Capacitance-voltage Characterization Technology Of Stacked Bonding Structure In 3D Integration

Three-dimensional integration is one of the development directions of IC technology.It is of great scientific significance and application potential to research the measurements and characterizations of the stacked bonding structure,a basic stack structure in three-dimensional integration.In this thesis,a non-destructive solution based on CV(Capacitance-Voltage)characteristics is proposed to extract parameters,which is verified by the numerical simulations and experiments.First,an accurate model is developed for the LF(Low Frequency)and HF(High Frequency)CV characteristics of MIS(Metal-Insulator-Semiconductor)structure.Based on the conventional basic model of the ideal MIS structure,the substrate surface potential,inversion condition and weak inversion equation are calibrated.Comparisons with the conventional model show that the accuracy of the derived analytical model is improved up to 99% or more.Then the influence of interface states is included into the analytical model.Second,the LF and HF CV model of the ideal stacked bonding structure is proposed.Based on the derived accurate CV model of the MIS structure,the LF and HF CV relationship expressions of the ideal stacked bonding structure with different doping types are reduced and verified by the good agreements with the numerical simulation by MEDICI,a two-dimensional semiconductor simulator.And then,in order to investigate the physical mechanism of CV characteristics of this structure,the space charge layer,the surface potential of the semiconductor layer and the potential of the metal layer are investigated in detail under the various bias conditions.Moreover,a deeply discussion is implemented to characterize the impacts of the doping concentration,insulator thickness on the LF and HF CV characteristics.Third,the LF and HF CV model of the real stacked bonding structure is derived.The LF and HF CV relationship expressions of the proposed structure are modified considering the work-function between the metal and the semiconductor,the insulator fixed charges and the interface states.The results show that the CV model exhibits a high degree of complexity.Different semiconductor surface potential states lead to four types of CV curves which are very different each other.The mechanism is analyzed and validated using two-dimensional numerical simulation based on MEDICI.Fourth,a non-destructive method to extract the physical parameters of the stacked bonding structure is derived through the CV method.Based on the above model,the insulator thickness and doping concentration can be characterized by the LF and HF saturated capacitances,respectively.The fixed charges density can be measured by the zero point and the feature extreme point from the LF CV curves.The interface state density can be extracted using parameter identification method.The evaluability of the method is verified by the very low relative errors,mostly less than 6%,between the extracted and theoretical values.Fifth,the MIS structure and stacked bonding structure are fabricated and the parameters are extracted.The MIS structure is prepared by oxidation and deposition with copper as the metal layer on a p-type silicon substrate.Then,two pieces of MIS structures are bonded back-to-back using copper-copper bonding technology to obtain a stacked bonding structure.The samples of the fabricated structures are measured by SEM and HF CV characteristic tests.The reasonability and availability of the proposed model and method are verified by the successful characterization of the physical parameters from the experimental data.This work carries on an effective solution for the non-destructive characterization of the stacked bonding structure in three-dimensional integration.It is simple,convenient,low cost,high precision,and with important engineering value and practical significance.