A memory device including a first semiconductor die and a memory cube mounted on and connected with the first semiconductor die is described. The memory cube includes multiple stacked tiers, and each tier of the multiple stacked tiers includes second semiconductor dies laterally wrapped by an encapsulant and a redistribution structure disposed on the second semiconductor dies and the encapsulant. The second semiconductor dies of the multiple stacked tiers are electrically connected with the first semiconductor die through the redistribution structures in the multiple stacked tiers. Each redistribution structure in the multiple stacked tiers includes redistribution patterns, the redistribution structure closest to the first semiconductor die further includes a thermally conductive layer connected to the first semiconductor die, wherein a material of the redistribution patterns in the multiple stacked tiers is different from a material of the thermally conductive layer of the redistribution structure closest to the first semiconductor die, and the thermally conductive layer is electrically isolated from the second semiconductor dies in the multiple stacked tiers and the first semiconductor die.