Electrode passivation

Abstract

A coating providing high abrasion and chemical resistance composed of a barrier layer from vanadium, molybdenum, niobium, tantalum and the like, and an outer layer of diamond-like carbon. The coating is especially applicable for acoustic wave device (AWD) based sensors, and for passivating an electrode such as an electrode deposited on the AWD sensing area. The coating provides excellent mechanical and acoustical characteristics for coating acoustic wave devices allowing the sensor to operate in harsh environments.

1 . A method of passivating an electrode, the method comprising the steps of:
 depositing a barrier layer onto said electrode or a portion thereof, the barrier layer comprising at least one metal selected from the group consisting of tantalum, niobium, vanadium, molybdenum, or a combination thereof; and,   depositing an abrasive resistant layer comprising Diamond-Like Carbon (DLC) onto said barrier layer.   
     
     
         2 . A method according to  claim 1  further comprising the step of depositing an adhesion layer disposed between said electrode and said barrier layer. 
     
     
         3 . A method according to  claim 2 , wherein said adhesion layer comprises zirconium. 
     
     
         4 . A method according to  claim 2 , wherein said adhesion layer comprises titanium. 
     
     
         5 . A method according to  claim 2 , wherein said adhesion layer comprises a metal selected from a group consisting of chromium, vanadium, niobium, tantalum, or a combination thereof. 
     
     
         6 . A method according to  claim 1 , wherein the DLC is boron doped diamond. 
     
     
         7 . A method according to  claim 1 , wherein the electrode is deposited on an acoustic wave device. 
     
     
         8 . A method according to  claim 1 , further comprising the step of depositing at least one chemically selective probe onto said abrasive resistant layer. 
     
     
         9 . A method according to  claim 1 , further comprising the step of employing the abrasive resistant layer as a working electrode in an electrochemical measurement. 
     
     
         10 . A method according to  claim 1 , wherein said electrode comprises platinum. 
     
     
         11 . A method according to  claim 1 , wherein said electrode comprises a metal selected from a group consisting of, gold, silver, copper, aluminum, or a combination thereof. 
     
     
         12 . A method according to  claim 1 , wherein said electrode comprises palladium. 
     
     
         13 . A method according to  claim 1 , wherein said electrode comprises ruthenium. 
     
     
         14 . A method according to  claim 1 , wherein said electrode comprises rhenium. 
     
     
         15 . A method according to  claim 1 , wherein said electrode comprises osmium. 
     
     
         16 . A method according to  claim 1 , wherein said electrode comprises iridium. 
     
     
         17 . A method according to  claim 1 , wherein said electrode comprises carbon. 
     
     
         18 . A method as claimed in  claim 1 , wherein a carbide alloy interface is formed between the barrier layer and the abrasive resistant layer. 
     
     
         19 . A method of passivating an electrode comprising the steps of:
 depositing an adhesion layer comprising titanium, zirconium, or a combination thereof, over at least a portion of the electrode;   depositing a barrier layer comprising niobium, tantalum, or a combination thereof, onto said adhesion layer or a portion thereof; and,   depositing an abrasive resistant layer of diamond like carbon (DLC) onto said barrier layer.   
     
     
         20 . A method as claimed in  claim 19 , wherein:
 said electrode comprises gold or platinum; and,   said barrier layer having a thickness of between 25-300 nm.