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.

Date

2021

Authors

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

Conference

Design-Process-Technology Co-optimization XV

Volume

11614

Pages

82-88

Publisher

SPIE