The Design Of Silicon-Based Constant Regulative Diode

As a semiconductor material whose reserves is largest in the lithosphere, Silicon is widely used in microelectronics and other fields for excellent properties. Silicon discrete device have important applications in automotive electronics, industrial automation and3G communication as a important role in semiconductor device field for mature technology, high reliability and lower costs. CRD, providing constant current, is an crucial device composing constant current device, steady voltage source and the protection circuit for good characteristics, lower price, simple operation. But high pinch-off voltage, narrow constant current region and lower dynamic impedance, the CRD’s application has been limited.Based on the application background and the value of CRD, this paper introduces the development in the field at home and abroad. According to CRD’s principle and device design requirements, it designs the device structure parameters combined with semiconductor device physics and semiconductor physics. Then simulate the device’s IV curve by numerical simulation method using numerical simulation equations and device physics, and analyzing results after comparing with design requirements. By optimizing parameters, such as channel doping concentration, channel width, channel length, gate-drain spacing, constant current increases from5.5×10-6A to6.7×10-6A and breakdown voltage from35V to54V. To reduce the peak electric field of the PN junction edge, field plate is used to optimized structure and breakdown voltage increases from54V to60V, to improve as much as10%. Then it analyzes the current temperature coefficient and dynamic impedance of the used FP structure, the coefficient of-0.26%and the dynamic impedance of60KΩ.Finally, it gives the process flow and layout of the device, and the main process is introduced briefly.The results show that the theoretical formula coincides with the actual characteristics. We should compromise between CRD’s pinch-off voltage, constant current and breakdown voltage. Field plate can improve the breakdown characteristics. The used FP structure has good characteristics, greater current value, wider constant current region, lower pinch-off voltage and higher breakdown voltage compared with the same type product, which is suitable for high-precision, high-current areas.