NiederdruckCVD

NiederdruckCVD, also known in English as low‑pressure chemical vapor deposition, is a thin‑film deposition technique in which gaseous precursors react on a heated substrate to form a solid film at much lower pressures than conventional atmospheric‑pressure CVD. Typical pressures range from a few millitorr to several mbar, which reduces gas–phase collisions and allows for more uniform film growth.

The process begins by introducing precursor gases into a vacuum chamber equipped with a heated stage. The gases adsorb onto the substrate surface, where surface‑mediated reactions such as cracking, dissociation, or polymerisation produce the desired material. Excess gases and reaction by‑products are pumped out through a series of turbomolecular or cryogenic pumps, maintaining the low pressure environment. Because the mean free path of molecules is longer at low pressure, adatom diffusion on the surface dominates, leading to smoother, more crystalline films.

Industrially, NiederdruckCVD is widely used for deposition of silicon dioxide, silicon nitride, aluminum oxide, and various III‑V semiconductors such as gallium nitride. It is especially valuable in producing high‑quality dielectric layers for microelectronic devices, optoelectronic components, and protective coatings. In research settings, the method enables precise control of film composition and thickness on complex substrates, including flexible polymers and nanostructured surfaces.

Key equipment includes a load‑lock chamber, mass‑flow controllers for precise gas mixing, a heating system that can reach temperatures up to 1200 °C, and a high‑capacity pumping system composed of roughing, turbomolecular, and ion pumps. In addition, real‑time monitoring tools such as quartz crystal microbalances and residual‑gas analyzers can be employed to optimise growth parameters.

Advantages of NiederdruckCVD are the high uniformity, reduced contamination from background gases, and the ability to grow films with superior crystalline quality. However, the technique requires sophisticated vacuum infrastructure, and the growth rates are typically lower than those achievable in atmospheric‑pressure CVD. The trade‑off between cost, complexity, and film performance is a key consideration for the choice of deposition method.