The influence of transport operations on the wafer strength and breakage rate

The breakage rate of silicon wafers depends on the applied load during the manufacturing process, especially in the different handling steps. In order to optimize the handling processes the influence of different handling techniques on the strength and the damage of wafers needs to be understood. In this investigation three existing types of commercial gripper techniques (Bernoulli gripper, vacuum cup gripper, and vacuum area gripper) are characterized in an automation setup regarding strength and damage. For the evaluation of their damage potential the mechanical strength of the wafers is determined by the 4-point bending test and a statistical analysis is performed using the Weibull distribution. In comparison to a reference batch it is observed that Bernoulli and vacuum cups grippers are able to damage wafers and increase the breakage rate, while the vacuum area gripper induces no damage in the wafers.