Browse Prior Art Database

Single Sample Modulation Transfer Function and Wafer Contrast Measurement System

IP.com Disclosure Number: IPCOM000038820D
Original Publication Date: 1987-Mar-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Badami, DA: AUTHOR [+5]

Abstract

A single sample modulation transfer function (MTF) and wafer contrast (WC) measurement system utilizing microprocessor-controlled laser end point detection (LEPD) analysis to determine photolithographic tool resolution capabilities is reported. Image transfer resolution measurements of photolithographic printing systems currently use multi-wafer/sample analysis techniques. A number of separate wafers are exposed under various conditions and then developed to endpoint to extract data used to calculate MTF and/or wafer contrast. This method is time consuming and the accuracy of the measurements is a function of wafer to wafer variations. Fig. 1 shows a wafer contrast measurement tool which is more efficient and accurately measures a photolithographic systems image transfer resolution utilizing a single wafer sample for analysis.

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Single Sample Modulation Transfer Function and Wafer Contrast Measurement System

A single sample modulation transfer function (MTF) and wafer contrast (WC) measurement system utilizing microprocessor-controlled laser end point detection (LEPD) analysis to determine photolithographic tool resolution capabilities is reported. Image transfer resolution measurements of photolithographic printing systems currently use multi-wafer/sample analysis techniques. A number of separate wafers are exposed under various conditions and then developed to endpoint to extract data used to calculate MTF and/or wafer contrast. This method is time consuming and the accuracy of the measurements is a function of wafer to wafer variations. Fig. 1 shows a wafer contrast measurement tool which is more efficient and accurately measures a photolithographic systems image transfer resolution utilizing a single wafer sample for analysis. The single sample holder in the developer solution tank holds the test wafer which has been exposed to a test mask in the printing system being evaluated. A test mask (covered with chrome or other opaque material), shown in Fig. 2, is composed of a column of grids, with one clear grid and each succeeding grid array composed of equal lines and spaces of increased frequency. Arrays in the test wafer (Fig. 1), including the baseline array (clear grid), are developed to endpoint. Each LEPD head is positioned to monitor the development rate of one array with its own...