| With the rapid development of electronic technology, the conventional Schottky Diodes(SBD) with low breakdown voltage and high reverse leakage current has been unable to meet the demands of low-power-loss and high-power market. Thus the Schottky Diodes with high voltage capability which has a new structure and barrier materials has been proposed. This Schottky Diodes have the advantages of low leakage current and forward voltage drop, high breakdown voltage, high-frequency response and strong surge current and anti-overvoltage capability. Except for the application of the high-frequency rectifier circuit, Switched-Mode Power Supply circuit and protection circuit to Freewheeling and rectifier in low voltage, and high current circuit, Schottky Diodes are widely used in high-speed logic circuits, communication Power Supply, the inverter and high-speed computers. It has broad market prospects and important application value.In order to improve the performance of the Schottky Diodes, a floating-limiting ring and field plate terminal structure have been adopted in this thesis. By improving the device manufacturing process of the barrier materials and the Schottky Diodes with breakdown voltage higher than 120 V have been designed and prepared. The main works of this thesis include the following aspects:(1) The basic theory of the Schottky Diodes was analyzed. The influence of epitaxial materials on device performance have been researched. The final study shows that to apply a certain reverse breakdown voltage on the SBD rectifier, the epitaxial material which is designed by punch through mode can be employed to optimize device conduction properties.(2) The Schottky Diodes which size is 60 mils × 60 mils has been designed and fabricated, its terminal structure using guard ring and the metal field plate. The test results show that the breakdown voltage of the device is 112 V, and the value of traditional Schottky Diode reverse breakdown voltage is generally 45 V. At this point, the corresponding leakage current of the device is only 2μA; when the current is large as 3A, the voltage drop on the device is approximately 0.71 V.(3) Improving the barrier materials of the Schottky Diodes during the device manufacturing process, using NiPt60 alloy which have a large work function replaced the conventional barrier of metal Ni. The results come out of reliability test show that the device has a good thermal stability, and shows a good operating characteristic at the temperature of 175℃. As for the conventional nickel barrier Schottky Diode, the maximum working junction temperature only can reach 125℃. It indicates that the changes of the Schottky barrier materials not only improves the electrical characteristics of the die, but also make sure that it has a high reliability and stability.(4) In order to further improve the device performance, using Silvaco-TCAD simulation software to simulate and analyze the structure parameters and technological process of the device, and using the methods of improving the preparation process of the device:(1) before growing the epitaxial, take appropriate chemical etching measures on the silicon surface;(2) push the junction at high temperature annealing after ion implantation to form P+ guard ring;(3) using sputtering process depositing barrier metal and performed high-temperature synthesis;(4) after the anti-engraved metal adopt PMA annealing. The results show that the above of preparation process can be greatly reduced the leakage current of the die, and improved the reverse breakdown characteristics of the device. |
PDF Full Text Request