Semiconductor device with filling layer and method for fabricating the same

A method for fabricating a semiconductor device, comprising:

• providing a substrate;
• forming a gate electrode over the substrate;
• forming a source region and a drain region in the substrate;
• depositing an isolating layer over the substrate and the gate electrode;
• providing a patterned photoresist over the isolating layer;
• forming a plurality of contact holes in the isolating layer to expose the gate electrode, the source region, and the drain region;
• forming a plurality of metal contacts in the gate electrode, the source region, and the drain region;
• forming a contact liner in the contact holes;
• forming a plurality of conductive plugs in the contact holes, wherein the plurality of conductive plugs are surrounded by the contact liner;
• and
• forming a filling layer in the isolating layer;
• wherein the filling layer includes boron carbonitride;
• wherein the forming of the filling layer comprises:
• providing a hard mask over the isolating layer;
• performing an etching process to remove a portion of the isolating layer;
• depositing a filling material over the isolating layer, the contact liner, the barrier layer, and the plurality of conductive plugs, and within a space of the removed portion of the isolating layer;
• and
• performing a planarization process to remove the filling material over a top surface of the isolating layer.