In a method of forming a dielectric layer pattern, lower patterns are formed on a substrate. A first dielectric layer is formed on sidewalls and upper surfaces of the lower patterns and a surface of the substrate. A mask pattern is formed on the first dielectric layer to partially expose the first dielectric layer. The exposed first dielectric layer on upper surfaces and upper sidewalls of the lower patterns is partially removed and the removed first dielectric layer is deposited on surfaces of the first dielectric layer between the lower patterns, to form a second dielectric layer having a thickness greater than that of the first dielectric layer. The second dielectric layer on the sidewalls of the lower patterns and the substrate is etched to form a dielectric layer pattern. Accordingly, damage to the underlying layer may be reduced, and an unnecessary dielectric layer may be completely removed.