Low-Oxygen Etching Composition for Si Over SiGe Selectivity
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Solution Overview
Problem
Existing etching compositions fail to provide sufficient selective solubility of silicon relative to silicon germanium, especially in narrow gaps, leading to poor etch rates and surface conditions after etching, which are critical for miniaturizing and improving the performance of Fin FETs and GAA FETs.
Innovation Solution
An etching composition containing a semiclathrate hydrate-forming compound with controlled oxygen concentration and specific properties, such as quaternary ammonium halides or phosphonium salt compounds, to suppress silicon germanium dissolution and enhance silicon dissolution, achieving excellent selective solubility and surface smoothness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching compositions are used, then etching can be performed, but selective solubility of silicon relative to silicon germanium is insufficient
Solution Approach 1:
The patent changes the chemical composition parameters of the etching liquid by incorporating specific compounds (ammonium fluorosulfonate, phosphonium fluorosulfonate, or sulfonium fluorosulfonate) with controlled concentrations. This composition modification enables the etching liquid to achieve both high selective solubility of silicon relative to silicon germanium and consistent etch rates, resolving the contradiction between manufacturing precision and reliability
Solution Approach 2:
The patent creates a composite etching system by combining fluorosulfonate-containing compounds with other etching agents. This composite approach allows the etching liquid to simultaneously provide selective silicon dissolution and maintain stable etching performance across different substrate conditions, addressing both selective solubility and etch rate consistency requirements
2Area of moving object
If etching is performed in narrow gaps for miniaturization, then transistor density increases, but etch rate becomes extremely low
Solution Approach 1:
The patent modifies the etching chemistry parameters by using fluorosulfonate compounds that generate highly reactive species capable of efficiently etching silicon even in confined narrow gaps. This chemical parameter change maintains high etch rates despite the geometric constraints of miniaturized structures, enabling increased transistor density without sacrificing productivity
3Manufacturing precision
If etching is performed in narrow gaps, then miniaturization is achieved, but selective solubility may differ from smooth substrate
Solution Approach 1:
The patent employs fluorosulfonate-containing compounds that provide localized chemical reactivity tailored to the specific geometry of narrow gaps. This local quality adjustment ensures that the etching liquid maintains consistent selective solubility characteristics whether etching smooth substrates or confined narrow gap structures, enabling reliable miniaturization with uniform etching behavior across different substrate topographies
4Ease of manufacture
If conventional etching is used, then silicon can be etched, but surface smoothness after etching is poor
Solution Approach 1:
The patent changes the chemical reaction parameters by using fluorosulfonate compounds that produce a more controlled and uniform etching process. This results in smoother substrate surfaces after etching while maintaining effective silicon removal, thereby improving manufacturing precision without sacrificing ease of manufacture
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 etching composition effectively suppresses silicon germanium dissolution, promotes silicon dissolution, and ensures a smooth substrate surface, enabling high-accuracy etching for semiconductor devices, particularly in structures like GAA FETs.
Implementation Method 1
an etching composition containing a semiclathrate hydrate-forming compound (A), wherein the semiclathrate hydrate-forming compound (A) is a compound having a melting point of 5° C. or higher when the semiclathrate hydrate-forming compound (A) is made into an aqueous solution having a concentration of 1 mol/L
Data Source
AI summary
An etching composition containing a semiclathrate hydrate-forming compound (A), wherein the compound (A) comprises a compound having a melting point of 5° C. or higher when the compound (A) is made into an aqueous solution having a concentration of 1 mol/L, the etching composition has an oxygen concentration of 2 ppm by mass or less, and the etching composition has a mass ratio of oxygen to the compound (A) of from 1×10−8 to 1×10−4.