Application of holographic interferometry to in-plane and out-of-plane misalignment and deformation measurements in packaging applications

Packaging of electronic and photonic components requires high accuracy, which needs to be verified in the process of manufacturing and testing. Since very small misalignments and/or deformations can lead to unacceptable performance, a measurement approach is needed that would reveal displacements as small as a few tens of nanometers or less. In addition, misalignments and deformations occur both in the out-of-plane and in-plane directions, which may be very difficult to separate from each other. It was previously demonstrated that the two types of measurements can be implemented with different approaches: holographic interferometry for out-of-plane and Moiré interferometry for in-plane, but it is very desirable to have a single system with sufficient accuracy in both lateral and longitudinal directions. An optical technique developed by our group and presented in this paper is based on a holographic approach and combines the principles of holographic interferometry and phase modulating adaptive optics that could provide in-plane and out-of-plane measurements with high accuracy.