Thin Silicon Wafer Device Concept with Advanced Laser Annealing and Sintering Process

A new anode/cathode design and process concept for thin wafer based silicon devices is proposed to achieve the goal of providing improved control for activating the injecting layer and forming a good ohmic contact. The concept is based on laser annealing in a melting regime of a p-type anode layer covered with a thin titanium layer with high melting temperature and high laser light absorption. The improved activation control of a boron anode layer is demonstrated on the Soft Punch Through IGBT with a nominal breakdown voltage of 1700 V. Furthermore, the silicidation of the titanium absorbing layer, which is necessary for achieving a low VCE ON, is discussed in terms of optimization of the device electrical parameters.