Fluorine Passivation for Ultrathin Gate Oxide Interface Defects
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Solution Overview
Problem
The semiconductor industry faces challenges in reducing interface defect density and capacitive effective thickness in ultrathin gate oxides, which affect carrier mobility and current leakage in increasingly complex and smaller IC devices.
Innovation Solution
A method involving fluorine passivation of the semiconductor substrate surface, followed by the formation of a gate dielectric layer and a metal gate electrode, which reduces interface defects and allows for effective atomic layer deposition of high-k gate oxides, thereby minimizing current leakage and enhancing device reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ultrathin gate oxides are used to reduce capacitive effective thickness, then device scaling is improved, but interface defect density increases and carrier mobility decreases
Solution Approach 1:
The substrate surface is subjected to fluorine passivation treatment before gate oxide formation to preemptively reduce interface defects. This preliminary action modifies the substrate surface properties to ensure lower interface defect density when the ultrathin gate oxide is subsequently formed, thereby maintaining both thin oxide benefits and high reliability
Solution Approach 2:
The invention changes the chemical state of the substrate surface by introducing fluorine atoms through passivation. This parameter change in surface chemistry reduces interface defect density, enabling the formation of ultrathin gate oxides with improved electrical characteristics and lower carrier scattering
2Manufacturing precision
If ultrathin gate oxides are used to reduce capacitive effective thickness, then device scaling is improved, but gate leakage current increases
Solution Approach 1:
Fluorine passivation is performed on the substrate surface before gate oxide deposition to preemptively passivate dangling bonds and reduce interface states. This preliminary treatment creates a cleaner interface that reduces tunneling current and leakage paths in the subsequent ultrathin gate oxide structure
Solution Approach 2:
The invention converts the potentially harmful effect of interface defects into a benefit by using fluorine passivation to create a controlled, optimized interface. The fluorine treatment transforms the substrate surface into a state that naturally reduces leakage current, turning what would be a defect-prone interface into a low-leakage structure
3Ease of manufacture
If conventional cleaning methods are used, then manufacturing simplicity is maintained, but interface defect density remains high
Solution Approach 1:
The invention changes the chemical parameters of the cleaning process by introducing fluorine-containing species. This chemical modification of the cleaning treatment enables effective reduction of interface defects while maintaining a relatively simple process implementation, improving reliability without significantly complicating manufacturing
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 approach results in lower interface defect density and reduced gate leakage current without compromising the thickness or dielectric constant of the gate oxide, improving carrier mobility and device scalability.
Implementation Method 1
fluorine passivation of the semiconductor substrate surface
Implementation Method 2
effective atomic layer deposition of high-k gate oxides
Data Source
AI summary
A method of cleaning a semiconductor structure includes rotating a semiconductor structure. The method of cleaning further includes cleaning the semiconductor structure with a hydrogen fluoride (HF)-containing gas. A method of forming a semiconductor device includes forming a recess in a source/drain (S/D) region of a transistor. The method of forming further includes cleaning the recess with a HF-containing gas, the HF-containing gas having an oxide removing rate of about 2 nanometer/minute (nm/min) or less. The method of forming further includes epitaxially forming a strain structure in the recess after the cleaning the recess, the strain structure providing a strain to a channel region of the transistor.