Challenge

Photolithography sets the technology level of a fabrication facility making it the most critical and challenging part of the semiconductor manufacturing process. In lithography, a device structure is imaged in photoresist and subsequently transferred onto a wafer. The process is tightly connected to that of etch because together, they determine the actual feature size on the wafer. Lithography for technology nodes of 65 nm and below faces serious challenges leading to various patterning schemes such as double exposure, double patterning, immersion lithography and, in the future, extreme UV, demanding precise process control with no tolerance for error. Process monitoring and control in lithography requires precise measurement of full feature profiles, including: CD, side wall angle, etch depth, and fine profile features such as foot, notch, and undercut.

Solution

Nova’s scatterometry-based metrology solutions enable full CD and shape profiling measurements that include top, middle and bottom CD, sidewall angles, foot, notch and undercut, and other fine feature parameters as well as the optical properties (n, k) of the underlying materials. High accuracy and fleet matching coupled with high throughput of up to 150 WPH, make Nova’s metrology an Advanced Process Control enabler for wafer patterning.

Nova provides a full metrology solution for wafer patterning process monitoring and control by offering integrated metrology on the track system or on the etcher with a stand-alone metrology platform for lot-to-lot control. Both platforms feature APC schemes including feed backward to the track and the scanner, as well as feed forward and feed backward to the etcher.