I-V characteristics of polysilicon resistors at high electric field and the non-uniform conduction mechanism

The non-linear I-V characteristics of polysilicon resistors at high electric fields have been extensively studied. I-V measurements over a temperature range from -194 to 144°C were made on resistors fabricated in polysilicon films deposited by either LPCVD or APCVD with boron, phosphorus or arsenic as dopants having concentration in the range from 1 × 1016 to 5 × 1019 cm-3. As doping level decreases below a critical doping concentration N*, I-V curves deviate asymmetrically from a hyperbolicsine function. The number of grains ζNg along the effective conduction path versus doping levels shows downward concavity with its maximum value near N*. ζNg is also a function of measurement temperature. It is shown that such anomalous conduction phenomena cannot be explained by previous uniform grain-size models. This paper presents a non-uniform conduction model which effectively describes the high-field conduction behavior of polysilicon resistors and shows that the non-uniform polycrystalline structure has significant effects on the non-linear I-V characteristics. © 1984.