A PowerPoint presentation with the process can be found here
The Google Docs spreadsheet with the current progress of the project can be found here

Abstract

The entire solar cell process depends on the:

• P⁺ (n-type region) Phosphrous donor atoms
• P⁺ (electric field region) Ionized immobile Phosphorous donor atoms
• B^- (electric field region) Ionized immobile Boron acceptor atoms
• B^- (p-typeregion) Boron acceptor atom and hole
  

The space charge layer contains the electric field with the ionized immobile atoms.

Solar cells fabricated on p-type 4" wafers
Resistivity (ρ) = 5-15 Ω-cm

Process Steps

1. Grow 5000A SiO2
   BTU Bruce Furnace
   

   Step	Time (min)	Temperature °C	Ambient
   Push In		800	N2
   Ramp Up	20	1000	Dry O2
   Soak	120	1000	Wet O2
   Ramp Down	40	800	N2
   Pull-Out

2. Level 1 Patterning
1. Dehydration Bake
2. HMDS Primer application
3. Photoresist Coating
4. Exposure (UV light 75 mJ/cm²)
5. Development
3. Backside Photoresist application
   Goal is to protect backside oxide. Adhesion promoter HMDS Primer is used @ 4500 rpm, using the hand coater. Hand coat using Shipley 812 photoresis. Dispense 8 ml again at 4500 rpm for 1 minute. Bake at 90 °C for 1 minute.
4. Oxide etch
   Etch in buffered HF for 8 minutes (est. etch rate of 1000A/min).
5. Resist Strip
   O2 Plasma etcher, 300 Watts, 1.0 sccm O2 flow, 45 min.
6. RCA Clean
7. Diffusion
1. Dispense Phosphorous dopant Emulsitone N-250
2. Hand Spin @ 3000 RPM for 1 minute
3. Bake for 20 min. at 20 °C
4. Push into Bruce Furnace (Tube 3, Recipe #120)