A method of making a photomask layout is provided. A graphic data of a photomask is provided. The graphic data includes at least one rectangular pattern. A correction step is performed to the graphic data by using a computer. The correction step includes adding a substantially ring-shaped pattern inside the rectangular pattern. A method of forming a photomask by using the photomask layout obtained by the said method is also provided. In an embodiment, the photomask is suitable for defining micro-lenses of a solid-state image sensor.