Aqueous Etch Residue Removal Composition
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Solution Overview
Problem
Current methods for removing post-etch residues from microelectronic devices, particularly those involving silicon and dielectric layers like TEOS, face challenges in achieving a high etch-residue removal rate without compromising the silicon or dielectric layers, often resulting in either over-etching or insufficient residue removal.
Innovation Solution
An aqueous composition comprising hydrogen fluoride, ammonium fluoride, a sulfoxide or sulfone solvent, and water, with optional ammonium compounds, is used to selectively remove silicon oxide residues while minimizing etching of the amorphous silicon and TEOS dielectric layers, achieving a controlled and balanced etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If compositions comprising hydrofluoric acid (HF) are used for oxide residue removal, then a good oxide residue removal rate is achieved, but the etching rate of the TEOS layer increases (selectivity for oxide residues against TEOS is rather low)
Solution Approach 1:
The patent changes the chemical parameters of the etching composition by using buffered HF (containing ammonium fluoride) instead of pure HF, and by adjusting the concentration of HF to 0.005-0.3% by weight. This parameter change reduces the aggressiveness of the etchant toward TEOS while maintaining effectiveness against oxide residues, thereby improving selectivity.
Solution Approach 2:
The patent introduces ammonium fluoride as an intermediary substance that buffers the HF solution. This intermediary moderates the etching action, reducing direct attack on TEOS layers while still enabling effective oxide residue removal. The ammonium fluoride acts as a chemical mediator that controls the reactivity of the system.
2Productivity
If higher HF concentration is used to increase oxide residue removal rate, then productivity improves, but side wall etch-residue cleaning deteriorates
Solution Approach 1:
The patent optimizes the HF concentration parameter to a specific range (0.005-0.3% by weight) that balances two competing requirements: sufficient oxide residue removal and effective side wall cleaning. This precise parameter control ensures both productivity and manufacturing precision are maintained simultaneously.
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 provides a high etch-residue removal rate with low dielectric etching rates, ensuring the integrity of both silicon and dielectric layers, thereby improving the selectivity and effectiveness of the etching process.
Implementation Method 1
an aqueous composition comprising HF, an ammonium fluoride, and a particular solvent is capable of removing post-etch residues comprising silicon oxide
Implementation Method 2
5 to 30 % by weight of an organic solvent selected from a sulfoxide and a sulfone
Data Source
AI summary
Disclosed herein is a composition for removing post-etch residues in the presence of a layer comprising silicon and a dielectric layer including a silicon oxide, the composition including:(a) 0.005 to 0.3 % by weight HF;(b) 0.01 to 1 % by weight of an ammonium fluoride of formula NRE4F, where RE is H or a C1 to C4 alkyl group;(c) 5 to 30 % by weight of an organic solvent selected from the group consisting of a sulfoxide and a sulfone;(d) 70 % by weight or more water, and(e) optionally 0.01 to 1 % by weight of an ammonium compound selected from the group consisting of ammonia and a C4 to C20 quaternized aliphatic ammonium.