Patent ID: 6624517
Filing Date: 2003-09-23
Classification: C23C,H01L

Abstract:
A low-resistance contact structure in a semiconductor structure comprising:a portion of a semiconductor wafer having a silicon region on an exposed surface, said silicon region including a diffusion region; a dielectric layer located on said silicon region, said dielectric layer having an upper surface; a high aspect ratio contact opening defined by an opening having a first size in said dielectric layer, sidewalls having a second size extending through said dielectric layer to said diffusion region in said silicon region of said semiconductor wafer, and a bottom having a third size located on said diffusion region of said silicon region of said semiconductor wafer; a layer of titanium metal deposited on the upper surface of said dielectric layer and deposited on the sidewalls and the bottom of the high aspect ratio contact opening extending through said dielectric layer, said layer of titanium metal having a first thickness on the sidewalls and the bottom of the high aspect ratio contact opening reducing the second size of the sidewalls of the high aspect ratio contact opening and reducing the third size of the bottom of the high aspect ratio contact opening, and having a second thickness on the upper surface of said dielectric layer, the first thickness of said layer of titanium metal being thinner than the second thickness, the second thickness of the layer of titanium metal reducing the first size of the opening of the high aspect ratio contact opening such that the first size of the high aspect ratio contact opening is smaller than the second size of the sidewalls of the high aspect ratio contact opening and smaller than the third size of the bottom of the high aspect ratio contact opening; a titanium silicide layer within said high aspect ratio contact opening adjacent said diffusion region of said silicon region, said titanium silicide layer formed from the first thickness of said layer of titanium metal on the bottom of the high aspect ratio contact opening, said titanium silicide layer contacting the first thickness of said layer of titanium metal on the sidewalls of the high aspect ratio contact opening; a predominantly amorphous structure titanium nitride film containing carbon impurities therein substantially covering said titanium metal deposited on the high aspect ratio contact opening sidewalls, substantially covering said titanium metal on the upper surface of the dielectric layer, and substantially covering said titanium silicide layer, said titanium nitride film causing the first size of the opening of the high aspect ratio contact opening having a layer of titanium metal thereon to be smaller than the second size of the sidewalls of the high aspect ratio contact opening having a layer of titanium metal thereon, and smaller than the third size of the bottom of the high aspect ratio contact opening having titanium silicide thereon; and a conductive material filling said high aspect ratio contact opening and covering at least a portion of said predominantly amorphous structure titanium nitride film containing carbon impurities therein substantially covering said titanium metal on said upper surface of said dielectric layer, said conductive material having a smaller size at the first size of the opening of the high aspect ratio contact opening in said dielectric layer and having a larger size at the second size of the sidewalls of the high aspect ratio contact opening in said dielectric layer and the third size of the bottom of the high aspect ratio contact opening in said dielectric layer.