Study On The Interaction Between Silver Paste And Several N-type And P-type Polycrystalline Material

At present,silver paste as the main electronic connection material has been widely used in the industrial production of semiconductor devices,due to its high conductivity and low temperature sintering and curing characteristics,silver paste as a high-power semiconductor device connection material shows great advantages.However,the bonding process between silver paste and different semiconductor materials has a great influence on the performance of the device,in this paper,the silver paste is coated on the surface of n-type Zn_1-xAl_xO,p-type Ca₃Co₄O₉ and CuAlO₂ polycrystals respectively to study the effects of sintering and curing of silver paste on the interfacial microstructure and electrical properties at different temperatures.Zn_1-xAl_xO（x=0～0.005）series polycrystals was prepared by sintering at 1400°C/12h by solid-phase reaction method,and the effect of Al doping on ZnO polycrystal structure and electrical transport performance was studied.Al-doped ZnO polycrystals were all hexagonal wurtzite structure single phase in the range of solid solubility（x～0-0.004）,and the lattice constant was slightly reduced.x=0 polycrystals is a semiconductor electrical transport behavior,x=0.001～0.005 polycrystals transformation into metal behavior,Zn_0.996Al_0.004O polycrystal resistivity is the lowest,room temperature resistivity is 9.59mΩ·cm.The silver paste was coated on the surface of Zn_0.996Al_0.004O polycrystal block,and after sintering and curing at different temperatures（200～800℃）,the samples were all hexagonal wurtzite structure single phase,and the lattice parameters increased slightly;the samples sintering and curing at high temperature（800°C）and low temperature（200°C）have interfacial resistance of 0.39MΩand 3.7Ωat room temperature,respectively,which was reduced by 5 orders of magnitude,and the intrinsic room temperature resistivity was 2541.71mΩ·cm and 20.37mΩ·cm,respectively,which was reduced by more than 2 orders of magnitude.The significant increase the resistance at high temperature is due to the fact that Ag⁺occupying the Zn²⁺position in the crystal lattice and Ag⁺aggregating at the grain boundary reduce the carrier concentration and mobility,while at low temperature（200℃）,the Ag⁺diffused in the AZO lattice is weak,and the resistance decreases significantly.Ca₃Co₄O₉ polycrystal samples were prepared by sintering at 800°C/24h+870°C/24h by solid-phase reaction method,and the silver paste was coated on the surface of the polycrystal samples,and after sintering and curing at different temperatures（200～800℃）,（00l）orientation function decreased from 0.46 to 0.02,because high temperature sintering and curing,a little of Ag particles were dispersed on the samples surface;the samples sintering and curing at high temperature（800°C）and low temperature（200°C）have interfacial resistance of 5.7Ωand 4.5Ωat room temperature,respectively,and intrinsic room temperature resistivity of 0.105Ω·cm and 0.057Ω·cm,respectively.The interface resistance increases slightly at high temperature,which is due to the increase of crystal defects and crystal boundaries of Ca₃Co₄O₉ polycrystals after sintering and curing of silver paste,and the scattering effect on carriers is intensified.Ag did not diffuse into the lattice of Ca₃Co₄O₉,and the silver paste showed good interfacial contact with Ca₃Co₄O₉ polycrystals in all processes.CuAlO₂ polycrystal samples with delafossite structure were prepared by sintering at1100°C/12h+1150°C/12h by solid phase reaction method,the silver paste was coated on the surface of the polycrystal samples,and after sintering and curing at different temperatures（200～800℃）,the samples were all single phase of rhomboid delafossite structure,the samples sintering and curing at high temperature（800°C）and low temperature（200°C）have interfacial resistance of 180.7kΩand 104.5kΩat room temperature,respectively,and intrinsic room temperature resistivity of 1112Ω·cm and 998Ω·cm,respectively.Due to the poor intrinsic conductivity of CuAlO₂,the interface resistance with silver paste is large and its performance is poor.