On the Way to understand the Warpage in 8” Taiko Semiconductor Wafers for Power Electronics Applications (Si and SiC)

A linear correlation between the curvature provided by the Stoney equation, considered in an “extended” linear regime, and the arithmetic mean of the main curvatures of a bifurcated plain wafer, has been demonstrated and considered as valid also for the case of a taiko wafer. An extension of the Stoney formula for the case of a back side metallized 8” silicon taiko wafer has been developed, within the frame of the theory of elasticity. It results that there is a good correlation between the calculated curvatures and warpage, determined by the stress released by a given back side metallization (BSM) and the corresponding experimental quantities of the same thick metal layers deposited on an 8” silicon taiko wafer. This development suggests the possibility to extend this approach to the case of 8” taiko wafers based on a wide band gap semiconductor such as silicon carbide (SiC).