Control of Critical Dimensions of Etched Structures on Semiconductor Wafers

Abstract

A system for real-time monitoring and control of critical dimensions during semiconductor wafer fabrication is provided. The system measures structures in situ, that is, as they are being etched onto a wafer layer.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a method and system for monitoring and controlling processing carried out on a semiconductor substrate, and more particularly for controlling critical dimensions (CDs) of features formed on the semiconductor substrate.[0003]2. Description of the Related Art[0004]In the integrated circuit industry today, millions of semiconductor devices are built on a single chip. The current demands for high density and performance associated with ultra large scale integration require submicron features, increased transistor and circuit speeds and improved reliability. Every device on the chip must be electrically isolated to ensure that it operates independently without interfering with another.[0005]Such demands require formation of device features with high precision and uniformity, which in turn necessitates careful process monitoring, including frequent and detailed inspections of the devices while...

AI Technical Summary

Benefits of technology

The present invention is about a way to watch and control the size of important parts during the process of making semiconductor wafers. The method can measure things as they are being etched onto the wafer layer. This helps to make sure that the wafers are being made correctly.

Problems solved by technology

Deviations of a feature's CD and profile from design dimensions may adversely affect the performance of the finished semiconductor device.

Furthermore, the measurement of a feature's CD and profile may indicate processing problems, such as stepper defocusing or photoresist loss due to over-exposure.

Although conventional SEM's are useful for measuring CD's, they generally do not provide immediate feedback to the photolithography process.

Consequently, the results of conventional SEM inspections are not typically used to adjust subsequent etch processing; that is, the CD measurement of a particular wafer is not used to decide what etch recipe should be used to process that wafer.

As a further consequence of the inspection necessarily taking place at a physically separate tool, the wafers must be transferred to and from the tool for every inspection performed, which is inefficient.

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