Daniel L. Goodman

The Role of Mass Transfer in Removal of Cross-Linked Sacrificial Layers in 3DI Applications

The demand for higher functionality in smaller form-factor electronic devices continues to grow. This growth is enabled in large part by wafer-scale packaging technologies for 2-D, 2.5-D, and 3-D integration. Solder bump, copper pillar, and TSV processes are key enablers for advanced packaging. Sacrificial polymer materials such as photoresist and polyimides are used for patterning and/or passivation steps [1,2]. Typical challenges in removing these materials include long process times, short bath life, corrosion, sludge formation, and filter clogging. This paper presents a novel tool design that addresses these issues by a high rate of hydrodynamic agitation that maintains a thin boundary layer at the wafer surface. The outcome is quick removal and breakdown of the sacrificial layer, independent of pitch and without all the negative side effects.

Fluid Flow and Defect Density Considerations when Drying Bumped Wafers Using Spin and Surface Tension Gradient Methods

Spin rinse drying (SRD) and surface tension gradient drying (STG) are used to clean and dry wafers after wet processing. These methods are effective at removing surface fluid and fluid trapped by capillary forces in small (<1um) features. SRD and STG processes combine driven fluid flows with controlled evaporation of thin water films to leave a dry wafer with low defect density (i.e. a low number of physical particle process adders, or areas of haze or oxidation).