Air Gap Seal Material Using Oxygen-Doped SiC for Etch Resistance
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Solution Overview
Problem
Existing seal materials for air gaps in semiconductor devices suffer from low conformity and etch resistance, leading to defects such as collapse of the seal material and trapping of chemical solutions, which result in low device yield and failure.
Innovation Solution
A highly rigid silicon carbide doped with oxygen (HRSCO) layer is used as the seal material, which can be formed as a bilayer seal structure to enhance etch resistance and conformity, and also serves as a contact etch stop layer (CESL) and self-aligned contact (SAC).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing seal materials are used for air gaps, then the manufacturing process is simpler, but the seal material suffers from low conformity and etch resistance, leading to collapse and defects
Solution Approach 1:
The patent employs a bilayer seal structure composed of silicon nitride and silicon oxide layers. The silicon nitride layer provides high etch resistance to prevent collapse during fabrication, while the silicon oxide layer offers good conformity to complex air gap geometries. This composite material approach resolves the contradiction by combining materials with complementary properties to achieve both high manufacturing precision and structural integrity.
Solution Approach 2:
The seal material is divided into multiple functional layers (silicon nitride layer and silicon oxide layer) with distinct roles. The silicon nitride layer specifically addresses etch resistance requirements, while the silicon oxide layer handles conformity requirements. This segmentation allows each layer to be optimized for its specific function, resolving the contradiction between etch resistance and conformity without requiring a single complex material.
2Productivity
If existing seal materials are used, then the process is less complex, but chemical solutions are trapped and device yield decreases
Solution Approach 1:
The bilayer structure of silicon nitride and silicon oxide creates a sealed configuration that prevents chemical solution trapping. The combination of these materials provides both the mechanical integrity needed to maintain seals and the chemical resistance required to prevent solution entrapment, thereby improving device yield without excessive complexity.
Solution Approach 2:
The patent employs a contact etch stop layer (CESL) that is intentionally designed to be etched away during subsequent processing steps. This sacrificial layer approach allows for precise control of the sealing process and prevents defects while the layer itself is temporary and removed after serving its purpose, improving yield without permanent complexity.
3Reliability
If existing seal materials are used, then material selection is simpler, but leak current increases and device performance decreases
Solution Approach 1:
The silicon nitride and silicon oxide layers work together to provide superior electrical isolation properties. Silicon nitride offers high dielectric strength and low leak current, while silicon oxide provides excellent insulation and interface quality. This composite structure achieves superior electrical performance and reliability by combining the complementary electrical properties of both materials.
Data Source
AI summary
The present disclosure relates to a semiconductor device including first and second terminals formed on a fin region and a seal layer formed between the first and second terminals. The seal layer includes a silicon carbide material doped with oxygen. The semiconductor device also includes an air gap surrounded by the seal layer, the fin region, and the first and second terminals.