Research On Technologies Of GaN-based Magnetic Sensor Chips Based On Two-Dimensional Electron Gas Channel Structure

Magnetic sensors based on the principle of Hall effect are widely used in nuclear detection,biomedical sensing,automotive electronics and power electronics owing to its lower cost,easy to be integrated and good linearity in a large magnetic field range.Nowadays,the conventional Hall sensors are made of the narrow bandgap semiconductors,such as silicon(Si),gallium arsenide(GaAs),indium antimonide(InSb)and other materials.However,these semiconductor materials do not perform well in harsh environment such as high temperature due to the limitation of their natural characteristics such as low carrier mobility or small bandgap.As one of the mature wide bandgap semiconductor materials,GaN has been proven to be promising candidates for the preparation of high temperature Hall sensors owing to their wide bandgap(>3.0 eV).The two-dimensional electron gas(2DEG)that presences in GaN heterojunction induced by piezoelectric and spontaneous polarization effect is of considerable interest for the high sensitivity Hall sensors.The electron mobility of 2DEG can be as high as2000 cm~2/V·s without intentional doping.In addition,compared with SiC which is also the third-generation semiconductor material,the noise of GaN Hall sensors can be reduced obviously.In this thesis,the horizontal and vertical Hall sensors based on AlGaN/GaN heterojunction are demonstrated by simulation and practical fabrication work.The main research contents include:(1)Layout design of horizontal and vertical Hall sensors based on GaN heterojunction is finished by using L-edit integrated circuit layout design software.The 6-inch AlGaN/GaN heterojunction Hall sensors are fabricated by mature GaN micro/nano processing technology,and the PCB board-level packaging of the sensors are carried out by slicing and wire bonding.(2)Three-dimensional structure of AlGaN/GaN heterojunction horizontal Hall sensors are analysed and demonstrated by performing the simulation software,focusing on the device performance in the temperature range of 300 to 650 K.At the same time,the two-dimensional device simulation of the AlGaN/GaN heterojunction vertical Hall sensors are employed,and the influence of geometric parameters and temperature environment on the electrical characteristics of the sensor is emphatically analyzed.(3)In this thesis,the packaged AlGaN/GaN heterojunction horizontal Hall sensors are tested experimentally.The offset voltage,output characteristics,sensitivity characteristics,temperature characteristics and angle characteristics are discussed systematically.The effects of four different geometric parameters on the performance of the sensors are investigated.The results show that the proposed horizontal Hall sensors can able to work in high temperature with low temperature coefficients and have good electrical properties.(4)This thesis is the first report of successfully manufactured AlGaN/GaN heterojunction vertical Hall sensors.Six kinds of device structures with different geometric parameters are designed,and the effects of different geometric parameters on the performance of the sensors are discussed.The electrical characteristics of Hall sensors such as offset voltage,output characteristics,sensitivity characteristics,temperature characteristics and angle characteristics are discussed systematically.The results show that the vertical Hall sensor fabricated in this thesis has good electrical properties and temperature stability.