Method and Apparatus for Planarization of Substrate Coatings

Abstract

A system for forming a coating comprises applying a first coating to a substrate having a plurality of topographical features, planarizing a top surface of the first coating, and drying the first coating after planarizing the top surface. The first coating may be applied over the plurality of topographical features, and may be substantially liquid during application. The first coating may optionally be a conformal coating over topographical features of the substrate. The conformal coating may be dried prior to planarizing the top surface of the first coating. A solvent may be applied to the conformal coating, with the top surface of the conformal coating being substantially planar after application of the solvent. The first coating may have a planar surface prior to drying the first coating, and the first coating may be dried without substantial spin-drying by modifying an environment of the first coating.

What is claimed is: 
     
         1 . A system for applying a coating, the system comprising:
 a chamber having:   a platen configured to hold a wafer;   a first nozzle configured to deliver a first coating to the wafer, the chamber configured to first dry the first coating, wherein the platen is configured to spin the wafer at a first speed during delivery of the first coating to the wafer, the platen further configured to spin the wafer at a second speed during first drying of the first coating; and   a second nozzle configured to deliver a solvent to the first coating after first drying to re-liquefy the first coating, a top surface of the first coating achieving a substantially planar state after application of the solvent, the chamber further configured to second dry the first coating after delivery of the solvent, the first coating having a substantially planar top surface after second drying.   
     
     
         2 . The system of  claim 1 , wherein:
 the first coating is a conformal coating conforming to topographical features on the wafer; and   the chamber is configured to planarize the top surface of the conformal coating after drying the conformal coating.   
     
     
         3 . The system of  claim 2 , wherein:
 the chamber is further configured to planarize the top surface of the first coating by applying a solvent to the conformal coating, the solvent reflowing the coating to produce a reflowed first coating; and   the chamber is further configured to dry the reflowed first coating.   
     
     
         4 . The system of  claim 1 , wherein the platen is further configured to vibrate the wafer during application of the first coating and during drying of the first coating. 
     
     
         5 . The system of  claim 1 , wherein the chamber is configured to dry the first coating by controlling an environment contained in the chamber. 
     
     
         6 . The system of  claim 5 , wherein the chamber is configured to control the environment by modifying at least one of a gas pressure, a gas flow rate, or a temperature. 
     
     
         7 . The system of  claim 1 , further comprising a thickness monitor configured to measure a thickness of the first coating, wherein the chamber is configured to apply a second coating on the top surface of the first coating, the second coating having a thickness depending on at least the thickness of the first coating. 
     
     
         8 . An apparatus for forming a coating, the apparatus comprising:
 a coating chamber having a platen configured to hold a substrate;   a first nozzle configured to deliver a first coating in a liquid state to the substrate, the substrate having a non-planar top surface, the coating chamber configured to first dry the first coating, wherein the platen is configured to spin the substrate at a first speed during delivery of the first coating to the substrate, the platen further configured to spin the substrate at a second speed during first drying of the first coating; and   a second nozzle configured to deliver a solvent to the first coating after first drying to re-liquefy the first coating, a top surface of the first coating achieving a substantially planar state after application of the solvent, the coating chamber further configured to second dry the first coating after delivery of the solvent, the first coating having a substantially planar top surface after second drying, wherein the top surface of the first coating is planarized prior to second drying the first coating.   
     
     
         9 . The apparatus of  claim 8 , wherein the solvent is configured to reflow at least a portion of the first coating. 
     
     
         10 . The apparatus of  claim 8 , wherein the platen is further configured to spin the substrate at a first speed during application of the first coating, and spin the substrate at a second speed lower than the first speed during the first drying. 
     
     
         11 . The apparatus of  claim 8 , wherein the platen is further configured to vibrate the substrate during application of the first coating and during drying of the first coating. 
     
     
         12 . The apparatus of  claim 8 , wherein the coating chamber is configured to dry the first coating by controlling an environment contained in the coating chamber. 
     
     
         13 . The apparatus of  claim 12 , wherein the coating chamber is configured to control the environment by modifying at least one of a gas pressure, a gas flow rate, or a temperature. 
     
     
         14 . The apparatus of  claim 8 , further comprising a thickness monitor configured to measure a thickness of the first coating, wherein the coating chamber is configured to apply a second coating on a planar top surface of the first coating, the second coating having a thickness depending on at least the thickness of the first coating measured by the thickness monitor. 
     
     
         15 . A device for applying a coating, the device comprising:
 a chamber having:
 a platen configured to hold a wafer, the wafer having a plurality of topographical features disposed thereon; 
 a first nozzle configured to deliver a first coating over the plurality of topographical features, the chamber configured to first dry the first coating to a solid state, wherein the platen is configured to spin the wafer at a first speed during delivery of the first coating, the platen further configured to spin the wafer at a second speed during first drying of the first coating; and 
 a second nozzle configured to deliver a solvent to the first coating after first drying to re-liquefy the first coating, the chamber further configured to second dry the first coating after delivery of the solvent, the first coating having a substantially planar top surface after second drying. 
   
     
     
         16 . The device of  claim 15 , wherein the first coating is a conformal coating, and the chamber is configured to planarize a top surface of the conformal coating after drying the conformal coating. 
     
     
         17 . The device of  claim 16 , wherein:
 the chamber is further configured to planarize a top surface of the first coating by applying a solvent to the conformal coating, the solvent reflowing the coating to produce a reflowed first coating; and   the chamber is further configured to dry the reflowed first coating.   
     
     
         18 . The device of  claim 15 , wherein the platen is further configured to vibrate the wafer during application of the first coating and during drying of the first coating. 
     
     
         19 . The device of  claim 15 , wherein the chamber is configured to dry the first coating by controlling at least one environmental parameter of the chamber. 
     
     
         20 . The device of  claim 19 , wherein the chamber is configured to control at least one of a gas pressure, a gas flow rate, or a temperature.