Browse Prior Art Database

Method for optical subfield positioning in lithography

IP.com Disclosure Number: IPCOM000020325D
Publication Date: 2003-Nov-12
Document File: 3 page(s) / 136K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for optical subfield positioning in lithography. Benefits include improved performance.

This text was extracted from a Microsoft Word document.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 64% of the total text.

Method for optical subfield positioning in lithography

Disclosed is a method for optical subfield positioning in lithography. Benefits include improved performance.

General description

         The disclosed method positions a reticle pattern in the optical sweet spot of a scanning lithography tool.

         The key elements of the method include:

•         Reticle with a pattern size that is smaller than the optical slot in a lithography scanner

•         Method of characterizing the optical slot to determine the optimal position for pattern placement

•         Translating reticle loader or stage that can reset the Y-intercept in an X-scanning system

Advantages

         The disclosed method provides advantages, including:

•         Improved performance due to improved critical dimension (CD) control.

Detailed description

The disclosed method is optical subfield positioning in lithography. The aberrations in a set of lithography tools are characterized and/or critical dimensions are measured (see Figures 1 and 2). The electrically measured critical dimensions (ECDs) are obtained along the optical slot in two lithography tools for 55±10-nm lines on a 290-nm pitch. The optimal slot positions are obtained for a given product field size.

As an example, assume the product die utilizes 50% of the optical slot (13 mm). Data from Figures 1 and 2 are used to minimize the ECD variation within die the optimal field locations for each tool. A translating reticle stage positions the reticle over the best field location (optical sweet sp...