MTJ Etching with Improved Uniformity and Profile by Adding Passivation Step

摘要

A hard mask stack for etching a magnetic tunneling junction (MTJ) structure is described. An electrode layer is deposited on a stack of MTJ layers on a bottom electrode. A photoresist mask is formed on the electrode layer. The electrode layer is etched away where it is not covered by the photoresist mask to form a metal hard mask. The metal hard mask is passivated during or after etching to form a smooth hard mask profile. Thereafter, the photoresist mask is removed and the MTJ structure is etched using the metal hard mask wherein the metal hard mask remaining acts as a top electrode. The resulting MTJ device has smooth sidewalls and uniform device shape.

主权项

1. A method for etching a magnetic tunneling junction (MTJ) structure comprising:
providing a stack of MTJ layers on a bottom electrode; depositing an electrode layer on said stack of MTJ layers; forming a photoresist mask on said electrode layer; etching away said electrode layer where it is not covered by said photoresist mask to form a metal hard mask; passivating said metal hard mask by purging O2, H2O vapor, or air into the etching chamber or by low power O2 plasma treatment or by exposing said metal hard mask to ambient air or by water rinse during or after said etching away of said electrode layer wherein after said passivating, said metal hard mask has smooth sidewalls; thereafter removing said photoresist mask; and thereafter etching said MTJ structure using passivated said metal hard mask wherein said metal hard mask remaining acts as a top electrode.