Epitaxial Fin Structure With Inner Spacers for Reliable GAA Scaling
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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
The use of selective epitaxial growth (SEG) processes and multi-patterning techniques to form semiconductor layers and structures, such as FinFETs and gate all around (GAA) transistors, with precise control over etching and deposition to create patterns with smaller pitches and improved isolation and spacer structures, enhancing the reliability and performance of semiconductor devices.
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 manufacturing difficulty increase
Solution Approach 1:
The fabrication process is divided into multiple patterning steps (e.g., self-aligned double patterning, self-aligned triple patterning) where each step creates a portion of the final pattern. This segmentation allows complex small-geometry structures to be formed through sequential simpler steps, managing overall process complexity while achieving high functional density
Solution Approach 2:
Mandrel structures and spacer layers are formed in advance before the final pattern transfer. These preliminary structures serve as templates that guide subsequent etching steps, enabling precise feature formation at small dimensions while simplifying the overall manufacturing process through pre-planned pattern development
2Productivity
If feature sizes continue to decrease to increase functional density, then chip area utilization is improved, but manufacturing reliability and consistency deteriorate
Solution Approach 1:
Different regions of the substrate receive different treatments through selective masking and localized etching processes. This allows optimization of each region's features for specific functional requirements while maintaining overall manufacturing reliability, as each local area can be precisely controlled according to its specific needs
Solution Approach 2:
The self-aligned nature of the multi-patterning process provides inherent feedback control, where previously formed structures (mandrels, spacers) automatically define the positions of subsequent features. This eliminates the need for separate alignment steps and reduces alignment errors, thereby improving manufacturing reliability at small feature sizes
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 allows for the formation of high-quality semiconductor devices with improved reliability and reduced parasitic capacitance, leading to enhanced operational speed and reduced risk of short circuits, thereby addressing the challenges of miniaturization in semiconductor fabrication.
Implementation Method 1
The use of selective epitaxial growth (SEG) processes and multi-patterning techniques to form semiconductor layers and structures
Data Source
AI summary
A method for forming a semiconductor device structure includes forming a fin structure, and the fin structure has multiple sacrificial layers and multiple semiconductor layers laid out alternately. The method also includes forming a gate stack wrapped around the fin structure and forming a spacer layer extending along sidewalls of the fin structure and the gate stack. The method further includes partially removing the fin structure and the spacer layer to form a recess exposing side surfaces of the semiconductor layers and the sacrificial layers. A remaining portion of the spacer layer forms a gate spacer. In addition, the method includes forming an inner spacer layer along a sidewall and a bottom of the recess and partially removing the inner spacer layer using an isotropic etching process. Remaining portions of the inner spacer layers form multiple inner spacers. The method includes forming an epitaxial structure in the recess.