Control of residual stress and adhesion in solder-contact metallization

Nick Barbosa and Richard P. Vinci

Department of Materials Science and Engineering, Lehigh University


Certain sectors of the semiconductor industry will benefit from the ability to thin the silicon wafers used to produce devices. However, they anticipate unacceptable wafer bow induced by the stress in the backside metallization used as a solder contact. Metallization schemes have typically been selected for electrical, thermal and soldering performance, not for stress level. It has been shown that the room temperature stress level of metals can vary from highly compressive to highly tensile, depending on such factors as deposition method, deposition gas pressure, thermal treatment and layer thickness. We are examining the potential to reduce the bow to satisfactory levels by controlling the stress level of the metal stack.

A successful stack must have the following characteristics: straightforward integration into manufacturing, net induced curvature of less than 100 µm on a 200 mm wafer, high solderability, high reliability (adhesion), ohmic contact to the underlying Si, and thermal conductivity at least as good as stacks currently in use.


Sample Images



This project was initiated in 2001. Findings will be posted as they become available.


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Last update: November 2001