Electroless Deposition of Platinum on Copper

Abstract

Embodiments of the current invention describe a method of plating platinum selectively on a copper film using a self-initiated electroless process. In particular, platinum films are plated onto very thin copper films having a thickness of less than 300 angstroms. The electroless plating solution and the resulting structure are also described. This process has applications in the semiconductor processing of logic devices, memory devices, and photovoltaic devices.

1 . A method of forming a film, comprising:
 providing a substrate comprising a copper film and a dielectric film, wherein the copper film has a thickness of less than 300 um; and   depositing a noble metal film selectively on the copper film using an electroless plating solution.   
     
     
         2 . The method of  claim 1 , wherein depositing the noble metal film on the copper film is selective to the copper film. 
     
     
         3 . The method of  claim 1 , wherein depositing the noble metal film comprises depositing a platinum film. 
     
     
         4 . The method of  claim 3 , wherein depositing the platinum film comprises using an electroless plating solution comprising:
 a platinium supply chemical comprising chloroplatinic acid (H 2 PtCl 6 );   a reducing agent comprising hydrazine;   a stabilizer; and   a surfactant.   
     
     
         5 . The method of  claim 4 , further comprising pre-treating the chloroplatinic acid in the electroless plating solution before depositing the platinum film, wherein pre-treating comprises:
 forming a mixture of chloroplatinic acid and TMAH;   boiling the mixture; and   cooling the mixture.   
     
     
         6 . The method of  claim 1 , wherein depositing the noble metal film using an electroless plating solution is performed using a self-initiating electroless process. 
     
     
         7 . The method of  claim 1 , further comprising pre-cleaning the substrate before depositing the noble metal film, the pre-cleaning comprising an acidic cleaning solution followed by an alkaline cleaning solution. 
     
     
         8 . The method of  claim 1 , further comprising forming a molecular masking layer on the dielectric film before depositing the noble metal film. 
     
     
         9 . The method of  claim 1 , further comprising post-cleaning the substrate after depositing the noble metal film. 
     
     
         10 . A structure, comprising:
 a layer including a copper portion having a thickness of less than 300 um and a dielectric portion; and   a noble metal layer over only the copper portion.   
     
     
         11 . The structure of  claim 10 , wherein the noble metal layer is platinum. 
     
     
         12 . The structure of  claim 10 , further comprising a surface modifier over only the dielectric portion. 
     
     
         13 . The structure of  claim 10 , wherein the noble metal layer is a capping layer and the copper portion is an interconnect line of a semiconductor device. 
     
     
         14 . The structure of  claim 10 , wherein the copper portion is a bottom copper electrode of a memory device. 
     
     
         15 . The structure of  claim 10 , wherein the noble metal layer is a passivation layer. 
     
     
         16 . An electroless plating solution, comprising:
 a platinium supply chemical comprising chloroplatinic acid (H 2 PtCl 6 );   a reducing agent comprising hydrazine, wherein the electroless plating solution is formulated for the deposition of platinum onto copper.   
     
     
         17 . The electroless plating solution of  claim 16 , further comprising an accelerator comprising a derivative of an aliphatic sulfonic acid. 
     
     
         18 . The electroless plating solution of  claim 16 , further comprising a surface modifier. 
     
     
         19 . The electroless plating solution of  claim 16 , wherein the electroless plating solution does not include a complexing agent. 
     
     
         20 . The electroless plating solution of  claim 16 , wherein the platinum supply chemical comprises chloroplatinic acid pre-treated with TMAH.