Using plasma enhanced chemical vapor deposition at 13.56 MHz, thin microcrystalline silicon (muc-Si:H) 'seed-layers' were developed with the aim to improve nucleation and growth of muc-Si:H on foreign substrates such as glass or metals. Without a seed-layer an amorphous interface zone is regularly observed in these cases, which is undesirable in view of characterizing the films for material research and which also represents a problem for device development. While very thin and highly crystalline films can simply be prepared using very high hydrogen diluted discharges, such processes suffer from poor thickness homogeneity and reproducibility. To obtain a better technological control of the seed-layer preparation, we introduced a hydrogen-dilution 'grading' method, based on gradually increasing silane flow during the deposition. Films with excellent homogeneity are obtained in a stable and reproducible process. The structural composition can be tuned between amorphous and highly crystalline by a simple modification of the grading shape, even at the low film thickness of 10 nm.