System and method for forming metal interconnection in image sensor

Abstract

A method for forming a metal interconnection in an image sensor includes forming a first interlayer dielectric (ILD) layer having a contact plug over a substrate, forming a diffusion barrier layer over the first ILD layer, performing a forming gas annealing, forming a second ILD layer over the diffusion barrier layer, etching the second ILD layer and the diffusion barrier layer to form a trench, forming a conductive layer to fill the trench, and planarizing the conductive layer to form a metal interconnection electrically connected to the contact plug

1 . A method for forming a metal interconnection in an image sensor, the method comprising:
 forming a first interlayer dielectric (ILD) layer having substantially planar upper and lower surfaces and a contact plug that extends from the upper surface to the lower surface over a substrate;   forming a diffusion barrier layer over the first ILD layer; and   performing a forming-gas annealing process after said forming a diffusion barrier layer.   
   
   
       2 . The method of  claim 1 , further comprising forming a second ILD layer over the diffusion barrier layer. 
   
   
       3 . The method of  claim 2 , wherein the second ILD layer has a multi-layered structure. 
   
   
       4 . The method of  claim 2 , further comprising forming a silicon-rich oxide layer over the second ILD layer. 
   
   
       5 . The method of  claim 2 , wherein the second ILD layer comprises a fluorinated silicate glass (FSG) layer containing nitrogen. 
   
   
       6 . The method of  claim 5 , wherein the FSG layer includes one of N 2  or N 2 O. 
   
   
       7 . The method of  claim 5 , wherein the FSG layer is formed by flowing a mixture gas at a flow rate of N 2  ranging from approximately 300 sccm to approximately 3,000 sccm, a flow rate of N 2 O ranging from approximately 400 sccm to approximately 2,000 sccm, a flow rate of SiH 4  ranging from approximately 100 sccm to approximately 800 sccm, or a flow rate of SiH 4  ranging from approximately 300 sccm to approximately 1,000 sccm. 
   
   
       8 . The method of  claim 5 , wherein the FSG layer is formed under a pressure ranging from approximately 0.1 Torr to approximately 10 Torr. 
   
   
       9 . The method of  claim 2 , further comprising etching through the second ILD layer and the diffusion barrier layer to form a trench. 
   
   
       10 . The method of  claim 1 , further comprising filling a trench with a conductive material that is electrically connected to the contact plug. 
   
   
       11 . The method of  claim 1 , further comprising planarizing a conductive layer and an upper surface of a conductive material. 
   
   
       12 . The method of  claim 1 , wherein the diffusion barrier layer comprises one of SiC or SiN. 
   
   
       13 . The method of  claim 1 , wherein said performing a forming-gas annealing process is performed in a mixture gas ambient of H 2  and N 2  under a condition that a ratio of H 2 /N 2  is in a range of approximately 3% to approximately 30%. 
   
   
       14 . The method of  claim 1 , wherein said performing a forming-gas annealing process occurs at a temperature ranging from approximately 400° C. to approximately 600° C. for approximately 10 minutes to approximately 3 hours. 
   
   
       15 . The method of  claim 1 , wherein the contact plug comprises tungsten with a Ti/TiN bilayer stacked. 
   
   
       16 . An image sensor comprising:
 a first interlayer dielectric (ILD) layer having substantially planar upper and lower surfaces and a contact plug that extends from the upper surface to the lower surface over a substrate;   a diffusion barrier layer disposed over the first ILD layer;   a second ILD layer disposed over the diffusion barrier layer;   a trench etched through the second ILD layer and the diffusion barrier layer; and   a conductive material within the trench, wherein the conductive layer is electrically connected to the contact plug.   
   
   
       17 . The image sensor of  claim 16 , wherein the second ILD layer has a multi-layered structure. 
   
   
       18 . The image sensor of  claim 16 , further comprising a silicon-rich oxide layer disposed over the second ILD layer. 
   
   
       19 . The image sensor of  claim 16 , wherein the second ILD layer comprises a fluorinated silicate glass (FSG) layer containing nitrogen. 
   
   
       20 . The image sensor of  claim 19 , wherein the FSG layer includes one of N 2  or N 2 O. 
   
   
       21 . The image sensor of  claim 16 , wherein the diffusion barrier layer comprises one of SiC or SiN. 
   
   
       22 . The image sensor of  claim 16 , wherein the contact plug comprises tungsten with a Ti/TiN bilayer stacked.