Specific Process Knowledge/Etch/Etching of Silicon Nitride/Etch of Silicon Nitride using RIE: Difference between revisions

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For a general introduction to RIE at Danchip see [[Specific Process Knowledge/Etch/RIE (Reactive Ion Etch)|RIE (Reactive Ion Etch)]]
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=<span style="color:#FF0000"> Both RIE's (RIE1 and RIE2) for silicon based etching have been decommissioned </span> =
* <span style="color:#FF0000"> This information is save because it might be valuable as inspiration for other dry etch systems.
For a general introduction to RIE at DTU Nanolab see [[Specific Process Knowledge/Etch/RIE (Reactive Ion Etch)|RIE (Reactive Ion Etch)]]


Etching of silicon nitride using RIE can be done with several recipes. It can be etched by our standard  silicon etch recipe: OH_PolyA which is based on SF6. It can also be etched using the recipe 1Nitride which is based on CHF3. The difference of these two etches has not been investigate in details. Look in the table below to see what we know
Etching of silicon nitride using RIE can be done with several recipes. It can be etched by our standard  silicon etch recipe: OH_PolyA which is based on SF6. It can also be etched using the recipe 1Nitride which is based on CHF3. The difference of these two etches has not been investigate in details. Look in the table below to see what we know
===Some RIE recipes for etching of silicon nitride:===
{| border="2" cellspacing="0" cellpadding="7"
!Name
!SF6 flow
!O2 flow
!CHF3 flow
!N2 flow
!Pressure
!Power
|-
|'''OH_PolyA'''
|32 sccm
|8 sccm
|.
|.
|80 mTorr
|30 W
|-
|'''BGE-NITR'''
|.
|.
|8 sccm
|43 sccm
|38 mTorr
|50 W
|-
|}
===Expected result using the above RIE recipes for etching of silicon nitride:===
You should be aware that the result can deviate quit a lot from what is written here depending on ex. the mask loading.
{| border="2" cellspacing="0" cellpadding="8"
! valign="top" |Name
! valign="top" |Tested with mask load:
! valign="top" |Etch rate
!valign="top" |Anisotropy
!valign="top" |Selectivity to nitride:resist
!valign="top" |Selectivity to nitride:oxide
!valign="top" |Selectivity to nitride:silicon
!valign="top" |Comments
|- valign="top"
|'''OH_PolyA'''
|10-20%
|0.05 µm/min ''(tested before 2014)''
|?
|~1:1
|~2-3:1
|~1:13
|.
|-valign="top"
|'''BGE-NITR'''
|10-20%
|0.04 µm/min ''(tested before 2014)''
|Expected to be very anisotropic - not verified
|?
|~1:1
|~1:1
|Especially good to remove nitride on one side of the wafer avoiding getting anything etched on the back side.
|}
[[image:bc_5_7 jpeg.jpg|300x300px|left|thumb|SEM picture shoving the etch profile for a wafer with 150 nm nitride that has been etched in RIE1 which has been decommissioned but similar results are expected on RIE2. The wafer has been etched for 3.5 min with the recipe "BGE_NITR" (pressure increased to 42 mTorr), and most of the wafer (>99 %) has been etched. The structures are made with e-beam lithography, and the Al etch mask has been removed before the SEM inspection. Wafer tilted 45 degrees.]]

Latest revision as of 12:05, 24 March 2023

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Both RIE's (RIE1 and RIE2) for silicon based etching have been decommissioned

  • This information is save because it might be valuable as inspiration for other dry etch systems.

For a general introduction to RIE at DTU Nanolab see RIE (Reactive Ion Etch)

Etching of silicon nitride using RIE can be done with several recipes. It can be etched by our standard silicon etch recipe: OH_PolyA which is based on SF6. It can also be etched using the recipe 1Nitride which is based on CHF3. The difference of these two etches has not been investigate in details. Look in the table below to see what we know

Some RIE recipes for etching of silicon nitride:

Name SF6 flow O2 flow CHF3 flow N2 flow Pressure Power
OH_PolyA 32 sccm 8 sccm . . 80 mTorr 30 W
BGE-NITR . . 8 sccm 43 sccm 38 mTorr 50 W

Expected result using the above RIE recipes for etching of silicon nitride:

You should be aware that the result can deviate quit a lot from what is written here depending on ex. the mask loading.

Name Tested with mask load: Etch rate Anisotropy Selectivity to nitride:resist Selectivity to nitride:oxide Selectivity to nitride:silicon Comments
OH_PolyA 10-20% 0.05 µm/min (tested before 2014) ? ~1:1 ~2-3:1 ~1:13 .
BGE-NITR 10-20% 0.04 µm/min (tested before 2014) Expected to be very anisotropic - not verified ? ~1:1 ~1:1 Especially good to remove nitride on one side of the wafer avoiding getting anything etched on the back side.
SEM picture shoving the etch profile for a wafer with 150 nm nitride that has been etched in RIE1 which has been decommissioned but similar results are expected on RIE2. The wafer has been etched for 3.5 min with the recipe "BGE_NITR" (pressure increased to 42 mTorr), and most of the wafer (>99 %) has been etched. The structures are made with e-beam lithography, and the Al etch mask has been removed before the SEM inspection. Wafer tilted 45 degrees.
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