FinFET Trimming via Selective Oxide Removal
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Solution Overview
Problem
In the semiconductor industry, the fabrication of FinFETs faces challenges in achieving independent adjustment of performance for N-type and P-type semiconductor devices due to the limitations in trimming and processing of fin structures, which affects the short channel effect and drain induced barrier lowering.
Innovation Solution
A selective trimming process is implemented where the P-fin structure is oxidized to form a germanium oxide layer, which is then selectively removed, allowing for independent adjustment of the fin structure dimensions and performance of semiconductor devices, while the N-fin structure remains untrimmed, enabling improved control over channel regions and reducing fin bending and collapse concerns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a selective trimming process is implemented for P-fin structure, then independent performance adjustment of N-type and P-type devices is achieved, but the fabrication process complexity increases
Solution Approach 1:
The fin structure trimming process is segmented into two distinct stages: (1) selective oxidation of P-fin to form germanium oxide layer while leaving N-fin unchanged, and (2) selective removal of the germanium oxide layer from P-fin. This segmentation enables independent dimensional control of N-type and P-type devices, resolving the technical contradiction by achieving adaptability through process division.
Solution Approach 2:
A germanium oxide layer is introduced as an intermediary substance during the trimming process. This intermediate layer forms selectively on the P-fin structure through oxidation, serves as a removable mask that protects the P-fin during subsequent etching, and is then selectively removed to achieve the desired trimming. This intermediary approach enables precise independent control of fin dimensions for different device types.
2Reliability
If fin structure dimensions are increased or aspect ratios are reduced, then resistance is reduced and device performance is improved, but short channel effect control becomes more difficult
Solution Approach 1:
Different fin dimensions and characteristics are created for different device types through selective trimming. N-type devices retain their original fin dimensions while P-type devices receive trimmed fins with different dimensions. This local quality differentiation allows each device type to be optimized for its specific performance requirements while managing short channel effects appropriately for each device category.
Solution Approach 2:
The fin structure parameters (dimensions, aspect ratio) are changed selectively for P-type devices through the oxidation and removal process, while N-type device fin parameters remain unchanged. This parameter change approach enables independent optimization of fin geometry for different device types, allowing resistance reduction and performance improvement while maintaining appropriate short channel effect control for each device category.
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 short channel effect and reduces drain induced barrier lowering for P-type devices, allowing for independent performance adjustment of N-type and P-type devices, and enables the fabrication of fins with larger dimensions or lower aspect ratios, reducing resistance and improving device performance.
Implementation Method 1
oxidizing the P-fin structure to form a germanium oxide layer
Implementation Method 2
selectively removing the germanium oxide layer formed on the P-fin structure
Data Source
AI summary
A method for forming a semiconductor structure is provided. The method for forming the semiconductor structure includes forming a first fin structure with a first composition and a second fin structure with a second composition, oxidizing the first fin structure to form a first oxide layer and oxidizing the second fin structure to form a second oxide layer, removing the second oxide layer formed on the second fin structure, oxidizing the second fin structure to form a third oxide layer over the second fin structure, and forming a first metal gate electrode layer over the first oxide layer and a second metal gate electrode layer over the third oxide layer.