a wafer metrology consortium under MAGNET

WP4 - 450mm Standard Calibration Wafer

WP4 - 450mm Standard Calibration Wafer

The transition from 300mm to 450mm wafer sizes introduces new technological challenges associated with metrology calibration and tool-to-tool matching.  This necessitates the development of a generic 450mm standard calibration wafer set that will support tool and process qualification. Such a standard calibration wafer is also in line with the motivation to bring about significant cost reduction on all fronts of the new 450mm process.  The standard wafer will cover several metrology methods and address both front-end of line (FEOL) and back-end of line (BEOL) processes of the IC production.

The increase of wafer size, thickness and handling requirements introduce wafer deformations such as bowing, warping and rippling associated with stress, weight, wafer chucking, and temperature variations. Both optical and x-ray metrologies are angle-of-incidence sensitive and are affected by local and global wafer deformations. In addition, the overall need to navigate over a large distance at high speed and accuracy will require the development of standard set of calibration targets for precise stage error mapping.

In order to develop solutions for the 450mm wafer metrology, a series of specialized and accurate target schemes will be designed, qualified and agreed by all partners in order to become a generic calibration tool. A wafer set will be required because some targets’ fabrication require different process steps and a distinction between front-end of line (FEOL) and back-end of line (BEOL) wafers must be made.

Goal

The goal for this work group is to demonstrate a standard 450mm calibration wafer that will include agreed-upon targets for all metrology methods and tools. The calibration wafers will be used for tool alignment at the vendor, for tool-to-tool matching within a fab and between fabs for preventive maintenance qualification as well as for tool selection.