Method of planarizing polysillicon plug

A method of forming polysilicon plug, comprising the steps of:

• providing a dielectric layer with an opening;
• depositing a polysilicon layer over the dielectric layer so that the opening is completely filled and a top surface of the dielectric layer is covered with the polysilicon layer, wherein the top surface of the polysilicon layer has a recess above the opening;
• depositing a high molecular weight compound to form a high molecular weight film over the polysilicon layer, using an inductive coupled plasma etcher comprising a high-density difluoromethane plasma in a manner that etching and polymerization reactions occure simultaneously, wherein the film fills the recess completely;
• and
• performing an anisotropic etching of the high molecular weight film and the polysilicon layer to completely remove the film and the polysilicon layer above the dielectric layer so that the polysilicon layer remaining inside the opening becomes a planarized polysilicon plug.

A process for manufacturing a conductive plug, comprising the steps of:

• a dielectric layer having a via opening;
• depositing a conductive material to form a conductive layer that fills the via opening and covers the dielectric layer;
• depositing a high molecular weight compound using an inductive coupled plasma etcher comprising a high-density difluoromethane plasma in a manner that etching and polymerization reactions occur simultaneously over the conductive layer to form a high molecular weight sacrificial film over the conductive layer;
• and
• etching the sacrificial film and the conductive layer above the dielectric layer to remove the sacrificial film entirely and the conductive layer above the dielectric layer.