Polymeric film growth on inorganic substrates plays an important role in the technology of sensors and microelectronics. A study of the film growth of a pre polymer of the dicyanate of bisphenol A (DCBA) spin-coated onto silicon substrates is presented in which layer-by-layer growth is demonstrated. This mode of growth is thought to be related to an enrichment of the trimer (see Figure) including a triazine ring.