Design And Performance Optimization Of Microwave Near-field Scanning Probe

The ability to accurately test the broadband characteristics of semiconductor integrated circuits is of great significance to the rapid development of chip technology.Chip integrated circuits continue to develop in the direction of increasingly higher integration and smaller sizes,which brings more severe tests to the test.Traditional microscopy cannot break through the resolution limit of the far-field,and it is difficult to effectively measure the local parameter information of the sample.The application of microwave near-field scanning microscopy to the on-chip detection of the electromagnetic parameters of integrated circuits can break through the diffraction limit and obtain high spatial resolution of micron or nanometer level image.This technology can realize on-chip screening before chip segmentation and packaging,avoiding waste of subsequent processing time and resources and improving the accuracy of testing.The key research objectives of this paper include two parts: design of probe in the near-field test system and optimization of probe performance.They are studied and analyzed through the combination of theoretical analysis,electromagnetic simulation verification and experimental testing.The main research contents are as follows:First,combined with the theory of near-field microwave testing technology,the difference between near-field and far-field is analyzed.The signal source,probe tip,and sample in the near-field area affect each other and the Abbe's theory of image formation is no longer applicable.The resolution limit in the far field can be broken by detecting the evanescent waves in this area.The commonly used microwave probes and calibration methods are introduced,the principles,advantages and disadvantages of several near-field dielectric constant measurement methods are analyzed,and the advantages of the probe test system are explained.The probe performance testing technology is theoretically researched,and the error introduced by the non-ideal parts during the test of this method is analyzed.The causes and mechanisms of various losses in the probe are studied,and the methods to optimize the performance of the probe and reduce the loss of the probe are briefly described.Secondly,according to the test requirements of 10MHz?110GHz broadband and high spatial resolution,the design of microwave near-field probes were studied,and the design plan of grouped probes was formulated.Need to follow the three basic rules of low-loss,low reflection and high reliability in probe design are analyzed based on the principle of test system.Optimized the previous probe,changed the tip type of the probe,designed a new linear gradient coaxial and GSG probe,solved the problem of impedance discontinuity caused by the nonlinear change of probe size was solved.The effects of structural parameters such as probe conductor size and tip length on the characteristic impedance,insertion loss and return loss were studied and analyzed in detail.The return loss of samples with different thicknesses was simulated by the probe,and the law of resonance frequency and return loss amplitude changing with thickness was found.The GSG probes made were used to test the samples with different dielectric constants.Considering that the size of the GSG probe and the transmission port of the test system did not match and it was difficult to connect,a coaxial transition device was designed to be easy to assemble or bond,and the influence of different connection modes on the performance of the two was analyzed and optimized.Finally,the transmission loss of the designed coplanar GSG probe is optimized.A simulation analysis was carried out on the loss of probe conductor and dielectric substrate when using different materials.The structure of the conventional GSG probe was improved and optimized by considering the three aspects of conductor loss,dielectric loss and radiation loss,The etched coplanar GSG probe,embedded slotted GSG probe and embedded connected GSG probe were designed successively,and studied the relationship between the newly added structural parameters and the probe loss.Through the analysis and comparison of the performance,it was proved effective about the designed structure to reduce the loss provides a data basis for the production and processing of the probe.In this paper,according to the requirements of broadband and high-resolution testing,the linear gradient grouping probe in the near-field testing system is designed based on the theory of near-field microwave microscopy,and the transmission loss performance of GSG probe is optimized.Through the combination of theoretical analysis,simulation and experimental testing,the research and verification are carried out.