A New "Critical-Current at Linear-Threshold" Method for Direct Extraction of Deep-Submicron MOSFET Effective Channel Length

X. Zhou, Member, IEEE, K. Y. Lim, Student Member, IEEE, and D. Lim

Figures

Fig. 1 | Fig. 2 | Fig. 3 | Fig. 4

Fig-1

Fig. 1 Measured Ids at Vgs = Vt0 with the maximum-gm definition (solid circle) compared with the constant-current definition Id0x(W/Ldrawn) (Id0 = 0.1 µA, W = 20 µm) (open circle).  rch0 is first extracted (or calibrated) by fitting long-channel Icrit data (open square), and then, <Rsd0> is extracted by fitting all Icrit data (dotted line for <Icrit>).  The extracted (or modeled) <Leff> is then found from (6) (dotted line for <Leff>).

Fig-2

Fig. 2 Modified “calibration–extraction” algorithm to account for the influence of the parallel-field-dependent mobility on rch0 at long channel (open square).  Directly measured Leff (dashed line) using (9) and the corresponding Rsd0 (open triangle) using (8) are shown together with the averaged ones (dotted lines for <Icrit> and <Leff>).

Fig-3

Fig. 3 Extracted rch0 and <Leff> for three different fitting ranges of Ldrawn, showing the converged results when longer channel-length data is used in the rch0 calibration.

Fig-4

Fig. 4 Verification of the modeled <Leff> (symbols) compared with the best estimate of Lmet (lines), assuming 70% lateral diffusion.  Data are shown for DCD = 0 (circles and solid lines) and DCD = 20 nm (triangles and dotted lines). DL = Lg - <Leff> or Lg - Lmet are shown on the right axis. DL = 2sxj with s = 0.65 (dotted) and s = 0.75 (dashed) are also shown as a reference.