To reduce test time and test cost for pre-bond and post-bond test of three dimensional embedded cores

this paper proposed an optimization method based on span and virtual layers for wrapper scan chains in three dimensional embedded cores.Firstly

the proposed technique made the number of wrapper scan chains in high layers and low layers as equal as possible by maximizing the span of wrapper scan chains.Then

under the constraints of TSVs(Through Silicon Vias)number

the scan elements contained in virtual layers were assigned to wrapper scan chains layer by layer

which effectively balanced the length of pre-bond and post-bond wrapper chains.Experimental results show the presented methodology can greatly reduce the pre-bond/post-bond test time and hardware overhead for three dimensional embedded cores.