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.
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 language | English |
|---|---|
| Number of pages | 1 |
| Publication status | Published - 30 Jul 2018 |
| MoE publication type | Not Eligible |
| Event | 18th 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 2018 → 1 Aug 2018 https://ald2018.avs.org/ |
Conference
| Conference | 18th International Conference on Atomic Layer Deposition, ALD/ALE 2018 |
|---|---|
| Abbreviated title | ALD/ALE 2018 |
| Country/Territory | Korea, Republic of |
| City | Incheon |
| Period | 29/07/18 → 1/08/18 |
| Internet address |
Keywords
- PillarHall
- LHAR
- ALD
- conformality
- Characterization