Method for fabricating semiconductor devices

Abstract From the Canadian patent

Abstract, A new method for fabricating semiconductor devices, especially CMOS devices, as well as the resulting devices, is disclosed. The method involves incorporating dopants into a semiconductor substrate (e.g. 10) through a region (e.g. 50) of the substrate surface (e.g. 20) and, diffusing the implanted dopants into the substrate to form a tub. Prior to the diffusion step, a trench (e.g. 80) is formed in, and extending beneath, the surface which partially or completely encircles the region. The trench serves to prevent the formation, or reduce the size of a, relatively low dopant concentration region which would, otherwise lead to undesirable leakage currents in the completed CMOS …