Free form microlens sysems enable new laser beam profiles for RTP

Abstract

The use of laser technologies for the well defined selective heating of wafers and thin film semiconductors for melt and non-melt RTP processes is an alternative way to fulfil the design goals of next generation semiconductor devices for data processing or photovoltaic. A variety of efficient and reliable laser sources are available from UV to IR that can match the absorption characteristics of nearly any material. To make technical and economical use of these advantages the laser power has to be focussed on the surface with a well defined beam geometry and intensity profile. For a fast processing of 300mm wafers or Gen 8 LCD or solar panels a beam with line or rectangular geometry is needed. In addition to the beam geometry, the intensity distribution in scanning direction is an essential parameter for a controlled temporal heating and cooling profile of the materials. These beam profiles control the vertical thermal penetration depth and reduce the thermal load of the semiconductor layers and substrates by faster scanning speed and μs- and ns-illumination regime.