Improved SiCOH Hardmask with Graded Transition Layers

A method comprising:

• forming a SiCOH hardmask on a semiconductor substrate using a continuous plasma enhanced chemical vapor deposition (PECVD) process, wherein the forming a SiCOH hardmask comprises:
• forming an oxide adhesion layer on a surface of a substrate in a first step by introducing oxygen at a steady high flow rate, and introducing a silicon precursor at a steady lower flow rate into a reaction chamber, wherein the oxide adhesion layer comprises oxygen rich silicon oxide;
• forming a graded transition layer on the oxide adhesion layer in a second step by introducing a porogen at an increasing flow rate, reducing the flow rate of oxygen to a level below the flow rate of the porogen and the flow rate of the silicon precursor, and increasing the flow rate of the silicon precursor to a level above the flow rate of oxygen and the flow rate of the porogen, wherein the graded transition layer comprises a high concentration of oxygen in the region contacting the oxide adhesion layer and a gradually decreasing concentration of oxygen towards upper surface;
• forming a dielectric layer on the graded transition layer in a third step by maintaining a steady high flow rate of the silicon precursor at a level above the flow rate of the porogen and the flow rate of oxygen, maintaining a steady low flow rate of oxygen at a level below the flow rate of the silicon precursor and the flow rate of the porogen, and maintaining a steady intermediate flow rate of the porogen at a level below the flow rate of the silicon precursor and above the flow rate of oxygen;
• forming an inverse graded transition layer on the dielectric layer in a fourth step by increasing the flow rate of oxygen to a level above the flow rate of the silicon precursor and the flow rate of the porogen, reducing the flow rate of the silicon precursor to a level below the flow rate of oxygen, and reducing the flow rate of the porogen to zero, wherein the inverse graded transition layer comprises a low concentration of oxygen in the region contacting the dielectric layer and a gradually increasing concentration of oxygen towards an upper surface;
• and
• forming an oxide layer on the inverse graded transition layer in a fifth step by maintaining the flow rate of oxygen at a steady high flow rate, and maintaining a steady lower flow rate of the silicon precursor, wherein the oxide layer comprises oxygen rich silicon oxide.