Oxide Layer Densification via DHF-H2O2 Etching
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Solution Overview
Problem
In semiconductor integrated circuits, the thickness and quality of interfacial layers in high-k gate stacks are challenging to control due to subsequent thermal processes, affecting MOSFET device performance, and require different oxide film thicknesses for high-voltage and low-voltage devices on the same die.
Innovation Solution
A method involving a quality enhancement process using a mixture of dilute hydrofluoric acid (DHF) and hydrogen peroxide (H2O2) to etch and densify the oxide layer simultaneously, reducing thickness and enhancing quality without damaging the semiconductor substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thermal processes are used to form oxide layers in high-k gate stacks, then the oxide layer can be formed, but the thickness and quality control becomes difficult due to subsequent thermal processes affecting the interfacial layer
Solution Approach 1:
The patent changes the chemical parameters of the etching solution by using a mixture of dilute hydrofluoric acid (DHF) and hydrogen peroxide (H2O2) in specific ratios. This chemical parameter change enables simultaneous etching and densification of the oxide layer, achieving both thickness reduction and quality enhancement without relying on thermal processes that compromise control precision
2Adaptability or versatility
If different thickness gate oxide films are formed for high-voltage and low-voltage devices on the same die, then area-efficient high voltage device with low voltage control devices can be fabricated, but the process complexity increases
Solution Approach 1:
The patent applies local quality by treating different regions of the oxide layer differently through the DHF-H2O2 mixture process. The etching and densification can be controlled to achieve different final thicknesses and qualities in different areas, enabling both thick oxide for high-voltage devices and thin oxide for low-voltage devices on the same die without requiring completely separate formation processes
3Manufacturing precision
If the oxide layer thickness is reduced to improve device performance, then the quality of the oxide layer may deteriorate, but if the thickness is increased to improve quality, then the device performance decreases
Solution Approach 1:
The patent merges two opposing functions into a single process step: etching (to reduce thickness) and densification (to enhance quality). The DHF component etches the oxide layer to reduce thickness, while the H2O2 component simultaneously densifies the oxide layer to improve quality. This combination resolves the trade-off between thickness reduction and quality maintenance
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 controls and reduces the oxide layer thickness while improving its quality, enhancing the electrical performance of semiconductor devices by forming thinner, denser oxide layers suitable for both high-voltage and low-voltage applications.
Implementation Method 1
a quality enhancement process using a mixture of dilute hydrofluoric acid (DHF) and hydrogen peroxide (H2O2) is performed to etch the oxide layer
Implementation Method 2
a quality enhancement process using a mixture of dilute hydrofluoric acid (DHF) and hydrogen peroxide (H2O2) is performed to etch the oxide layer and densify the oxide layer at the same time
Data Source
AI summary
A method of forming an oxide layer is provided in the present invention. The method includes the following steps. A first oxide layer is formed on a semiconductor substrate, and a quality enhancement process is then performed to etch the first oxide layer and densify the first oxide layer at the same time for forming a second oxide layer. The first oxide layer is etched and densified at the same time by a mixture of dilute hydrofluoric acid (DHF) and hydrogen peroxide (H2O2) in the quality enhancement process. The thickness of the second oxide layer may be reduced and the quality of the second oxide layer may be enhanced by the quality enhancement process at the same time.