Semiconductor Cleaning Composition for Low-k and Cobalt Protection
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Solution Overview
Problem
Current liquid compositions fail to effectively remove dry etching residue while suppressing damage to low-dielectric-constant interlayer insulating films, cobalt or cobalt alloys, alumina, zirconia-based hard masks, and silicon nitride in semiconductor integrated circuit production, leading to deterioration of electrical characteristics.
Innovation Solution
A liquid composition comprising boric acid, hydrogen fluoride, a benzotriazole compound, and a compound with a pyrrolidone structure, specifically designed to be added to water, which effectively removes dry etching residue and minimizes damage to these materials by adjusting pH and concentration ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If oxygen plasma is used to remove dry etching residue, then the residue removal is effective, but damage to low-k film, cobalt, cobalt alloy, and etch stop layer occurs resulting in deterioration of electrical characteristics
Solution Approach 1:
The patent replaces the oxygen plasma process (physical/chemical method) with a liquid composition washing process (chemical method). The liquid composition containing boric acid, hydrogen fluoride, and benzotriazole compound removes dry etching residue through chemical dissolution without causing damage to sensitive materials like low-k film, cobalt, and etch stop layers.
Solution Approach 2:
The patent changes the processing parameters by using a specifically formulated liquid composition with controlled concentrations of boric acid (0.003-1.5% by mass), hydrogen fluoride (0.006-0.3% by mass), and benzotriazole compound (0.003-1% by mass), maintaining pH between 1-4. This parameter optimization enables effective residue removal while protecting sensitive materials from damage.
2Productivity
If fluorine-based gas is used for dry etching to form via, then etching efficiency is high, but cobalt quality changes affecting electrical properties
Solution Approach 1:
The patent introduces an etch stop layer (alumina) as an intermediary between the fluorine-based etching gas and the cobalt wiring material. This intermediary layer protects the cobalt from direct exposure to the etching gas, preventing quality degradation while allowing efficient via formation through the interlayer insulating film.
Solution Approach 2:
The patent applies preliminary protection by forming an etch stop layer on the cobalt surface before performing dry etching. This pre-established protective layer prevents harmful interactions between the fluorine-based etching gas and the cobalt material, ensuring electrical properties are maintained throughout the etching process.
3Object-affected harmful factors
If conventional liquid compositions are used for washing, then material damage is reduced, but dry etching residue cannot be removed at satisfactory level
Solution Approach 1:
The patent uses a composite liquid composition containing multiple chemical components working together: boric acid (0.003-1.5% by mass) for gentle cleaning, hydrogen fluoride (0.006-0.3% by mass) for effective residue dissolution, and benzotriazole compound (0.003-1% by mass) for corrosion inhibition. This composite formulation achieves both effective residue removal and material protection simultaneously.
Solution Approach 2:
The patent references and improves upon conventional liquid composition formulations by incorporating proven protective components (boric acid, hydrogen fluoride, benzotriazole) in optimized concentrations. This builds upon existing knowledge of material-safe cleaning agents while enhancing residue removal capability through precise formulation.
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 successfully removes dry etching residue and prevents damage to the mentioned materials, enabling the production of semiconductor elements with high precision and quality, maintaining high yield and electrical integrity.
Implementation Method 1
hydrogen fluoride (B2) in an amount of 0.006 to 0.3% by mass
Implementation Method 2
a benzotriazole compound (C) in an amount of 0.003 to 1% by mass
Data Source
Figure 1~2
AI summary
The present invention relates to: a liquid composition suitable for the washing of a semiconductor element provided with a low-dielectric-constant interlayer insulating film; and a method for washing a semiconductor element. The liquid composition according to the present invention is characterized by containing tetrafluoroboric acid (A) in an amount of 0.01 to 30% by mass, or boric acid (B1) and hydrogen fluoride (B2) at a (boric acid)/(hydrogen fluoride) ratio of (0.0001 to 5.0% by mass)/(0.005 to 5.0% by mass), and having a pH value of 0.0 to 4.0. The liquid composition according to the present invention can reduce the damage of a low-dielectric-constant interlayer insulating film, cobalt or a cobalt alloy, alumina, a zirconia-based hard mask and a silicon nitride during the process of producing a semiconductor integrated circuit, and accordingly can be used suitably for removing dry etching residues occurring on the surface of the semiconductor integrated circuit.