Provided is a method of forming a semiconductor device. The method may include forming a first insulating layer on a semiconductor substrate. A first polycrystalline silicon layer may be formed on the first insulating layer. A second insulating layer may be formed on the first polycrystalline silicon layer. A second polycrystalline silicon layer may be formed on the second insulating layer. A mask pattern may be formed on the second polycrystalline silicon layer. The second polycrystalline silicon layer may be patterned using the mask pattern as an etch mask to form a second polycrystalline silicon pattern exposing a portion of the second insulating to layer. A sidewall of the second polycrystalline silicon pattern may include a first amorphous region. The first amorphous region may be crystallized by a first recrystallization process. The exposed portion of the second insulating layer may be removed to form a second insulating pattern exposing a portion of the first polycrystalline silicon layer. The exposed portion of the first polycrystalline silicon layer may be removed to form a first polycrystalline silicon pattern exposing a portion of the first insulating layer. The exposed portion of the first insulating layer may be removed to form a first insulating pattern exposing a portion of the semiconductor substrate.