Research On GAN Power Die Device Applied In Base Station

With the implementation and construction of 5G networks,a large number of dedicated 5G communication base stations need to be built.As one of the core components of base stations,the demand for power die modules has increased significantly.The power die module of the 5G base station requires its operating frequency to be above 3.5GHz.The traditional LDMOS device is difficult to meet the requirements due to the limitation of the application frequency.GaN devices rely on their high application frequency,high output power density,high breakdown voltage,high breakdown voltage and Temperature-resistant characteristics gradually replace traditional LDMOS devices and become a new hot spot for base station power output modules,and their demand has increased significantly.In order to meet the increasing market demand for GaN devices,this article is dedicated to researching a GaN power die suitable for base station power output.This paper analyzes the influence of the device's structural size parameters through software simulation,determines the basic size of the device layout according to the simulation results,and designs the overall process flow to complete the device tapeout,optimize the key processes in the tapeout process,and complete the design and production of devices,the main research content includes:Firstly,use Silvaco simulation software to study the impact of structure size on performance.When the gate length is reduced from 0.6?m to 0.2?m,the threshold voltage will be negatively biased,the absolute value will increase,and the source-drain current will increase slightly,but the short channel effect of the device will become more and more obvious;when the gate-source spacing decreases,the source leakage current will increase significantly,but when the distance between the drain and the drain is less than0.5 ?m,the gate leakage current will also increase,the operating temperature under the same conditions will increase.Other size parameters will also have an impact on device performance,but they are not particularly obvious compared to the gate length and gatesource spacing.Secondly,optimize the key process of device tapeout.Aiming at the problem of gaps in the gate trench metal filling process,two etching gases,SF6 and CF4,were used respectively.By adjusting the parameters of the ICP equipment,the angle of the gate trench after etching was improved,and the angle was reduced from about 67° to about55°,and improved the quality of gate metal filling.Tests on the devices formed by the two kinds of gas etched gate grooves found that compared to CF4 gas,SF6 gas etched gate grooves can effectively reduce Schottky leakage current,but at the same time it will lead to gate control capability reduced and poor current output capability.At the same time,the Schottky surface treatment process is optimized,and the hydrochloric acid cleaning process is added to improve the damage of the oxygen plasma to the Schottky surface.In addition,the effects of two passivation layers with different refractive indexes on the performance of the device were compared,and it was found that the device with a higher refractive index had a larger output current value.Thirdly,design and manufacture GaN power die devices.The DC test of the device shows that its transconductance is 263 m S/mm,the maximum output current density reaches 1010 m A/mm,the Schottky reverse breakdown voltage is above 40 V,and the breakdown voltage of the device reaches 150V;the cut-off frequency of the small signal test reaches 18GHz;The output power density of the large-signal power test die is about5W/mm,which can meet the output power requirements of base station equipment.Finally,a package structure of the power die is given.