Effects of substrate temperature on etched feature of chromium film and its application to field emitter arrays(FEAs)

The etched features of the thin Chromium (Cr) films deposited on SiO₂-Si substrate were investigated as a function of substrate temperature during rf-sputtering deposition. In this work, the changes of both the grain structures and crystallographic orientations of sputtered Cr-films as a function of substrate temperature were examined by Scanning Electron Microscopy (SEM) and X-Ray Diffraction spectroscopy (XRD). In these measurements, we found that the tapering angle (θ_t) of thin Cr-film after reactive ion etching depends on the deposition condition, especially, substrate temperature during rf-sputtering process. Based on the obtained results, we formed the two kinds of Cr-gated Mo-tip field emitter arrays (FEAs): one is a FEAs with tapered gate electrode (tapering gated FEAs. θ_t ≤ 90°) and another is a FEAs with tapering-free gate electrode (non-tapering gated FEAs, θ_t = 90°), compared the electron emission characteristics for this two kinds of FEAs. In the case of non-tapering gated FEAs, we obtain the more emission current than that of tapering gated FEAs while the gate leakage current of non-tapering gated FEAs was almost same value compared to that of tapering gated FEAs. Through the optimized the etched shape of gated electrode, the total transconductance (G_m) of FEAs was increased without over-coating on tip as well as increase the packing density of FEAs.