LAM 9400/Processes/LNF Aluminum

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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

LAM 9400 Aluminum 500nm.png
LAM 9400 Aluminum 700nm.png
LAM 9400 Aluminum 3000nm.png

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.

Aluminum corrosion on lines.jpg

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)