METHOD FOR CLEANING OPTICAL SURFACE MONITORING DEVICE

To provide a cleaning method capable of removing abrasive grains stuck to a light passage in a polishing table.SOLUTION: This cleaning method guides light through a light passage 50A provided in a polishing table 3 to a substrate W during polishing of the substrate W, passes reflected light from the substrate W through the light passage 50A, supplies pure water through the light passage 50A with a pure water discharge valve 74 kept closed on a pure water discharge line 54 communicated with the light passage 50A in a state where rotation of the polishing table is stopped and in a state where the substrate W is not present on a polishing pad 2 after the polishing of the substrate W, stops supplying of the pure water and opens the pure water discharge valve 74 to discharge the pure water from the light passage 50A after passage of prescribed pure water supply time, then supplies a chemical solution through the light passage 50A, and removes abrasive grains stuck to the light passage 50A with the chemical solution.SELECTED DRAWING: Figure 2 【課題】研磨テーブル内の光通路に付着した砥粒を除去することができる洗浄方法を提供する。【解決手段】本洗浄方法は、基板Ｗの研磨中に、研磨テーブル３内に設けられた光通路５０Ａを通じて基板Ｗに光を導き、かつ基板Ｗからの反射光を光通路５０Ａ内を通過させ、基板Ｗの研磨後、研磨テーブルの回転を止めた状態で、かつ研磨パッド２上に基板Ｗが存在しない状態で、光通路５０Ａに連通する純水排出ライン上５４の純水排出弁７４を閉じたまま、純水を光通路５０Ａ内に供給し、所定の純水供給時間が経過した後、純水の供給を止めるとともに、純水排出弁７４を開いて、純水を光通路５０Ａから排出し、その後、光通路５０Ａ内に薬液を供給して、光通路５０Ａに付着した砥粒を薬液によって除去する。【選択図】図２