In the Photovoltaic (PV) industry, due to material cost considerations, there is a growing trend to reduce the silicon (Si) wafer thickness. The reduction in thickness however leads to new technical challenges related to manufacturing and yield. In particular, breakage-free handling of thin wafers becomes crucial as the mechanical properties are affected by the thickness reduction. Different handling devices are used in the PV industry but one of the most commonly used devices is the Bernoulli gripper. Limitations of such devices when handling thin silicon wafers are currently not well known. In addition, very little work has been done to date to develop formal methods for analyzing and optimizing the performance of such handling devices, especially for thin silicon wafers. This proposal aims to address fundamental issues related to handling of thin (<200 μm) and large (up to 156 mm x 156 mm) silicon wafers using a Bernoulli gripper. The research aims to prevent wafer breakage and thereby improve yield during handling. Using a two-step approach the handling stress induced in the wafer will be evaluated from the gripper control variables and the wafer mechanical properties. It will then be possible to predict the probability of wafer breakage using the fracture strength distribution from appropriate wafer bending tests. The methodology will enable the optimization of gripper control variables to prevent wafer breakage by limiting the applied stresses when possible. Similar model-based approaches could also be implemented for controlling other wafer handling devices or processes. In light of the above goal, the specific objectives of the proposed research are to:

1. Set up an instrumented operational handling/transfer station,
2. Experimentally characterize the Bernoulli wafer handling process,
3. Model and validate the handling process (pressure, deformation and breakage), and
4. Optimize the handling process control variables.