Copper Interconnect Technology In Aluminum Welding Point Of Tantalum Nitride Diffusion Barrier Process Optimization

With the down-scaling of the device,backend interconnection plays as a much more and more important role for the density,speed,power and reliability of the chip.The improvement of interconnect material and interconnect technology become a key point of the progress of semiconducting manufacture technology.After 0.13μm technology node,Cu line has replaces the Al line and become the mainstream technology.One of the typical backend interconnect structure is formed from several Cu interconnect layers with a top Al boudpad layer.In this kind of interconnect structure,the diffusion barrier layer under the Al line is TaN.If the process of TaN is not correctly optimized,Cu will be easily diffused into the Al boudpad layer.And this will cause serious problems such as inline defect formation,bouding adhesion,yield lose and reliability issues.In this thesis,the problem and mechanism of Cu diffusion at Al boudpad area are studied.And based on this,the TaN deposition process is optimized by a series of comparison experiment.The diffusion barrier capability of TaN film processed by different PVD Sputter equipments was compared.And also we compared the different TaN film properties after fine tuning some process key parameters such as N2 gas flow and sputter power.And more,the barrier capability comparison of different kind of Ta/TaN stack film is also performances.Finally we find several kind of optimized TaN film process having strong enough barrier capability to eliminate the Cu diffusion phenomena at Al pad area.Considering the mass production requirement,we selected the N rich TaN film as the final solution to implement into the real production line.This low cost and high efficiency TaN film process can significantly reduce the defect on production,and improve the yield and reliability of production.