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<i>This page is written by <b>Evgeniy Shkondin @DTU Nanolab</b> if nothing else is stated. <br>
<i>This page is written by <b>Evgeniy Shkondin @DTU Nanolab</b> if nothing else is stated. <br>
All images and photos on this page belongs to <b>DTU Nanolab</b>.<br>
All images and photos on this page belongs to <b>DTU Nanolab</b>.<br>
The fabrication and characterization described below were conducted in <b>2020 by Evgeniy Shkondin.</b> The shield design was developed by <b>Henrik Nielsen (Nanolab, ThinFilm)</b>, and build by Nanolab Facility service</b>.<br></i>
The fabrication and characterization described below were conducted in <b>2020 by Evgeniy Shkondin.</b> The shield design was developed by <b>Henrik Nielsen (Nanolab, ThinFilm)</b>, and built by Nanolab Facility service</b>.<br></i>




== '''Thermal evaporation of Chromium''' ==
= Thermal evaporation of Chromium=


Chromium can be thermally evaporated in the [[Specific_Process_Knowledge/Thin_film_deposition/thermalevaporator|Thermal Evaporator]] (NANO 36 THERMAL EVAPORATOR SYSTEM). At DTU Nanolab, we use dedicated 4" long chromium plated tungsten rods (supplier: KJLC). During power ramp up, the material warms up and sublimates. Unlike deposition of Al and Ag, where simple crucibles are used with point-source evaporation from bottom to the substrate, the deposition of chromium proceeds in all directions. To prevent the deposition on the side-walls and the bottom of the chamber a specific protecting shield is mounted beneath the tungsten rod.
Chromium can be thermally evaporated in the [[Specific_Process_Knowledge/Thin_film_deposition/thermalevaporator|Thermal Evaporator]] (NANO 36 THERMAL EVAPORATOR SYSTEM). At DTU Nanolab, for the Cr thermal source we have experimented with Cr pellets in a W boat as well as dedicated 4" long chromium plated tungsten rods (supplier: KJLC).  


The process and resulting material characteristics described on this page were done using the Cr plated W rod. However, we have found that using Cr pellets is easier in the long run as it does not require modifying the chamber layout. So the current method you will most likely use is evaporation of Cr pellets from a boat (2025). There will be some differences from what is described below, e.g., uniformity will be different. You can still use the results from XRD/XRR, XPS, SEM, and AFM as an indication of what you might expect and as a guide for relevant investigations.
==Cr evaporation from Cr-coated W rod==
During power ramp up, the material warms up and sublimates. Unlike deposition of Al and Ag, where simple crucibles are used with point-source evaporation from bottom to the substrate, the deposition of chromium from a coated rod proceeds in all directions. To prevent the deposition on the side-walls and the bottom of the chamber a specific protecting shield is mounted beneath the tungsten rod.


<b>The shield design was developed by Henrik Nielsen (Nanolab, ThinFilm), and build by Nanolab Facility service. The process was developed and tested by Evgeniy Shkondin (Nanolab, ThinFilm) in december 2020.</b>
<b>The shield design was developed by Henrik Nielsen (Nanolab, ThinFilm), and build by Nanolab Facility service. The process was developed and tested by Evgeniy Shkondin (Nanolab, ThinFilm) in december 2020.</b>
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</gallery>
</gallery>


== '''Set-up installation''' ==
== '''Set-up and installation of the rod''' ==


The deposition of Chromium requires a major change of the tool hardware installation. Ask Nanolab responsible employee if you need to perform this change.
The deposition of Chromium requires a major change of the tool hardware installation. Ask Nanolab responsible employee if you need to perform this change.
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=== '''Deposition of 100 nm''' ===
=== '''Deposition of 100 nm''' ===


The adjusted tooling factor 173%. Full 6" wafer is loaded with shadow-mask. Deposition thickness setpoint is set to 100 nm.
The adjusted tooling factor 173%. Full 6" wafer is loaded with shadow-mask. No rotation. Deposition thickness setpoint is set to 100 nm.


Pressure fluctuations during the ramp-up:
Pressure fluctuations during the ramp-up:
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[[image:eves_20210126_Cr_thermal_evaporator_09.png|center|300x300px|thumb|Figure 8. Thickness distribution across 6" wafer. Measurement is performed using [[Specific_Process_Knowledge/Characterization/Profiler#Dektak_XTA_stylus_profiler|Dektak profilometer]].]]
[[image:eves_20210126_Cr_thermal_evaporator_09.png|center|300x300px|thumb|Figure 8. Thickness distribution across 6" wafer. Measurement is performed using [[Specific_Process_Knowledge/Characterization/Dektak_XTA|Dektak stylus profilometer]].]]


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