Semiconductor Structure With Sacrificial Epitaxial Layer Gap
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Solution Overview
Problem
Current semiconductor structures face challenges in reducing leakage current and optimizing performance due to parasitic devices formed when source/drain doped layers come into contact with protrusions, which affects the epitaxy process and results in poor device performance.
Innovation Solution
A semiconductor structure is developed with a gap formed between the bottom of the source/drain doped layer and the protrusion, achieved by forming a sacrificial epitaxial layer at the bottom of the source/drain groove and removing it after the doped layer is formed, allowing for isolation and preventing parasitic devices, while ensuring the quality of the epitaxial growth of the source/drain doped layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the source/drain doped layer is formed in contact with the protrusion, then the manufacturing process is simplified, but parasitic devices are formed causing increased leakage current
Solution Approach 1:
An isolation layer is introduced as an intermediary between the source/drain doped layer and the protrusion. This isolation layer prevents direct contact that would form parasitic devices, thereby reducing leakage current while still allowing the source/drain doped layer to be formed through a relatively simple epitaxial process.
Solution Approach 2:
The structure is segmented by introducing the isolation layer that divides the contact interface between the source/drain doped layer and the protrusion. This segmentation allows the source/drain doped layer to be formed without direct contact with the protrusion, preventing parasitic device formation while maintaining manufacturing simplicity.
2Reliability
If the source/drain doped layer is isolated from the protrusion, then leakage current is reduced, but the epitaxy process quality may be affected
Solution Approach 1:
The isolation layer serves as a mediator that enables the source/drain doped layer to be formed through epitaxy without direct contact with the protrusion. This maintains the quality of the epitaxial growth by providing a suitable surface while still achieving isolation to reduce leakage current.
Solution Approach 2:
The top surface of the isolation layer is positioned at a specific height parameter - lower than the top surface of the protruding structures - which allows the epitaxial process to proceed with high quality while maintaining the necessary isolation to prevent parasitic device formation and reduce leakage current.
3Reliability
If the gate structure is formed spanning the channel structure, then channel control capability is improved, but the device complexity increases
Solution Approach 1:
The gate structure is designed to perform multiple functions simultaneously: it provides strong channel control capability by spanning the channel structure, and its positioning on the isolation layer helps maintain simpler manufacturing processes. This multi-functionality achieves improved reliability without proportionally increasing device complexity.
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 effectively reduces leakage current and optimizes the performance of the semiconductor structure by preventing parasitic devices and maintaining the quality of the epitaxial growth of the source/drain doped layers, thereby enhancing the overall performance.
Implementation Method 1
forming a sacrificial epitaxial layer at the bottom of the source/drain groove
Implementation Method 2
forming source/drain doped layers, located in the channel structure on two sides of the device gate structure
Data Source
AI summary
A semiconductor structure and a method for forming the same are provided. One form of a method includes: forming a source/drain groove in the channel structure on two sides of a gate structure; forming a sacrificial epitaxial layer on a bottom of the source/drain groove; forming, on the sacrificial epitaxial layer, a source/drain doped layer in the source/drain groove; and removing the sacrificial epitaxial layer, to form a gap between a bottom of the source/drain doped layer and the protrusion. After the sacrificial epitaxial layer is formed, the source/drain doped layer located in the source/drain groove may be formed on the sacrificial epitaxial layer using the epitaxy process on the basis of the sacrificial epitaxial layer. Therefore, the epitaxy process for forming the source/drain doped layer is prevented from adverse effects, the epitaxial growth quality of the source/drain doped layer is ensured, and a performance of the semiconductor structure is optimized.