A semiconductor device assembly that includes a second side of an interposer being connected to a first side of a substrate. A plurality of interconnects may be connected to a second side of the substrate. First and second semiconductor devices are connected directly to the first side of the interposer. The interposer is configured to enable the first semiconductor device and the second semiconductor device to communicate with each other through the interposer. The interposer may be a silicon interposer that includes complementary metal-oxide-semiconductor circuits. The first semiconductor device may be a processing unit and the second semiconductor device may be a memory device, which may be a high bandwidth memory device. A method of making a semiconductor device assembly includes attaching both a memory device and a processing unit directly to a first side of an interposer and connecting a second side of the interposer to a substrate.