A method for forming a semiconductor device structure is provided. The method includes forming a dielectric layer over a semiconductor substrate. The method includes forming a mask layer over the dielectric layer. The mask layer has an opening exposing a portion of the dielectric layer. The method includes removing the portion of the dielectric layer through the opening to form a recess in the dielectric layer. The method includes removing the mask layer. The method includes performing a plasma cleaning process over the dielectric layer. The plasma cleaning process uses a carbon dioxide-containing gas.