A method and apparatus for multi-zone injection apparatus of multiple process gases onto a work piece during manufacture. The multi-zone injection apparatus uses a gas injection plate with multiple injection zones to deliver the multiple process gases into the chamber for deposition onto the work piece (for example, a silicon wafer). The gas showerhead separates the multiple process in a manner that avoids premixing the process gases, thereby minimizing gas-phase nucleation and particulate generation. The showerhead also allows real-time independent control over the gas flow rates in N channels to achieve deposition uniformity. Different gases can be configured in adjacent channels to provide M zones of multi-gas radial control.