Modeling and Separate Extraction Technique for Gate Bias-Dependent Parasitic Resistances and Overlap Length in MOSFETs

Abstract

We report a technique for separate extraction of extrinsic source/drain (S/D) resistances ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$R_{\mathrm {Se}}/R_{\mathrm {De}})$ </tex-math></inline-formula> and gate bias ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{{\mathbf {GS}}})$ </tex-math></inline-formula> -dependent but channel length (L)-independent intrinsic source/drain ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$R_{\mathrm {Si}}/R_{\mathrm {Di}})$ </tex-math></inline-formula> resistances for the overlap region in MOSFETs. For extraction of the overlap length ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$L_{\mathrm {ov}})$ </tex-math></inline-formula> in the heavily doped S/D regions, an analytical capacitance model for the depletion region is employed with the gate-to-source and gate-to-drain capacitance–voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$C_{{{G-S}}}$ </tex-math></inline-formula> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$C_{{{G-D}}})$ </tex-math></inline-formula> characteristics. After verifying the extracted overlap length through a 2-D technology computer-aided design simulation, we successfully extract <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm{V}_{\mathrm {\mathbf {GS}}}$ </tex-math></inline-formula> -dependent <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 {\mathbf {Si}}}= 0.9{\sim }3.7~\Omega $ </tex-math></inline-formula> and <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 {\mathbf {Di}}}= 1.0{\sim }3.9~\Omega $ </tex-math></inline-formula> in an n-channel MOSFET with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$W=140~\mu $ </tex-math></inline-formula> m and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$L=0.35 ~\mu $ </tex-math></inline-formula> m. In addition, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{\mathrm {\mathbf {GS}}}$ </tex-math></inline-formula> - and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$L$ </tex-math></inline-formula> -independent extrinsic S/D resistances are separately extracted to be <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 {Se}}=5.1~\Omega $ </tex-math></inline-formula> and <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 {De}}= 5.0~\Omega $ </tex-math></inline-formula> , respectively.