Chemical Mechanical Polishing Process Method and Device

Abstract

A CMP method includes: provide a substrate with a dielectric layer and a conductive layer, using a mixture of a first polishing liquid and a second polishing liquid to do first CMP polish the substrate placed on the polishing disc to remove the conductive layer covering the upper surface of the intermediate dielectric layer; after the substrate is rinsed with a cleaning solution, the second polishing solution is applied to do second CMP polish on the substrate to remove a part of the dielectric layer, so that the upper surface of the dielectric layer is lower than the upper surface of the conductive layer filled in the groove, so as to ensure that the conductive layer in the groove can protrude from the surface of the dielectric layer. This technique improves product yield for single disc CMP process.

1 . A method of chemical mechanical polishing process, comprising:
 providing a substrate formed with a dielectric layer and a conductive layer, wherein the dielectric layer comprises a groove, wherein the conductive layer is disposed on an upper surface of the dielectric layer and is filled in the groove, and wherein the conductive layer comprises a tungsten layer;   performing a first chemical-mechanical polishing on the substrate placed on a polishing disc, wherein the first chemical-mechanical polishing applies a mixed polishing liquid comprising a first polishing liquid and a second polishing liquid to remove the conductive layer from the upper surface of the dielectric layer; wherein a polishing rate of the mixed polishing liquid on the conductive layer is greater than a polishing rate of the mixed polishing liquid on the dielectric layer;   rinsing the substrate placed on the polishing disc with a cleaning liquid to remove the mixed polishing liquid remaining on the substrate; and   performing a second chemical-mechanical polishing on the substrate placed on the polishing disc, wherein the second chemical-mechanical polishing applies the second polishing liquid to remove a part of the dielectric layer, so that an upper surface of the dielectric layer is configured to be lower than a top surface of the conductive layer filled in the groove; and wherein the polishing rate of the second polishing liquid on the conductive layer is lower than the polishing rate of the second polishing liquid on the dielectric layer.   
     
     
         2 . The method of  claim 1 , wherein the conductive layer further comprises a titanium nitride layer disposed between the dielectric layer and the tungsten layer. 
     
     
         3 . The method according to  claim 2 , wherein the mixed polishing liquid comprising the first polishing liquid and the second polishing liquid is applied to perform the first chemical mechanical polishing on the substrate placed on the polishing disc to remove the upper surface of the conductive layer covering on the surface includes:
 in a process of performing the first chemical mechanical polishing of the substrate with the mixed polishing liquid, applying a preset chemical mechanical polishing endpoint detection program to detect whether the titanium nitride layer has been polished;   stopping the first chemical mechanical polishing of the substrate with the mixed polishing liquid when it is detected that the titanium nitride layer has been polished.   
     
     
         4 . The method according to  claim 1 , wherein the second chemical-mechanical polishing of the substrate placed on the polishing disc to remove the part of the dielectric layer comprises:
 performing the second chemical-mechanical polishing on the substrate by applying the second polishing liquid to remove the dielectric layer with a preset thickness, wherein the preset thickness ranges from 40 nm to 200 nm.   
     
     
         5 . The method according to  claim 1 , wherein, in the mixed polishing liquid, a mass ratio of the first polishing liquid and the second polishing liquid is 1:1˜1:4. 
     
     
         6 . The method according to  claim 5 , wherein the first polishing liquid comprises a basic liquid, a catalyst and a stabilizer, and wherein a composition of the second polishing liquid is a same as a composition of the basic liquid. 
     
     
         7 . The method of  claim 6 , wherein the basic liquid comprises solid abrasive particles, hydrogen peroxide, and water; wherein,
 the solid abrasive particles are colloidal silica;   a mass percentage of the hydrogen peroxide in the basic liquid is 1% to 3%;   a mass percentage of the water in the basic liquid is 50% to 95%; and   a pH value of the basic liquid is 1-3.   
     
     
         8 . The method according to  claim 6 , wherein the catalyst is ferric nitrate, and wherein a mass percentage of the catalyst in the first polishing liquid is 0.1% to 1%. 
     
     
         9 . The method according to  claim 6 , wherein the stabilizer is ammonium persulfate, and wherein a mass percentage of the stabilizer in the first polishing liquid is 0.05% to 10%. 
     
     
         10 . The method according to  claim 7 , wherein a solid content of the first polishing liquid and a solid content of the second polishing liquid are a same, and wherein the solid content is 8% to 14%. 
     
     
         11 . The method according to  claim 10 , wherein an average particle size of the solid abrasive particles in both the first polishing liquid and the second polishing liquid is 100 nm˜140 nm. 
     
     
         12 . The method of  claim 1 , wherein the cleaning liquid is deionized water. 
     
     
         13 . A chemical-mechanical polishing apparatus, comprising:
 a polishing disc;   a polishing head, located above the polishing disc, wherein the polishing head is used for pressing a substrate which is to be polished on the polishing disc for chemical-mechanical polishing; wherein the substrate comprises a dielectric layer and a conductive layer, wherein the dielectric layer comprises grooves, wherein the conductive layer is disposed on an upper surface of the dielectric layer and fills the grooves, and wherein the conductive layer includes a tungsten layer;   a polishing liquid supply assembly for providing abrasive liquid to a surface of the polishing disc;   a cleaning component for providing cleaning liquid to the surface of the polishing disc; and   a control assembly configured to connect with the polishing liquid supply assembly and the cleaning component respectively, wherein the control assembly is used for:   controlling the polishing liquid supply assembly to provide a mixed polishing liquid comprising a first polishing liquid and a second polishing liquid to a surface of the polishing disc, so as to remove the conductive layer from an upper surface of the dielectric layer; wherein a polishing rate of the mixed polishing liquid on the conductive layer is greater than a polishing rate of the mixed polishing liquid on the dielectric layer;   controlling the cleaning component to provide a cleaning liquid to the surface of the polishing disc to remove the mixed polishing liquid remaining on the substrate; and   controlling the polishing liquid supply assembly to supply the second polishing liquid to the surface of the polishing disc, so as to remove a part of the dielectric layer, so that an upper surface of the dielectric layer is lower than a top surface of the conductive layer filled in the grooves, wherein a polishing rate of the second polishing liquid for the conductive layer is lower than a polishing rate of the second polishing liquid for the dielectric layer.   
     
     
         14 . The chemical-mechanical polishing apparatus of  claim 13 , wherein the conductive layer further comprises a titanium nitride layer disposed between the dielectric layer and the tungsten layer. 
     
     
         15 . The chemical-mechanical polishing apparatus of  claim 13 , wherein a number of substrates to be polished simultaneously on each of the polishing discs is four.