The Effect of Thick Interconnections Formed by Gold Electroplating on the Characteristics of Metal--Oxide--Semiconductor Field-Effect Transistors

This paper describes the electrical properties of metal--oxide--semiconductor field-effect transistors (MOSFETs) with thick gold (Au) interconnections formed by electroplating. The tensile stress loaded in the channel region of MOSFETs with thick Au interconnections induces a slight (2--5%) enhancement of transconductance, $g_{\text{m}}$, in N-channel (N-ch) MOSFETs. Hot-carrier stress tests with and without thick Au interconnections were carried out to investigate the long-term reliability of N-ch MOSFETs. The lifetime of $g_{\text{m}}$ with thick Au interconnections was estimated to be over ten years, which is the same as that without them. These results demonstrate that thick Au interconnections do not deteriorate the electrical properties or long-term reliability of underlying MOSFETs.