A method of fabricating a semiconductor device is disclosed. The method includes forming an opening with a tapered profile in a first material layer. An upper width of the opening is greater than a bottom width of opening. The method also includes forming a second material layer in the opening and forming a hard mask to cover a portion of the second material layer. The hard mask aligns to the opening and has a width smaller than the upper width of the opening. The method also includes etching the second material layer by using the hard mask as an etch mask to form an upper portion of a feature with a tapered profile.