Investigation And Application Of Metal Deposition For The Electrical Interconnection Structure Of Electronic Components

The electrical interconnection is an essential step in realizing the function of electronic components and the manufacture of functional electronic devices.The layer interconnection structure in high density interconnect printed circuit boards and the terminal electrode for packaging the pins of chip inductor are the important parts of electrical interconnection structure.With the higher requirements for electronic devices in terms of high performance,integration and reliability,improving the reliability and integration density of printed circuit boards by microvia structure,and improving quality factor of chip inductor by novel structure design are the significant research direction in fields of electrical interconnection.Accordingly,based on the investigation of additive adsorption and synergistic effect to enhance the efficiency of copper electroplating microvia filling,and facilitating the manufacturability of novel chip inductor structure by new technique are the research hotspots and difficulty.This dissertation focuses on the formation of electrical interconnection structure by metal deposition.Based on mechanism research,the electrochemical test,molecular dynamics calculation and metal deposition were employed to enhance the efficiency of copper electroplating microvia filling and achieve the industrial manufacture capability of L-shape terminal electrode on chip inductor.The synthesis,test and filter of leveler were investigated to establish the research system of copper electroplating formula.Two technologies of improving microvia filling efficiency were obtained by exploring the mechanism of additive adsorption/desorption and convection-dependent competitive adsorption between additives in open circuit,and the influence of additive pre-adsorption on microvia filling.The theoretical model of anisotropic growth of electroless nickel-phosphorus?Ni-P?plating on fine sliver lines was built,according to the investigation of mass transfer differences which attributed to the difference of wettability and diffusion way at material boundaries.The industrial manufacture of L-shape terminal electrode using anisotropic Ni-P plating was accomplished after solving the relevant technical problems and then applied to production which has gained better economic and social benefit.The main results in this dissertation include:?1?Localized bis?3-sulfopropy?-disulfide?SPS?pre-adsorption to speed up copper electroplating microvia filling.In this section,firstly,the imidazole and 1,4-butanediol diglycidyl ether were employed to synthesize the leveler which named polymerizates of imidazole and epichlorohydrin?IMEP?,the galvanostatic measurements?GM?and electrodeposition then were carried out to test and screen the synthetic levelers.A research system with essential evaluation indicator was built,which contributed a basic copper electroplating formula of microvia?diameter:100?m,depth:80?m?filling with dimple<10?m.The filling process was achieved with 1.5 A/dm² in Harring cell for 45 min.Then,the influence of SPS,poly?ethylene glycol?-block-poly?propylene glycol?copolymer?EO/PO?,IMEP pre-adsorption to microvia filling was investigated by GM and electrodeposition.The results indicated the disappearance of microvia filling by SPS pre-adsorption which is of great significance to the management and maintenance of copper electroplating process for microvia filling.Furthermore,a practical fast microvia filling method in copper electroplating was developed with the aid of bottom-localized SPS pre-adsorption.The pretreatment which decreases the microvia filling time from 45min to 25 min was based on the difference of SPS adsorption and oxidant mass transfer between inside and outside of microvia.Besides,the compatibility between localized SPS pre-adsorption process and common electroplating filling process was discussed for realizing industrial application.?2?Convection-dependent competitive pre-adsorption between SPS and EO/PO to accelerate copper electroplating micvia and trench filling.In this section,firstly,in the absence of halogen ion,the convection-dependent competitive adsorption between SPS and EO/PO on unpowered?in open circuit?copper surface which is based on the competitive of adsorption sites was found in sulfuric acid solution by GM and electrodeposition.Further research by GM,electrochemical impedance spectroscopy?EIS?,molecular dynamic simulation and electrodeposition suggested a mechanism of this competitive adsorption:with the increase of both convection intensity and EO/PO concentration,the adsorption of EO/PO is enhanced,and the adsorption of SPS decreases as a result of the adsorbed EO/PO molecules have occupied more adsorption sites.Then the investigation of Cl^-by GM and electrodeposition showed that the Cl^-would significantly suppress the adsorption of SPS in open circuit.Meanwhile,in the presence of Cl^-,although the convection-dependent competitive adsorption between SPS and EO/PO was still found,the SPS adsorption clearly decreased.Besides,the convection-dependent competitive adsorption between SPS and PEG?including glycol?was proved by GM.It revealed that the polarization of PEG?concerned with the molecular weight of PEG?is positively correlated with the suppression of PEG to coexisting SPS adsorption.A copper electroplating formula of silicon trench?width:25?m,depth:115?m?filling was obtained with 1.5 A/dm² electroplating in Harring cell for 80 min.Incidentally,it was observed that the Ti contained seed layer on trench bottom is harmful to the trench filling.Finally,the convection-dependent competitive adsorption behavior between SPS and EO/PO was served as a powerful handle to manipulate the accumulation of SPS at microvia or trench bottom before electroplating for improving the efficiency of microvia or trench filling.For example,after the pre-adsorption of SPS together with EO/PO,the electroplating time of microvia and trench filling decreased more than 30%.?3?Micron-size anisotropic growth of electroless nickel-phosphorus?Ni-P?plating on fine sliver lines to form L-shape terminal electrode structure of chip inductor.In this section,firstly,a micron-size anisotropic growth of electroless Ni-P plating was realized on the fine sliver lines with the width of?15?m,the growth of Ni-P occurred preferentially in the width direction?Dw?at a growth rate approximately twice than that in the thickness direction?Dt?.The growth rate in Dw reaches more than 15?m in 30 min,in contrast to a growth rate about 6?m in D_t.The influence of Pb²⁺concentration,mass transfer and forced convection on growth of Ni-P layer were discussed,then a possible mechanism for the formation of Ni-P layer morphology as functions of mass transfer and Pb²⁺distribution was proposed to explain the growth behavior of anisotropic electroless Ni-P plating.On this basis,this anisotropic electroless Ni-P plating process was employed to form a novel L-shape terminal electrode structure of chip inductor.A possible mechanism for the formation of Ni-P particle on ceramic was proposed based on the residuary Pd²⁺after pre-treatment and dissociative activated-particulate in plating bath.The industrial application?1kk samples at a time?of L-shape terminal electrode manufacture was accomplished after laboratory test and pilot test.