On-chip spiral inductors with diffused shields using channel-stop implant

We investigated the Diffused shield Under the Oxide (DUO) for the first time. DUO is an extremely shallow diffusion layer in the n-well under the field oxide. DUO can be formed by high energy implantation through the field oxide, and it can be formed by the process of the channel stop implant for MOSFETs simultaneously. Application of DUO provided a 79% improvement in Q-factor and the comparable shield effect on the n-well. This structure is one of the suitable ground shield for the spiral inductor of the rf CMOS.