Semiconductor Surface Preparation via Fluorine Plasma and Hydrogen Termination
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Solution Overview
Problem
Existing semiconductor surface preparation methods for epitaxial deposition, such as using HF solutions, result in critical dimension loss, hydrocarbon adsorption, and dopant diffusion, which degrade the quality of epitaxial layers, especially in patterned wafers and CMOS processes.
Innovation Solution
A method involving dry-etching a semiconductor substrate with a fluorine-containing species to remove the surface oxide layer, followed by exposure to hydrogen atoms to terminate the surface, thereby preventing contaminant adsorption and enabling high-quality epitaxial deposition without direct plasma exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If HF solution is used to remove surface oxide layer, then oxide removal is achieved, but critical dimension loss and hydrocarbon adsorption occur
Solution Approach 1:
The patent changes the chemical parameters of the cleaning process by using fluorine-containing plasma instead of HF liquid solution. This parameter change eliminates hydrocarbon adsorption while maintaining oxide removal capability, and prevents critical dimension loss through controlled plasma conditions and substrate temperature management.
Solution Approach 2:
The patent substitutes the chemical wet etching mechanism (HF solution) with a plasma-based chemical vapor phase process. This substitution eliminates the need for liquid handling and subsequent drying steps that cause hydrocarbon contamination, while achieving comparable or superior oxide removal with better dimensional control.
2Productivity
If high temperature processing is used for oxide removal, then oxide removal efficiency is improved, but dopant diffusion occurs
Solution Approach 1:
The patent changes the temperature parameter during the plasma cleaning process by optimizing substrate temperature control. The substrate is heated to a controlled range that enables efficient oxide removal through enhanced reaction kinetics, while staying below the threshold that would cause significant dopant diffusion, thus maintaining dopant distribution stability.
3Productivity
If direct plasma exposure is used for surface cleaning, then cleaning efficiency is improved, but surface damage occurs
Solution Approach 1:
The patent introduces an intermediary approach by using a carefully controlled fluorine-containing plasma environment that selectively reacts with oxide species while minimizing direct ion bombardment damage to the semiconductor surface. The plasma conditions are optimized to achieve cleaning through chemical reaction rather than physical sputtering, preserving surface quality.
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 minimizes critical dimension loss, prevents hydrocarbon contamination, and maintains dopant integrity, ensuring high-quality epitaxial layer growth on both patterned and unpatterned wafers, including those in CMOS processes.
Implementation Method 1
dry-etching the substrate with a fluorine containing species to remove the surface oxide layer
Implementation Method 2
fluorine containing species to remove the surface oxide layer
Implementation Method 3
exposing the surface of the bulk semiconductor to hydrogen atoms
Implementation Method 4
preventing contaminant adsorption
Implementation Method 5
atomic products of decomposition of the fluorine containing gas by the plasma
Implementation Method 6
ionic products of decomposition of the fluorine containing gas by the plasma
Data Source
AI summary
Provided is a method of epitaxial deposition, which involves dry-etching a semiconductor substrate with a fluorine containing species and exposing the dry-etched substrate to hydrogen atoms, prior to epitaxially depositing a semiconductor layer to the surface of the substrate.