Replacement Metal Gate Fill for FinFETs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In FinFET structures, the challenge lies in filling the gate contact material into the replacement gate trench, especially as the gate length decreases below 20 nm, leading to high gate resistance and degraded AC performance due to increased aspect ratios and poor fill efficiency.
Innovation Solution
The solution involves etching back the work function metal and, in an alternative embodiment, the high-k dielectric material to create space before filling the gate contact material, using a process that includes depositing a high-k dielectric material and work function metal partially, followed by an organic fill and subsequent etching to ensure proper filling with a metal gate contact material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the gate length is decreased to continue scaling, then device density is improved, but gate resistance increases and AC performance degrades due to increased aspect ratios
Solution Approach 1:
The gate structure is segmented into multiple functional layers: high-k dielectric material layer and work function metal layer, each performing specific functions. This segmentation allows optimization of each layer independently to reduce gate resistance while maintaining scaling benefits
Solution Approach 2:
The gate structure uses composite materials combining high-k dielectric material with work function metal, creating a multi-material system that achieves both low resistance and high density. The composite structure enables simultaneous optimization of electrical performance and device scaling
2Reliability
If the opening is completely filled with gate contact material, then gate resistance is reduced, but the aspect ratio becomes too high causing poor fill efficiency
Solution Approach 1:
The high-k dielectric material and work function metal are deposited to only partially fill the opening, leaving sufficient space for complete metal fill. This partial filling approach ensures that the final metal gate contact material can completely fill the opening without being constrained by excessive aspect ratio, thereby achieving both low gate resistance and good fill efficiency
Solution Approach 2:
The high-k dielectric material and work function metal are deposited in advance before the final metal fill step. This preliminary action prepares the gate structure with proper spacing and electrical properties, enabling subsequent complete metal fill to achieve low resistance without manufacturing difficulties
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 enhances the fill efficiency of the gate contact material, reducing gate resistance and improving device performance by optimizing the gate structure and filling process.
Implementation Method 1
a high dielectric constant (high-k) dielectric material in the opening and over the at least one fin
Implementation Method 2
a work function metal in contact with the high-k dielectric material
Data Source
AI summary
A semiconductor structure which includes: a fin on a semiconductor substrate; and a gate structure wrapped around the fin. The gate structure includes: spaced apart spacers to form an opening, the spacers being perpendicular to the fin, the spacers having a height with respect to the fin; a high-k dielectric material in the opening and over the fin, the high-k dielectric material in contact with the spacers and a bottom of the opening; a work function metal in contact with the high-k dielectric material that is over the fin, the spacers and the bottom of the opening, the work function metal that is in contact with the high-k dielectric material having a height in the opening that is less than the height of the spacers, the high-k dielectric material and the work function metal only partially filling the opening; and a metal completely filling the opening.