CLEANING SOLUTION FOR POSTTREATMENT OF POLISHING PROCESS AND CLEANING METHOD FOR SEMICONDUCTOR ELEMENT USING THIS SOLUTION

PROBLEM TO BE SOLVED: To make it possible to efficiently remove a damaged film formed on the surface of an oxide layer or an insulation layer without damaging a barrier layer by applying a cleaning solution having excellent cleaning effect on a contaminated layer, which contains specified amounts of phosphoric acid and tetrafluoroboric acid, and deionized water for the remaining amount of the above two. SOLUTION: The solution contains 0.1 to 99 volume % of phosphoric acid, 0.1 to 25 volume % of tetrafluoroboric acid and deionized water for the remaining volume of the above two. For instance, a semiconductor element formed with a plug conductive layer 53 for embedding a contact hole is polished and its surface is flattened. At this time, a polishing pad and a polishing agent react with the surface of a wafer mechanically and chemically, thereby forming a contaminated layer 63, and a chemical reaction occurs with an oxide layer or an insulation layer 23, and a damaged film 33 is formed on the surface. Next, wet type cleaning treatment is performed using a cleaning solution containing tetrafluoroboric acid and phosphoric acid, then the contaminated layer 63 is removed while preventing the corrosion of a barrier layer 43, and the damaged film 33 can be efficiently removed.