
temperature and cycle numbers. In the same run was employed LHAR and
vertical trench test structures (AR 20:1). Conformality of both structures
were analyzed by SEM cross-sections, with appropriate sample
preparations.
Findings show that conformality in LHAR is comparable to vertical HAR
within accuracy limits of step coverage metrology within the comparable
AR range. Furthermore, in this study, higher aspect ratios in LHAR test chip
shows significant differences between the process variations while in VHAR
they are small. Therefore, even optical microscope metrics from LHAR
provides fast relative insight to the process variations and can be utilized in
monitoring. LHAR enables also access to gain more detailed compositional
information on the trench wall e.g. by ToF-SIMS, which is under
examination and a topic of further studies.
Original languageEnglish
Number of pages1
Publication statusPublished - 30 Jul 2018
MoE publication typeNot Eligible
Event18th International Conference on Atomic Layer Deposition, ALD/ALE 2018: Featuring the 5th International Atomic Layer Etching Workshop - Songdo Convensia in Incheon, Incheon, Korea, Republic of
Duration: 29 Jul 20181 Aug 2018
https://ald2018.avs.org/

Conference

Conference18th International Conference on Atomic Layer Deposition, ALD/ALE 2018
Abbreviated titleALD/ALE 2018
CountryKorea, Republic of
CityIncheon
Period29/07/181/08/18
Internet address

Fingerprint

Atomic layer deposition
Aspect ratio
Monitoring
Scanning electron microscopy
Secondary ion mass spectrometry
MEMS
Laminates
Microscopes
Thin films
Substrates

Keywords

  • PillarHall
  • LHAR
  • ALD
  • conformality
  • Characterization

Cite this

Utriainen, M., Gao, F., Puurunen, R. L., Riedel, S., & Kia, A. M. (2018). Monitoring Conformality in ALD Manufacturing: Comparing Lateral and Vertical High Aspect Ratio Test Structures. Abstract from 18th International Conference on Atomic Layer Deposition, ALD/ALE 2018, Incheon, Korea, Republic of.
Utriainen, Mikko ; Gao, Feng ; Puurunen, Riikka L. ; Riedel, Stefan ; Kia, Alireza M. / Monitoring Conformality in ALD Manufacturing : Comparing Lateral and Vertical High Aspect Ratio Test Structures. Abstract from 18th International Conference on Atomic Layer Deposition, ALD/ALE 2018, Incheon, Korea, Republic of.1 p.
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abstract = "Atomic Layer Deposition (ALD) technology enables manufacturing ofconformal thin films into such deep microscopic trenches and cavities thatthe film characterization becomes a true challenge. In ALD applicationsthese 3D microstructured substrates are typically vertically oriented highaspect ratio (HAR) structures. Monitoring and control of conformality reliespredominantly on cross-sectional sample preparation and SEM/TEMcharacterization. This approach has several challenges, e.g. need to breakthe wafer, seeing only thin slice, cleavage plane inaccuracy, multiplerepeated samples to get reliable data and long response times.A potential approach to circumvent the challenges is a MEMS-based allsilicon lateral high aspect ratio (LHAR) test structure, PillarHall{\circledR} developedat VTT [1-2]. The LHAR test chip is IC cleanliness proven and thuspotentially compatible to any cleanroom environment. This study focusesto research questions: How reliable and accurate is LHAR test in 300 mmwafer manufacturing environment and, especially, how does it compare tovertical HAR structures.The LHAR Test Chip (LHAR3 -series, AR range 2:1 - 10000:1, 500nm gapheight) was employed for the first time on the carrier wafer in 300 mmwafer ALD process (Jusung Eureka 3000) in Fraunhofer IPMS. The ALDprocess was foundry’s default ZrO2/Al2O3 laminate process, 22 nm, carriedout in two process variation runs (A=optimized for 3D, B=planar) at sametemperature and cycle numbers. In the same run was employed LHAR andvertical trench test structures (AR 20:1). Conformality of both structureswere analyzed by SEM cross-sections, with appropriate samplepreparations.Findings show that conformality in LHAR is comparable to vertical HARwithin accuracy limits of step coverage metrology within the comparableAR range. Furthermore, in this study, higher aspect ratios in LHAR test chipshows significant differences between the process variations while in VHARthey are small. Therefore, even optical microscope metrics from LHARprovides fast relative insight to the process variations and can be utilized in monitoring. LHAR enables also access to gain more detailed compositionalinformation on the trench wall e.g. by ToF-SIMS, which is underexamination and a topic of further studies.",
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author = "Mikko Utriainen and Feng Gao and Puurunen, {Riikka L.} and Stefan Riedel and Kia, {Alireza M.}",
note = "Only aAbstract reviewed, if not published in JVST A journal; 18th International Conference on Atomic Layer Deposition, ALD/ALE 2018 : Featuring the 5th International Atomic Layer Etching Workshop , ALD/ALE 2018 ; Conference date: 29-07-2018 Through 01-08-2018",
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Utriainen, M, Gao, F, Puurunen, RL, Riedel, S & Kia, AM 2018, 'Monitoring Conformality in ALD Manufacturing: Comparing Lateral and Vertical High Aspect Ratio Test Structures' 18th International Conference on Atomic Layer Deposition, ALD/ALE 2018, Incheon, Korea, Republic of, 29/07/18 - 1/08/18, .

Monitoring Conformality in ALD Manufacturing : Comparing Lateral and Vertical High Aspect Ratio Test Structures. / Utriainen, Mikko; Gao, Feng; Puurunen, Riikka L.; Riedel, Stefan; Kia, Alireza M.

2018. Abstract from 18th International Conference on Atomic Layer Deposition, ALD/ALE 2018, Incheon, Korea, Republic of.

Research output: Contribution to conferenceConference AbstractScientificpeer-review

TY - CONF

T1 - Monitoring Conformality in ALD Manufacturing

T2 - Comparing Lateral and Vertical High Aspect Ratio Test Structures

AU - Utriainen, Mikko

AU - Gao, Feng

AU - Puurunen, Riikka L.

AU - Riedel, Stefan

AU - Kia, Alireza M.

N1 - Only aAbstract reviewed, if not published in JVST A journal

PY - 2018/7/30

Y1 - 2018/7/30

N2 - Atomic Layer Deposition (ALD) technology enables manufacturing ofconformal thin films into such deep microscopic trenches and cavities thatthe film characterization becomes a true challenge. In ALD applicationsthese 3D microstructured substrates are typically vertically oriented highaspect ratio (HAR) structures. Monitoring and control of conformality reliespredominantly on cross-sectional sample preparation and SEM/TEMcharacterization. This approach has several challenges, e.g. need to breakthe wafer, seeing only thin slice, cleavage plane inaccuracy, multiplerepeated samples to get reliable data and long response times.A potential approach to circumvent the challenges is a MEMS-based allsilicon lateral high aspect ratio (LHAR) test structure, PillarHall® developedat VTT [1-2]. The LHAR test chip is IC cleanliness proven and thuspotentially compatible to any cleanroom environment. This study focusesto research questions: How reliable and accurate is LHAR test in 300 mmwafer manufacturing environment and, especially, how does it compare tovertical HAR structures.The LHAR Test Chip (LHAR3 -series, AR range 2:1 - 10000:1, 500nm gapheight) was employed for the first time on the carrier wafer in 300 mmwafer ALD process (Jusung Eureka 3000) in Fraunhofer IPMS. The ALDprocess was foundry’s default ZrO2/Al2O3 laminate process, 22 nm, carriedout in two process variation runs (A=optimized for 3D, B=planar) at sametemperature and cycle numbers. In the same run was employed LHAR andvertical trench test structures (AR 20:1). Conformality of both structureswere analyzed by SEM cross-sections, with appropriate samplepreparations.Findings show that conformality in LHAR is comparable to vertical HARwithin accuracy limits of step coverage metrology within the comparableAR range. Furthermore, in this study, higher aspect ratios in LHAR test chipshows significant differences between the process variations while in VHARthey are small. Therefore, even optical microscope metrics from LHARprovides fast relative insight to the process variations and can be utilized in monitoring. LHAR enables also access to gain more detailed compositionalinformation on the trench wall e.g. by ToF-SIMS, which is underexamination and a topic of further studies.

AB - Atomic Layer Deposition (ALD) technology enables manufacturing ofconformal thin films into such deep microscopic trenches and cavities thatthe film characterization becomes a true challenge. In ALD applicationsthese 3D microstructured substrates are typically vertically oriented highaspect ratio (HAR) structures. Monitoring and control of conformality reliespredominantly on cross-sectional sample preparation and SEM/TEMcharacterization. This approach has several challenges, e.g. need to breakthe wafer, seeing only thin slice, cleavage plane inaccuracy, multiplerepeated samples to get reliable data and long response times.A potential approach to circumvent the challenges is a MEMS-based allsilicon lateral high aspect ratio (LHAR) test structure, PillarHall® developedat VTT [1-2]. The LHAR test chip is IC cleanliness proven and thuspotentially compatible to any cleanroom environment. This study focusesto research questions: How reliable and accurate is LHAR test in 300 mmwafer manufacturing environment and, especially, how does it compare tovertical HAR structures.The LHAR Test Chip (LHAR3 -series, AR range 2:1 - 10000:1, 500nm gapheight) was employed for the first time on the carrier wafer in 300 mmwafer ALD process (Jusung Eureka 3000) in Fraunhofer IPMS. The ALDprocess was foundry’s default ZrO2/Al2O3 laminate process, 22 nm, carriedout in two process variation runs (A=optimized for 3D, B=planar) at sametemperature and cycle numbers. In the same run was employed LHAR andvertical trench test structures (AR 20:1). Conformality of both structureswere analyzed by SEM cross-sections, with appropriate samplepreparations.Findings show that conformality in LHAR is comparable to vertical HARwithin accuracy limits of step coverage metrology within the comparableAR range. Furthermore, in this study, higher aspect ratios in LHAR test chipshows significant differences between the process variations while in VHARthey are small. Therefore, even optical microscope metrics from LHARprovides fast relative insight to the process variations and can be utilized in monitoring. LHAR enables also access to gain more detailed compositionalinformation on the trench wall e.g. by ToF-SIMS, which is underexamination and a topic of further studies.

KW - PillarHall

KW - LHAR

KW - ALD

KW - conformality

KW - Characterization

M3 - Conference Abstract

ER -

Utriainen M, Gao F, Puurunen RL, Riedel S, Kia AM. Monitoring Conformality in ALD Manufacturing: Comparing Lateral and Vertical High Aspect Ratio Test Structures. 2018. Abstract from 18th International Conference on Atomic Layer Deposition, ALD/ALE 2018, Incheon, Korea, Republic of.