Etch Characteristics of Cofesib Magnetic Films Using Inductively Coupled Plasma Reactive Ion Etching for Magnetic Random Access Memory

Abstract

Inductively coupled plasma reactive ion etching of CoFeSiB magnetic thin films was studied in a Cl 2 /O 2 /Ar gas mix. The etch rate, etch selectivity and etch profile of this magnetic film were examined on varying gas concentration, coil rf power, gas pressure and dc-bias voltage. As the Cl 2 gas increased, the etch rate monotonously decreased and etch residues decreased but etch slope was slanted. The use of the TiN hard mask gave rise to high selectivity of CoFeSiB to the TiN mask due to large decrease in etch rate of TiN in Cl 2 /O 2 /Ar gas mix. The addition of O 2 into the gas mix led to the anisotropic etching of CoFeSiB films without the etch residues.

A study on the etching characteristics of magnetic tunneling junction materials using DC pulse-biased inductively coupled plasmas

“…have been investigated as alternate techniques in improving these disadvantages. [16][17][18][19] But plasma etching using halogen-based gas such as Cl 2 causes other problem such as corrosion and also causes heavy redeposition on the sidewall of the pattern by chlorine etch compounds even though the higher substrate temperature tends to volatilize the chlorine-based residual etch byproducts by increasing their vapor pressure. 20) Therefore, many non-corrosive gas combinations such as CO/NH 3 , CH 3 OH, etc., which are known to form volatile compounds with magnetic materials, have been proposed for the etching of MTJ stacks in recent researches.…”