Ion beam deposition of a low resistivity metal

Abstract

Methods for forming thin, low resistivity metal layers, such as tungsten (W) and ruthenium (Ru) layers. The methods include depositing a metal material onto a substrate via ion beam deposition with assist in a process chamber at a temperature of at least 250° C. to produce the metal film. A resulting thin tungsten film has large and highly oriented α(110) grains having a resistivity less than 10 μΩ-cm and thickness less than 300 Å, with no discernable β-phase. A resulting thin ruthenium film has a resistivity less than 12 μΩ-cm and a thickness less than 300 Å.

What is claimed: 
     
         1 . A method of forming a thin metal film, the method comprising:
 depositing a metal material from a target onto a substrate via ion beam deposition in a process chamber, the substrate at a temperature of at least 250° C.; and   simultaneously bombarding at least some of the deposited material from the substrate in the process chamber with an assist ion beam at a net deposition rate of at least 0.5 angstroms/second.   
     
     
         2 . The method of  claim 1 , wherein the target comprises tungsten, the metal material comprises tungsten, and the metal film comprises tungsten. 
     
     
         3 . The method of  claim 1 , wherein the substrate is at a temperature of at least 300° C. 
     
     
         4 . The method of  claim 1 , wherein the assist ion beam has an etch angle ranging from about +10 to about −70 degrees or about −10 to about +70 degrees, and the ion beam deposition has a deposition angle ranging from about +10 to about −70 degrees or about −10 to about +70 degrees, and both the etch angle and the deposition angle are adjusted simultaneously. 
     
     
         5 . The method of  claim 1 , wherein the assist ion beam has an etch angle ranging from about 15 to about 50 degrees. 
     
     
         6 . The method of  claim 1 , wherein the depositing a metal material from a target onto a substrate via ion beam deposition utilizes an ion beam having a voltage less than 1000V. 
     
     
         7 . The method of  claim 1 , wherein the depositing a metal material from a target onto a substrate via ion beam deposition utilizes an ion beam having a voltage greater than 1500V. 
     
     
         8 . The method of  claim 1 , wherein the simultaneously bombarding at least some of the deposited material with an assist ion beam utilizes an assist ion beam with a voltage of at least 100V and no more than 1000V. 
     
     
         9 . A method of forming a thin metal film, the method comprising:
 depositing a metal material from a target onto a substrate via ion beam deposition at an angle off-normal to the substrate in a process chamber, the substrate at a temperature of at least 250° C.; and   simultaneously etching at least some of the deposited material from the substrate in the process chamber with an assist ion beam to produce the metal film.   
     
     
         10 . The method of  claim 9 , having a net deposition rate of the metal material between 0.5 angstroms/second and 250 angstroms/second. 
     
     
         11 . The method of  claim 9 , wherein the assist ion beam has an etch angle of about +10 to about −70 degrees or about −10 to about +70 degrees, and the ion beam deposition has a deposition angle of about +10 to about −70 degrees or about −10 to about +70 degrees, and both the etch angle and the deposition angle are adjusted simultaneously. 
     
     
         12 . The method of  claim 9 , wherein the depositing a metal material from a target onto a substrate via ion beam deposition utilizes an ion beam having a voltage less than 1000V. 
     
     
         13 . The method of  claim 9 , wherein the depositing a metal material from a target onto a substrate via ion beam deposition utilizes an ion beam having a voltage greater than 1500V. 
     
     
         14 . The method of  claim 9 , wherein the simultaneously etching at least some of the deposited material with an assist ion beam utilizes an assist ion beam with a voltage of at least 100V and no more than 1000V. 
     
     
         15 . An ion beam deposition system comprising:
 an ion beam deposition source;   a metal target positioned at an angle from about 20 to about 40 degrees relative to an ion beam from the ion beam deposition source;   an assist ion beam source;   a substrate assembly for retaining a substrate, the substrate assembly positioned to receive a sputter plume from the metal target and to receive an ion beam from the assist ion beam source, the substrate assembly pivotable in relation to the target and to the assist ion beam source; and   at least one heater configured to heat the substrate to a temperature of at least 250° C.   
     
     
         16 . The deposition system of  claim 15 , wherein the substrate assembly is pivotable from normal to off-normal in relation to the metal target and in relation to the assist ion beam source. 
     
     
         17 . A metal film comprising:
 a thickness of about 100 to about 300 Angstroms,   a resistivity of about 8 to 12 μΩ-cm, and   a crystalline structure comprising α(110), α(200) and α(211), where the α(110) and α(211) are dominant orientations.   
     
     
         18 . The metal film of  claim 17 , wherein the metal film is tungsten and the resistivity is about 8.5 to 10.5 μΩ-cm. 
     
     
         19 . The metal film of  claim 18 , having no discernable β-phase. 
     
     
         20 . The metal film of  claim 17 , wherein the crystalline structure has a highly α(110) texture with an average grain size greater than 100 nm.