Method for forming a conductive plug between conductive layers of an integrated circuit

1. A method for forming a contact structure, the method comprising the steps of:

• forming a first conductive material overlying a semiconductor substrate;
  
  forming a dielectric layer overlying the first conductive layer;
  
  forming a resist layer over the dielectric layer;
  
  patterning the resist layer to form an opening that exposes portions of the dielectric layer;
  
  placing the semiconductor substrate into a reactive ion etching chamber and in-situ processing the semiconductor substrate as follows;
  
  etching portions of the dielectric layer using a gas mixture that includes a fluorocarbon source gas to form an opening in the dielectric layer, the opening having a bottom portion and a sidewall portion;
  
  etching a portion of the resist layer using a gas mixture that includes a fluorocarbon source gas and an oxygen source gas to remove the portion of the resist layer and expose a top surface portion of the dielectric layer adjacent the sidewall portion;
  
  etching the top surface portion of the dielectric layer adjacent the sidewall portion to form a taper that extends between a top surface of the dielectric layer and the sidewall portion, wherein the taper towards the top surface portion has a radius Y and the taper towards the sidewall portion has a radius X wherein X<
  
  Y; and
  
  removing remaining portions of the resist layer;
  
  depositing a second conductive material within the opening; and
  
  polishing away a top portion of the conductive material and a top portion of the dielectric layer to remove the taper.