Oxygen point defect stabilized metastable M3‐phase VO2 films

•M3-VO2 phase, a polymorph phase of VO2, was stabilized by oxygen point defect in the ambient environment.•Oxygen point defect was located at the tetrahedral interstitial site with the lowest formation energy among defects in VO2.•Oxygen point defect at the tetrahedral interstitial site induces the M3-VO2 phase by increasing the length and angle of the zigzag V-V chain.•M3-VO2 phase had a higher phase transition temperature and a sharper phase transition than the M1-VO2 phase•M3-VO2 phase transits to the rutile VO2 phase without an intermediate polymorph phase.