Fixed ring and the polishing head

The present invention relates to a fixing ring, apparatus for chemical mechanical polishing, chemical mechanical polishing apparatus comprises a polishing platen and a polishing head, the polishing head comprises a stationary ring and a wafer carrier, the wafer carrier, polishing contact with the wafer for holding a semiconductor wafer and respectively with the polishing head is rotated in opposite directions to polish the wafer fixing ring comprising: an annular base, disposed below the wafer carrier, surrounding the wafer side surface, for holding a wafer; at least one frangible wire is fixed to the annular base surface, Zhou Chang direction along an annular base body extends around a week; off state detecting means respectively with frangible wires, and any alarm signal when a frangible wire tears; signal processing means, and the on-off state detection means outputs terminal is connected, the alarm signal into a polishing stop signal for instructing the polishing head and polishing is stopped. Which can effectively reduce the loss due to the rupture of the fixing ring to bring the process is conducive to improve the efficiency of wafer preparation process.