High-reliability microwave silicon power transistor with stepped electrode structure and TiN diffusion barrier

A high-reliability microwave silicon power transistor is described that has a stepped electrode structure and TiN diffusion barrier. This structure, used for high-power and high-frequency devices, is discussed by comparing it to the conventional planar structure. The new structure permits microwave devices to achieve high levels of performance. For high-power dissipation devices having a beam lead metal system, however, the Au-Si reaction and localized Pt-silicide growth are major failure mechanisms. To improve these failures, the Ti layer must be thickened and further TiN applications in beam lead metal systems are discussed. Experimental results of high-temperature long-term operations proved that high-power microwave transistors with excellent reliability can be obtained by using a stepped electrode structure with TiN diffusion barrier.