Study and optimize on the process of Floating gate with dry etching

The split-gate flash memory is widely used in the market, and the dry etching process has an important effect on the parameters and performance of the Floating grate. The plasmas containing Cl2 and CF4 were used to etch the top half of polycrystalline gate, and the HBr/He-O2 gases with a high selectivity to oxide were adopted to etch the bottom half. The orthogonal tests were made upon the process parameters and the optimal process parameters of the main etch step were finally determined, and then morphology and uniformity of the Floating grate were obtained that fabrication demand when adding a proper over etch step.