Method and apparatus for modifying the profile of narrow, high-aspect-ratio gaps using RF power

Abstract

A method and apparatus for modifying the profile of narrow, high-aspect-ratio gaps on a semiconductor substrate are used to fill the gaps in a void-free manner. Differential heating characteristics of a substrate in a high-density plasma chemical vapor deposition (HDP-CVD) system helps to prevent the gaps from being pinched off before they are filled. The power distribution between coils forming the plasma varies the angular dependence of the sputter etch component of the plasma, and thus may be used to modify the gap profile, independently or in conjunction with differential heating. A heat source may be applied to the backside of a substrate during the concurrent deposition/etch process to further enhance the profile modification characteristics of differential heating.

What is claimed is:  
     
         1 . A method for forming a layer on a substrate in a chamber during a high-density plasma chemical vapor deposition (HDP-CVD) process, said method comprising steps of: 
 (a) flowing a process gas suitable for forming a plasma into the chamber to form a layer on a front side of the substrate; and    (b) heating a backside of the substrate during the HDP-CVD deposition process.    
     
     
         2 . The method of  claim 1  wherein step (b) of heating the backside of the substrate is performed by heating a susceptor supporting the substrate.  
     
     
         3 . The method of  claim 2  wherein the susceptor is heated by the plasma.  
     
     
         4 . The method of  claim 1  wherein step (b) of heating the backside of the substrate is performed with a heater integrated with a wafer support structure, the wafer support structure supporting the substrate in the chamber.  
     
     
         5 . The method of  claim 4  wherein the substrate is chucked to the wafer support structure.  
     
     
         6 . The method of  claim 5  wherein a heat-transfer gas thermally couples the substrate to the wafer support structure.  
     
     
         7 . The method of  claim 1  wherein step (b) of heating the backside of the substrate is performed with a lamp.  
     
     
         8 . The method of  claim 1  wherein the plasma is formed from both inductively coupled energy and from capacitively coupled energy.  
     
     
         9 . An apparatus for forming a layer on a substrate in a chamber comprising: 
 a plasma generator capable of inductively coupling to a layer-forming process gas to produce a high-density plasma in the chamber; and    a substrate support structure with a heater, the heater capable of heating a backside of the substrate.    
     
     
         10 . The apparatus of  claim 9  further comprising an RF bias generator coupled to the substrate support structure.  
     
     
         11 . The apparatus of  claim 9  wherein the plasma generator includes a first inductive coupling structure and a second inductive coupling structure, the first inductive coupling structure being powered independently from the second inductive coupling structure.  
     
     
         12 . A method for forming a layer on a substrate in a chamber during an HDP-CVD process, said method comprising steps of: 
 (a) forming a high-density plasma in the chamber;    (b) flowing a process gas suitable for depositing a layer on a front side of the substrate into the chamber; and    (c) heating a front side of the substrate during the HDP-CVD deposition process with the plasma, wherein the substrate is not thermally coupled to a substrate support structure.    
     
     
         13 . The method of  claim 12  wherein at least one trench with an edge is defined in a field of the substrate.  
     
     
         14 . The method of  claim 12  wherein the trench has a gap equal to or less than about 0.25 microns and has an aspect ratio equal to or greater than about 5:1 prior to deposition of the layer.  
     
     
         15 . A substrate-processing apparatus comprising: 
 (a) a processing chamber with a wafer support structure;    (b) a gas delivery system configured to deliver a process gas to said processing chamber;    (c) a plasma system configured to form an inductively coupled plasma within said processing chamber;    (d) a vacuum system configured to set and maintain a selected pressure within said processing chamber;    (e) a controller configured to control said gas delivery system, said plasma system, and said vacuum system; and    (f) a memory, coupled to said controller, comprising a computer-readable medium having a computer-readable program embodied therein for directing operation of the substrate processing apparatus, said computer-readable program comprising: 
 (i) a first set of computer instructions for controlling said gas delivery system and said plasma system to flow a plasma gas into said chamber and to form a plasma at a first plasma power therefrom;  
 (ii) a second set of computer instructions for controlling said gas delivery system to flow a source gas into said chamber; and  
 (iii) a third set of computer instructions for controlling the plasma system to heat the substrate with the plasma and to not thermally couple the substrate to the wafer support structure.  
   
     
     
         16 . A method for modifying a profile of a trench on a substrate in an HDP-CVD processing system, the method comprising steps of: 
 (a) flowing a process gas suitable for forming a layer on a field of the substrate and on a sidewall of the trench into a processing chamber of the HDP-CVD processing system;    (b) forming a plasma from the process gas in the chamber by inductively coupling RF energy to the process gas;    (c) biasing the plasma with a bias power of at least 0.057 W per square millimeter of a surface area of the substrate to concurrently sputter the layer as the layer is formed.    
     
     
         17 . A substrate-processing apparatus for filling trenches on a substrate with a dielectric material, the apparatus comprising: 
 (a) a processing chamber with a substrate support structure;    (b) a gas delivery system configured to deliver a process gas to said processing chamber;    (c) an RF source plasma system configured to form a high-density plasma within said processing chamber;    (d) an RF bias plasma system coupled to the substrate support structure;    (e) a vacuum system configured to set and maintain a selected pressure within said processing chamber;    (f) a controller configured to control said gas delivery system, said RF source plasma system, and said vacuum system; and    (g) a memory, coupled to said controller, comprising a computer-readable medium having a computer-readable program embodied therein for directing operation of the substrate processing apparatus, said computer-readable program comprising: 
 (i) a first set of computer instructions for controlling said gas delivery system and said RF source plasma system to flow a plasma gas into said chamber and to form a plasma therefrom;  
 (ii) a second set of computer instructions for controlling said gas delivery system to flow a source gas into said chamber; and  
 (iii) a third set of computer instructions for controlling said RF bias plasma system to provide a bias power density of at least about 0.057 W per square millimeter over a surface area of the substrate.  
   
     
     
         18 . A method for forming a layer on a substrate in a chamber during an HDP-CVD process, the method comprising steps of: 
 (a) flowing a process gas suitable for forming the layer on a front side of the substrate into the chamber;    (b) forming a high-density plasma from the process gas in the chamber by coupling a total RF source power to the process gas from a first inductive coupling structure and a second inductive coupling structure, wherein a first RF source power to the first inductive coupling structure is at least about 56% of the total RF source power.    
     
     
         19 . The method of  claim 18  wherein the first inductive coupling structure is a side coil and the second inductive coupling structure is a top coil.  
     
     
         20 . The method of  claim 18  where the process gas comprises silane.  
     
     
         21 . The method of  claim 18  wherein the substrate includes a trench.  
     
     
         22 . A substrate-processing apparatus for filling trenches on a substrate with a dielectric material, the apparatus comprising: 
 (a) a processing chamber;    (b) a gas delivery system configured to deliver a process gas to said processing chamber;    (c) an RF source plasma system configured to form a high-density plasma within said processing chamber, the RF source plasma system including a first inductive coupling structure and a second inductive coupling structure and being configured to power the first inductive coupling structure differentially from the second inductive coupling structure;    (d) a vacuum system configured to set and maintain a selected pressure within said processing chamber;    (e) a controller configured to control said gas delivery system, said RF source plasma system, and said vacuum system; and    (f) a memory, coupled to said controller, comprising a computer-readable medium having a computer-readable program embodied therein for directing operation of the substrate processing apparatus, said computer-readable program comprising: 
 (i) a first set of computer instructions for controlling said gas delivery system and said plasma system to flow a plasma gas into said chamber and to form a plasma at a first plasma power therefrom;  
 (ii) a second set of computer instructions for controlling said gas delivery system to flow a source gas into said chamber; and  
 (iii) a fourth set of computer instructions for controlling said plasma system to provide a total RF power to the first inductive coupling structure and to the second inductive coupling structure wherein the first inductive coupling structure receives at least about 56% of the total RF power.