The Design,Fabrication And Performance Study Of The Glass-Based Isolated Transformer Chip

The isolated devices are found in many fields such as industry,automobile,medical,communication,energy and so on.The isolated devices are mainly divided as opto-couplers isolated devices,capacitor isolated devices and transformer isolated devices.Among them,the on-chip isolated transformers of the transformer isolated devices have advantages in size,consumption and other aspects,so it is widely used and studied.In recent years,there are many researches on both on-chip transformers for signal isolation and on-chip transformers for power transfer,and researchers want to promote the performance of the on-chip transformers by improvements and innovations of the transformer structures and materials.Now,many of the on-chip transformers are silicon-based and have large substrate losses and substrate parasitic capacitance which are due to the small resistivity and large relative permittivity of the silicon,thus the performance of the on-chip transformer will be influenced.And many of the on-chip transformers use BCB,polyimide and silicon-dioxide as the material to fabricate the isolation layer between the primary coil and secondary coil for a good isolation capacity.But the fabrication of the isolation layer also makes the process more complex.Compared with silicon substrate,the glass substrate has larger resistivity and smaller relative permittivity which results in smaller substrate losses and substrate parasitic capacitance,thus the performance of the on-chip transformer will be promoted.And glass substrate also has a good breakdown field strength,so it can be used as the isolation layer.This thesis proposes a glass-based double-side isolated transformer chip,which also named the glass-based double-side on-chip isolated transformer.It can promote the transformer performance,and at the same time,it uses the glass substrate as the isolation layer between the primary coil and secondary coil which simplifies the process and leads to a good isolation capacity.This thesis designs the basic structure of the glass-based double-side on-chip isolated transformer,and explains the meanings of the important parameters.Through HFSS software simulation,the influences of the parameters on transformer performance are studied.And then,according to the actual application requirements,based on the basic structure of the glass-based double-side on-chip isolated transformer,a simple-type glass-based double-side on-chip isolated transformer is proposed which adds pad to the structure,and the relative simulation is done.Then in order to reduce the complexity of the later packaging process,this thesis leads the underlying pad of the secondary coil to the primary coil layer.Based on the simple-type glass-based double-side on-chip isolated transformer,a glass-based double-side on-chip isolated transformer with through glass via is designed which uses the photosensitive glass to make the through glass via,and also the relative simulation is carried out.As for the simple-type glass-based double-side on-chip isolated transformer and the glass-based double-side on-chip isolated transformer with through glass via,this thesis designs the fabrication process and the layout of both structures.And also the fabrication steps are carried out for both transformers.