Research progress on preparation and remanufacturing of refractory metal targets for sputtering

PAN Yafei; HUANG Lei; ZHANG Jiuxing

doi:10.13732/j.issn.1008-5548.2025.05.004

Abstract：Significance The semiconductor industry,as a pillar of the national economy and a strategic cornerstone,is facing new develop-ment opportunities with breakthroughs in third-generation semiconductor technologies.In this process,chip manufacturing pro-cesses and the material supply chain have become the keys to promote industry progress.Refractory metal targets,such as tung-sten(W)and molybdenum(Mo),are indispensable for the manufacturing of semiconductor integrated circuits due to their excellent physical and chemical properties.These materials,prepared as functional thin films through sputtering,are widely applied in several key areas of electronic information industries.However,a significant challenge lies in the low utilization rates of high-purity sputtering targets,typically below 30％for planar targets and under 70％for rotating targets.Consequently,recy-cling and reusing spent targets after sputtering not only have considerable economic benefits but also contribute significantly to environmental protection. Progress This study reviews the current application status of refractory metal targets in the semiconductor industry,analyzes their preparation processes,and predicts future development trends.Refractory metal sputtering targets are generally produced using two major methods:melting technologies and powder metallurgy.Melting technologies such as electron beam melting and arc melting are commonly used for tantalum(Ta)and niobium(Nb)targets,while tungsten(W)and molybdenum(Mo)targets are predominantly prepared through powder metallurgy.Especially for alloys with significant differences in density and melting points,powder metallurgy ensures the uniformity of the target's structure and composition.Methods such as hot pressing(including vacuum and inert gas),hot isostatic pressing,cold isostatic pressing,and spark plasma sintering are commonly used to achieve full densification.Moreover,this study analyzes in detail the influence of key factors such as density,purity,grain size,and crystal orientation on target properties.The use of high-purity powder raw materials is crucial,as impurities can degrade electrical and optical properties,impacting device performance.Current technologies for preparing high-purity refrac-tory metal powders mainly include physical-chemical methods,plasma spheroidization,atomization,and plasma rotating elec-trode methods,with atomization emerging as the mainstream process.This study also explored the recycling and remanufactur-ing technologies for waste targets.High-purity target recovery primarily involves electron beam vacuum remelting or converting spent targets into high-purity powder.However,these methods could increase cost and lead to material loss.In addition,during converting,impurities may be introduced,potentially compromising the purity of remanufactured targets.Compared to the recy-cling process,remanufacturing process,which involves filling etched area with the same material without soldering has minimal material loss,lower costs,and better preservation of target properties.Spark plasma sintering,as an efficient sintering and bonding technique,has been successfully applied in the remanufacturing process of targets such as W,Mo,W-10％Ti,W-30％Si,and Mo-10％Nb. Conclusions and prospects The development of refractory metal targets is expected to focus on the following key areas:1)High purity and high uniformity:As integrated circuit feature sizes shrink,the demand for higher purity and uniformity in targets increases.2)Large size and high flatness:To meet the requirements for processing large-sized silicon wafers,improving the size and surface flatness of targets is crucial.3)Innovation of preparation technology:Continuous improvement and innovation of preparation technologies,such as powder metallurgy,hot pressing,spark plasma sintering,and spray melting,will improve target performance and reduce manufacturing costs.4)Recycling and remanufacturing:Adapting to increasingly strict environ-mental regulations and maximizing cost-effectiveness make recycling and remanufacturing key industry priorities.With growing investments from domestic enterprises and research institutes,China will make great progress in the research and preparation of high-purity refractory metal targets.With these advancements,China will reduce its dependence on imported targets,increase the market share of domestic target materials,and bolster China's electronic materials industry to rival and surpass the levels of developed countries.