View source for Specific Process Knowledge/Etch/III-V RIE/III V RIE ETCHES

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==CHF3/O2 etch==

A plasma with a gas mixture of CHF<sub>3</sub> and O<sub>2</sub> is used to etch SiO<sub>2</sub> and Si<sub>3</sub>N<sub>4</sub> dielectricas; flour radicals are responsible for etching the dielectrica while oxygen removes the polymer that is formed during the etch. The polymer deposition rate and SiO<sub>2</sub>  etch rate are very sensitive to the flow ratio of CHF<sub>3</sub>  and O<sub>2</sub> . The current processes have been optimized from this point of view.

There are 3 standard programs:


{| border="1" style="text-align: center; width: 1000px; height: 350px;"
! colspan="8" style="text-align: center;" style="background: #efefef;" | CHF<sub>3</sub>/O<sub>2</sub> etch rates, nm/min
|-
! scope="row" width="15%" |Process Name
! width="40%" |Process parameters
! width="10%" |SiO<sub>2</sub>
! width="10%" |Si<sub>3</sub>N<sub>4</sub>
! width="10%" |AZ5206
! width="10%" |ZEP520A
! width="10%" |Negative DUV: UVN 2030-0.5
! width="60%" |Comments/links
|-
!SiO2_602 
!
*CHF<sub>3</sub>-flow: 16 sccm, 
*O<sub>2</sub>-flow: 2 sccm,
*Power = 60 W,
*Vbias = 325 V,
*Process pressure = 100 mTorr
|30'''<sup>{(1)}</sup>'''
|&nbsp;
|29'''<sup>{(2)}</sup>'''
|36'''<sup>{(3)}</sup>'''
|&nbsp;
|&nbsp;
|-
!High selectivity to resist
!
*CHF<sub>3</sub>-flow: 17 sccm, 
*O<sub>2</sub>-flow: 0 sccm,
*Power = 150 W,
*Vbias = ? V,
*Process pressure = 150 mTorr
|85
|&nbsp;
|&nbsp;
|&nbsp;
|10.6
|''Done dec2019/jan2020 by Qugig@nanolab and bghe@nanolab''
|-
!Lower etch rate, medium selectivity to resist
!
*CHF<sub>3</sub>-flow: 17 sccm, 
*O<sub>2</sub>-flow: 0 sccm,
*Power = 100 W,
*Vbias = ? V,
*Process pressure = 20 mTorr
|49-62 (depending on conditioning)
|&nbsp;
|&nbsp;
|~12
|&nbsp;
|''Done dec2019/jan2020 by Qugig@nanolab and bghe@nanolab'' [[/Details SiO2_100|Images and reproducibility]]
|-
!Si3N4Ti
!
*CHF<sub>3</sub>-flow: 16 sccm, 
*O<sub>2</sub>-flow: 2 sccm,
*Power = 23? W,
*Vbias = ? V,
*Process pressure = ? mTorr
|&nbsp;
|38
|&nbsp;
|&nbsp;
|&nbsp;
|&nbsp;
|-
<!-- recipe wrong other parameters on RIE
!Si3N4Std'''<sup>{(4)}</sup>'''
!
*CHF<sub>3</sub>-flow: 15 sccm, 
*O<sub>2</sub>-flow: 1 sccm,
*Power = 13 W,
*Vbias = 200 V,
*Process pressure = 10 mTorr
|6
|17
|&nbsp;
|&nbsp;
-->
|}

'''(1)''' Measured with laser reflectometry 106 (?) nm on G360 fully etched after 3:30: 05-10-11
'''(2)''' From Dektak measurement on G360 2005-10-11
'''(3)''' From Dektak measurement on D002 (I & II) 2005-10-12. D002 is a pure InP-wafer.
'''(4)''' Etch rate measured on 140nm wide holes

== CH4/H2 etch==

This plasma etch is used for etch of InP and InGaAs(P).

In order to ensure unchanged etching conditions during etch, the chamber needs to be primed before using this etch. There are 2 priming programs, '''clecond''' and '''precond'''. '''Clecond''' also cleans the chamber with Oxygen before priming it. 

There are 2 standard etch programs for etching InP, InGaAs and InGaAsP: '''InPstd''' is for InP-etch while '''InGaAs1''' is for InGaAs- and InGaAsP-etch.

The etch-rates for the CH<sub>4</sub> / H<sub>2</sub> etch depends highly on the total etching area and on the size of the structrures that are etched, eg ridges or small holes. All rates are given for a total etch area of 2 inches and for etching of ridges, if not otherwise commented. Dektak has been used for the measurement if nothing else is mentioned.


{| border="1" style="text-align: center; width: 600px; height: 350px;"
! colspan="7" style="text-align: center;" style="background: #efefef;" | CH<sub>4</sub>/H<sub>2</sub> etch rates, nm/min
|-
! scope="row" width="10%" |Process Name
! width="40%" |Process parameters
! width="10%" |InP
! width="10%" |InGaAs
! width="10%" |GaAs
! width="10%" |AlAs
! width="10%" |SiO<sub>2</sub>
|-
!InPstd 
!
*CH<sub>4</sub>-flow: 8.4 sccm, 
*H<sub>2</sub>-flow: 42 sccm,
*Power = 60 W,
*Vbias = 450 V,
*Process pressure = 80 mTorr,
*Base pressure = 0.01 mTorr
|29
|9
|&nbsp;
|&nbsp;
|1
|-
!InGaAs1
!
*CH<sub>4</sub>-flow: 8.4 sccm, 
*H<sub>2</sub>-flow: 42 sccm,
*Power = 60 W,
*Vbias = 450 V,
*Process pressure = 80 mTorr,
*Base pressure = 0.01 mTorr
|29
|9
|&nbsp;
|&nbsp;
|&nbsp;
|}

==BCB polymer and Resist etch==

The BCB-etch is mainly a O<sub>2</sub> etch but a small amount of CHF<sub>3</sub> is added to remove Si.
There are 3 standard processes: '''BCB_LP''' and '''BCB30LP''' are low pressure (anisotropic) medium power etches for planarization of BCB, while '''BCB100W''' is a high power etch to totally remove thick layers of BCB.

Other resists (ZEP520A, AZ-resists) can be etched by a O<sub>2</sub> etch. The standard program is called '''ASH?m''', where the process time is optional.

{| border="1" style="text-align: center; width: 600px; height: 350px;"
! colspan="5" style="text-align: center;" style="background: #efefef;" | O<sub>2</sub>/CHF<sub>3</sub> etch rates, nm/min
|-
! scope="row" width="10%" |Process Name
! width="40%" |Process parameters
! width="10%" |BCB
! width="10%" |SiO<sub>2</sub>
! width="10%" |AZ5214

|-
!BCB_LP 
!
*CHF<sub>3</sub>-flow: 3 sccm, 
*O<sub>2</sub>-flow: 12 sccm,
*Power = 30 W,
*Vbias = 220 V,
*Process pressure = 10 mTorr
|70 +/- ?
|6 +/- ?
|&nbsp;
|-
!BCB30LP
!
*CHF<sub>3</sub>-flow: 6 sccm, 
*O<sub>2</sub>-flow: 24 sccm,
*Power = 30 W,
*Process pressure = 10 mTorr
|127
|&nbsp;
|&nbsp;
|-
!BCB100W
!
*CHF<sub>3</sub>-flow: 10 sccm, 
*O<sub>2</sub>-flow: 42 sccm,
*Power = 100 W,
*Vbias = ~540 V,
*Process pressure = 100 mTorr
|880
|&nbsp;
|815
|}



{| border="1" style="text-align: center; width: 600px; height: 170px;"
! colspan="6" style="text-align: center;" style="background: #efefef;" | O<sub>2</sub>/ etch rates, nm/min
|-
! scope="row" width="10%" |Process Name
! width="40%" |Process parameters
! width="10%" |BCB
! width="10%" |ZEP520A
! width="10%" |AZ5214
! width="10%" |SiO<sub>2</sub>
|-
!ASH?m 
!
*O<sub>2</sub>-flow: 50 sccm,
*Power = 20 W,
*Vbias = ~170 V,
*Process pressure = 150 mTorr
|?
|98
|70
|6 +/- ?
|}

==Chamber Cleaning==

Cleaning of the chamber is very important to achieve reproducible etch results. After every etch the chamber should be cleaned. For most CHF<sub>3</sub>/O<sub>2</sub> etch programs a simple '''clean''' procedure is sufficient. When BCB has been etched one must use '''cleanbcb''', where CHF<sub>3</sub> is added. If CH<sub>4</sub> is used in the process (all programs etching III-V compounds) a '''vlclean''' procedure is necessary. 


{| border="1" style="text-align: center; width: 600px; height: 170px;"
! colspan="6" style="text-align: center;" style="background: #efefef;" | Cleaning programs
|-
! scope="row" width="20%" |Process Name
! width="15%" |O<sub>2</sub>-flow (sccm)
! width="15%" |Pressure (mTorr)
! width="15%" |Power (W)
! width="15%" |Vbias (V)
! width="15%" |Time (min)
|-
!clean
|50
|&nbsp;
|&nbsp;
|&nbsp;
|10
|-
!Lclean
|50
|&nbsp;
|&nbsp;
|&nbsp;
|20
|-
!vlclean
|50
|&nbsp;
|&nbsp;
|&nbsp;
|30
|-
!cleanbcb
|50
|100
|100
|&nbsp;
|10
|}