Study in Metal-Gas-Semiconductor Field-Effect Transistor with High Radiation Hardness

本研究旨在以气体取代闸极绝缘层氧化物，以实现抗辐射的金属-气体-半导体场效电晶体。可以预期栅极的高击穿电压和器件可靠性的附加效应。例如，SF_6气体的高压绝缘长期以来一直应用于电力Transformer，然而，在集成电路领域中，场效应晶体管的应用尚未公开。一组Si_3N_4和热磷酸被证明是不够的，因为热磷酸对硅衬底表面的腐蚀是不利的。2006年，利用所开发的技术，成功地制备出了具有N_2气栅绝缘的MGSFET，并使FET工作正常。这可能是气体绝缘场效应晶体管在世界上的首次成功。在MOS和MGS晶体管的强制栅击穿之后，MOS晶体管的栅漏电流变得更大，而MGS晶体管的栅漏电流则小得多。这意味着MGS对宇宙线辐射和热载流子效应具有潜在的抗辐射特性。和

This study is to aim at realization of metal-gas-semiconductorfield-effect transistor (MGSFET) with radiation hardness by replacing gate insulator oxide by gas. Additional effects of high breakdown voltage of the gate and device reliability can be expected. High voltage insulation with, for example, SF_6 gas has long been applied to power transformer, however, the application to field-effect transistor in not yet disclosed in integrated circuit field.In 2005, an insulator material to be removed and its etching solution were chosen to realize the device structure. A set of Si_3N_4 and hot-phosphoric acid was proven to be inadequate because that the hot-phosphoric acid adversely etched silicon substrate surface. Thus, a set of SiO_2 and buffered HF solution was chosen.In 2006, utilizing the developed techniques, an MGSFET with N_2 gas gate insulation was successfully obtained resulting in normal FET operation. This may be the world-first success for gas-insulated FET. After forced gate breakdown of MOS and MGS transistors, the gate leakage current becomes bigger for the MOS, otherwise, much smaller for the MGS. This implies MGS has a potential of radiation-hardness characteristics against cosmic-ray radiation and hot-carrier effect. and