1. A monolithic three-dimensional memory device, comprising: a stack including an alternating plurality of electrically insulating layers and electrically conductive layers located over a substrate; a memory opening extending through the stack; a memory film located at a periphery of the memory opening; and a semiconductor channel contacting an inner sidewall of the memory film, wherein: the memory film comprises, from outside to inside, at least one charge storage element, and a tunneling dielectric contacting the semiconductor channel; the tunneling dielectric comprises a layered stack including at least, from outside to inside, a dielectric metal oxide layer having a dielectric constant greater than 7.9 and a silicon oxide layer; and the tunneling dielectric further comprises an element selected from: a silicon nitride layer in contact with an inner sidewall of the dielectric metal oxide layer and an outer sidewall of the silicon oxide layer; or an additional dielectric metal oxide layer in contact with an inner sidewall of the dielectric metal oxide layer and an outer sidewall of the silicon oxide layer.