Gate Dielectric Nitrogen Segmentation for Leakage Reduction
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Solution Overview
Problem
Current methods for manufacturing semiconductor devices with multiple gate dielectric thickness layers result in non-uniform nitrogen profiles, leading to increased leakage current, particularly in high voltage devices with thicker gate dielectrics, reducing reliability.
Innovation Solution
A method involving the formation of masking layers over semiconductor substrates, exposure to nitrogen-containing plasma, and subsequent oxygen incorporation to create layers of varying gate dielectric thickness, ensuring uniform nitrogen distribution and reduced leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If non-thermal nitridation (plasma nitridation) is performed on gate dielectrics to reduce leakage current, then leakage current is suppressed, but nitrogen distribution becomes non-uniform, reducing device reliability
Solution Approach 1:
The gate dielectric structure is segmented into multiple layers with different nitrogen concentrations. The method forms a first gate dielectric layer with high nitrogen content near the semiconductor substrate interface, and a second gate dielectric layer with lower nitrogen content above it. This layered segmentation allows each layer to serve different functions: the first layer provides effective leakage suppression at the critical interface, while the second layer maintains overall dielectric integrity and uniformity, thus resolving the contradiction between leakage suppression and reliability.
Solution Approach 2:
The patent applies local quality by creating non-uniform nitrogen distribution in a controlled manner through selective nitridation of the first gate dielectric layer. The nitrogen concentration is locally optimized at the substrate interface where leakage occurs most, rather than uniformly throughout the entire gate dielectric. This localized nitrogen enrichment suppresses leakage current effectively while maintaining uniformity in the upper portion of the gate dielectric, thereby improving reliability.
2Manufacturing precision
If gate dielectric thickness is reduced to meet device performance requirements, then high performance is achieved, but leakage current increases, especially in high voltage devices
Solution Approach 1:
The patent changes the nitrogen concentration parameter within the gate dielectric structure to achieve leakage suppression without increasing physical thickness. By introducing nitrogen atoms into the first gate dielectric layer through selective nitridation, the effective barrier against leakage current is enhanced. This allows thin gate dielectric structures to maintain low leakage characteristics, resolving the contradiction between achieving thin-dielectric performance and preventing leakage.
3Adaptability or versatility
If multiple gate oxide processing is performed to integrate different thicknesses for core and I/O devices, then compatibility with different voltage requirements is achieved, but process complexity increases
Solution Approach 1:
The patent applies preliminary action by forming the first gate dielectric layer with selective nitridation before subsequent processing steps. This preliminary nitrogen incorporation establishes the low-leakage foundation early in the process, allowing later steps to focus on thickness differentiation for core and I/O devices without re-addressing leakage issues. This sequencing reduces overall process complexity while maintaining voltage compatibility across different device types.
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 reliability of semiconductor devices by minimizing leakage current across different voltage regions, maintaining compatibility with existing processes and avoiding additional patterning steps.
Implementation Method 1
performing non-thermal nitridation (e.g., plasma nitridation) on the gate dielectrics
Implementation Method 2
introducing nitrogen atoms into the gate dielectrics to suppress leakage currents
Implementation Method 3
incorporating oxygen into the first layer of gate dielectric material located in the left active region
Data Source
AI summary
The present invention provides a method for manufacturing a semiconductor device having multiple gate dielectric thickness layers. The method, in one embodiment, includes forming a masking layer over a semiconductor substrate in a first active region and a second active region of a semiconductor device, patterning the masking layer to expose the semiconductor substrate in the first active region, and subjecting exposed portions of the semiconductor substrate to a nitrogen containing plasma, thereby forming a first layer of gate dielectric material over the semiconductor substrate in the first active region. The method, in that embodiment, may further include incorporating oxygen into the first layer of gate dielectric material located in the first active region, and then removing the patterned masking layer, and forming a second layer of gate dielectric material over the first layer of gate dielectric material in the first active region and over the semiconductor substrate in the second active region, thereby resulting in a first greater thickness gate dielectric in the first active region and a second lesser thickness gate dielectric in the second active region.