Electrical Performance And Stability Of STI-LDMOS Based On Dislocation And Hot Carrier

Based on Shallow Trench Isolation Laterally Diffused Metal Oxide Semiconductor device(STI-LDMOS)was applied widely in power management,display driver,digital media and mixed digital integrated circuits due to high voltage stress in gate,high integration and the preparation process was compatible with low voltage MOS device.Many scholars were interested in the electrical performance and stability of STILDMOS in these days.Therefore,the performance of STI-LDMOS was studied deeply to promote electrical performance and stability of STI-LDMOS in this paper.The main research contents are as follows:(1)A method was put forward to eliminate dislocation existed in STI-LDMOS device and the electrical performance of STI-LDMOS was studied.Microscopic analysis was applied to observe and analysis the distribution and density of dislocation located in the internal and surface of STI-LDMOS.It was concluded that dislocation was dramatically reduced with the increase of oxidation temperature,and dislocation can be eliminated when the temperature reached to A++.There was a great news that leakage current and breakdown voltage were improved by eliminating dislocation in STI-LDMOS.The leakage current of N type and P type LDMOS were reduced 79.42%and 57.09% respectively and the breakdown voltage was also improved to some extent.(2)On the basis of the above studies,the Hot Carrier Injection(HCI)effect of N type STI-LDMOS was studied in order to improve the reliability and stability of high voltage device.Reliability and stability were two factors should be take into account when device working in a long term,while some unexpected phenomenon appeared to worsen electrical performance of N type STI-LDMOS.HCI effect was discussed to enhance the reliability and stability of N type STI-LDMOS device.The ion implantation condition in Ndrift region was studied to improve HCI effect.As a result,the HCI effect of N type STI-LDMOS was distinctly promoted by increasing ion concentration in Ndrift2 region and decreasing ion concentration in Ndrift1 region.Which was mainly because the degradation of saturation current of N type STI-LDMOS was improved which increased the HCI lifetime of N type STI-LDMOS due to the optimization of ion concentrate of Ndrift region.(3)Based on the above conclusions,the electrical performances of N type STILDMOS device were tested to improve the electrical property by optimizing the ion concentrate in Ndrift region,which was applied to enhance the HCI effect.The leakage effect current and saturation current of N type STI-LDMOS device were decreased with the ion concentration decreasing in Ndrift region.The leakage effect current and saturation current decreased by 44.08% and 16.01% respectively.While the threshold voltage and breakdown voltage hardly changed with ion concentrate of Ndrift region.