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 SiO 2 on the wafer) Robot loader Gas Control Cabinet Quartz tube Quartz wafer carrier Temperatures can range from 900 o C to 1200 o C with uniformity of 2 o C 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 adjusted Load/Unload switch

Wafers entering the furnace

Typical Oxidation Process 1.Load in N minutes in N 2 and O 2 (dry oxidation) minutes N 2 +O 2 +H 2 (wet oxidation or steam oxidation) 4.5 minutes in N 2 +O 2 5.Unload in N 2

Wafers being unloaded Wafers are unloaded at the robot arm. Again, the quartz boats are never moved or touched

Once the SiO 2 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 #7 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 2/27 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