Bottom electrode etching process in MRAM cell

US8334213B2 · kind B2 · utility

Assignee

• MagIC Technologies, Inc. · US

Inventor

• Guomin Mao · San Jose, US

Key dates

• Filing date: Jun 5, 2009
• Grant date: Dec 18, 2012
• Expiry date: Jun 9, 2030

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10N50/01

Abstract

A BE patterning scheme in a MRAM is disclosed that avoids damage to the MTJ array and underlying ILD layer while reducing BE-BE shorts and BE-bit line shorts. A protective dielectric layer is coated over a MTJ array before a photoresist layer is coated and patterned on the dielectric layer. The photoresist pattern is transferred through the dielectric layer with a dielectric etch process and then through the BE layer with a metal etch that includes a certain amount of overetch to remove metal residues. The photoresist is stripped with a sequence involving immersion or spraying with an organic solution followed by oxygen ashing to remove any other organic materials. Finally, a second wet strip is performed with a water based solution to provide a residue free substrate. In another embodiment, a bottom anti-reflective coating (BARC) is inserted between the photoresist and dielectric layer for improved critical dimension control.