Selective SiGe Etching Chemistry for Gate Dielectric Protection
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Solution Overview
Problem
The semiconductor industry faces challenges in selectively etching silicon germanium (SiGe) without damaging adjacent materials like gate insulating layers and semiconductor substrates during the plasma etching process, which can impact device yield and performance.
Innovation Solution
An etching composition comprising fluorine-containing acids, oxidizing agents, inorganic acids, organic acids, polymerized naphthalene sulfonic acids, and amines is used to selectively remove SiGe, minimizing damage to surrounding materials by controlling the etch rates and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma etching process is used to etch SiGe, then etching efficiency is improved, but damage to gate insulating layer and semiconductor substrate occurs
Solution Approach 1:
The patent changes the chemical parameters of the etching process by using a specifically formulated liquid etching composition containing fluorine-containing acid, oxidizing agent, inorganic acid, organic acid, and additive. This chemical formulation achieves high SiGe etching efficiency while controlling the etching selectivity to prevent damage to gate insulating layers and substrates, resolving the contradiction between etching efficiency and material damage.
Solution Approach 2:
The patent introduces an intermediary etching composition that selectively interacts with SiGe while being less aggressive toward other materials. The composition acts as a mediator between the SiGe material and the etching process, enabling efficient removal of SiGe through chemical reactions while the selective nature of the composition protects adjacent structures from damage.
2Speed
If plasma etching is used to remove SiGe, then etching speed is improved, but selectivity against other materials deteriorates
Solution Approach 1:
The patent modifies the chemical parameters by formulating a liquid etching composition with specific components and concentrations: fluorine-containing acid (0.1-10 wt%), oxidizing agent (1-50 wt%), inorganic acid (10-80 wt%), organic acid (1-20 wt%), and additive (0.01-5 wt%). This parameter optimization enables fast etching speed while maintaining high selectivity against gate insulating layers, metal conductors, and other materials through controlled chemical reactivity.
Solution Approach 2:
The etching composition exhibits local quality by having different reactivity toward different materials. The chemical formulation is designed to be highly reactive with SiGe while being less reactive with other materials in the semiconductor structure, enabling selective etching that maintains both speed and precision.
3Reliability
If additional protective steps are employed to avoid etching damage, then device reliability is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent extracts the protective function from separate process steps and integrates it into the etching composition itself. By formulating the etching solution with selective inhibitors and controlled chemistry, the composition inherently protects sensitive structures during etching, eliminating the need for additional protective layers or process steps while maintaining device reliability.
Solution Approach 2:
The etching composition performs multiple functions simultaneously: it etches SiGe efficiently, protects gate insulating layers through selective inhibition, prevents substrate damage, and controls etching uniformity. This multi-functional composition replaces what would traditionally require multiple separate process steps, reducing manufacturing complexity while improving reliability.
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 composition achieves high SiGe/dielectric material etch selectivity, effectively removing SiGe while minimizing the removal of adjacent dielectric materials, thus enhancing device performance and yield.
Implementation Method 1
at least one fluorine-containing acid, the at least one fluorine-containing acid containing hydrofluoric acid or hexafluorosilicic acid
Implementation Method 2
at least one oxidizing agent
Data Source
AI summary
The present disclosure is directed to etching compositions that are useful for, e.g., selectively removing silicon germanium (SiGe) from a semiconductor substrate as an intermediate step in a multistep semiconductor manufacturing process.