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Oxidation of Deposited Anti-Reflective Coating in Order to Prevent Resist Poisoning

IP.com Disclosure Number: IPCOM000006697D
Original Publication Date: 2002-Jan-23
Included in the Prior Art Database: 2002-Jan-23
Document File: 3 page(s) / 486K

Publishing Venue

Motorola

Related People

Lionel Riviere-Cazaux: AUTHOR

Abstract

A deposited Anti Reflective Coating (DARC) can react with an overlying photoresist. This problem is known as resist poisoning. A process described herein creates a blocking layer between the DARC and the photoresist. This blocking layer prevents the resist poisoning and does not affect the optical properties of the DARC.

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TITLE

Oxidation of Deposited Anti-Reflective Coating in Order to Prevent Resist Poisoning

AUTHORS

Lionel Riviere-Cazaux

ABSTRACT

A deposited Anti Reflective Coating (DARC) can react with an overlying photoresist. This problem is known as resist poisoning. A process described herein creates a blocking layer between the DARC and the photoresist. This blocking layer prevents the resist poisoning and does not affect the optical properties of the DARC.

THE PROBLEM

·         Silicon rich nitride is frequently used as a DARC (deposited antireflective coating) for lithography. As a DARC, silicon rich nitride has good control over photoresist critical dimensions by preventing standing waves and diffracted light.

+

DARC

•              A DARC can react with the photoresist and prevent complete development of the photoresist. This results in micromasking (etch defects) and yield issues.

EXPOSITION

INCOMPLETE DEVELOPMENT

MICROMASKING

·         One type of resist poisoning defects is pearl defect; as shown below.

GateOxide

Gate Poly

    Gate exposition

Gate etch

Spacer deposition  and etch

Poisoned resist

PearlDefect

THE SOLUTION

·         The solution proposed to this problem consists of processing the wafers in a thermal oxidation process after the DARC deposition. The oxidation process creates a very thin layer (5 to 20Å) of silicon oxynitride that prevents a chemical reaction between the photoresist and the DARC.

·         Thermal oxidation processes are processes done in furnaces or in rapid thermal reactors with oxygen (O2), ozone(...