An apparatus for direct liquid injection (DLI) of chemical precursors into a processing chamber is provided. The apparatus includes a vaporizer assembly having an injection valve for receiving a liquid reactant, vaporizing the liquid reactant, and delivering the vaporized liquid reactant. The injection valve includes a valve body encompassing an interior region therein, a gas inlet port, a liquid inlet port, and a vapor outlet port all in fluid communication with the interior region. The vaporizer assembly further includes a first inlet line having a first end fluidly coupled with the liquid inlet port and a second end to be connected to a liquid source. The vaporizer assembly further includes a second inlet line with a first end fluidly coupled with the gas inlet port, a second end fluidly coupled with a carrier gas source, and a heater positioned between the first end and the second end.