Semiconductor Gate Profile Control to Prevent CMP Dishing
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Solution Overview
Problem
The semiconductor industry faces challenges in achieving uniform gate surface profiles across integrated circuits due to differences in polishing rates between various gate structures, leading to 'dishing' effects during chemical mechanical polishing (CMP) processes, which degrade IC performance.
Innovation Solution
The use of dummy device cell arrays with a balanced gate surface area ratio of 1:1 between dummy NMG and PMG structures, formed with equal numbers of dummy N-cells and P-cells, ensures matching polishing rates for active NMG and PMG structures, preventing CMP-related dishing effects and maintaining uniform gate heights.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chemical mechanical polishing (CMP) is used to planarize gate structures, then surface flatness is improved, but dishing effects occur due to different polishing rates between various gate structures
Solution Approach 1:
The patent introduces dummy device cell arrays with dummy gate structures that have the same dimensions and materials as active gate structures. This creates a homogeneous polishing environment where all gate structures (active and dummy) polish at the same rate, eliminating dishing effects and achieving uniform gate surface profiles across the entire wafer.
Solution Approach 2:
The dummy gate structures act as intermediaries that mediate the polishing process. By providing additional polishing targets with identical properties to active gates, they balance the polishing load and ensure consistent polishing rates across different gate structures, preventing dishing while maintaining surface flatness.
2Manufacturing precision
If dummy device cell arrays with balanced gate surface area ratio are introduced, then polishing rate matching is achieved, but device area is increased
Solution Approach 1:
The patent carefully controls the dimensions and gate surface area of dummy structures to match active structures precisely. By adjusting parameters such as gate length, width, and material composition, the dummy gates achieve the same polishing rate as active gates while minimizing the additional area required for dummy device cell arrays.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in substantially uniform gate top surface profiles and equal gate heights across active device cell arrays, enhancing IC performance by minimizing CMP-induced defects and ensuring consistent polishing rates.
Implementation Method 1
differences in polishing rates between various gate structures, leading to 'dishing' effects during chemical mechanical polishing (CMP) processes
Data Source
AI summary
An integrated circuit (IC) with active and dummy device cell arrays and a method of fabricating the same are discloses. The IC includes a substrate, an active device cell, and a dummy device cell. The active device cell includes an array of source/drain (S/D) regions of a first conductivity type disposed on or within the substrate and an array of gate structures with a first gate fill material disposed on the substrate. The dummy device cell includes a first array of S/D regions of the first conductivity type disposed on or within the substrate, a second array of S/D regions of a second conductivity type disposed on or within the substrate, and an array of dual gate structures disposed on the substrate. Each of the dual gate structures includes the first gate fill material and a second gate fill material that is different from the first gate fill material.