A memory device including a base chip and a memory cube mounted on and connected with the base chip is described. The memory cube includes multiple stacked tiers, and each tier of the multiple stacked tiers includes semiconductor chips laterally wrapped by an encapsulant and a redistribution structure. The semiconductor chips of the multiple stacked tiers are electrically connected with the base chip through the redistribution structures in the multiple stacked tiers. The memory cube includes a thermal path structure extending through the multiple stacked tiers and connected to the base chip. The thermal path structure has a thermal conductivity larger than that of the encapsulant. The thermal path structure is electrically isolated from the semiconductor chips in the multiple stacked tiers and the base chip.