FinFET Epitaxial Surface Preparation After Ion Implantation
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Solution Overview
Problem
The increasing demand for higher drive currents in smaller integrated circuits poses challenges in defect removal and epitaxial layer quality during the manufacturing of Fin Field-Effect Transistors (FinFETs), particularly due to ion implantation-induced defects and native oxide formation on semiconductor substrates.
Innovation Solution
A surface treatment process involving a wet clean process with hydrofluoric acid, followed by a dry etching process and a baking step in a hydrogen-containing environment to reduce oxygen concentration and defects on the substrate surface, enabling the formation of high-quality epitaxial layers without nucleation of extended defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ion implantation is performed to increase drive currents, then transistor performance is improved, but defect density and native oxide formation increase on the substrate surface
Solution Approach 1:
The patent applies preliminary action by performing a surface treatment process (wet clean with HF, dry etch, and bake) before epitaxial growth to remove ion implantation-induced defects and native oxides. This pre-treatment prepares the substrate surface in advance to ensure high-quality epitaxial layer formation despite the harmful effects of ion implantation used for transistor performance enhancement.
2Ease of manufacture
If conventional cleaning processes are used after ion implantation, then substrate surface is cleaned, but extended defects are nucleated during subsequent epitaxial growth
Solution Approach 1:
The patent applies parameter changes by modifying the substrate treatment parameters through a multi-step process: using HF-based wet clean to remove oxides, followed by dry etch to remove carbonaceous contaminants, and finally a bake step at elevated temperature in a nitrogen or forming gas atmosphere. These parameter changes prevent the nucleation of extended defects during epitaxial growth while maintaining substrate cleanliness.
3Manufacturing precision
If multiple surface treatment steps are implemented to reduce defects, then epitaxial layer quality is improved, but process complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the surface treatment into three distinct sequential steps: (1) wet clean with HF-based solution to remove native oxides, (2) dry etch to remove organic contaminants, and (3) bake in nitrogen or forming gas to passivate surface and prevent defect nucleation. Each step targets specific contaminants and prepares the surface for the next step, achieving high epitaxial layer quality through systematic segmentation of the treatment process.
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 process effectively reduces oxygen concentration and defect density on the substrate surface, allowing for the growth of high-quality epitaxial layers and improved electrical and optical properties in FinFETs, enhancing the overall performance of semiconductor devices.
Implementation Method 1
A surface treatment process involving a wet clean process with hydrofluoric acid
Implementation Method 2
a baking step in a hydrogen-containing environment to reduce oxygen concentration and defects on the substrate surface
Implementation Method 3
followed by a dry etching process
Data Source
AI summary
A method includes forming an implanted region in a substrate. The implanted region is adjacent to a top surface of the substrate. A clean treatment is performed on the top surface of the implanted region. The top surface of the implanted region is baked after the clean treatment. An epitaxial layer is formed on the top surface of the substrate. The epitaxial layer is patterned to form a fin.