Wally’s dream job

The first process to be done: Wafer Cleaning Wafers must be free of contamination at all stages of the antenna fabrication process Wafers must be free of contamination at all stages of the antenna fabrication process Wafers are cleaned in a strong acid and rinsed in DI water Wafers are cleaned in a strong acid and rinsed in DI water Safety glasses and chemical gloves are required for this step Safety glasses and chemical gloves are required for this step Once cleaned, wafers are ready for the next process Once cleaned, wafers are ready for the next process

Engr 1202 ECE Lab Micro Planar Antenna Traveler

Safety Glasses Chemical Gloves Correctly labeled containers Neat, organized work area

1. Pour 100 ml of Hydrogen Peroxide (H2O2) into a crystallizing dish 2. Carefully add 150 ml of Sulfuric Acid (H2SO4) to the Hydrogen Peroxide 3. This solution is exothermic (creates heat) and may start to gently smoke 4. Carefully place one wafer into the solution. The solution will start to bubble, this is due to the release of oxygen as the Hydrogen Peroxide is reduced to H2O. This is a “one time” only use cleaning solution 5. This cleaning mixture removes both organic material and metallic material 6. This cleaning solution is known as “Piranha” clean as the rapid bubbling resembles attacking piranha.

Crystallizing dishes marked for sulfuric acid and hydrogen peroxide are used to clean the wafers

Place wafer into sulfuric acid/hydrogen peroxide cleaning mixture using special wafer tweezers marked with green tape Crystallizing dish Wafer tweezers Cleaning solution of 150 ml sulfuric acid into 100 ml of hydrogen peroxide

After 10 minutes in the sulfuric acid/hydrogen peroxide solution the wafers are loaded into a wafer carrier and put into the cascade DI water rinse for 5 minutes. After 10 minutes in the sulfuric acid/hydrogen peroxide solution the wafers are loaded into a wafer carrier and put into the cascade DI water rinse for 5 minutes. Wafer Carrier Cascade DI water tank

After the 5 minute DI water rinse, the wafer carrier is submerse in the 10% HF bath for After the 5 minute DI water rinse, the wafer carrier is submerse in the 10% HF bath for 10 seconds. Be very careful around HF HF bath 10% HF - 90% DI water

After the HF dip, return the wafers to the cascade rinse tank and rinse in DI water for 15 minutes or 12 mega-ohm resistivity, which ever comes first.

After complete DI water rinsing, the wafer carrier is placed into the wafer dryer to dry the wafers and complete the cleaning process Nitrogen valve behind wafer dryer must be turned on before using Wafer carrier must be carefully loaded into the wafer dryer to avoid breaking wafers Wafer Dryer

Clean the work area when wafer cleaning is complete.

Wafer cleaning successfully completed

Finished Antenna Wafer Light Bulb Sailboat

Finished Antenna Wafer Shopping cart Star

Completed antenna chips

Homework Assignment Assignment #8 –worksheet from web site Assignment #8 –worksheet from web site 1. Meet as a team 2. Record members in attendance and time of meeting 3. Decide on application, Cellular, Bluetooth/Wi-Fi, RFID 4. Determine frequency band to be used 5. Find wavelength 6. Decide on antenna design length – preliminary choice, can be changed later 7. Find antenna length 8. Submit ONE worksheet per team (sample worksheet on next slide)