Processes

Thin films of gold can be deposited via sputtering or evaporation.

Sputtering:

Dep rate= 9.4nm/min, power=400W RF, pressure=10mT Argon, substrate height =120

Single-Layer Process Setup

1. Click on the“Edit” tab of the menu selection and then click “Process.” The Process Edit dialog box will show the setup of the last process run.
2. Click the “New” button in the dialog box. Add a name for the new process and click “Enter” to save the new name.
3. Click the “Layer” tab to assure the layer parameters are displayed.
4. Click the “Initial Rate” setting. This is the deposition speed and is measured in A/s. The “Final Thickness” can be adjusted to a thickness measured in kA. Note: 1kA=100nm

A process for anisotropic bulk etching of silicon wafers is available at MMF. A dedicated temperature controlled bath with a cooled lid is located in the Base/Litho bench. This bath has 0.1C temperature control and features a coolant loop around the bath lid acting as a condenser, preventing loss of etchant thereby maintaining etchant concentration.
MMF stocks 25% by weight electronic grade TMAH in water.

• The Alumina etch utilizes a C4F8, CHF3 and Ar chemistry to slowly etch away the resistant alumina film.
• The Oxford ICP 100 etcher is used with this chemistry and the etch rate has been measured to be about 50 nm/min
• This gas chemistry will etch Si, so be sure to stop fairly quickly after the alumina is completely etched.
• Surface roughness seems to vary on etch time. Be sure to measure with the Ambios Profilometer

• The Oxford Plasmalab ICP 100 etcher utilizes an etch chemistry of C4F8 and oxygen to etch the silicon dioxide while stopping quite well on microscope glass and Si.
• The etch rate has been measured to be about 300 nm/min.

• The Oxford Plasmalab ICP 100 uses CHF3, oxygen and argon to etch lithium niobate.
• The etch rate seems to vary significantly but was measured at about 20 nm/min.
• As etch time increases the etch seems to slow as a passivation layer is formed on the lithium niobate sample.

Two methods to apply HMDS coating on:

1. YES Vapor Prime Oven protocol coat. Preferred.

2. 20% HMDS spin coating.

Operating the contact aligner:

1. Turn on the power supply located under the bench
   1. If not turning on flip breaker- press and hold start
   2. Wait 30 min and try again
2. Turn on the power to the aligner
3. Turn on the nitrogen
4. Turn on the vacuum
5. Test intensity of the bulb
1. Place the intensity meter on top of the chuck
2. Set exposure system to manual
3. Move exposure system to “expose” position (switch locate on the right side of the aligner)

Headway Spinner Bench
Operating Instructions

1. Place tin foil, orange absorbent pad or cleaning wipe in the spin bowl to keep bowl clean.
2. Choose 3”, 4” or small chuck and make sure chuck has O-ring in place for vacuum suction. Place the chuck in the spinner bowl making sure the flat edge of the chuck is aligned with the flat edge on the connection, and fully press the chuck in the bowl.

Photolithographic Process for S 1813 Positive Photoresist on Al Coated Si Wafer

1. Clean Al Coated Wafers
   1. Heat AZ KWIK Strip Remover to 60 °C.
   2. When bath is at temperature, place wafer in dish and start 10 minute timer.
   3. When time is complete, take wafer out of KWIK Strip and wash off with deionized water. Blow dry with nitrogen gun.
2. Dehydration Bake
   1. Place cleaned Al coated Si wafer on vacuum hot plate, and perform a dehydration bake for 10 minutes at 150 °C. Let the wafer cool to room temperature after bake.
3. Spin Coat Wafers with S 1813.

Photolithographic Process for AZ 1512 Positive Photoresist on Bare Silicon Wafer

1. O2 Plasma Clean in PVA.
2. Adhesive promotor coating: Programmed HMDS coating (Program 1)
3. Spin coating:(Note. To ensure adhesive promotor active, start PR spin coating right after HMDS coating.) 
   1. Dispense sufficient amount of AZ 1512 from the center of the wafer covering 50% of the wafer surface.
   2. Spin at 3000 rpm for 30 s with an acceleration of 3000 rpm/s.
4. Soft Bake: 110°C (1 min)
5. Exposure: 2.4 seconds with expose dose ~40 mJ.
6. Develop:
   1. 50 seconds gentle agitation in AZ 300MIF solution.
   2. (Optional) Stir the wafer slightly to remove red PR residue floating on top of wafer.
7. Rinsing: Dip into water to remove developer
8. Dry: Blow dry the wafer with compressed Nitrogen gun. 

SEMITOOL SPD015
Operating Instructions

1. Make sure that the MAIN and SYS lights are green on the oxidation wet bench.
2. Turn on the appropriate controller for the SRD bowl using the ON/OFF switch.
3. While pressing the Door Release Latch button, open the desired door and insert wafer or mask holder cassette. Close door while still holding the Door Release Latch button until door is secure.
4. Press Start button for desired spin rinse dryer.

To release wafers bonded using Dyantex wafergrip a specialized solvent called Stripaid is used. An attached PDF provides process detail for the use of this solvent. Be aware that the order of steps is very important, acetone evaporates quickly so a fast transfer into 2-proponal (isoproponal) is crucial, else residue may dry on the substrate that will prove difficult to remove.
Remember to have the following bath ready before removing wafers from solution for all the steps.