基于SMIC 0.13μm CIS工艺的单光子TOF传感器像素设计

A Single-Photon TOF Sensor Pixel Based on SMIC 0.13μm CIS Technology

设计了一种基于SMIC 0.13μm CIS工艺的单光子飞行时间(TOF)传感器像素结构。针对传统单光子雪崩二极管(SPAD)结构的不足,采用p阱和STI共同作为保护环,避免器件提前发生边缘击穿从而减小器件面积,增加深n阱使有源区耗尽层变窄,从而降低雪崩击穿电压,增加硅外延层将器件的光谱响应峰值转移到所需要的光波长,以此提高器件对指定波长光的吸收能力。通过浮动SPAD阳极电压的方式,采用低压CMOS晶体管实现主动式淬灭电路从而快速地控制雪崩电流淬灭,以达到缩短死区时间的目的。通过SILVACO TCAD和Cadence IC设计套件对工艺、像素器件结构以及相关电路进行仿真,验证了该设计的可行性。

This paper introduces a single-photon TOF sensor pixel based on SMIC 0.13μm CIS technology.With an aim at the disadvantages of traditional SPAD structures,this paper uses p-well and STI as guard ring to avoid edge pre-breakdown,so that device area can be decreased.Deep n-well is added to decrease the depletion layer width of active region,thus reducing the avalanche breakdown voltage.The silicon epitaxial layers is added to shift the spectral response peak to required wavelengths to increase the absorption capacity of required light.By floating SPAD anode and using low-voltage CMOS active quenching,this circuit can quench avalanche current rapidly to reduce the quenching time and dead time.In order to verify the feasibility of this design,SILVACO TCAD and Cadence tools are used to simulate the technology,the device structure and the related circuit.