2013-11

2013-11Edit

2013-10-04

test wafer, sputter clean room spec
vacuum ~1.8 e-7 mb (to check). Pumped over night
clean sample, DC plasma 60V, 1' P_Ar = 1.1 e-2 mb (to check)
clean source, 1' @ 500W (I=, V=)
open shutter, 1.9 - 2nm/s
150nm

14/11

Desoxydation wafer (Hélène, SPEC) 
    HF:ODI 1:20, 30"
    rinçage ODI 30"

Same sputter on BPC1, except P ~2.5e-7 (to check). Pumped 3hrs

mercredi 20/11

Resist process

bake 1' @ 110°C (solvent evaporation)
spin S1813 (batch A016B7G001, per 15/07/2012) 60" @ 4krpm
bake 2' @ 110°C

Have to clean both wafers (ethanol + IPA) and reprocess -> OK for dust

Expo MJB4 150mJ/cm2 @ 10mW/cm2 = 15" Vac contact

Dev MF319 45" @ 19.0°C, rinse ODI 60" bescher + 30" water tap

Etch Nb

RIE CF4/Ar 20/10, P=50µb, 50W.
Témoin, au bout de 3'15 le signal laser commence à descendre, 4' est en bas, rajoute 20" (~10%)(voit interférences dans SiO2)
Wafer BPC1: idem, se produit de la même manière.

/!\ Résine a chauffé, se voit sur les bords du wafer. Réticulée.

jeudi 21/11

Témoin: Remove aceton: ne part pas bien. Met ensuite 10' remover 1165. Résidus visibles au microscope (ci-dessous à droite)

- délaqueuse 20cc O2, 100W, 5'  (ci-dessus à droite) -> OK!!

Wafer BPC1: remove hot aceton + hot NMP (1165) 40' + 5' US -> remains the same amount of residues (or a bit less)
ozone plasma cleaner, 1'30 -> seems OK visually.

STEP 2: bilayer process for tunnel junction

I'll try PMGI SF8 / PMMA A6
I have had hard times with MAA / PMMA bilayers, especially with the proximity effect due to the undercut dose.
Now, I'm leaving this to develop PMGI/PMMA, and see if we get better -easier- results.

See e-beam bilayer processing guidelines

resist bilayer process

spin PMGI SF8 (batch 1206047, exp. 7/1/2013) @ 3000rpm 60" -> in principle 500nm
bake hot plate 173.2°C (measured: 160°C), 5'
spin PMMA A6 (batch 11060394, exp. 7/1/2012) @ 6000rpm 60" 
    -> in principle 240nm - 280nm (selon endroit sur wafer semble-t-il)
bake hot plate 173.2°C, 10'
spin UV III @ 4000rpm 60"
bake hot plate 140°C, 60"

NB: measure hot plate temperature with testo termometer -> 160°C, when set for 173.2°C... (and 104°C when set for 111°C)

Do this on test wafer BPCT1 + bilayer development wafer (Si 100 doped standard) BPCD7 (check name)
! On test wafer, have to remove PMGI because of bad spin
Remover PG -> does not clean completely
Remover 1165 (just a try) -> does not work
Aceton -> does not work
MF319 -> OK (~2' to remove residuals)

then bake hot plate for 2' to evaporate water from rinse, and respin test wafer
NB: on development wafer, there are traces of non uniform spin. On test wafer, the spins are very uniform.

Cleave on scriber