Czochralski silicon with constant controlled oxygen level of 15+/-0.5 ppma (ASTM F121–80) and varying carbon content intentionally doped at five different levels from 0.1 ppma to 4.1 ppma (ASTM F123–81) was used to fabricate 16K dynamic random access memories, MOS test capacitors with guard rings, and pn junctions. The results of the experiment have been analyzed for relative yield to functional and refresh characteristics, MOS generation and bulk recombination lifetime, pn junction leakage, and both surface and bulk defect densities. Peak performance of the silicon did not occur at the lowest carbon level, but was dominated by the oxygen precipitate defect density and depth of the denuded zone near the active device regions. The results of the capacitor measurements, the DRAM yield measurements, the junction leakage measurements and the bulk and surface lifetime measurements are self-consistent and emphasize the need for control of the oxygen precipitation whether it is nucleated by carbon or other homogeneous and heterogeneous processes. There is no evidence that carbon has any impact on the device performance other than its impact on the precipitation kinetics of the interstitial oxygen.