Dielectric with sidewall passivating layer

Abstract

A polymer dielectric material includes a sidewall passivating layer on the opposing sidewall surfaces of an opening in the dielectric layer for a via or trench. The sidewall passivating layer may be deposited on the sidewall surfaces, as well as the bottom surface of an opening having a first depth in the polymer dielectric layer. After the sidewall passivating layer is added, the depth of the opening may be increased to a second depth. The sidewall passivating layer provides a barrier to removal of the polymer dielectric from the sidewalls, preventing or reducing undercutting below a hard mask.

1 . A device comprising: 
 a semiconductor substrate having a conductive layer, a barrier layer over the conductive layer, and a polymer dielectric layer over the barrier layer;    an opening in the polymer dielectric layer having a bottom surface and substantially vertical opposing sidewall surfaces; and    a passivating layer on at least the opposing sidewall surfaces of the opening.    
   
   
       2 . The device of  claim 1  wherein the passivating layer comprises a barrier material including at least carbon and fluorine.  
   
   
       3 . The device of  claim 1  further comprising a passivating layer on the bottom surface of the opening.  
   
   
       4 . The device of  claim 1  wherein the passivating layer has a depth of between about 2 nanometers and about 20 nanometers.  
   
   
       5 . The device of  claim 1  wherein the bottom layer of the opening is spaced from the barrier layer.  
   
   
       6 . The device of  claim 1  further comprising a conductive element in the opening.  
   
   
       7 . A method comprising: 
 etching a polymer dielectric material over a barrier layer on a substrate to provide an opening having a first depth, the opening having a bottom surface and sidewall surfaces;    forming a passivating layer over the bottom surface and sidewall surfaces of the opening, the passivating layer providing a barrier layer; and    etching the polymer dielectric material at the bottom of the opening to remove the passivating layer and the polymer dielectric material from the bottom surface of the opening and increase the depth of the opening to a second depth.    
   
   
       8 . The method of  claim 7  wherein forming the passivating layer comprises depositing a carbon and fluorine based material over the polymer dielectric material.  
   
   
       9 . The method of  claim 7  wherein the first depth is above the barrier layer.  
   
   
       10 . The method of  claim 7  further comprising cleaning the passivating layer from the sidewall surfaces.  
   
   
       11 . The method of  claim 7  wherein forming the passivating layer comprises forming a passivating layer to a depth of between about 2 nanometers and about 20 nanometers.