The roughening kinetics of copper films synthesized by low pressure chemical vapor deposition (LPCVD) on Si(100) substrates was investigated by scanning tunneling microscopy (STM). By applying the dynamic scaling theory to the STM images, a steady growth roughness exponent &agr;=0.81±0.05 and a dynamic growth roughness exponent &bgr;=0.62±0.09 were determined. The value of &agr; is consistent with growth model predictions incorporating surface diffusion. The value of &bgr;, while higher than expected from these models, can be related to LPCVD processing conditions favoring growth instabilities. ©1996 American Institute of Physics.