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我们把用SIMOX工艺所形成的纵向隔离结构和新开发的横向隔离结构结合起来,研制出抗辐照CMOS/SIMOX器件。 n沟MOSFET的纵向隔离由多层高浓度氧掺杂多晶硅和埋层二氧化硅组成,横向隔离由多层薄的侧壁二氧化硅、侧壁多晶硅和厚的场二氧化硅组成。p沟MOSFET的纵向隔离结构与n沟MOSFET相同,但其横向隔离中没有侧壁多晶硅层,而是使用厚的场二氧化硅层。高浓度氧掺杂多晶硅和侧壁多晶硅层用来屏蔽被俘获在埋层二氧化硅和场二氧化硅中的辐照感生正电荷。利用这些隔离结构和薄栅二氧化硅层开发的CMOS/SIMOX器件,即使在经受2Mrad(Si)的~(60)Co伽马射线辐照之后,仍具有良好的工作特性。
We combine the vertical isolation structure formed with the SIMOX process with the newly developed lateral isolation structure to create a radiation-resistant CMOS / SIMOX device. Longitudinal isolation of n-channel MOSFETs consists of multiple layers of highly doped oxygen-doped polysilicon and buried silica, with lateral isolation consisting of multiple layers of thin sidewall silicon dioxide, sidewall polysilicon and thick field silicon dioxide. The vertical isolation structure of the p-channel MOSFET is the same as that of the n-channel MOSFET, but there is no sidewall polysilicon layer in the lateral isolation, but a thick field silicon dioxide layer is used. High concentration oxygen-doped polysilicon and sidewall polysilicon layers are used to mask the radiation-induced positive charges trapped in buried silica and field silica. CMOS / SIMOX devices developed with these isolation structures and thin gate silicon dioxide layers have good operating characteristics even after exposure to ~ (60) Co gamma radiation of 2 Mrad (Si).