FinFET Spacer Structure With Silicon-Rich Etch Protection
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Solution Overview
Problem
The challenge of forming reliable semiconductor devices at smaller sizes is exacerbated by the increasing complexity of fabrication processes as feature sizes continue to decrease, making it difficult to achieve consistent and efficient manufacturing.
Innovation Solution
A semiconductor device structure is formed using FinFETs, where fins are patterned through photolithography and self-aligned processes, with the use of multiple mask layers and dielectric layers to create a spacer structure that enhances etching precision and yield, including the use of silicon rich layers and protection layers to improve etching selectivity and prevent over-etching.
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 fabrication process is divided into multiple sequential stages including forming first and second trenches at different depths, selective epitaxial growth in specific regions, and staged doping processes. This segmentation allows complex 3D FinFET structures to be built systematically through manageable steps, reducing overall process complexity while maintaining small feature sizes
Solution Approach 2:
Shallow trench isolation structures are formed preliminarily before FinFET fabrication to define active regions and provide electrical isolation. This preliminary action establishes the foundation for subsequent fin formation and gate stacking, enabling precise control of small features without interference from surrounding areas
2Productivity
If feature sizes decrease to increase functional density, then chip area utilization is improved, but manufacturing reliability decreases
Solution Approach 1:
Silicon-rich layers are introduced as intermediary structures between the silicon substrate and overlying dielectric layers. These layers act as buffer zones that accommodate stress and prevent defects from propagating through the device stack, thereby maintaining manufacturing reliability despite reduced feature sizes
Solution Approach 2:
The epitaxial growth process utilizes controlled changes in temperature, pressure, and gas composition to precisely control fin height, width, and crystal orientation. By adjusting these parameters, the process maintains manufacturing yield and device performance even as feature dimensions are scaled down
3Manufacturing precision
If multiple mask layers and dielectric layers are used to enhance etching precision, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
Self-aligned spacer structures are formed by depositing conformal dielectric layers around fin structures, then performing anisotropic etching to create vertical sidewalls. The spacer width is automatically defined by the deposition thickness, eliminating the need for separate alignment steps and reducing process complexity while maintaining high precision
Solution Approach 2:
Multiple dielectric layers with different materials and functions are nested within each other, with shallower trenches filled by one dielectric and deeper trenches by another. This nested structure provides both mechanical support and electrical isolation at different levels, achieving complex functionality through organized layering rather than scattered components
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 method improves the precision and efficiency of semiconductor device fabrication by reducing over-etching and enhancing the reliability of the final structure, thereby improving the yield and performance of semiconductor devices.
Implementation Method 1
The silicon rich layer is used as an etch stop layer to prevent over etching of the protection layer thereover and protect the dielectric layer when patterning the protection layer using an etching process
Implementation Method 2
an oxide layer is formed over the exposed portions of the silicon rich layer
Data Source
AI summary
A semiconductor device structure is provided. The semiconductor device structure includes a substrate. The semiconductor device structure includes a gate stack formed over the substrate. The semiconductor device structure includes a spacer structure formed over a sidewall of the gate stack. The spacer structure includes a dielectric layer, a silicon rich layer, and a protection layer. The dielectric layer is formed between the gate stack and the silicon rich layer. The silicon rich layer is formed between the dielectric layer and the protection layer. A first atomic percentage of silicon in the silicon rich layer is greater than about 50%. The semiconductor device structure includes a source/drain structure formed over the substrate. The spacer structure is formed between the source/drain structure and the gate stack.