Wally’s dream jobWally’s dream job

The first process to be done:The first process to be done:Wafer CleaningWafer Cleaning

Wafers must be free of contamination at Wafers must be free of contamination at all stages of the antenna fabrication all stages of the antenna fabrication processprocess

Wafers are cleaned in a strong acid and Wafers are cleaned in a strong acid and rinsed in DI waterrinsed in DI water

Safety glasses and chemical gloves are Safety glasses and chemical gloves are required for this steprequired for this step

Once cleaned, wafers are ready for the Once cleaned, wafers are ready for the next processnext process

Engr 1202 ECE LabEngr 1202 ECE LabMicro Planar Antenna TravelerMicro Planar Antenna Traveler

OPERATION DATE DATE DATE DATE DATE DATE DATE DATE PROCESSNAME WF 1 WF 2 WF 3 WF 4 WF 5 WF 6 WF 7 WF 8 DESCRIPTION

Starting Material Silicon 100mm or other substrateClean Clean H2O2 / H2SO4 2:3 for 10 min Use 100ml:150ml for single wafer Rinse - DIH2O - 5 min minimum

Dip - 10:1 - DIH2O/HF - 10 secRinse - DIH2O - 15 minutes max Record resistivity ______________Dry - Rinser/Dryer - Dry only cycle

Dielectric Formation Use 1100C oxidation furnace # 6 Load wafers, N2 running

5' N2 to stabilize temperature5' N2 + O230' N2 + O2 + H2 (steam)5' N2 + O2Unload, N2 running

Deposit Conductor Conductor material ____________________Load conductor if necessary. Record machine name/number _________Start pump down cycle Record time at start _____________Begin deposition Record pressure at start _____________Record final thickness ____________AVent chamber and unload wafers

Create Mask Create autocad drawingArray drawing and print directly on to ink-jet transparency

Trim Mask Trim mask to about 105 mm diameterConductor Spin photoresist - 60 sec @ 4K rpm - Microposit 1813 photoresist Photolithography Soft bake - 60 sec hotplate @ 115C

Align - align wafer flat to stop on wafer chuckCheck mask aligner UV lamp intensityExpose - typical 10-15 sec.Develop - use either spray developer or manual developingInspect - lab manager or TA Strip PR and repeat if necessaryHard bake - 10' @ 90C (optional)

Conductor Etch Etch with appropriate etch solution. Record etch solution _____________Rinse in DIH2O for 10 minDry - Rinser/Dryer - Dry only cycle

Inspect - lab manager or TAPR strip 5' Acetone + 5' Methanol + 5' DIH2o rinse + N2 dryDice Saw cut with microautomation 1100 diamond saw Clean and dry

Safety Glasses

Chemical Gloves

Correctly labeled containers

Neat, organized work area

1.1. Pour 100 ml of Hydrogen Peroxide (H2O2) into a crystallizing Pour 100 ml of Hydrogen Peroxide (H2O2) into a crystallizing dishdish

2.2. Carefully add 150 ml of Sulfuric Acid (H2SO4) to the Hydrogen Carefully add 150 ml of Sulfuric Acid (H2SO4) to the Hydrogen PeroxidePeroxide

3.3. This solution is exothermic (creates heat) and may start to This solution is exothermic (creates heat) and may start to gently smoke gently smoke

4.4. Carefully place one wafer into the solution. The solution will Carefully place one wafer into the solution. The solution will start to bubble, this is due to the release of oxygen as the start to bubble, this is due to the release of oxygen as the Hydrogen Peroxide is reduced to H2O. This is a “one time” Hydrogen Peroxide is reduced to H2O. This is a “one time” only use cleaning solutiononly use cleaning solution

5.5. This cleaning mixture removes both organic material and This cleaning mixture removes both organic material and metallic materialmetallic material

6.6. This cleaning solution is known as “Piranha” clean as the This cleaning solution is known as “Piranha” clean as the rapid bubbling resembles attacking piranha.rapid bubbling resembles attacking piranha.

Crystallizing dishes marked for sulfuric Crystallizing dishes marked for sulfuric acid and hydrogen peroxide are used acid and hydrogen peroxide are used

to clean the wafersto clean the wafers

Place wafer into sulfuric acid/hydrogen Place wafer into sulfuric acid/hydrogen peroxide cleaning mixture using peroxide cleaning mixture using special wafer tweezers marked with special wafer tweezers marked with green tapegreen tape

Crystallizing dish

Wafer tweezers

CleaningCleaning solution solution

of 150 ml of 150 ml sulfuric sulfuric

acid into acid into 100 ml of 100 ml of hydrogen hydrogen peroxide peroxide

After 10 minutes in the sulfuric After 10 minutes in the sulfuric acid/hydrogen peroxide solution the wafers acid/hydrogen peroxide solution the wafers are loaded into a wafer carrier and put into are loaded into a wafer carrier and put into

the cascade DI water rinse for 5 minutesthe cascade DI water rinse for 5 minutes..

Wafer Carrier

Cascade DI water tank

After the 5 minute DI water rinse, the After the 5 minute DI water rinse, the wafer carrier is submerse in the 10% wafer carrier is submerse in the 10% HF bath for 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 After the HF dip, return the wafers to the cascade rinse tank and rinse in DI water for cascade rinse tank and rinse in DI water for

15 minutes or 12 mega-ohm resistivity, 15 minutes or 12 mega-ohm resistivity, which ever comes first.which ever comes first.

After complete DI water rinsing, the wafer After complete DI water rinsing, the wafer carrier is placed into the wafer dryer to dry carrier is placed into the wafer dryer to dry

the wafers and complete the cleaning the wafers and complete the cleaning processprocess

Nitrogen valve Nitrogen valve behind wafer behind wafer dryer must be dryer must be

turned on turned on before usingbefore using

Wafer carrier Wafer carrier must be must be carefully carefully

loaded into the loaded into the wafer dryer to wafer dryer to avoid breaking avoid breaking

waferswafers

Wafer DryerWafer Dryer

Clean the work area when wafer Clean the work area when wafer cleaning is completecleaning is complete. .

Wafer cleaning successfully Wafer cleaning successfully completedcompleted

Homework AssignmentHomework Assignment((If not already submittedIf not already submitted))

Assignment #8 –worksheet from web siteAssignment #8 –worksheet from web site1.1. Meet as a teamMeet as a team2.2. Record members in attendance and time of meetingRecord members in attendance and time of meeting3.3. Decide on application, Cellular, Bluetooth/Wi-Fi, RFIDDecide on application, Cellular, Bluetooth/Wi-Fi, RFID4.4. Determine frequency band to be usedDetermine frequency band to be used5.5. Find wavelengthFind wavelength6.6. Decide on antenna design length – preliminary choice, Decide on antenna design length – preliminary choice,

can be changed latercan be changed later7.7. Find antenna lengthFind antenna length8.8. Submit ONE worksheet per team (sample worksheet Submit ONE worksheet per team (sample worksheet

on next slide)on next slide)