In this work, we investigated the current-voltage (I-V) characteristics of an Au/Si3N4/n-Si (metal-insulator-semiconductor (MIS)) Schottky diode in a wide temperature range of 160-400 K. By using the thermionic emission (TE) theory, the forward bias I-V characteristics were analyzed to estimate the MIS Schottky diode parameters. Experimental results show that the main electrical parameters, such as the ideality factor (n) and the zero-bias barrier height (Phi(B0)), are considerably dependent on temperature. The semi-logarithmic ln I-V characteristics based on the TE mechanism showed a decrease in n and an increase in Phi(B0) with increasing temperature. The values of n and Phi(B0) changed from 9.50 and 0.34 eV (at 160 K) to 3.43 and 0.74 eV (at 400 K), respectively. Therefore, these results cannot be explained purely on the basis of TE theory. The temperature dependence of the energy distribution of interface states (N-ss) was obtained from the forward bias I-V measurements by taking into account the bias dependence of the effective barrier height (Phi(e)) and n. In addition, the values of series resistance (R-s) were determined using Cheung's method and Ohm's law.