Stabilized Gate Electrode Stack for Leakage Reduction
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Solution Overview
Problem
The continued miniaturization of silicon metal oxide semiconductor field effect transistors (MOSFETs) is reaching scaling limits, leading to increased leakage currents and thermal instability, which hampers further performance improvement in complementary metal oxide semiconductor (CMOS) devices.
Innovation Solution
Incorporating carbon and/or nitrogen into the semiconductor-containing layer and/or the metal semiconductor alloy layer, or providing a layer of carbon and/or nitrogen between them, to form a stabilized gate electrode stack, which eliminates the need for forming a metal semiconductor alloy on the gate structure and provides thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If traditional MOSFET scaling is continued, then device miniaturization is achieved, but leakage currents increase and thermal stability deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the gate electrode by incorporating carbon and nitrogen elements. This modifies the material properties to achieve thermal stability and reduced leakage currents while maintaining the scaled device dimensions. The carbon-nitrogen-doped metal semiconductor alloy layer provides a stable gate work function that is insensitive to thermal annealing, resolving the reliability issues associated with continued scaling.
Solution Approach 2:
The patent creates a composite gate electrode structure consisting of multiple layers including a carbon-nitrogen-doped metal semiconductor alloy layer and a semiconductor-containing layer. This composite structure combines the benefits of metal conductivity with semiconductor properties and carbon-nitrogen stabilization, achieving both miniaturization and improved reliability through material composition rather than dimensional scaling alone.
2Reliability
If carbon and nitrogen are incorporated into the gate electrode layers, then thermal stability and reduced leakage currents are achieved, but manufacturing process complexity increases
Solution Approach 1:
The patent applies preliminary doping of carbon and nitrogen into the metal semiconductor alloy layer before subsequent processing steps. This preliminary action establishes the stable gate work function early in the manufacturing process, preventing the need for complex post-processing adjustments and simplifying the overall fabrication sequence while achieving thermal stability.
Solution Approach 2:
The patent merges the doping of carbon and nitrogen into a single integrated process step applied to the metal semiconductor alloy layer. Rather than requiring separate doping processes for each element, the method combines them into one manufacturing operation, reducing process complexity while achieving the desired thermal stability and leakage current reduction.
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 reduces leakage currents and thermal degradation, maintaining device performance and stability even at higher temperatures, thus overcoming the limitations of traditional scaling methods.
Implementation Method 1
Incorporating carbon and/or nitrogen into the semiconductor-containing layer and/or the metal semiconductor alloy layer, or providing a layer of carbon and/or nitrogen between them, to form a stabilized gate electrode stack
Data Source
AI summary
A gate structure is provided on a channel portion of a semiconductor substrate. The gate structure may include an electrically conducting layer present on a gate dielectric layer, a semiconductor-containing layer present on the electrically conducting layer, a metal semiconductor alloy layer present on the semiconductor-containing layer, and a dielectric capping layer overlaying the metal semiconductor alloy layer. In some embodiments, carbon and/or nitrogen can be present within the semiconductor-containing layer, the metal semiconductor alloy layer or both the semiconductor-containing layer and the metal semiconductor alloy layer. The presence of carbon and/or nitrogen within the semiconductor-containing layer and/or the metal semiconductor alloy layer provides stability to the gate structure. In another embodiment, a layer of carbon and/or nitrogen can be formed between the semiconductor-containing layer and the metal semiconductor alloy layer.