Procedure – BOE Etching (Buffered Oxide Etch) for solar cell wafers
· Turn on DI water system in service bay
· Always use safety goggles and chemical gloves when working with chemicals
· BOE contains HF, before use, understand the dangers of HF
1. Load the wafers to be etched in BOE into a wafer carrier using green tape tweezers. Position wafers so backside is visible when looking at the wafers in the BOE
2. Carefully remove the lid from the BOE
3. Carefully place the wafer carrier into the BOE bath. Add BOE if the wafers are not completely covered.
4. For solar cell wafers, etch time is 12 -15 minutes. All SiO2 must be removed from both the front and back. Backside SiO2 is thicker than the front side and will take longer to remove.
Incomplete removal of all SiO2 – note the BOE adheres to the silicon wafer
Complete removal of all SiO2 – note the BOE does not adhere to the backside
5. Remove the wafer carrier from the BOE and place into the cascade rinse tank. Use a tray to catch any drips from the wafer carrier as it is moved.
6. Rinse to 12 mega-ohm
7. Remove wafer carrier from cascade rinse.
8. Load wafer into rinser/dryer wafer carrier - Do not mix cleaning and rinser/dryer wafer carriers. Do not use tweezers to transfer the wafers, dump transfer between carriers. The rinser/dryer wafer carrier has a red and yellow button on one end.
9. Turn on nitrogen for rinser/dryer (located behind rinser/dryer)
10. Start rinser/dryer
11. At the end of the dry cycle, remove the wafer carrier and turn off rinser/dryer nitrogen.
12. Dump transfer wafers for the rinser/dryer wafer carrier to your original wafer carrier.
13. Return the rinser/dryer wafer carrier to the rinser/dryer
Procedure - BOE etching (Buffered Oxide Etch) for solar cell wafers revised 7-6-2015.docx 7/6/2015