Specific Process Knowledge/Etch/Wet Silicon Oxide Etch (BHF): Difference between revisions

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==Wet Silicon Oxide Etch (BHF, HF and BOE 7:1 Etchant VLSI with Surfactant (wetting agent))==

Silicon oxide can be etched using HF. At DTU Nanolab it is mainly used in a buffered version BHF (premixed). You can find safety datasheets on Kemibrug [http://kemibrug.dk here] The BHF has a more stable etch rate and is more gentle to photoresist due to an almost pH neutral solution which makes photoresist a good masking material for the oxide etch.  

BOE 7:1 Etchant VLSI with Surfactant (BHF with wetting agent) can also be used for etching silicon oxide. This is mainly for etching small holes. If you have wetting problems in BHF try the BOE 7:1 Etchant VLSI with Surfactant. It is also a good idea to wet the sample in water for a few minutes before etching.

Wafers with metals or other materials, not allowed in the dedicated oxide etch baths, can be etched using a '''plastic''' in Fume hood 01 or 02 (Acids/bases) in D-3. Samples with III-V materials (e.g. InP and GaAs) must be etched in Fume hood 07: III-V Avids/bases in D-3.

 

'''The user manual for various HF baths in RCA and Fume hoods, APV's and contact information can be found in LabManager''' [http://labmanager.dtu.dk/function.php?module=Machine&view=view&mach=64 by clicking here]

 

|style="background:WhiteSmoke; color:black"|<b>[[Specific_Process_Knowledge/Etch/Wet_Silicon_Oxide_Etch_(BHF)#Comparing_different_5.25_HF_baths|1% HF / 5% HF / 10% HF]]</b>

|style="background:WhiteSmoke; color:black"|<b>[[Specific_Process_Knowledge/Etch/Wet_Silicon_Oxide_Etch_(BHF)#SiO_etch_bath|BOE 7:1 Etchant VLSI with Surfactant]]</b>

*Mainly for etching deep into borofloat or quartz wafers. '''Only Nanolab staff are allowed to work with this HF'''.

|style="background:LightGrey; color:black"|Link to safety APV and SDS (You must be logged in to Kemibrug to view SDSs)

*:[http://labmanager.nanolab.dtu.dk/d4Show.php?id=1897&mach=64 see APV here]

*:[https://kemibrug.dk/Kemikalier/Action?id=RCU2MHolYzIlODIlN2UlYzIlODB2JWMyJTgxJTdleiVjMiU4N0RZeiVjMiU4OXYlN2UlYzIlODElYzIlODhESkhKSUxMVGQlYzIlODclN2N2JWMyJTgzJTdlJWMyJTg4diVjMiU4OSU3ZSVjMiU4NCVjMiU4MyVjMiU4OCU1ZVlSSQ==#K see SDS here]

*:[https://kemibrug.dk/Kemikalier/Action?id=RCU2MHolYzIlODIlN2UlYzIlODB2JWMyJTgxJTdleiVjMiU4N0RZeiVjMiU4OXYlN2UlYzIlODElYzIlODhERkZMSkhFR1RkJWMyJTg3JTdjdiVjMiU4MyU3ZSVjMiU4OHYlYzIlODklN2UlYzIlODQlYzIlODMlYzIlODglNWVZUkk=#K see SDS here]

*:[https://kemibrug.dk/Kemikalier/Action?id=RCU2MHolYzIlODIlN2UlYzIlODB2JWMyJTgxJTdleiVjMiU4N0RZeiVjMiU4OXYlN2UlYzIlODElYzIlODhERkZMSkhOSVRkJWMyJTg3JTdjdiVjMiU4MyU3ZSVjMiU4OHYlYzIlODklN2UlYzIlODQlYzIlODMlYzIlODglNWVZUkk=#K see SDS here]

*:[https://kemibrug.dk/Kemikalier/Action?id=RCU2MHolYzIlODIlN2UlYzIlODB2JWMyJTgxJTdleiVjMiU4N0RZeiVjMiU4OXYlN2UlYzIlODElYzIlODhERkVKS0lNTFRkJWMyJTg3JTdjdiVjMiU4MyU3ZSVjMiU4OHYlYzIlODklN2UlYzIlODQlYzIlODMlYzIlODglNWVZUkk=#K see SDS here]

*Wet thermal oxide:~6nm/min(1%) / 25nm/min(5%) / 52nm/min(10%)

*Thermal oxide 80 nm/min

*1% / 5% HF

*BOE 7:1 Etchant VLSI with Surfactant (BHF with a wetting agent)

<gallery caption="Different places to do wet silicon oxide etch" widths="420px" heights="425px" perrow="5"> image:BHF clean.JPG|BHF in wetbench 04 in D-3 (Oxide etch 2: BHF (clean)). Wet silicon oxide etch bath positioned to the right in the wetbench. This bath can also be used for BHF with wetting agent.  

image:KOH_BHF.JPG|BHF in wetbench 01 Si etch in D-3 (Oxide etch 1: BHF). The BHF bath is positioned in the middle of the bench. This is primarily used to remove oxide before and after a Si etch.

image:BHF clean.JPG|BHF in wetbench 05 in D-3 (Oxide etch 3: 10% HF). Wet silicon oxide etch bath positioned to the right in the wetbench. This bath can also be used for BHF, BHF with wetting agent or 40% HF on request. This bath is also used for cleaning quarts carriers from the PECVD4 system.

image:RCA-HF.jpg|HF baths in RCA bench in B-1. These may only be used together with RCA cleaning and furnace processes.

</gallery>

==Comparing different HF baths==

! 1% HF in RCA Bench

! 10% HF in D3 wet bench 5 (Oxide etch 3)

! 1% HF Plastic beaker

|2"- 6" wafers or any that fits in a dedicated holder

==40% HF==

{|border="1" cellspacing="1" cellpadding="2" style="text-align:left;"  

! 40% HF in Plastic beaker, only done by Nanolab staff

==BOE 7:1 Etchant VLSI with Surfactant bath==

! BOE 7:1 Etchant VLSI with Surfactant bath