Methods of forming trench isolated integrated circuit devices including grooves, and trench isolated integrated circuit devices so formed

A trench isolated integrated circuit device comprising:

• an integrated circuit substrate including therein a trench having sidewalls;
• a lower device isolation layer in the trench and extending onto the trench sidewalls, the lower device isolation layer including grooves therein, a respective one of which extends along a respective one of the sidewalls;
• and
• an upper device isolation layer on the lower device isolation layer and in the grooves.

A method of forming an integrated circuit, comprising:

• sequentially forming a buffer insulation layer and a hard mask layer on a substrate face;
• successively patterning the hard mask layer and the buffer insulation layer to form an opening that exposes a predetermined region of the substrate;
• selectively etching the predetermined region of the substrate to form a trench including a floor and sidewalls;
• forming a lower device isolation layer including grooves within the trench, wherein the grooves are disposed adjacent the sidewalls remote from the floor;
• forming an upper device isolation layer on the lower device isolation layer to fill the grooves and the trench;
• and
• etching the hard mask layer and the buffer insulation layer, such that the grooves extend a predetermined depth from the substrate face.