Specific Process Knowledge/Etch/ICP Metal Etcher/silicon oxide/By BGHE

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I tried with two different gas regimes: CF4 and C4F8. I only made a few tests with CF4 since I got a very bad selectivity to the resist mask and I dicided to go for the C4F8 instead.

C4F8

I started out with a recipe developed by Peixiong called pxSiO2try9, look at his results here

Parameter Mask material Barc etch Coil power Platen power Pressure Flow rate C4F8 Flow rate H2 Flow rate Ar T Process time Comment Results CD change (mask 55% trench) after s007467 is it <50% after barc etch

trench opening as a fraction of pitch

Profile angles Etch depth in SiO2 Etch rate Etch depth in resist Selectivity (resist:SiO2) Etch rate in Si
s008684 880nm KRF barc etch CF 50s 1000W 200W 2.5mTorr 13sccm 30sccm 0 0 1:30min The layer in this case is 300nm Si3N4

35% (1µm pitch)
47% (6µm pitch)

83-88

>300nm/min (Si3N4)

240nm

~1:2 (Si3N4)

?

s007419 750nm KRF none 800W 200W 2.5mTorr 8sccm 30sccm 0 0 5min Increased the platen power. The selectivity and profile looks good but the resist profile has been rounded more on the edge and this will effect the profile for a deeper etch.

46.6% (1µm pitch)
47.8% (2µm pitch)
48.4% (4µm pitch)

86-90

270nm (1µm pitch)
400nm (2.5µm pitch)

54 nm/min (1µm pitch)
80 nm/min (2.5µm pitch)

100nm

1:4 (2.5µm pitch)

s007410 750nm KRF none 800W 75W 2.5mTorr 8sccm 30sccm 0 0 7min Reduced the platen power.Effect: ARDE - less CD increase but more possitive ptappered profile.

42.3% (2µm pitch)
47.0% (average) (3µm pitch)

80-82

0 nm (1µm pitch)
270 nm (3µm pitch)

0 nm/min (1µm pitch)
39nm/min (?µm pitch)

100nm

1:0 (1µm pitch)
1:2.7 (2µm pitch)

s006656 750nm KRF none 1000W 150W 2.5mTorr 15sccm 0sccm 30sccm 0 10min Tried with C4F8/Ar instead of C4F8/H2 => much lower etch rate and bad selectivity to the resist.

358 nm

35.8 nm/min (2µm pitch)

526nm

1:0:68

s007409 750nm KRF none 800W 150W 2.5mTorr 8sccm 30sccm 0 0 5min Repeated Pexiongs recipe without barc etch and only 5 min's runs. It probably takes about 1 min to get through the barc. If you count that in then the etch rate and relectivity to resist is almost the same as for the first run. Effect: CD increase

47.4% (1µm pitch)
47.5% (2µm pitch)
50.0% (3µm pitch)

86-89

280 nm (1µm pitch)
370 nm (2µm pitch)

56 nm/min (1µm pitch)
74 nm/min (2µm pitch)

160nm

1:1.8 (1µm pitch)
1:2.3 (2µm pitch)

s006106 750nm KRF Barc etch O2 75s 800W 150W 2.5mTorr 8sccm 30sccm 0 0 10min From Peixiong

60%

79

1053 nm (center)
1043 nm (edge)

105 nm/min

280nm

1:3:75 (2µm pitch)

CF4

I stopped trying with CF4 because I got bad selectivty to the resist and decided to focus on the recipe with C4F8 instead.

Parameter/Wafer ID s006687 s006701 s007258 s007350 s007352
Mask material 750nm KRF 750nm KRF 750nm KRF 750 nm KRF 750nm KRF
Barc etch none none none none none
Coil power 800W 800W 800w 800w 800w
Platen power 100W 100W 100w 60W 30w
Pressure 4mTorr 4mTorr 4mTorr 4mTorr 4mTorr
Flow rate CF4 20sccm 25sccm 30sccm 30sccm 30sccm
Flow rate H2 20sccm 15sccm 10sccm 10sccm 10sccm
T 0 0 0 0 0
Process time 10min 10min 2min30 2min30 3min30
Comment Little resist left, Trenching A little trenching very little trenching in large lines - anti trenching in small lines
Results
profile near edge
Profile near middel
tilted
profile
s007350 2µm pitch
s007350 2µm pitch
s007350 1µm pitch
s007352 1µm pitch
s007352 2µm pitch
Etch depth in SiO2 374nm 505nm 578nm 336nm 235nm
Etch rate 37.4nm/min 50.5nm/min 231nm/min 134.4nm/min 88nm/min
Etch depth in resist 345nm 633nm 700nm 405nm 308nm
Selectivity (resist:SiO2) 1:1.1 1:0.80 1:0.83 1:0.83 1:0.76