Design And Thinning Electrical Performance Characteristics Of Silicon-based BCD Basic Devices

With the miniaturization of electronic products,the development of multi-functional integration,and the requirements for better human-computer interaction,flexible chips have gradually been widely used in medical,automotive,Internet of Things and other fields.At the same time,with the rapid development of power integrated circuits,the BCD process has received more and more attention because of its high integration and high power density.However,at present,when the development of flexible chips and BCD processes is hot,there is still insufficient research on the electrical properties of basic devices after thinning under BCD process.In order to better predict the changes in the electrical properties of flexible chips under the BCD process and the needs of the design and manufacture of flexible chips,thesis studies the electrical performance characteristics of the basic devices after thinning under the BCD process,the main work content is as follows:Firstly,the BCD process and thinning process are systematically elaborated,including the introduction of DMOS devices,the description of BCD process and thinning process,and the advantages of BCD process and thinning on chips are analyzed.Secondly,under the 0.35μm BCD process,five basic devices(NMOS,PMOS,NPN,PNP,LDMOS)are designed,including device size,test circuit and device layout,the relevant electrical parameters of each basic device are proposed,the simulation environment of each device is set,and the relevant electrical parameters of each device before thinning are obtained through simulation,so as to compare with the electrical parameters of the thinned device later,and according to the layout DRC rule,the layout of each device is designed for subsequent tape-out.Finally,the designed device layout is tape-out and the 6-inch 675μm thick wafer after tape-out is thinned to 100μm,and then the electrical performance of each basic device after thinning is tested,the test results are compared with the electrical parameters of the device before thinning.The test results show that:(1)For MOS transistors,the breakdown voltage after thinning and the saturation current value in the working state are reduced,and these values are reduced to half of the original when the wafer is thinned to 100μm.In addition,the threshold voltage of the thinned MOS transistor increases,the subthreshold slope decreases,and the switching speed becomes faster,but the substrate current also increases.(2)For bipolar transistors,the gain of NPN and PNP increases slightly after thinning,and the saturation current in the working state is greatly reduced.(3)For LDMOS,the threshold voltage does not change much from the saturation current value during operation,the breakdown voltage and on-resistance decrease,and the substrate current increases.