Semiconductor engineering

Publications & Papers

Technical papers on lithography process windows, reticle qualification, OPC response, and focus calibration — from Terrence Zavecz's semiconductor engineering career. PDFs open in a new tab.

Weir PW — Process Analysis & Modeling

Rapid and precise monitor of reticle haze

BACUS (2007) 6730-46 · Sept. 2007

The most commonly reported effect of haze is a gradual loss in transmission of the reticle that results in a need to increase the exposure-dose in order to maintain properly sized features. Transmission loss results in an increase in the Across Chip Linewidth Variation that is accompanied by a corresponding reduction in the manufacturing process window.

More significantly, even the early stages of reticle haze result in a degradation of Best Focus, Depth of Focus and the Exposure latitude prior to any noticeable large area transmission loss. Production lots subject to reticle hazing on critical layers will experience a direct loss of lithographic yields, loss of capacity, an increase in rework rates and an ultimate loss in overall final-test yield before image exposure-dose increase is detected.

A sampled metrological inspection of a regular array of points across the exposure field is therefore able to detect any form of reticle haze if the analysis monitors the feature-profile response rather than simply feature widths. A model-driven method for the early detection of reticle-haze using basic feature metrology is developed in this study. Application results from a production reticle are used to demonstrate validation of the technique that employs a highly accurate method of calculation of the uniformity of the reticle exposure-response for individual features.

Tuned Reticle Enhancements Optimized for Process Response

Semiconductor FabTech FT33-07 · Q1 April 2007

In this study, a Process Behavior Model methodology is presented for the analysis of feature profiles and films to derive the relative robustness of response to process variations for alternative feature designs. Analysis is performed without regard to the specific mechanics of the design itself. The design alternatives of each feature are shown to be strong contributors not only to resolution and depth-of-focus but also to the stability of final image response; that is the ability of the feature profile to remain at optimum under varying conditions of process exposure excursion.

A method of extracting the systematic component of each feature's design-iteration is derived providing the ability to quantify the specific OPC response sensitivity to changes in the exposure and process films as well as drift introduced by the tools of the exposure set. See also FabTech.org.

Line Edge Roughness

MLW 0305 (2005)

Spatial analysis and resolution of line edge, width roughness from CD-SEM.

Modeled Focus Calibration & Uniformity

Weir PSFM — software for calibration of reticles and specialty features such as the Phase Shift Focus Monitor (PSFM), Z-Spin, PGM and FOCAL structures.

Thermal Response of Feature Profiles

LithoWorks PEB in conjunction with Weir PW.

TEA Systems Corporation

These papers reflect work through TEA Systems Corporation — lithography process-window software, training, and consulting. For products, education, and services, visit TEAsystems.com.

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