We have constructed a (semi)-global six-dimensional potential energy surface (PES) for HFCO, incorporating the equilibrium, cis- and trans- isomers (HOCF) as well as the transition states connecting them. The PES is based on a fit to 15000 CCSD(T)-F12/cc-pVTZ-F12 ab initio energies. The sum-of-products PES, obtained using neural network exponential fitting functions, was used to compute vibrational state frequencies using block improved relaxation with the multiconfiguration time dependent Hartree (MCTDH) approach. The PES is accurate (RMSE = 130 cm^-1) up to 40,000 cm1 above the minimum energy. The equilibrium region of the PES was fit very well based on a comparison of the vibrational frequencies with those from a recent local HFCO PES (Pradhan and Brown, 2016) and experimental measurements (RMSE = 10.9 cm^-1 compared to experiment). The vibrational frequencies for the trans- and cis-isomers are computed from the PES and compared to anharmonic MP2/aug-cc-pVTZ and CCSD(T)/ aug-cc-pVTZ results; the trans- and cis-isomers have yet to be detected experimentally. Based on the accuracy of the vibrational energies at equilibrium, the present results for the cis- and trans-isomers could facilitate the identification of these species. The PES will also enable the study of intramolecular vibrational energy redistribution and its control leading to the elusive equilibrium HFCO to trans-HOCF conversion.