Devices and methods related to a sputtered titanium tungsten layer formed over a copper interconnect stack structure

Abstract

Disclosed are devices and methods related to metallization of semiconductors. A metalized structure can include a stack disposed over a compound semiconductor, with the stack including an ohmic metal layer, a titanium/chromium layer, a metal nitride layer such as a titanium nitride layer, and a copper/aluminum layer. The titanium/chromium layer and metal nitride layer can act as a barrier between the copper/aluminum layer and a substrate.

1 . (canceled) 
     
     
         2 . A metalized stack structure for a semiconductor device, the stack comprising:
 an ohmic metal layer disposed over a substrate;   a first titanium or chromium layer disposed over the ohmic metal layer and having a thickness of 1,000 angstroms or more;   a first metal nitride layer disposed over the first titanium or chromium layer and having a thickness of 500 angstroms or more; and   a copper or aluminum layer disposed over the first metal nitride layer, the first titanium or chromium layer and the first metal nitride layer configured to act as a barrier between the copper or aluminum layer and the substrate.   
     
     
         3 . The metalized stack structure of  claim 2  further including a second metal nitride layer disposed over the copper or aluminum layer. 
     
     
         4 . The metalized stack structure of  claim 3  further including a platinum, palladium, or nickel layer disposed over the second metal nitride layer. 
     
     
         5 . The metalized stack structure of  claim 4  further including a gold layer disposed over the platinum, palladium, or nickel layer. 
     
     
         6 . The metalized stack structure of  claim 5  further including a second titanium or chromium layer disposed over the gold layer. 
     
     
         7 . The metalized stack structure of  claim 5  wherein the gold layer has a thickness of 1,200 angstroms or more. 
     
     
         8 . The metalized stack structure of  claim 6  wherein the second metal nitride layer has a thickness of 500 angstroms or more, the platinum, palladium, or nickel layer has a thickness of 250 angstroms or more, and the second titanium or chromium layer has a thickness of 90 angstroms or more. 
     
     
         9 . The metalized stack structure of  claim 2  wherein the metal nitride layer is formed by use of an evaporator with an ion source in conjunction with introduction of nitrogen (N 2 ) gas during an evaporation process. 
     
     
         10 . The metalized stack structure of  claim 2  wherein the first metal nitride layer is a titanium nitride layer, the first titanium or chromium layer is a titanium layer, and the copper or aluminum layer is a copper layer. 
     
     
         11 . The metalized stack structure of  claim 2  wherein the ohmic metal layer is an ohmic gold layer. 
     
     
         12 . The metalized stack structure of  claim 2  wherein the substrate is gallium arsenide. 
     
     
         13 . A semiconductor device comprising:
 a semiconductor device formed on a substrate; and   a metalized stack structure configured for use with the semiconductor device and including an ohmic metal layer disposed over the substrate, a first titanium or chromium layer disposed over the ohmic metal layer and having a thickness of 1,000 angstroms or more, a first metal nitride layer disposed over the first titanium or chromium layer and having a thickness of 500 angstroms or more, and a copper or aluminum layer disposed over the first metal nitride layer, the first titanium or chromium layer and the first metal nitride layer configured to act as a barrier between the copper or aluminum layer and the substrate.   
     
     
         14 . The semiconductor device of  claim 13  further including a second metal nitride layer disposed over the copper or aluminum layer, a platinum, palladium, or nickel layer disposed over the second metal nitride layer, a gold layer disposed over the platinum, palladium, or nickel layer, and a second titanium or chromium layer disposed over the gold layer. 
     
     
         15 . The semiconductor device of  claim 14  wherein the first and second titanium or chromium layers are titanium layers, the first and second metal nitride layers are titanium nitride layers, the copper or aluminum layer is a copper layer, and the platinum, palladium, or nickel layer is a platinum layer. 
     
     
         16 . The semiconductor device of  claim 13  wherein the semiconductor device is an N-ohmic or P-ohmic semiconductor device. 
     
     
         17 . A method of forming a semiconductor device, the method comprising:
 forming an ohmic metal layer disposed over a substrate;   forming a first titanium or chromium layer disposed over the ohmic metal layer and having a thickness of 1,000 angstroms or more;   forming a first metal nitride layer disposed over the first titanium or chromium layer and having a thickness of 500 angstroms or more; and   forming a copper or aluminum layer disposed over the first metal nitride layer, the first titanium or chromium layer and the first metal nitride layer configured to act as a barrier between the copper or aluminum layer and the substrate.   
     
     
         18 . The method of  claim 17  wherein the first metal nitride layer is a titanium nitride layer and forming the titanium nitride layer includes evaporating titanium with an assist from an ion source and introducing nitrogen gas during the evaporating. 
     
     
         19 . The method of  claim 17  further including forming a second metal nitride layer disposed over the copper or aluminum layer, forming a platinum, palladium, or nickel layer disposed over the second metal nitride layer, forming a gold layer disposed over the platinum, palladium, or nickel layer, and forming a second titanium or chromium layer disposed over the gold layer. 
     
     
         20 . The method of  claim 19  wherein the first and second titanium or chromium layers are titanium layers, the first and second metal nitride layers are titanium nitride layers, the copper or aluminum layer is a copper layer, and the platinum, palladium, or nickel layer is a platinum layer. 
     
     
         21 . The method of  claim 17  wherein the semiconductor device is an N-ohmic or P-ohmic semiconductor device.