CCD多晶硅层间复合绝缘介质研究

电荷耦合器件(CCD)多晶硅交叠区域绝缘介质对成品率和器件可靠性具有重要的影响。将氮化硅和二氧化硅作为CCD多晶硅层间复合绝缘介质,采用扫描电子显微镜(SEM)和电学测试系统研究了多晶硅层间氮化硅和二氧化硅复合绝缘介质对CCD多晶硅栅间距和多晶硅层间击穿电压的影响。研究结果表明,多晶硅层间复合绝缘介质中的氮化硅填充了多晶硅热氧化层的微小空隙,可以明显改善绝缘介质质量。多晶硅层间击穿电压随着氮化硅厚度的增加而增大,但太厚的氮化硅会导致CCD暗电流明显增大。由于复合绝缘介质质量好,可以减小CCD多晶硅的氧化厚度。

Study on Inter-layer Insulating Dielectric of Polysilicon of Charge-coupled Devices

The inter-layer insulating dielectric of polysilicon remarkably affects the yield and reliability of charge-coupled device (CCD). In this study, the compound dielectrics were combined with oxide and nitride of silicon, and their effects on the space length of polysilicon gate and the inter-layer breakdown voltage were researched by scanning electron microscopy (SEM) and electrical measurement system. It was shown that, the nitride can perfectly fill the micro-viods inside polysilicon oxide and the performance of the insulating dielectric is remarkly improved. Thicker nitride results in higher breakdown voltage of the inter-layer polysilicon, but too thick nitride will induce large dark current. Due to the high quality of this multiple insulating dielectric, the thickness of the polysilicon oxide can be obviously reduced.