Pressure modulation method to obtain improved step coverage of seed layer

Abstract

A multi-step process for the deposition of a material into high aspect ratio features on a substrate surface is provided. The process involves depositing a material on the substrate at a first pressure for a first period of time and then depositing the material on the substrate at a second pressure for a second period of time. Modulation of the pressure influences the ionization and trajectory of the particles, which are ionized in a plasma environment. The method of the invention in one aspect allows for optimum deposition at the bottom of a high aspect ratio feature during a high pressure step and increased deposition on the sidewalls of the feature during at least a low pressure step.

1 . A method for depositing material on a substrate, comprising: 
 (a) providing a plasma in a chamber at a first pressure;    (b) sputtering a material from a target disposed in the chamber;    (c) ionizing the sputtered material;    (d) depositing sputtered material onto the substrate at a first chamber pressure;    (e) modulating the pressure in the chamber between at least the first and a second chamber pressure; and    (f) depositing sputtered material onto the substrate at the second chamber pressure.    
     
     
         2 . The method of  claim 1 , wherein the first chamber pressure and the second chamber pressure are maintained for a total period of time less than about 120 seconds.  
     
     
         3 . The method of  claim 1 , further comprising: 
 (g) repeating (d), (e) and (f) during multiple steps of deposition to form a layer on the substrate.    
     
     
         4 . The method of  claim 1 , wherein the first chamber pressure is between about 35 mTorr and about 70 mTorr.  
     
     
         5 . The method of  claim 1 , wherein the second chamber pressure is between about 10 mTorr and about 20 mTorr.  
     
     
         6 . The method of  claim 1 , wherein the first chamber pressure is between about 35 mTorr and about 70 mTorr and the second chamber pressure is between about 10 mTorr and about 20 mTorr.  
     
     
         7 . The method of  claim 1 , wherein the first chamber pressure is higher than the second chamber pressure.  
     
     
         8 . The method of  claim 1 , wherein the material is selected from the group of copper, tantalum, tantalum nitride, tungsten, tungsten nitride, titanium, titanium nitride and combinations thereof.  
     
     
         9 . A method for depositing material in a feature formed on a substrate, comprising: 
 (a) providing a plasma in a chamber;    (b) sputtering a material from a target disposed in the chamber;    (c) ionizing the material; and    (d) depositing a material onto the feature while modulating the chamber pressure.    
     
     
         10 . The method of  claim 9 , wherein the chamber pressure is modulated between about 10 mTorr and about 70 mTorr.  
     
     
         11 . The method of  claim 10 , wherein the material is selected from the group of copper, tantalum, tantalum nitride, tungsten, tungsten nitride, titanium nitride and combinations thereof.  
     
     
         12 . A method for depositing one or more layers in a feature formed on a substrate, comprising: 
 (a) providing a plasma in a chamber having a target and a coil disposed therein;    (b) providing a signal to the target;    (c) providing a signal to the coil;    (d) depositing a first layer onto the feature at a first chamber pressure; and    (e) depositing a second layer onto the feature at a second chamber pressure.    
     
     
         13 . The method of  claim 12 , further comprising ionizing the material prior to (d).  
     
     
         14 . The method of  claim 12 , wherein the chamber pressure during (d) and (e) is modulated between about 10 mTorr and about 70 mTorr.  
     
     
         15 . The method of  claim 12 , further comprising filling the feature.  
     
     
         16 . The method of  claim 12 , wherein the first layer and/or the second layer comprise a material is selected from the group of copper, tantalum, tantalum nitride, tungsten, tungsten nitride, titanium nitride and combinations thereof.  
     
     
         17 . A program product, which when read and executed by a computer, comprises the steps of: 
 (a) providing a signal to a target disposed in the chamber;    (b) providing a signal to a coil; and    (c) modulating the chamber pressure during the deposition of a material onto a substrate.    
     
     
         18 . The method of  claim 17 , wherein the chamber pressure is modulated between about 10 mTorr and about 70 mTorr.  
     
     
         19 . The method of  claim 17 , wherein the chamber pressure is modulated between a first pressure and a second pressure lower than the first pressure.  
     
     
         20 . The method of  claim 17 , wherein modulating the chamber pressure comprises alternating the pressure between two or more values until a feature on a substrate is filled with material.