Dilbert
Next steps in the antenna
fabrication process
• Create a dielectric surface. The antenna
must sit on a dielectric or insulating
surface, not a semi-conducting surface.
• Determine the best conductor for the
antenna. The actual antenna will be made
out of a conducting metal
High Temperature Furnace
(used to grow SiO2 on the wafer)
Gas
Control
Cabinet
Robot
loader
Quartz
tube
Quartz
wafer
carrier
Temperatures can range from 900oC to 1200oC
with uniformity of 2oC over a distance of 36 inches
Furnaces are color coded to prevent contamination.
Furnace # 7 is marked as “RED” and is used only for silicon
dioxide formation on virgin clean wafers
Quartz
wafer
carrier is
never
removed
from robot
arm
Oxygen tanks in service bay
Check oxygen
tanks in service
bay for proper
pressure
Hydrogen tank in service bay
Check
hydrogen tank
for proper
pressure
Furnace gas cabinet-controls the
atmosphere inside each furnace tube
Furnace gas
cabinet
Gas panel for furnace #6
Verify all
gauges read
about 20 psi
Power lamp
does not
work
Manual
mode only
Nitrogen gas
is ALWAYS
“ON”
T/C POS
and Auto
Ign “ON”
Loading wafers
Wafers are
loaded into
quartz oxidation
boats at the
furnace.
Quartz boats
are NEVER
moved or
touched
Robot Loader to insert and remove
wafers from the furnace
Load/Unload
switch
Speed is
NOT
adjusted
Wafers entering the furnace
Typical Oxidation Process
1. Load in N2
2. 5 minutes in N2 and O2 (dry
oxidation)
3. 30-60 minutes N2+O2+H2 (wet
oxidation or steam oxidation)
4. 5 minutes in N2 +O2
5. Unload in N2
Wafers being unloaded
Wafers are
unloaded at the
robot arm.
Again, the quartz
boats are never
moved or
touched
Once the SiO2 is formed, the wafers will
have a different color, wafer color is based
on the thickness of the SiO2
Besides being a dielectric
(insulating) layer, the SiO2 has
another very important role to
play in microelectronics,
that of a barrier to the doping of
silicon
n-type silicon wafer shown in cross-section
At high temperature with an oxygen atmosphere
the silicon dioxide forms on all silicon surfaces
Using a photolithography process, small holes are
created in the silicon dioxide exposing bare silicon
Again, at high temperature, a p-type dopant
(boron) is introduced. The boron can not
penetrate the silicon dioxide but can penetrate the
bare silicon and diffuses into the silicon forming a
p-n junction
If a diode was the end product, the silicon dioxide
is removed from the back side (if not already
removed in previous steps) and metal contacts,
usually aluminum are deposited on top and bottom
creating a p-n diode.
For more complex devices, the steps are
repeated
Once the dielectric has been
formed on the silicon wafer
• It is time to decide on a conductor to
create the antenna.
• Conductor attributes will be evaluated
• Your team will create a decision matrix
using a simple EXCEL spreadsheet to
determine the conductor for your project
• The conductor chosen will be deposited on
your wafers next week
Conductor Attributes
Sample Conductor Decision Matrix
• Create a title for the spreadsheet
• Decide on weights for each attribute
• Decide on conductor rank for each attribute based on attributes chart
• Multiply weight times rank for each conductor
• Add the columns
• The conductor of choice is the one with the largest total
Homework
• Create a conductor decision matrix using the conductor
attributes chart.
• Homework #9 on the web site
• Both the conductor attributes chart and a sample
decision matrix are available on the web site
• This is a team assignment, only one per team
• Preview before submission
– Make sure entire spreadsheet prints on one page
– Include “Title” with team name
– Use gridlines
– Highlight the conductor of choice