The laser interference ablation in silicon using femto-, pico-, and nanosecond pulses was investigated. The experimental and computational results provide information about nanoscale thermal diffusion during the ultra-short laser-matter interaction. The temperature modulation depth was introduced as a parameter for quality assessment of laser interference ablation. Based on the experiments and calculations the new semi-empirical formula which combines the interference period with the laser pulse duration, thermal modulation depth and thermal diffusivity of the material was derived. The equation is in the excellent agreement with the experimental and modelling results of laser interference ablation. The new formula can be used for selecting the proper pulse duration for periodical structuring with required resolution and quality.