Gate Stack Structure With Protective Contact Isolation
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Solution Overview
Problem
The challenge of forming reliable semiconductor devices at smaller sizes is exacerbated by the complexity of fabrication processes as feature sizes continue to decrease, making it difficult to achieve high production efficiency and reduce costs.
Innovation Solution
A method involving the formation of a metal gate stack wrapped around semiconductor nanostructures with a gate dielectric layer and gate electrode, followed by recessing the gate dielectric layer and forming a protective structure over an epitaxial structure, which includes creating a conductive contact that penetrates through the protective structure to improve electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If feature sizes continue to decrease to increase functional density, then production efficiency and cost are improved, but fabrication process complexity and difficulty increase
Solution Approach 1:
The gate structure is segmented into multiple functional layers including gate dielectric layer, first gate electrode layer, second gate electrode layer, and capping layer. This segmentation allows each layer to be optimized independently for its specific function while maintaining overall device performance at scaled dimensions.
Solution Approach 2:
The patent employs a nested structure where the gate dielectric layer is positioned beneath the first gate electrode layer, which is in turn positioned beneath the second gate electrode layer, with the capping layer enclosing the top. This nested arrangement maximizes functional integration within the minimal vertical space available at reduced feature sizes.
2Productivity
If feature sizes continue to decrease to increase functional density, then production efficiency and cost are improved, but manufacturing reliability deteriorates
Solution Approach 1:
Different materials are selected for different layers based on their specific functional requirements: high-k dielectric materials for the gate dielectric layer to maximize capacitance, conductive materials for gate electrode layers, and protective materials for the capping layer. This local optimization ensures each component meets its performance criteria despite overall device miniaturization.
Solution Approach 2:
The gate structure utilizes composite material architecture combining dielectric materials, conductive materials, and protective materials in a multi-layer configuration. This composite approach leverages the advantageous properties of each material type to maintain device reliability while operating at reduced feature sizes.
Data Source
AI summary
A semiconductor device structure and a method for forming a semiconductor device structure are provided. The method includes forming a metal gate stack wrapped around multiple semiconductor nanostructures. The metal gate stack has a gate dielectric layer and a gate electrode, and the semiconductor nanostructures are adjacent to an epitaxial structure. The method also includes recessing the gate dielectric layer, and a protruding portion of the gate electrode protrudes from a top surface of the gate dielectric layer after the gate dielectric layer is recessed. The method further includes forming a protective structure over the epitaxial structure, and the protective structure laterally surrounds the protruding portion of the gate electrode. In addition, the method includes forming a conductive contact electrically connected to the epitaxial structure and penetrating through the protective structure.