Dual-Layer Proton Irradiation for Passive Component Enhancement and Noise Coupling Suppression on CMOS Process

This work presents the development of a dual-layer proton irradiation profile to decrease the fluence required to create a thermally stable localized high-resistivity silicon (HR-Si) substrate for on-chip passive component enhancement and to create a guard band to suppress noise coupling. Additional irradiation was done on the Si-SiO2 interface to prevent conductive layer formation and reduce the main irradiation’s fluence requirement. The thermally stable dual-layer profile was optimized experimentally by applying several interface and main irradiation fluence combinations to the on-chip inductor and comparing the quality factor before and after annealing. The optimum total fluence found for the dual-layer profile was
${4} \times {10}^{{14}}$
cm−2 with a measured mask-edge margin distance of
${22}~\mu $
m, corresponding to 60% fluence reduction and 56% margin reduction compared to conventional proton irradiation with 1015-cm−2 fluence. Adding a 20-
$\mu $
m-thick guard band formed by dual-layer proton irradiation between two circuits introduced 5-dB noise coupling suppression at 1 GHz, with a further 2.5-dB increase every time the thickness was doubled.