A high density, low profile, three dimensional memory module having multi-level semiconductor packages mounted on one or opposite sides of a printed wiring board. Each multi-level package of the memory module contains an upper level DRAM integrated circuit package that is surface mounted on the printed wiring board and at least one lower level DRAM integrated circuit package that is surface mounted on the printed wiring board below the upper level package, such that the upper and lower level packages are stacked one above the other. The upper level package is preferably a thin small outline package, and the lower level package is preferably a leadless chip scale package. The leads of the upper level package are of sufficient length so that the standoff height of the upper level package establishes a clearance thereunder in which to receive the lower level package. The lower level package is characterized by a smaller footprint and profile than the corresponding footprint and profile of the upper level package.