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Novel method of creating alignment marks with 193nm lithography

IP.com Disclosure Number: IPCOM000036115D
Publication Date: 2005-Jan-28
Document File: 3 page(s) / 12K

Publishing Venue

The IP.com Prior Art Database

Abstract

DUV or I-line lithography were used to create alignment marks in the past. However, critical layers are moved to ArF lithography for improved resolution and alignment. To take advantage of single machine overlay, it is beneficial to use ArF lithography to create alignment marks. This publication describe the method of creating alignment marks using ArF lithography with tri-layer scheme. This method can be used to create golden wafers for ArF scanners also.

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Novel method of creating alignment marks with 193nm lithography

We use tri-layer scheme (Ta-resist-dielectric) to create metal alignment marks using ArF lithography in this publication. The reason for tri-layer scheme is due to the mechanical and chemical property of ArF resist. Ta is the alignment mark material, which can be replaced by Tungsten. The Ta thickness is dependent on the scanner type. 1200A is the desired height for ASML. The resist can be I-line resist or durimide. The dielectric material is used as O2 RIE stop to create good topography. Dielectric material can also be used as BARC to minimize reflection at ArF lithography. CF4 RIE was used to remove dielectric and Ta while O2 RIE is used to remove resist. Below is the process flow:

Deposit NiFe

Deposit 1200A Ta

Coat 8000A resist

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Deposit 300A dielectric

193nm lithography Resist thickness:3000A

CF4 RIE

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O2 RIE

CF4 RIE

Resist stripping

Disclosed by Hitachi Corporation