The invention includes methods of forming layers conformally over undulating surface topographies associated with semiconductor substrates. The undulating surface topographies can first be exposed to one or more of titanium oxide, neodymium oxide, yttrium oxide, zirconium oxide and vanadium oxide to treat the surfaces, and can be subsequently exposed to a material that forms a layer conformally along the treated surfaces. The material can, for example, comprise an aluminum-containing compound and one or both of silane and silazane. The invention also includes semiconductor constructions having conformal layers formed over liners containing one or more of titanium oxide, yttrium oxide, zirconium oxide and vanadium oxide.