A method includes placing a semiconductor substrate in a deposition chamber, wherein the semiconductor substrate includes a trench, and performing an atomic layer deposition (ALD) process to deposit a dielectric material within the trench, including flowing a first precursor of the dielectric material into the deposition chamber as a gas phase; flowing a second precursor of the dielectric material into the deposition chamber as a gas phase; and controlling the pressure and temperature within the deposition chamber such that the second precursor condenses on surfaces within the trench as a liquid phase of the second precursor, wherein the liquid phase of the second precursor has capillarity.