Research On Hall Magnetic Sensor Based On CMOS Technology

In 1960,MOS structure was first used for the integrated circuit(IC).With the development of CMOS and BiCMOS technology,IC gradually possessed the characteristics of high recognition rate,high integration,strong driving ability,and low power consumption.As the cornerstone of the computer industry,sensors process natural language and translate it so that the computer can realize the interaction between the environment and computer.Besides,the development of the 5th mobile communications system,aircraft engines,and automotive industries are closely related to sensors,and the research of new materials will also bring promotion to sensitive components which play a key role in sensors.Therefore,sensors based on CMOS technology will meet a new inflexion from one billion dollars to more.In order to realize the measurement of magnetic field in all directions,the horizontal and vertical Hall devices can be integrated into the same chip.This article mainly studied the cross-like horizontal Hall devices,five-contact,and three-contact vertical Hall devices for the study of 3D Hall sensors.Considering that the current-related sensitivity of the cross-like Hall devices is highly dependent on the geometric correction factor,the effect of different sizes and aspect ratio(Length/Width)on the sensitivities were studied.Then,the devices were designed based on GLOBALFOUNDRIES 0.18 ?m BCDliteTM technology.It can be found that the cross-like horizontal Hall device showed good repeatability,consistency as well as small offset voltage.The current-related sensitivity can reach up to 125 V/AT.For vertical Hall device,the influence of structure and technology parameters on its current sensitivities were discussed since the highly doping concentration and shallow active regions in the CMOS technology are incompatible with a high-sensitivity demand.During the research,the sensitivities of the Hall sensors can be predicted by constructing a 2D model by finite element method(FEM),which divides a problem or structure into smaller,simpler parts.COMSOL is a FEM simulation software,in which the geometric and process parameters of Hall sensors can be easily varied for further analysis.The 2D and 3D models can be chosen in diverse modules to perform the studies,such as AC/DC and semiconductor modules.A variety of functions in COMSOL provides an easy-to-use method for the performance prediction of Hall sensors.Some representative structure parameters were selected for circuit design.The comparisons between the measurement and simulation results were further studied for the modification of the model.In COMSOL,when the active region's depth is 7 ?m and the doping concentration is 1.619 × 1016cm-3,the sensitivity of the five-contact vertical Hall device can reach to 107 V/AT.The sensitivity of the five-contact vertical Hall device based on the standard CMOS technology can also reach to 16.8 V/AT.Judging from the change curve of Stop,it can be found that as the increase of the active region's depth,the curve of Stop increases.Therefore,increasing the depth of the active region is an effective method to improve performance of the five-contact vertical Hall device.For the three-contact vertical Hall device,we mainly studied the influence of the sensing contact,P-type layers,and the active region on its sensitivity by analyzing the distribution of current density and the factor of Stop.When the depth of the active region is 7 ?m,Stop increased from 3.168 V/AT to 6.859 V/AT,close to 7.440 V/AT when there were no sensing contacts.This would limit the increase in sensitivity of three-contact vertical Hall device.Thus,the cooperation between the active region and the P-type layers can effectively change the behavior of the device.The main innovations of the paper are as follows:1.Simulation models for Hall sensors were constructed by FEM in order to understand their behavior.Hall sensors can vary in geometric shapes and materials.This method can reduce the development cycle by partially substituting chip tape-out with simulation.2.The current-related sensitivity of the top edge(Stop)was defined.This factor can not only be used to analyze the influence of structure and technology parameters on the sensitivity,but also to distinguish which play a key role in changing the behavior of Hall sensors.3.The impact of the sensing contacts,P-type layers and active region's depth were both taken into account by inspecting the distribution of the current density.