Plasma deposition of monosubstituted organosilicon precursors can result in layers containing extensive Si–Si bonded backbones. When these films are simultaneously exposed to ultraviolet light and oxygen, the Si–Si bonds are scissioned and oxygen inserted to form Si–O–Si polymer chains. It is shown that these films can be deposited by a low‐pressure dc plasma source. The plasma is created by electronic excitation of Xe and methylsilane with an axial magnetic field to confine the plasma near the substrate surface. The plasma has a narrow spread of relatively low (10–20 eV) particle energies. In this way the production of undesirable gas phase reactions is limited. The ability to work at low pressure, with correspondingly low deposition rates, makes it possible to deposit thin resist layers which are suitable for nanolithographic applications.