Patent ID: 8377821

Claim:
A method for forming a contact hole structure, comprising: providing a substrate having a metal layer on its surface; forming a dielectric layer covering the metal layer, wherein the dielectric layer consists of a low permittivity material; etching the dielectric layer to form a contact hole exposing the metal layer; forming a barrier layer covering the sidewalls of the contact hole and its exposed surface of the metal layer; removing the barrier layer on the exposed surface of the metal layer by a first sputtering; performing a second sputtering on the metal layer to remove impurities and particles; filling the contact hole with an electrically conductive material; and wherein the dielectric layer is made of carbon-doped silicon oxide, and process parameters for forming the dielectric layer comprise: a reaction temperature ranging from 300° C. to 400° C., a chamber pressure ranging from 4 Torr to 6 Torr, a reaction distance ranging from 5 mm to 9 mm, a power ranging from 400 W to 600 W, a flow rate of oxygen ranging from 100 to 300 Standard Cubic Centimeters per Minute (SCCM), a flow rate of helium ranging from 800 to 1200 SCCM, and a flow rate of octamethyl cyclotetrasiloxane ranging from 2000 to 4000 SCCM, to form the dielectric layer having a thickness of 3000Å to 5000Å.