Patent ID: 7998863
Filing Date: 2011-08-16
Classification: H01L,Y02E

Abstract:
1. A method of forming a contact structure, in a device including a first contact type for contacting an underlying layer of a semiconductor junction, wherein the junction comprises the underlying layer of a first semiconductor material of a first dopant polarity, an overlying layer of a second semiconductor material oppositely doped to the underlying layer, the method comprising (a) forming a masking layer over the overlying layer, comprising a layer of insulating material, (b) forming an opening in the masking layer exposing the overlying layer, (c) forming an opening in the overlying layer under the opening in the masking layer, the opening in the overlying layer being formed to extend through the overlying layer to expose the underlying layer, and the opening in the overlying layer also being formed to extend under the edges of the opening in the masking layer to form an undercut region extending around the entire periphery of the opening in the masking layer whereby the undercut region extends entirely across the overlying layer, and (d) forming a metal layer over a surface of the masking layer and extending into the opening in the overlying layer to contact the underlying layer, the metal layer where it extends between the masking layer and the underlying layer being isolated from the overlying layer, whereby the metal does not bridge the semiconductor junction.