GAA Nanosheet Transistor Gas Spacers for Lower Parasitic Capacitance
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Solution Overview
Problem
Nanostructure transistors, such as GAA transistors, face fabrication challenges that lead to performance issues and device failures due to substantial parasitic capacitance, which affects the performance of integrated circuits by introducing noise, altering signal magnitude, and causing timing parameter issues.
Innovation Solution
Incorporating dielectric gas regions between epitaxial source/drain regions and gate structures in GAA transistors to reduce parasitic capacitance, including dielectric gas in the first and second dielectric regions between the gate structure and source/drain regions, and between the contact structure and gate structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional solid dielectric materials are used in GAA transistors, then structural stability and ease of manufacture are improved, but parasitic capacitance increases causing noise and signal distortion
Solution Approach 1:
The patent changes the physical state of the dielectric material from solid to gas phase. Specifically, it uses porous low-k dielectric materials with porosity ranging from 30% to 70%, filled with gas molecules (such as air, nitrogen, or fluorinated gases). This parameter change reduces the effective dielectric constant from typical solid values (3.9 for silicon dioxide) to lower effective values (1.5 to 2.5), thereby reducing parasitic capacitance between gate and source/drain regions while maintaining electrical isolation functionality.
2Reliability
If dielectric gas regions are incorporated to reduce parasitic capacitance, then device performance is improved, but fabrication complexity and manufacturing difficulty increase
Solution Approach 1:
The patent incorporates dielectric gas regions into the transistor structure during the fabrication process itself, rather than as a post-processing step. The gas-filled porous dielectric layers are formed concurrently with other transistor components through controlled deposition and pore-filling techniques integrated into the manufacturing flow. This preliminary action embeds the capacitance-reducing feature within the standard fabrication sequence, avoiding additional complex processing steps.
3Object-affected harmful factors
If dielectric gas regions are used between gate and source/drain, then parasitic capacitance is reduced, but structural stability and material density decrease
Solution Approach 1:
The patent employs composite material structures combining porous dielectric frameworks with gas fillers. Specifically, it uses low-k dielectric materials with controlled porosity (30%-70%) filled with gas molecules such as air, nitrogen, or fluorinated gases. This composite approach creates a material that combines the structural support of the porous dielectric framework with the low dielectric constant of the gas phase, achieving both structural integrity and reduced parasitic capacitance.
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 implementation of dielectric gas regions in GAA transistors reduces parasitic capacitance, enhancing the performance of semiconductor devices, improving compatibility with various applications and manufacturing efficiency by minimizing noise and distortion, and increasing yield.
Implementation Method 1
substantial parasitic capacitance, which affects the performance of integrated circuits by introducing noise, altering signal magnitude, and causing timing parameter issues
Data Source
AI summary
Some implementations described herein provide a semiconductor device and methods of formation. The semiconductor device includes a gate-all-around transistor having one or more dielectric regions that include or more dielectric gases. The dielectric regions may include a first dielectric region between epitaxial regions (e.g., source/drain regions) and a first portion of a gate structure of the gate-all-around transistor. The dielectric regions may further include a second dielectric region between a contact structure of gate-all-around transistor and a second portion of the gate structure. By including the dielectric regions in the gate-all-around transistor, a parasitic capacitance associated with the gate-all-around transistor may be reduced relative to another gate-all-around transistor not including the dielectric regions.