Integrated micro channels and manifold/plenum using separate silicon or low-cost polycrystalline silicon

A method and apparatus for cooling an electronics chip with a cooling plate having integrated micro channels and manifold/plenum made in separate single-crystal silicon or low-cost polycrystalline silicon. Forming the microchannels in the cooling plate is more economical than forming the microchannels directly into the back of the chip being cooled. In some embodiments, the microchannels are high-aspect-ratio grooves formed (e.g., by etching) into a polycrystalline silicon cooling base, which is then attached to a cover (to contain the cooling fluid in the grooves) and to the back of the chip.