A High-k LDMOS Improved by Floating Field Plates for Enhanced Cost Performance and Robustness

Abstract

An improved structure of the lateral double-diffused metal–oxide–semiconductor (LDMOS) field-effect transistor with high-permittivity layer is proposed. It features some floating field plates added on the device surface, which not only enhances the robustness to resist the effect of interface charges, but also improves the electric field distribution and ameliorates the relationship between the breakdown voltage (BV) and specific ON-resistance ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R} _{{ \mathrm{\scriptscriptstyle ON}}, {\text {SP}}}$ </tex-math></inline-formula> ). Moreover, since the addition of the floating field plates requires no change in the fabrication process, the proposed structure is as budget-friendly as the conventional one. In the simulations, the conventional structure achieves an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{ \mathrm{\scriptscriptstyle ON},{\text {SP}}}$ </tex-math></inline-formula> of 12.5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}\Omega \cdot $ </tex-math></inline-formula> cm2 at the BV of 245 V, while the proposed one made by the same process gains an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{ \mathrm{\scriptscriptstyle ON}, \text {SP}}$ </tex-math></inline-formula> of 11 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}\Omega \cdot $ </tex-math></inline-formula> cm2at the BV of 247 V. Namely, a 15% increase in the performance marked by the figure of merit (FOM; BV <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{{{2}}}/{R}_{ \mathrm{\scriptscriptstyle ON}, \text {SP}}$ </tex-math></inline-formula> ) is obtained without any increase in the cost.