A method includes forming a plurality of fins on a semiconductor substrate by defining a plurality of trenches in the substrate. A first insulating material layer comprising silicon, oxygen and carbon is formed in the trenches between the plurality of fins. The first insulating material layer has an upper surface that is at a level that is below an upper surface of the fins. A second insulating material layer is formed above the first insulating material layer. The second insulating material layer is planarized to expose a top surface of the plurality of fins. The second insulating material layer is removed to expose the first insulating material layer.