Epitaxial Source/Drain Masking for Flexible Feature Shapes
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Solution Overview
Problem
The semiconductor industry faces challenges in patterning epitaxial source/drain features due to shrinking feature sizes and the lack of flexibility in traditional processes, which limits the ability to form N-type and P-type source/drain features with varying shapes and volumes, and increases the risk of damaging existing features during patterning.
Innovation Solution
A method is introduced that uses a self-aligned mask layer formed by oxidizing an epitaxial cap layer over the source/drain features, allowing for the formation of N-type and P-type source/drain features using a single patterned mask and avoiding photolithography in the patterning process, thereby increasing error tolerance and flexibility in feature shapes and volumes, and enabling overlapping or bridging of features without causing short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional photolithography patterning is used to form epitaxial source/drain features, then the process follows conventional manufacturing steps, but the feature sizes become difficult to control and existing features are at risk of damage as minimum feature size reduces
Solution Approach 1:
The method forms a self-aligned mask layer over the first type of source/drain features before forming the second type of source/drain features. This preliminary masking action protects the existing features from damage during subsequent patterning and epitaxial growth processes, while enabling precise control of feature sizes through the mask layer thickness
Solution Approach 2:
A self-aligned mask layer is introduced as an intermediary protective layer between the first type of source/drain features and the processing steps for forming the second type of features. This mask layer acts as a mediator that prevents direct contact and potential damage while allowing controlled formation of new features
2Adaptability or versatility
If separate patterning processes are used for N-type and P-type source/drain features, then each feature type can be formed independently, but the process complexity increases and flexibility in feature shapes and volumes is limited
Solution Approach 1:
The method combines the patterning of N-type and P-type source/drain features into a single unified process using one patterned mask. The self-aligned mask layer enables both feature types to be formed simultaneously with different epitaxial growth conditions, reducing process complexity while maintaining flexibility in feature shapes and volumes
Solution Approach 2:
The single patterned mask serves multiple functions: it defines the pattern for both N-type and P-type source/drain features, and the self-aligned mask layer provides universal protection for existing features regardless of their type. This multi-functional approach increases adaptability while simplifying the overall process
3Productivity
If overlapping or bridging of source/drain features is implemented to increase integration density, then more components can be integrated into a given chip area, but the risk of short circuits between features increases
Solution Approach 1:
The self-aligned mask layer serves as an intermediary protective barrier that allows overlapping or bridging of source/drain features to be implemented safely. By positioning the mask layer to extend over the first type of features, the method enables increased integration density through feature overlap while the mask layer prevents electrical contact and potential short circuits
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 tolerance to process errors, prevents damage to existing source/drain features during patterning, and allows for the formation of overlapping or bridging features without short circuits, improving the manufacturing efficiency and flexibility in semiconductor device production.
Implementation Method 1
a self-aligned mask layer formed by oxidizing an epitaxial cap layer over the source/drain features
Data Source
AI summary
Embodiments of the present disclosure provide a method of forming N-type and P-type source/drain features using one patterned mask and one self-aligned mask to increase windows of error tolerance and provide flexibilities for source/drain features of various shapes and/or volumes. In some embodiments, after forming a first type of source/drain features, a self-aligned mask layer is formed over the first type of source/drain features without using photolithography process, thus, avoid damaging the first type of source/drain features in the patterning process.