When I simulate the NMOS model in ATHENA, when I want to anneal in nitrogen atmosphere after n+ ion implantation, the annealing operation is not possible when the annealing temperature is lower than 699.85 degrees Celsius; when it is higher than 699.85 degrees Celsius, the deckbuild software reports an error with an error alert as:
Error: time step reduction can't avoid negative
concentration! Writing out the last valid structure to
panic.str. Try altering the mesh.
May I ask why this phenomenon occurs and what modifications should be made to avoid this phenomenon for successful annealing?