Reducing stress effects on multi-project-wafer reticles by optimizing metal densities and density gradients in an MPW placement flow

Lifu Chang; Philippe Morey-Chaisemartin; Eric Beisser; Joshua Zusman; Frederic Brault

doi:10.1117/12.2583510

22 February 2021 Reducing stress effects on multi-project-wafer reticles by optimizing metal densities and density gradients in an MPW placement flow

Lifu Chang, Philippe Morey-Chaisemartin, Eric Beisser, Joshua Zusman, Frederic Brault

Author Affiliations +

Proceedings Volume 11614, Design-Process-Technology Co-optimization XV; 116140J (2021) https://doi.org/10.1117/12.2583510
Event: SPIE Advanced Lithography, 2021, Online Only

Abstract

We propose a new method applied on Multi-Project Wafer (MPW) reticles to reduce thermal-mechanical stress. Wafer bumping processes generate residual thermal-mechanical stress, causing crack and delamination across wide regions on a wafer. In this paper, we show the work achieving optimized metal layer densities and density gradients across the reticle to minimize the stress effects. We propose a new MPW chip placement flow that places chips on an MPW reticle meeting the minimum density gradients as the placement criterion. The flow also performs inter-die dummy metal fills to optimize densities with regard to each chip density. We show intentional crack-stop dummy metal rings the flow generates surrounding a chip. The dummy rings further reduce the propagation of stress cracks. We show the results of optimized density gradients and crack-stop rings across the chips on an MPW reticle.

Conference Presentation

Citation Download Citation

Lifu Chang, Philippe Morey-Chaisemartin, Eric Beisser, Joshua Zusman, and Frederic Brault "Reducing stress effects on multi-project-wafer reticles by optimizing metal densities and density gradients in an MPW placement flow", Proc. SPIE 11614, Design-Process-Technology Co-optimization XV, 116140J (22 February 2021); https://doi.org/10.1117/12.2583510

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