[en] We have investigated the influence of partial pressure of water vapor [P(H₂O)] in the crystallization process on the superconducting properties of YBa₂Cu₃O_7-y (YBCO) films fabricated by a trifluoroacetate-metal organic deposition (TFA-MOD) method. The starting solution with different compositions of Y: Ba:Cu = 1.0:2.0:3.0 and 1.0:1.5:2.0 were studied. The critical current density (J_c) values of YBCO films fabricated from Y:Ba:Cu 1.0:2.0:3.0 starting solution significantly increase (1.71 → 2.55 MA/cm²) with increasing P(H₂O) from 12.3 to 47.4 kPa. In the YBCO films fabricated from Y:Ba:Cu = 1.0:1.5:2.0 starting solution, high J_c values of over 2.5 MA/cm² were recognized in a wide range of P(H₂O) (12.3-47.4 kPa). One of the reason for J_c improvement is the suppression of coarsening of the secondary phases grains such as Y₂Cu₂O₅ and CuO due to increase in growth rate of YBCO layer in the crystallization process. The J_c values of all YBCO films decreased as P(H₂O) increased up to 70.1 kPa. This degradation of J_c values may be caused by difference of crystal growth mechanism in high growth rate.