Polishing method and apparatus

Abstract

A chemical mechanical polishing method for polishing an oxide film and a protective film formed on a substrate having recesses comprises four steps. The first step planarizes the oxide film using a polishing pad and a polishing agent containing cerium oxide particles by causing relative rotational motion between the substrate and the polishing pad. The second step continues polishing the oxide film to maintain the planarized property of the oxide film. The third step polishes the oxide film until at least a portion of the protective film becomes exposed. The fourth step polishes the oxide film until the oxide film is substantially removed and the protective film is substantially exposed. During the four steps, torque values are measured on the substrate or the polishing pad, and changes in torque with time are calculated. This information is used to determine the status of each of the steps during the polishing run.

1 . A polishing device for chemically mechanically polishing an oxide film adhered on a protective film formed on a substrate having recesses, comprising: 
 a substrate holding section for holding the substrate;    a polishing section having a polishing pad disposed opposite the substrate holding section;    a driving mechanism for rotating the one or both of the substrate holding section and the polishing pad;    a polishing agent supplier for supplying polishing agent between the substrate and the polishing pad;    a water supplier for supplying water between the substrate and the polishing pad;    a torque measuring device for measuring torque values on the driving mechanism either continuously or at intervals; and    a process monitoring device for monitoring the real-time status of a polishing run by calculating changes in torque with time using the measured torque values.    
   
   
       2 . The polishing device of  claim 1 , wherein the polishing run comprises: 
 a first step of planarizing the oxide film by bringing the oxide film into contact with a polishing pad, supplying a polishing agent containing cerium oxide particles between the oxide film and the polishing pad, and causing relative rotational motion between the substrate and the polishing pad;    a second step of continuing to polish the oxide film once the oxide film has been planarized, thereby maintaining the planarized property of the oxide film;    a third step of continuing to polish the oxide film until at least a portion of the protective film becomes exposed; and    a fourth step of continuing to polish the oxide film until the oxide film is substantially removed and the protective film is substantially exposed.    
   
   
       3 . The polishing device of  claim 2 , wherein monitoring the real-time status of a polishing run comprises detecting transition points between adjacent steps of the first through fourth steps and detecting anomalies in at least one of the first through fourth steps.  
   
   
       4 . The polishing device of  claim 1 , wherein the torque measuring device measures torque values based at least in part on one or more of the driving current, driving voltage, and driving power applied to the driving mechanism.  
   
   
       5 . The polishing device of  claim 3 , wherein the process monitoring device stops the driving mechanism when an anomaly is detected in any of the first through fourth steps.  
   
   
       6 . The polishing device of  claim 3 , wherein the process monitoring device controls one or both of the polishing agent supplier and the water supplier so that each of the first through fourth steps can use different polishing agents or water, and the composition of the polishing agent used for any particular step is based at least in part on properties associated with the oxide film or on the detected transition points.  
   
   
       7 . The polishing device of  claim 3  including a plurality of polishing pads having different hardness values, wherein the process monitoring device controls one or both of the substrate holding section and the polishing section so that polishing pads are chosen for use in each of the first through third steps based at least in part on properties associated with the oxide film or on the detected transition points.  
   
   
       8 . The polishing device of  claim 3 , wherein the process monitoring device controls one or both of the substrate holding section and the polishing section so that a different pressure can be applied between the polishing pad and the substrate for each of the first through third steps, each applied pressure being chosen based at least in part on properties associated with the oxide film during each step and on the detected transition points.