Date post: | 14-Dec-2015 |
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RvT comparison shows two distinct regions
Sharp transitions,High N2, high stress, smooth
Broad transitions,Low N2, lower stress, huge crevasses
Assume that measurement geometry is roughly constant, reasonable as chips identical and bonding likely to be similar.
High N2 fraction, high Tc TiN very smooth, irrespective of chamber
DSW016, 15:10 Ar:N2Tc=5.1KVery small , 25nm grainsRMS=0.25nm
MV028, 15:10 Ar:N2Tc=4.5KVery small, 25nm grainsRMS=0.4nm
Slightly reduced N2 TiN keeps smooth surface
DSW019, 15:2.5 Ar:N2Tc=4.7k~20nm grainsRMS=0.7nm
DSW024, 15:2.0 Ar:N2Tc=4.6K~20nm grainsRMS=0.4nm
Further reducing N2 leads to deep crevasses
45nm deep pits, comparable to film thicknessRMS roughness ~5nmSmall grains still visible if look very closely
DSW023 15:1.5 Ar:N2Tc~2K, ΔTc~1KMeso-scale nonuniformity causing broad Tc?
Lower Tc TiN similar, with deep crevasses
DSW021, 15:1.0 Ar:N2Tc=1.550nm deep pitsRMS=7nm
DSW022, 15:0.7 Ar:N2Tc=0.750nm deep pitsRMS=5nm
Open questions
• Is the reduced stress in the lower Tc films intrinsic or does the fractured surface relieve the stress?
• Does the fractured, rough surface matter? DSW026 similar to DSW023, and Jiansong saw high enough Qs at high power.
• If necessary, mitigate through thicker amorphous seed layer? Higher DC sample bias?