Substrate polishing apparatus

Abstract

Provided is a substrate polishing apparatus including a platen, a polishing pad including a hole on an upper surface of the platen and configured to rotate with the platen, an upper surface of the polishing pad including an opening, a head on the polishing pad and configured to support the substrate such that a polishing surface of the substrate faces the polishing pad, and an acoustic sensor in the hole and including a piezoelectric element on an edge of a droplet on a film portion.

What is claimed is: 
     
         1 . A substrate polishing apparatus comprising:
 a platen;   a polishing pad comprising a hole on an upper surface of the platen and configured to rotate with the platen, an upper surface of the polishing pad comprising an opening;   a head on the polishing pad and configured to support the substrate such that a polishing surface of the substrate faces the polishing pad; and   an acoustic sensor in the hole and comprising a piezoelectric element on an edge of a droplet on a film portion.   
     
     
         2 . The substrate polishing apparatus of  claim 1 , wherein the acoustic sensor further comprises:
 a first electrode;   a second electrode spaced apart from and facing the first electrode; and   a piezoelectric structure between the first electrode and the second electrode and in contact with the first electrode and the second electrode.   
     
     
         3 . The substrate polishing apparatus of  claim 2 , wherein the piezoelectric structure comprises:
 the film portion; and   the piezoelectric element,   wherein the film portion is perpendicular to the first electrode and the second electrode, and   wherein the piezoelectric element is generated based on the droplet comprising a piezoelectric material applied to the film portion being dried.   
     
     
         4 . The substrate polishing apparatus of  claim 3 , wherein the piezoelectric structure comprises a plurality of piezoelectric structures between the first electrode and the second electrode. 
     
     
         5 . The substrate polishing apparatus of  claim 4 , wherein at least one piezoelectric element included in a piezoelectric structure among the plurality of piezoelectric structures comprises a different piezoelectric material. 
     
     
         6 . The substrate polishing apparatus of  claim 4 , wherein at least one piezoelectric element included in a piezoelectric structure among the plurality of piezoelectric structures has a different form. 
     
     
         7 . The substrate polishing apparatus of  claim 3 , wherein the film portion comprises at least one of polyurethane (PU), polyethylene terephthalate (PET), and polypropylene (PP). 
     
     
         8 . The substrate polishing apparatus of  claim 3 , wherein the piezoelectric element comprises at least one of barium titanate (BaTiO 3 ), zinc oxide (ZnO), and zirconate titanate (PZT). 
     
     
         9 . The substrate polishing apparatus of  claim 2 , wherein the acoustic sensor further comprises a signal amplification film between the first electrode and the piezoelectric structure, and
 wherein the acoustic sensor is configured to increase a contact area between the first electrode and the piezoelectric element.   
     
     
         10 . The substrate polishing apparatus of  claim 2 , wherein the acoustic sensor further comprises a seed layer between the second electrode and the piezoelectric structure. 
     
     
         11 . The substrate polishing apparatus of  claim 1 , further comprising a cable connected to the acoustic sensor and configured to transfer signals to an outside of the substrate polishing apparatus. 
     
     
         12 . A substrate polishing apparatus comprising:
 a platen;   a polishing pad on an upper surface of the platen and configured to rotate with the platen;   a head configured to support the substrate such that a polishing surface of a substrate faces an upper surface of the polishing pad;   a housing having a sealed structure and embedded in the polishing pad; and   an acoustic sensor included in the housing,   wherein the acoustic sensor comprises a piezoelectric element on an edge of a droplet applied to a film portion.   
     
     
         13 . The substrate polishing apparatus of  claim 12 , wherein an upper surface of the housing is on a same plane as the upper surface of the polishing pad. 
     
     
         14 . The substrate polishing apparatus of  claim 13 , wherein the acoustic sensor comprises:
 a first electrode;   a second electrode spaced apart from and facing the first electrode; and   a piezoelectric structure between the first electrode and the second electrode and in contact with the first electrode and the second electrode.   
     
     
         15 . The substrate polishing apparatus of  claim 14 , wherein the piezoelectric structure comprises:
 the film portion perpendicular to the first electrode and the second electrode; and   the piezoelectric element generated based on the droplet comprising a piezoelectric material applied to the film portion being dried.   
     
     
         16 . The substrate polishing apparatus of  claim 15 , wherein the piezoelectric element has a ring shape. 
     
     
         17 . The substrate polishing apparatus of  claim 15 , wherein the piezoelectric element has an arch shape. 
     
     
         18 . The substrate polishing apparatus of  claim 15 , wherein the piezoelectric structure comprises a plurality of piezoelectric structures between the first electrode and the second electrode. 
     
     
         19 . The substrate polishing apparatus of  claim 18 , wherein a plurality of piezoelectric elements included in the plurality of piezoelectric structures, respectively, are different in at least one among material and shape. 
     
     
         20 . A substrate polishing apparatus comprising:
 a platen;   a polishing pad comprising a hole on an upper surface of the platen and configured to rotate with the platen, an upper surface of the polishing pad comprising an opening;   a head on the polishing pad and configured to support the substrate such that a polishing surface of a substrate faces the polishing pad;   a housing in the hole; and   an acoustic sensor included in the housing,   wherein the acoustic sensor comprises:
 a first electrode; 
 a second electrode spaced apart from and facing the first electrode; and 
 a piezoelectric structure between the first electrode and the second electrode and in contact with the first electrode and the second electrode, and 
   wherein the piezoelectric structure comprises:
 a film portion perpendicular to the first electrode and the second electrode; and 
 a piezoelectric element having a linear form and on an edge of a droplet applied to the film portion.