A New, Low-Thermal-Budget Planarization Scheme for Pre-Metal Dielectric Using Electron-Beam Cured Hydrogen Silsesquioxane in Device

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Abstract
Employing an electron-beam (E-beam) cured hydrogen silsesquioxane (HSQ) based inorganic spin-on-glass as a pre-metal dielectric (PMD) material, we developed a simple planarization process with low thermal budget and good planarity in stacked capacitor dynamic random access memory (STC DRAM) device. We observe the basic E-beam cured HSQ film characteristics such as Fourier-transform infrared absorption spectra (FTIR), wet etch rate, film shrinkage, refractive index (RI), X-ray photoelectron spectroscopy (XPS), and electron spin resonance spectroscopy (ESR) in non-patterned wafer. No degradation of device characteristics such as Vth change, hot carrier hardness, and gate oxide quality has been observed. This process resulted in lower leakage current and higher capacitance for Ta2O5 capacitor as well as better planarization performance compared with the conventional undoped silicate glass (USG) etch back process. These results show that E-beam curing process as a low thermal budget PMD scheme would be a promising process for high capacitor dielectric materials.