Chemistry Reference
In-Depth Information
The operating conditions for short silicon nanotips were:
chamber pressure 35 mTorr, RF power 100 W, ICP power 0 W, SF
gas
6
flow rate 65 sccm, O
flow rate 44 sccm, and substrate temperature
2
of 25
C. It has been done for 10 min. The two main features are:
first, more of O
°
gas has been flown into the chamber in order to
generate more O
2
−
radicals. However, in the silicon etching process,
the flow rate of SF
gas is generally a few times higher than that of
6
−
radicals for etching silicon
with high aspect ratio. These excessive O
the O
gas in order to generate more F
2
−
radicals will cause thicker
) as an etch mask layer. Second, the zero ICP
power. As described earlier, the ICP power predominantly controls
the chemical etch rate and RF power predominantly controls the
milling rate. Due to the zero ICP power, there is less chemical etching
of silicon by F ions. Figure 3.9 shows the microfabricated silicon
nanotips using the recipe described above. The height of the silicon
nanotips is less than 1
passivation layer (SiO
F
x
y
m. Surface analysis has confirmed that
the silicon is still crystalline and of device quality. The needles are
essentially structured crystalline substrate.
µ
Figure 3.9
SEM image of silicon nanotips formed on the silicon surface
(length less than 1
µ
m).
The operating condition for the long-height silicon nanotips
were: chamber pressure 50 mTorr, RF power 50 W, ICP power 950
W, SF
gas flow rate 65 sccm, O
flow rate 44 sccm, and substrate
6
2
Search WWH ::
Custom Search