Self-adaptive halogen treatment to improve photoresist pattern and magnetoresistive random access memory (MRAM) device uniformity

US10921707B2 · kind B2 · utility

Assignee

• TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY LTD. · TW

Inventors

• Yi Yang · Zhejiang, CN
• Dongna Shen · San Jose, US
• Jesmin Haq · Milpitas, US
• Yu-Jen Wang · San Jose, US

Key dates

• Filing date: Jul 19, 2019
• Grant date: Feb 16, 2021
• Expiry date: Jul 19, 2039

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01J37/32082
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A process flow for shrinking a critical dimension (CD) in photoresist features and reducing CD non-uniformity across a wafer is disclosed. A photoresist pattern is treated with halogen plasma to form a passivation layer with thickness (t1) on feature sidewalls, and thickness (t2) on the photoresist top surface where t2>t1. Thereafter, an etch based on O2, or O2 with a fluorocarbon or halogen removes the passivation layer and shrinks the CD. The passivation layer slows the etch such that photoresist thickness is maintained while CD shrinks to a greater extent for features having a width (d1) than on features having width (d2) where d1>d2. Accordingly, CD non-uniformity is reduced from 2.3% to 1% when d2 is 70 nm and is shrunk to 44 nm after the aforementioned etch. After a second etch through a MTJ stack to form MTJ cells, CD non-uniformity is maintained at 1%.