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)

Robot loader

Gas Control Cabinet

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

Nitrogen gas is ALWAYS

“ON”

T/C POS and Auto Ign “ON”

Power lamp does not work

Manual mode only

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

Speed is NOT

adjustedLoad/Unload switch

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

Test on Monday

• Multiple choice plus some calculation problems

• Test will cover– Four research areas – Cellular, “Bluetooth” &

Wi-Fi, RFID, GPS– Clean room safety and protocols– Finding wavelength from frequency and finding

frequency from wavelength– Study guide will be sent via e-mail