Planarization process for semiconductor device fabrication

A method, comprising:

• providing a semiconductor substrate;
• forming a first sacrificial gate structure and a second sacrificial gate structure on the semiconductor substrate;
• forming a stop layer overlying the first and second sacrificial gate structures;
• forming a dielectric layer overlying the stop layer;
• performing a first planarization process removing a first portion of the dielectric layer, wherein the first planarization process exposes the stop layer overlying the first sacrificial gate structure;
• and
• performing a second planarization process to remove a second portion of the dielectric layer, wherein the second planarization process exposes the stop layer overlying the second sacrificial gate structure.

A method, comprising:

• providing a semiconductor substrate;
• forming a first plurality of sacrificial gate structures on a first region of a semiconductor substrate and a second plurality of sacrificial gate structures on a second region of the semiconductor substrate, wherein the first plurality of sacrificial gate structures has a different pattern density than the second plurality of sacrificial gate structures;
• forming a stop layer overlying the first and second plurality of sacrificial gate structures;
• forming a dielectric layer overlying the stop layer and overlying the first and second plurality of sacrificial gate structures;
• performing a first planarization process removing the dielectric layer overlying the first plurality of sacrificial gate structures, and the first planarization process provides a residual amount of the dielectric layer overlying the second plurality of sacrificial gate structures;
• performing a second planarization process to remove the residual amount of the dielectric layer after performing the first planarization process;
• and
• after the second planarization process, performing a third planarization process to remove the stop layer overlying the first and the second plurality of sacrificial gate structures.