Research On Optimization Method Of 3D Memory Yield Based On Inter-layer Redundancy Sharing

With the improvement of integrated circuit technology and the scaling of transistor size,the three-dimensional integrated circuit technology is considered as one effective way to continue improving integrated circuits performance.Three dimensional integrated technology is suitable for high density applications,and memory is a typical representation of the high density characteristics in integrated circuits,which has become one hot topic in three-dimensional integrated technology.The interconnection between two layers is through-silicon vias(TSVs)in three-dimensional memory,which makes it possible to share the redundancies between layers.Memory dies stacking strategy and redundancy sharing strategy have an important effect on the yield of 3D memory.In order to improve the yield of three-dimensional memory,this paper proposes the following two methodologies: 1.Yield Optimization Technique for Three Dimensional Memory Based on Redundancy Sharing among Adjacent Layers.Memory dies stacking strategy and redundancy sharing structure have great effects on the yield of three-dimensional memory.To improve 3D memory yield and reduce the number of TSVs,this thesis proposes a redundancy sharing structure among adjacent layers.In the proposed sharing structure,the redundancies in each layer can not only be used to repair the faults in the layer where the redundancies reside,but also can be utilized by adjacent layers.On the basis of this structure,a new die-stacking strategy is presented.By constructing the selection constraints of memory dies,the presented strategy can choose suitable memory dies to stack 3D memory.In this way,the row and column redundancies are fully used.Experimental results show that the proposed redundancy sharing structure and die-stacking strategy can effectively improve 3D memory yield and reduce the number of TSVs consumed by spare rows and columns.2.Yield Optimization Technique for Three Dimensional Memory Based on Redundancy Sharing among Multi-block Global Redundancy.In order to improve the yield of three-dimensional memory,this thesis presents a multi-block global redundancy shared structure.In the redundancy sharing structure,the redundancy of each memory block is not only connected to the adjacent storage blocks in the left and right side,but also connected to the upper and lower vertically stacked memory dies.Therefore,the redundancy of the structure can be used by the adjacent storage blocks in the horizon and the adjacent storage blocks in the vertical direction.In order to make full use of the redundancy of the memory dies,a new scheme of memory dies stack is proposed.The scheme selects the appropriate memory dies to stack by storing the selection condition of memory dies.The experimental results show that the proposed method can effectively improve the yield of 3D memory compared with the pair-wise redundancy sharing and the global redundancy sharing schemes.With the increase of stacking layers,the yield of three dimensional memory is also increased,which indicates that the proposed scheme is suitable for large-scale memory.