Method for forming trenches having different widths and the same depth

A method of forming a patterned structure comprising:

• forming a material stack including a photoresist layer and an organic planarizing layer comprising an organic planarizing material over at least one underlying layer;
• forming a first trench in a first region of said organic planarizing layer and a second trench in a second region of said material stack by etching said organic planarizing layer, wherein two sidewalls of said first trench are separated by a first width and two sidewalls of said second trench are separated by a second width that is greater than said first width;
• and
• completely removing said organic planarizing material from said first trench to expose a topmost surface of said at least one underlying layer across an entirety of a bottom surface extending from one of said first sidewalls of said first trench to the other of said first sidewalls of said first trench, said entirety of said bottom surface not including a surface of any organic planarizing material after said complete removal of said organic planarizing material from said first trench, while concurrently forming an etch residue portion comprising said organic planarizing material, which is present when said entirety of said bottom surface does not include a surface of any organic planarizing material, on a center portion of a bottom surface of said second trench and above said topmost surface of said at least one underlying layer and concurrently exposing said topmost surface of said at least one underlying layer in peripheral portions of said bottom surface of said second trench.