Semiconductor Gate Stack Formation with Doped Dielectric Strain Tuning
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Solution Overview
Problem
The semiconductor industry faces challenges in forming reliable semiconductor devices at increasingly smaller sizes due to the complexity and difficulty of fabrication processes as feature sizes decrease, leading to issues in processing and manufacturing complex circuits.
Innovation Solution
The process involves forming FinFET structures with fins and gate all around (GAA) transistor structures, using a semiconductor stack with alternating sacrificial and channel layers, and employing multiple patterning and epitaxial growth techniques to create fin structures, isolation structures, and metal gate stacks, with dopants introduced into dielectric layers to tune strain and facilitate metal gate stack formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If feature sizes continue to decrease to increase functional density, then production efficiency increases and costs lower, but fabrication process complexity and difficulty increase
Solution Approach 1:
The fabrication process is divided into multiple discrete stages including forming semiconductor fins, depositing gate dielectric layers, forming gate electrodes, and creating source/drain regions. Each stage is independently optimized and controlled, allowing complex devices to be built through manageable sequential steps rather than attempting monolithic fabrication
Solution Approach 2:
The patent transitions from planar transistor structures to three-dimensional FinFET structures with vertical fins extending from the substrate. This dimensional change increases effective channel area and control without proportionally increasing lithographic feature size, thereby maintaining manufacturing feasibility while improving device performance
2Productivity
If feature sizes decrease to increase functional density, then more devices fit per chip area, but reliability of individual devices becomes harder to ensure
Solution Approach 1:
The gate dielectric layer structure is optimized locally with different thicknesses in different regions - thinner at the channel interface for better control and thicker in other regions for reliability. Material composition is also locally tailored, such as using high-k materials specifically where needed for electrical performance while maintaining overall structural integrity
Solution Approach 2:
The patent incorporates guard rings, isolation structures, and redundant design elements that provide protective margins against process variations and defects. These features are built in advance to cushion against potential reliability issues before they manifest in device failure
3Productivity
If complex circuits are formed at smaller sizes, then chip capacity increases, but processing and manufacturing difficulty increases
Solution Approach 1:
Semiconductor fins are formed and gate dielectric layers are deposited in advance before final gate electrode patterning. This preliminary structuring creates a robust foundation that simplifies subsequent processing steps and reduces the difficulty of forming complex circuit patterns at small dimensions
Solution Approach 2:
The patent employs multi-layer gate structures where gate electrodes are formed over gate dielectric layers, which themselves are formed over fin structures. This nested arrangement allows complex functionality to be achieved through layered construction, where each layer contributes specific functionality without requiring the entire structure to be fabricated in a single complex step
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 reliability and performance of semiconductor devices by improving etching selectivity, oxidation rates, and current flow, while reducing parasitic capacitance and enhancing operation speed.
Implementation Method 1
introducing dopants into an upper portion of the dielectric layer to tune strain and facilitate metal gate stack formation
Implementation Method 2
improving etching selectivity
Implementation Method 3
improving oxidation rates
Data Source
AI summary
A semiconductor device structure and a formation method are provided. The method includes forming a dummy gate stack over a substrate and forming a dielectric layer laterally surrounding the dummy gate stack. The method also includes introducing dopants into an upper portion of the dielectric layer and removing the dummy gate stack to form a trench surrounded by the dielectric layer. The method further includes forming a metal gate stack in the trench.