Experimentally it has been found that under irradiation of 6H-SiC with a focused N-2 pulsed laser beam the process of laser ablation (LA) is characterised by the repeated unusual stages: 1. production of liquid phase under irradiated C surface due to the lowering of the melting temperature of the crystal lattice caused by the enhancing from pulse to pulse concentration of the impurity atoms in the region of focused spot - accumulation effect; 2. extrusion of liquid phase on the surface in the form of nano-hills by pressure of the laser beam through a colder surface layer, which has been created due to atom sublimation by laser radiation (LR) - "a lid effect". This process leads to production of a cone crater takes place as a result of multiple extrusions of liquid substance onto the surface by laser pulses. The repetition of the described stage process was observed. Peculiarities of LA in 6H-SiC, a threshold character of the effect, the effect of accumulation and photoluminescence quenching are explained by Thermogradient effect at the initial stage of the LR interaction with a semiconductor and they speak in favour of the hydrodynamics model of LA.