Strained Semiconductor NBTI Mitigation via Molecular Plug Film
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Solution Overview
Problem
Strained semiconductor devices face Negative Bias Temperature Instability (NBTI) due to hydrogen atoms diffusing into the gate-oxide interfacial layer, degrading device performance, as dangling bonds in stress films are unstable and release hydrogen at high temperatures.
Innovation Solution
A method involving the formation of a molecular plug film structure using atomic layer deposition (ALD) and a stress film using chemical vapor deposition (CVD), where the annealing process breaks dangling bonds, increasing stress and using the molecular plug film as a barrier to block hydrogen diffusion, thereby improving NBTI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a stress film is deposited on the substrate surface to generate compressive or tensile stress, then carrier mobility is improved, but hydrogen atoms diffuse into the gate-oxide interfacial layer causing NBTI
Solution Approach 1:
A molecular plug film structure is introduced as an intermediary layer between the stress film and the gate oxide. This molecular plug film acts as a barrier to prevent hydrogen atoms generated in the stress film during annealing from diffusing into the gate oxide, thereby resolving the NBTI issue while maintaining the stress-induced carrier mobility improvement
Solution Approach 2:
The film structure is segmented into multiple functional layers: the stress film for generating mechanical stress, the molecular plug film structure for blocking hydrogen diffusion, and the gate oxide for electrical isolation. This segmentation allows each layer to perform its specific function without interfering with others, particularly preventing hydrogen from reaching the gate oxide
2Speed
If annealing is performed to increase stress in the stress film, then carrier mobility is enhanced, but hydrogen atoms are released from dangling bonds and diffuse into the gate oxide
Solution Approach 1:
The molecular plug film structure serves as a protective intermediary that blocks the path of hydrogen atoms released during annealing. It prevents these harmful hydrogen atoms from reaching the gate oxide interface, allowing the annealing process to proceed for stress enhancement without generating NBTI
Solution Approach 2:
The hydrogen atoms that would normally cause harm during annealing are instead directed toward the molecular plug film, which absorbs or blocks them. The molecular plug film transforms the potentially harmful hydrogen diffusion into a controlled process that does not affect the gate oxide, while still achieving the desired stress enhancement in the semiconductor device
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
The solution effectively prevents hydrogen diffusion, enhancing the stability and performance of strained semiconductor devices by increasing the stress on the MOS structure and blocking hydrogen molecules, significantly improving NBTI lifetime.
Implementation Method 1
performing an annealing process to apply stress on the MOS device
Implementation Method 2
the molecular plug film structure under the stress film can function as a molecular plug to block the diffusion of hydrogen molecules
Implementation Method 3
forming a molecular plug film structure on the MOS device comprises applying an atomic layer deposition (ALD) process
Implementation Method 4
depositing a stress film on the molecular plug film structure comprises: a chemical vapor deposition (CVD) process
Data Source
AI summary
A method of forming a strained semiconductor device includes: forming a substrate and a MOS device on the substrate; depositing a molecular plug film structure on the MOS device, The molecular plug film structure includes at least one molecular plug film, depositing a stress film on the molecular plug film structure, and performing an annealing process. The stress applied to the MOS device by the stress film is increased by the annealing process. The structure made by the method includes: a MOS device formed on a substrate, a molecular plug film structure formed on the MOS device, the molecular plug film structure includes at least one molecular plug film, and a stress film formed on the molecular plug film structure.