Specific Process Knowledge/Etch/DRIE-Pegasus/Pegasus-2/OldConfig

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Past configurations

Configuration valid from June 13 2022 to May 17 2023

6: Currently valid June 13 2022 to May 17 2023

Item	The currently applied modification	Comments
Available gasses and gas chemistry	Available gasses: SF6: 50 sccm O2: 50 sccm Ar: 283 N2: 500 sccm He: 11 sccm Not available: C4F8 (H2 currently fitted but closed) : 0 sccm CO2: (It is not in the software)	OnlySF6 and O2 are used for Si, PR, and Cr etch. The rest is only make-up
Plasma source heaters	The following heaters in the plasma source are off: Plenum Heater Inner Heater Magnetic Confinement Heater Chamber Heater	The temperature on the heaters in the plasma source are set to 20 degrees with a high tolerance. This essentially corresponds to powered off compared to default Pegasus temperatures which are in the 120-140 degrees range. The absence of fluorocarbons in the plasma makes it unnecessary to maintain a high temperature on the chamber walls in order to reduce polymer condensation (see below). Always make sure that the temperature settings in the recipes are not enabled. Click here to have more information.
Carbon free plasmas	The process chamber does not have any carbon containing etch gasses. Therefore, polymer build-up on the chamber walls is not an issue. The 'carbon free' policy does not, however, apply to the choice of masking materials and CSAR, AZ and DUV resists are allowed.
Chamber conditioning and cleaning	Running long oxygen cleans is not necessary and must be avoided. Neither are shorter cleans between wafers.	The absence of carbon containing etch gasses ensures that the process chamber is kept clean.
Recipes	In the past, only recipes in the 'std' folder were allowed to run. Now, you can develop your own recipes as long as they don't violate any of the limitations/restrictions and rules in this table.	Be extremely careful with recipes in other folders than your own or the 'std' folder as they may no longer be safe to run because of hardware changes.
Etch of chromium and silicon nitrides	Recipes for etching chromium and silicon nitrides have been developed.	Etching the two materials is only allowed for processes in combination with other Pegasus 2 specific recipes such as the CORE recipe. Always consult with Nanolab staff.
Electrostatic clamping, chip bonding with Galden oil and helium backside cooling are no longer being used.	The processes run in Pegasus 2 operate at such low powers that they do not require very efficient cooling. It has therefore been decided that the following options/procedures Electrostatic clamping of carriers/substrates Helium backside cooling Using bonding procedures such as droplets of Galden oil to increase thermal contact between chips and carrier will no longer be required.	So far we have not seen any changes in the results but if you do, please contact Nanolab staff.
Background knowledge required for safe operation	The users and supervisors of Pegasus-2 must carefully read the 4 papers listed in the comments in order to have a correct understanding of the etch process and experimental procedure and how it relates to the Bosch etch performance.	See the papers in the section below.

Configuration valid from May 25 2022 to June 13 2022

5: Currently valid from May 25 2022 onwards

Item	The currently applied modification	Comments
Available gasses and gas chemistry	Available gasses: SF6: 50 sccm O2: 50 sccm Ar: 283 N2: 500 sccm He: 11 sccm Not available: C4F8 (H2 currently fitted but closed) : 0 sccm CO2: (It is not in the software)	OnlySF6 and O2 are used for Si, PR, and Cr etch. The rest is only make-up
Plasma source heaters	Applies to Plenum Heater Inner Heater Magnetic Confinement Heater Chamber Heater	The temperature on the heaters in the plasma source are set to 20 degrees with a high tolerance. This essentially corresponds to powered off compared to default Pegasus temperatures which are in the 120-140 degrees range. Always make sure that the temperature settings in the recipes are not enabled. Click here to have more information.
RF power and pressure settings	All recipes run without coil power, very low platen power and low pressures	None of the recipes use coil power in order to prevent aluminium fluoride formation at the aluminium oxide dome. These particles may drop on the wafer or chuck and cause abnormalitites. Most of the recipes rely on very low pressure and low power - 0.2 mTorr and 10 Watt platen power is not an error and easily supports the plasma.
Carbon free plasmas	The process chamber does not have any carbon containing etch gasses. Therefore, polymer build-up on the chamber walls is not an issue. The 'carbon free' policy does not, however, apply to the choice of masking materials and CSAR, AZ and DUV resists are allowed.
Chamber conditioning and cleaning	Running long oxygen cleans is not necessary and must be avoided. Neither are shorter cleans between wafers.	The absence of carbon containing etch gasses ensures that the process chamber is kept clean.
Approved recipes	The 'std' folder holds the list of currently allowed recipes	Recipes in other folders may no longer be safe to run.
Etch of chromium and silicon nitrides	Recipes for etching chromium and silicon nitrides have been developed.	Etching the two materials is only allowed for processes in combination with other Pegasus 2 specific recipes such as the CORE recipe. Always consult with Nanolab staff.
Electrostatic clamping, chip bonding with Galden oil and helium backside cooling are no longer being used.	The processes run in Pegasus 2 operate at such low powers that they do not require very efficient cooling. It has therefore been decided that Electrostatic clamping of carriers/substrates Helium backside cooling Using bonding procedures such as droplets of Galden oil to increase thermal contact between chips and carrier will no longer be required.	So far we have not seen any changes in the results but if you do, please contact Nanolab staff.
Background knowledge required for safe operation	The users and supervisors of Pegasus-2 must carefully read the 4 papers listed in the comments in order to have a correct understanding of the etch process and experimental procedure and how it relates to the Bosch etch performance.	See the papers in the section below.
List of approved recipes	The list of currently approved recipes is: A gentle barc etch The ORE t1 resist mask Strip resist and barc A polysilicon etch for hard masks Cr etch The CORE Si etch with Cr hard mask

Configuration and setup valid September 13 2021 to May 25 2022

4: Currently valid from September 13 2021 onwards

Item	The currently applied modification	Comments
Available gasses and gas chemistry	Available gasses: SF6: 50 sccm O2: 50 sccm Ar: 283 N2: 500 sccm He: 11 sccm Not available: C4F8 (H2 currently fitted but closed) : 0 sccm CO2: (It is not in the software)	OnlySF6 and O2 are used for Si, PR, and Cr etch. The rest is only make-up
Plasma source heaters	Applies to Plenum Heater Inner Heater Magnetic Confinement Heater Chamber Heater	The temperature on the heaters in the plasma source are set to 20 degrees with a high tolerance. This essentially corresponds to powered off compared to default Pegasus temperatures which are in the 120-140 degrees range. Always make sure that the temperature settings in the recipes are not enabled. Click here to have more information.
RF power and pressure settings	All recipes run without coil power, very low platen power and low pressures	None of the recipes use coil power in order to prevent aluminium fluoride formation at the aluminium oxide dome. These particles may drop on the wafer or chuck and cause abnormalitites. Most of the recipes rely on very low pressure and low power - 0.2 mTorr and 10 Watt platen power is not an error and easily supports the plasma.
Carbon free plasmas	The process chamber does not have any carbon containing etch gasses. Therefore, polymer build-up on the chamber walls is not an issue. The 'carbon free' policy does not, however, apply to the choice of masking materials and CSAR, AZ and DUV resists are allowed.
Chamber conditioning and cleaning	Running long oxygen cleans is not necessary and must be avoided. Neither are shorter cleans between wafers.	The absence of carbon containing etch gasses ensures that the process chamber is kept clean.
Approved recipes	The 'std' folder holds the list of currently allowed recipes	Recipes in other folders may no longer be safe to run.
Etch of nickel and chromium	Recipes for etching nickel and chromium have been developed	The cross contamination consequences have yet to be determined
Background knowledge required for safe operation	The users and supervisors of Pegasus-2 must carefully read the 4 papers listed in the comments in order to have a correct understanding of the etch process and experimental procedure and how it relates to the Bosch etch performance.	See the papers in the section below.
List of approved recipes	The list of currently approved recipes is: A gentle barc etch The ORE t1 resist mask Strip resist and barc A polysilicon etch for hard masks Cr etch The CORE Si etch with Cr hard mask

Configuration and setup valid August 17 2021 to September 13 2021

3: Currently valid from August 17 2021 onwards

Item	The currently applied modification	Comments
Available gasses and gas chemistry	Available gasses: SF6: 50 sccm O2: 50 sccm Ar: 283 N2: 500 sccm He: 11 sccm Not available: C4F8 (H2 currently fitted but closed) : 0 sccm CO2: (It is not in the software)	OnlySF6 and O2 are used for Si, PR, and Cr etch. The rest is only make-up
Plasma source heaters	Applies to Plenum Heater Inner Heater Magnetic Confinement Heater Chamber Heater	The temperature on the heaters in the plasma source are set to 20 degrees with a high tolerance. This essentially corresponds to powered off compared to default Pegasus temperatures which are in the 120-140 degrees range. Always make sure that the temperature settings in the recipes are not enabled. Click here to have more information.
RF power and pressure settings	All recipes run without coil power, very low platen power and low pressures	None of the recipes use coil power in order to prevent aluminium fluoride formation at the aluminium oxide dome. These particles may drop on the wafer or chuck and cause abnormalitites. Most of the recipes rely on very low pressure and low power - 0.2 mTorr and 10 Watt platen power is not an error and easily supports the plasma.
Carbon free plasmas	The process chamber does not have any carbon containing etch gasses. Therefore, polymer build-up on the chamber walls is not an issue. The 'carbon free' policy does not, however, apply to the choice of masking materials and CSAR, AZ and DUV resists are allowed.
Chamber conditioning and cleaning	Running long oxygen cleans is not necessary and must be avoided. Neither are shorter cleans between wafers.	The absence of carbon containing etch gasses ensures that the process chamber is kept clean.
Approved recipes	The 'std' folder holds the list of currently allowed recipes	Recipes in other folders may no longer be safe to run.
Etch of nickel and chromium	Recipes for etching nickel and chromium have been developed	The cross contamination consequences have yet to be determined
Background knowledge required for safe operation	The users and supervisors of Pegasus-2 must carefully read the 4 papers listed in the comments in order to have a correct understanding of the etch process and experimental procedure and how it relates to the Bosch etch performance.	See the papers in the section below.

Configuration and setup valid March 2021 to August 2021

2: Currently valid from March 15 2021 onwards

Item	The currently applied modification	Comments
Available gasses and gas chemistry	Available gasses: SF6: 50 sccm O2: 50 sccm Ar: 283 N2: 500 sccm He: 11 sccm Not available: C4F8 (H2 currently fitted but closed) : 0 sccm CO2: (It is not in the software)	OnlySF6 and O2 are used for Si, PR, and Cr etch. The rest is only make-up
Plasma source heaters	Applies to Plenum Heater Inner Heater Magnetic Confinement Heater Chamber Heater	The temperature on the heaters in the plasma source are set to 20 degrees with a high tolerance. This essentially corresponds to powered off compared to default Pegasus temperatures which are in the 120-140 degrees range. Always make sure that the temperature settings in the recipes are not enabled. Click here to have more information.
RF power and pressure settings	All recipes run without coil power, very low platen power and low pressures	None of the recipes use coil power in order to prevent aluminium fluoride formation at the aluminium oxide dome. These particles may drop on the wafer or chuck and cause abnormalitites. Most of the recipes rely on very low pressure and low power - 0.2 mTorr and 10 Watt platen power is not an error and easily supports the plasma.
Carbon free plasmas	The process chamber does not have any carbon containing etch gasses. Therefore, polymer build-up on the chamber walls is not an issue. The 'carbon free' policy does not, however, apply to the choice of masking materials and CSAR, AZ and DUV resists are allowed.
Chamber conditioning and cleaning	Running long oxygen cleans is not necessary and must be avoided. Neither are shorter cleans between wafers.	The absence of carbon containing etch gasses ensures that the process chamber is kept clean.
Approved recipes	The 'std' folder holds the list of currently allowed recipes	Recipes in other folders may no longer be safe to run.
Etch of nickel and chromium	Recipes for etching nickel and chromium have been developed	The cross contamination consequences have yet to be determined
Background knowledge required for safe operation	Users and supervisors of Pegasus-2 should carefully read the 3 papers listed in the comments in order to have a correct understanding of the etch process and experimental procedure and how it relates to the Bosch etch performance.	See the papers in the section below.

Configuration and setup valid November 2020 to March 2021

1: Currently valid from November 2020 onwards

Item	The currently applied modification	Comments
Available gasses and gas chemistry	Available gasses: SF6: 50 sccm O2: 50 sccm Ar: 283 N2: 500 sccm He: 11 sccm Not available: C4F8 (H2 currently fitted but closed) : 0 sccm CO2: (It is not in the software)	OnlySF6 and O2 are used for Si, PR, and Cr etch. The rest is only make-up
Plasma source heaters	Applies to Plenum Heater Inner Heater Magnetic Confinement Heater Chamber Heater	The temperature on the heaters in the plasma source are set to 20 degrees with a high tolerance. This essentially corresponds to powered off compared to default Pegasus temperatures which are in the 120-140 degrees range. Always make sure that the temperature settings in the recipes are not enabled. Click here to have more information.
RF power and pressure settings	All recipes run without coil power, very low platen power and low pressures	None of the recipes use coil power in order to prevent aluminium fluoride formation at the aluminium oxide dome. These particles may drop on the wafer or chuck and cause abnormalitites. Most of the recipes rely on very low pressure and low power - 0.2 mTorr and 10 Watt platen power is not an error and easily supports the plasma.
Carbon free plasmas	The process chamber does not have any carbon containing etch gasses. Therefore, polymer build-up on the chamber walls is not an issue. The 'carbon free' policy does not, however, apply to the choice of masking materials and CSAR, AZ and DUV resists are allowed.
Chamber conditioning and cleaning	Running long oxygen cleans is not necessary and must be avoided. Neither are shorter cleans between wafers.	The absence of carbon containing etch gasses ensures that the process chamber is kept clean.
Approved recipes	The 'std' folder holds the list of currently allowed recipes	Recipes in other folders may no longer be safe to run.
Etch of nickel and chromium	Recipes for etching nickel and chromium have been developed	The cross contamination consequences have yet to be determined

As of December 2020 there is not yet any old configurations.

Publications on the CORE process

Nguyen, V. T. et al.

On the formation of black silicon in SF6-O2 plasma: The clear, oxidize, remove, and etch (CORE) sequence and black silicon on demand

2020 Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, 38(4), [043004].

https://doi.org/10.1116/6.0000196

Vy Thi Hoang Nguyen et al.

The CORE Sequence: A Nanoscale Fluorocarbon-Free Silicon Plasma Etch Process Based on SF6/O2 Cycles with Excellent 3D Profile Control at Room Temperature

2020 ECS J. Solid State Sci. Technol. 9 024002

https://doi.org/10.1149/2162-8777/ab61ed

Vy Thi Hoang Nguyen et al.

Ultrahigh aspect ratio etching of silicon in SF₆-O₂ plasma: The clear-oxidize-remove etch (CORE) sequence and chromium mask

2020 Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, 38(5), [053002]

https://doi.org/10.1116/6.0000357

Vy Thi Hoang Nguyen et al.

Cr and CrO_x etching using SF₆ and O2 plasma

2021 Journal of Vacuum Science and Technology B: Nanotechnology and Microelectronics, 39(3), [032201]

https://doi.org/10.1116/6.0000922