Lateral Non-Uniformity Reduction by Compensatory Metal Embedded in MOS Structure with Ultra-Thin Anodic Oxide

Abstract

In order to reduce the degradation caused by lateral non-uniformity (LNU) of gate oxides in metal-oxide-semiconductor (MOS) devices, a method to ameliorate the lateral oxide uniformity was proposed. By adopting the anodic oxidation compensation (ANO-compensation) technique to compensate the embedded aluminum layer, significant uniformity improvements were found in capacitance per unit area-voltage (C’-V) and current density-voltage (J-V) characteristics, and the percentage dispersions of capacitance per unit area and current density in accumulation regime also give the support to uniformity improvement. Besides, the outcomes of reliability tests also evidence that the LNU is reduced. Hence, with the advantages of superior oxide uniformity, the enhanced response in inversion capacitance was observed. At last, nitrate solution is used for validating the advantage of anodic oxidation compensation, and the J-V and C-V characteristics show that anodic oxidation compensation is necessary for fabricating reliable MOS-based devices.

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“…In the ANO process, the wafer is connected to the anode, and the platinum plate is connected to the cathode. Hydroxides will be attracted to the silicon to form the SiO2 film during the ANO process (3). Rapid thermal processing in N2 ambient at 950 °C for 15 s was implemented for post-oxidation annealing.…”