Chemical

Update on 10/18/2002

**Etch used for Silicon etch/cross section**
Doped damaged Silicon	- 20-1 (HNO3-HF) (2 sec) Note: Will not etch properly if oxide is present over Silicon. Light source may aid to reaction rate. Check: Optically - Dash Etch Note: Light source may aid to reaction rate.
Cross section Doped Si	- 20 - 1 (HNO3-HF) (2 sec) Note: Refer above
Cross section Metallization	- KOH ( 5 sec)
Cross section Oxide	- BOE ( 2 sec) - 20 - 1 (HNO3-HF) (2 sec)
Nitride passivation	- CF4 + O2 plasma (6 min Plasmod; 4 min TEGAL) Note: Mask all Au with Al tape, photoresist, or silicon grease. 　 Plasma will etch SiO2. Be sure to purge chamber with gas prior to etching. Check: Bond pad area for line. Die color will chnage from yellow to clear although some Si3N4 initially appears to be clear. Scribe line area for overetch. - Hot phosphoric (H2PO4) , 1-2 sec Note: Will attack metallization. Etch rate is 6.6 nm/min at 180 C
CVD Oxide passivation	- BOE (Buffereed Oxide Etch) , 0.65 - 1.0 min Note: Will attack metallization. - 10% HF Note: HF will slightly attack metallization (rough appearance). Slight dip in 10% HF will "smooth" SiO2 for SEM exmination. Underetch for internal probing. Device typically loses functionality after short wet etch (10 sec) Etchant containing HF will attack silver die attach and leave silver residue on die surface. Check: Bond pad for line. Don't be confused by rough bond pad metallization. Internal probe checking for continuity SEM examination.
IMD (SiO2) Inter Metal Dielectric Ex: Metal 1 - Metal2 1 ILO	- BOE - 10 % HF - Modified Oxide etch Check: Metal 2 to metal 1 contacts. Where metal 2 had crossed over metal 1. SEM analayis.
ILO(Covered Metal)	- KOH (Room temp, 5 min) Check: Optical inspection
ILO(Covered Poly)	- Dilute poly etch ( 20 sec) Check: Optically and with SEM at both ILO and poly level.
Nitride	- KOH (Room temp, 5 min) Check: Bond pad areas. Optical inspection