3D MEMORY CIRCUIT

Some embodiments provide a three-dimensional (3D) circuit that has data lines of one or more memory circuits on a different IC die than the IC die(s) on which the memory blocks of the memory circuit(s) are defined. In some embodiments, the 3D circuit includes a first IC die with a first set of two or more memory blocks that have a first set of data lines. The 3D circuit also includes a second IC die that is stacked with the first IC dies and that includes a second set of two or more memory blocks with a second set of data lines. The 3D circuit further includes a third IC die that is stacked with the first and second IC dies and that includes a third set of data lines, which connect through several z-axis connections with the first and second sets of data lines to carry data to and from the first and second memory block sets when data is being written to and read from the first and second memory block sets. The z-axis connections in some embodiments electrically connect circuit nodes in overlapping portions of the first and third IC dies, and overlapping portions of second and third IC dies, in order to carry data between the third set of data lines on the third IC die and the first and second set of data lines of the first and second of memory block sets on the first and second IC dies. These z-axis connections between the dies are very short as the dies are very thin. For instance, in some embodiments, the z-axis connections are less than 10 or 20 microns. The z-axis connections are through silicon vias (TSVs) in some embodiments.