3D Memory Formed of Unrepairable Memory Dice and Spare Layer

With the development of memory manufacturing technology, the density of memory die has been increased and more data can be stored in a small area than before. However, due to the complexity of the manufacturing process, faults in memory have increased. And it leads to poor yield and quality of memory. To improve yield and quality of the memory, the importance of memory test and repair is growing to maintain memory productivity. This paper presents solutions for test and repair in pre-bond. In the pre-bond, proposed method makes a new 3D stacked memory by using unrepairable memory dice which cannot be repaired with existing spare memories. Discard the bank with the largest number of faults in the unrepairable memory die and repair the remaining banks. The memory dice and a spare layer which made of the known good die or unrepairable memory die are stacked to create a 3D memory. A bank of the spare layer is mapped to discarded bank of unrepairable memory die to operate as one normal working memory die. The proposed method can lead to high yields of 3D stacked memory.