LAM 9400/Processes/LNF Aluminum

About this Process
Process Details
Equipment	LAM 9400
Technology	RIE
Material	Aluminum
Mask Materials	Photoresist, SiO2
Gases Used	BCl3, HBr
Date Created	November 2018
Authored By	Ashley Jian & Shawn Wright

This is a fast anisotropic aluminum etch.

Etch Profile

Etch Rates

These were measured using 1cm pieces on a 6" Si carrier. At this point we have limited data on how stable these etch rates are.

Main Etch

• Aluminum: 536 nm/min
• ALD Al2O3: 11 nm/min (49:1)

• SPR: 41 nm/min (13:1)
• SiO2: 36 nm/min (15:1)
• PMMA: 36 nm/min (15:1)
• ZEP: 29 nm/min (18:1)

Break Through

The breakthrough step is typically set to ~10 seconds, or enough time to get through any native oxide on the aluminum.

• Aluminum: 88 nm/min
• ALD Al2O3: 28 nm/min

• SPR: 29.6 nm/min
• SiO2: 48.4 nm/min
• PMMA: 73.4 nm/min
• ZEP: 49.4 nm/min
• GaN (N-Polar): 18.7 nm/min

SF₆ Ash

This is a short ashing step intended to replace Cl embedded in the sidewalls of the features with F in order to reduce how much corrosion happens when the sample encounters moisture in the air. Even small amounts of Cl on the surface of aluminum can form a HCl corrosion cell that can continually corrode aluminum. Below is an example of HCl corrosion on aluminum. It can also help to go from the etch directly into a DI water tank or QDR to attempt to rinse off any HCl.

Parameters

Parameter	Break Through	Main Etch	SF6 Ash
Pressure	5 mTorr	20 mTorr	20 mTorr
TCP Power	600 W	600 W	400 W
Bias Power	50 W	50 W	-
HBr Flow	25 sccm	40 sccm	-
BCl3 Flow	25 sccm	10 sccm	-
SF6 Flow	-	-	90 sccm
O2 Flow	-	-	10 sccm
Time	10 sec (typ)	Variable	20 sec (typ)