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Width dependence of hot-electron currents in MOSFET's fabricated with LOCOS, non-LOCOS, and a modified LOCOS processes are studied. The experimental results show that the substrate and gate currents are apparently enhanced in narrow width devices. The enhancement, however, is due to different voltage drops across the source-drain series resistance. The voltage drops are usually larger in wider devices. After correcting for the resistance effect, the substrate and gate currents scale with the device width. With this typical LOCOS process, the bird's beak and in-diffusion of field implant dopants do not cause excess hot-electron activities along the channel/field edges as has been suspected. Some other LOCOS process could, of course, produce a different result. Studies using wide test devices must consider the series resistance effect. With this precaution taken, models derived from wide-channel data will be applicable to narrow-channel devices, at least for some processes.

The phenomenon of and the physical mechanisms for the generation of minority carriers in the substrate of NMOS and CMOS are studied. Secondary impact ionization is not responsible. The responsible mechanisms are hot-electron-induced photocarrier generation and, under extreme conditions, forward biasing of the source-substrate junction. The photon generation is believed to be due to the bremsstrahlung of the channel hot electrons. A theoretical model based on the lucky electron concept and the bremsstrahlung mechanism is proposed. The calculated characteristics of photon generation agree well with experimental results. About 2 × 10-5photogenerated minority carriers are generated for every (primary) impact-ionization event in NMOSFET. Photocarrier-induced leakage current can be fitted with either an inverse square dependence on distance or an exponential dependence with an effective decay length of about 780 µm.

The lucky-electron concept is successfully applied to the modeling of channel hot-electron injection in n-channel MOSFET's, although the result can be interpreted in terms of electron temperature as well. This results in a relatively simple expression that can quantitatively predict channel hot-electron injection current in MOSFET's. The model is compared with measurements on a series of n-channel MOSFET's and good agreement is achieved. In the process, new values for many physical parameters such as hot-electron scattering mean-free-path, impact-ionization energy are determined. Of perhaps even greater practical significance is the quantitative correlation between the gate current and the substrate current that this model suggests.