Dear all,

I met a problem when I doing the lift-off after the E-ebeam lithography.

I tried to make some wire array (4-10) between two pads. The wire width is
200nm and the spacing is 10um. I use the E-beam lithography machine to
make this pattern on the PMMA(950M A6, 300nm thickness) and e-beam
evaporation 100A Cr/1000A Au and do the lift-off. But the at the inner part
of the
array (the area of the middle 4-6 wires), the metal can not be removed,
still stick on the wafer while other part is ok. That means the metal which
has large size can be removed but the some parts (gaps between the wires)
can not. I tried to heat, stir the acetone solution and dipped them for 24
hours but the problem is still existing.

Does anyone met the same problems before or have some suggestions?

Sincerely,
Zhiwei Zou