Method for Adjusting Metal Polishing Rate and Reducing Defects Arisen in a Polishing Process

Abstract

The invention discloses a method for adjusting metal polishing rate and reducing defects arisen in a polishing process, in which a electric conduction system is additionally provided to a polishing apparatus to electrify the polishing fluid; in the polishing process, the polishing fluid flows through the polishing pad and the wafer to be polished, such that the polished metal surface of the wafer is electrically charged so as to control the oxidation of the polished metal surface of the wafer. The invention has solved the problem that the dishing and erosion defects are prone to be formed in the existing polishing process, the potential of the polishing fluid is changed by means of the additional electric conduction system and thus the polishing rate of the polished metal is controlled so as to reduce the dishing and erosion defects occurred in the polishing process.

1 . A method for adjusting metal polishing rate and reducing defects arisen in a polishing process, comprising steps of:
 adding an electric conduction system to a polishing apparatus in order to electrify a polishing fluid; and   in the polishing process, electrically charging a polished metal surface of a wafer to be polished by the polishing fluid flowing through a polishing pad and the wafer, and thereby controlling an oxidation of the polished metal surface of the wafer.   
     
     
         2 . The method for adjusting metal polishing rate and reducing defects arisen in a polishing process according to  claim 1 , further comprising a step of providing a conducting element layer inside of a polishing turntable for polishing the wafer in the polishing apparatus, wherein an edge portion of the conducting element layer is exposed to outside of a side edge of the polishing turntable, and the polishing fluid, when flowing down around the polishing turntable, contacts the conducting element layer. 
     
     
         3 . The method for adjusting metal polishing rate and reducing defects arisen in a polishing process according to  claim 1 , wherein the conducting element layer is grounded. 
     
     
         4 . The method for adjusting metal polishing rate and reducing defects arisen in a polishing process according to  claim 1 , wherein the electric conduction system provides a high potential to the polishing fluid, and the polished metal surface is at a higher potential in the polishing fluid, so as to accelerate a reaction of the polished metal surface with chemical compositions in the polishing fluid to generate metal oxide(s) or metal ion(s), and the accelerated oxidation reaction of the metal surface in turn results in an increased polishing rate, such that a scratch degree of the metal surface and a polishing pressure are reduced. 
     
     
         5 . The method for adjusting metal polishing rate and reducing defects arisen in a polishing process according to  claim 1 , wherein the electric conduction system provides a low potential to the polishing fluid, and the polished metal surface is at a lower potential in the polishing fluid, and ions in the polishing fluid suppress a reaction of the polished metal surface with chemical compositions in the polishing fluid, so that the metal polishing rate is reduced and a more flat surface is thereby obtained. 
     
     
         6 . An apparatus for adjusting metal polishing rate and reducing defects arisen in a polishing process, comprising a polishing stand, wherein the polishing stand is provided with an electric conduction system, and the electric conduction system has a voltage output terminal to contact a polishing fluid of the polishing stand. 
     
     
         7 . The apparatus for adjusting metal polishing rate and reducing defects arisen in a polishing process according to  claim 6 , wherein a conducting element layer is provided inside of a polishing turntable of the polishing stand, and has an edge which is exposed to outside of a side edge of the polishing turntable and a leading-out terminal which is grounded.