NROM memory cells are proposed as one of the most promising non-volatile memories. Issues on scaling and endurance have risen due to the presence of both electrons and holes, for the control of their relative position and spread in the charge trapping material. Therefore, a deeper analysis of the injected-charge distribution region is very important for program/erase bias optimization, reliability prediction and future scaling. In this paper, we introduce and discuss two tools, based on subthreshold slope and temperature effects, able to correctly estimate program charge distribution features from simple ID - VGS measurements