Fluorine Plasma Passivation of High-k Gate Stack Defects
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Solution Overview
Problem
High-k dielectric materials face challenges such as carbon contamination and morphological changes due to high temperatures, leading to bonding defects and poor device performance in semiconductor processing.
Innovation Solution
A method involving low energy plasma fluorination using a fluorine source gas to form a fluorinated dielectric layer on a substrate, which passivates oxygen vacancies and other bonding defects, and forms a stable high-k gate stack without etching, using inductive pulse radio frequency or continuous wave capacitive plasma processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If high-k dielectric materials are deposited using CVD or ALD techniques, then the dielectric constant is improved, but carbon contamination and bonding defects are introduced
Solution Approach 1:
The patent applies fluorine plasma treatment to passivate the harmful carbon contamination and bonding defects (oxygen vacancies) introduced during CVD or ALD deposition. The fluorine atoms bond with the carbon and oxygen vacancies, converting the harmful contaminants into beneficial fluorinated regions that improve dielectric stability and reduce leakage current, while preserving the high dielectric constant of the material
2Ease of manufacture
If high-k dielectric materials are exposed to high temperatures during subsequent fabrication processes, then other materials can be deposited, but morphological changes and crystallization occur
Solution Approach 1:
The patent performs fluorine plasma treatment as a preliminary action before subsequent high-temperature fabrication processes. This pre-treatment stabilizes the high-k dielectric material by passivating bonding defects and reducing oxygen vacancies, creating a more thermally stable structure that resists crystallization and grain growth when exposed to high temperatures during later deposition steps
Solution Approach 2:
The fluorine plasma treatment acts as a protective cushioning layer that prevents the high-k dielectric material from suffering morphological degradation during subsequent high-temperature processing. The fluorinated regions serve as a buffer that absorbs thermal stress and prevents unwanted phase transitions, ensuring the material maintains its amorphous structure and low leakage properties
3Stability of the object's composition
If fluorine plasma treatment is applied to passivate bonding defects, then dielectric stability is improved, but etching of the dielectric layer may occur
Solution Approach 1:
The patent carefully controls the parameters of the fluorine plasma treatment, including fluorine gas flow rate, plasma power, pressure, and treatment duration, to achieve optimal passivation of bonding defects while preventing excessive etching. By adjusting these parameters, the process achieves the right balance between incorporating beneficial fluorine atoms to passivate oxygen vacancies and avoiding removal of the dielectric material itself
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 method effectively reduces bonding defects and stabilizes high-k dielectric materials, enhancing the quality of the gate dielectric layer and preventing grain growth and phase separation, thereby improving device performance.
Implementation Method 1
exposing the substrate to a low energy plasma comprising a fluorine source gas to form a fluorinated dielectric layer on the substrate
Implementation Method 2
to passivate oxygen vacancies and other bonding defects in the high-k gate stack
Data Source
AI summary
Embodiments of the present invention generally provide a method for forming a dielectric material with reduced bonding defects on a substrate. In one embodiment, the method comprises forming a dielectric layer having a desired thickness on a surface of a substrate, exposing the substrate to a low energy plasma comprising a fluorine source gas to form a fluorinated dielectric layer on the substrate without etching the dielectric layer, and forming a gate electrode on the substrate. In certain embodiments, the fluorine source gas is a carbon free gas. In certain embodiments, the method further comprises co-flowing a gas selected from the group consisting of argon, helium, N2, O2, and combinations thereof with the fluorine source gas.