Laser Die Transfer: laser-induced transfer of microcomponents

A key feature of semiconductor manufacturing over the past 30 years has been its ability to produce very small chips, the current state-of-the-art in production being around 0.25 mm in size. Conventional assembly is based on the handling of individual components by pick-and-place robots. This technology is unsuitable for many microsystems due to the di±culty of handling small (less than 1 millimeter) and thin (less than 100 micrometers) components and of scaling up these techniques for mass production. Thus, micro-assembly of miniature electronics demands processes that are able to accurately handle components with dimensions of several tens of micrometers with high assembly rates onto a broad range of substrates. Nowadays, three ways of solving this problem are under investigation: * Development of new processes based on mechanical handling of the micro- components; * Improvement of the conventional pick-and-place equipment; * Development of laser-induced transferring processes. This work presents a study on a new technique based on the laser-induced release of the micro-component from its carrier, its transfer towards the interconnecting substrate and its landing. This technique provides a very high assembly speed of over 100 components per second, compared to 2 components per second using the conventional pick-and-place method. In some specific areas, this approach can already be applied. This work summarizes the experimental study of the component detachment pro- cess, release dynamics and placement accuracy for di®erent laser sources and process parameters. Examples are given to show the possibility of controlling and manipulating the kinetic and dynamic behavior of the released component. Major attention is paid to factors responsible for the placement accuracy. Important issues presented are: the role of the spatial intensity profile of the laser beam and possibilities to improve its homogeneity, control of the component's release speed and heating up of the components by the laser pulse. One of the applications to which the Laser Die Transfer process is ready to be applied is the touchless release of thin components from the carrier tape. Based on the experimental results and theoretical insight gained in the current research, a demonstrator was built and successfully tested.