Low dielectric (low k) barrier films with oxygen doping by plasma-enhanced chemical vapor deposition (PECVD)

A method of processing a substrate, comprising:

• providing a substrate having conductive features formed in a dielectric material to a processing chamber;
• forming a plurality of layers on the substrate, comprising:
• a first dielectric layer formed in direct contact with the dielectric material, the first dielectric layer having barrier properties and comprising silicon, carbon, and nitrogen;
• a second dielectric layer having barrier properties and comprising silicon and carbon, wherein the second dielectric layer is nitrogen free;
• and
• a third dielectric layer comprising silicon, oxygen, and carbon, wherein the third dielectric layer has a dielectric constant of about 3 or less, wherein the second dielectric layer is formed by reacting a processing gas, comprising:
• a compound containing carbon and oxygen;
• an oxygen-free organosilicon compound;
• and
• an inert gas.

A method of processing a substrate, comprising:

• providing a substrate having conductive features formed in a dielectric material to a processing chamber;
• forming a plurality of layers on the substrate, comprising:
• a first dielectric layer formed in direct contact with the dielectric material, the first dielectric layer having barrier properties and comprising silicon, carbon, and nitrogen;
• a second dielectric layer having barrier properties and comprising silicon and carbon, wherein the second dielectric layer is nitrogen free;
• and
• a third dielectric layer comprising silicon, oxygen, and carbon, wherein the third dielectric layer has a dielectric constant of about 3 or less, wherein forming the second dielectric layer comprises supplying trimethylsilane to a processing chamber at a flow rate between about 50 sccm and about 300 sccm, supplying carbon dioxide at a flow rate between about 100 sccm and about 800 sccm, supplying helium at a flow rate between about 200 sccm and about 800 sccm, maintaining a substrate temperature between about 300° C. and about 400° C., maintaining a chamber pressure between about 2 Torr and about 5 Torr, and applying a RF power of between about 200 watts and about 500 watts.