Silicon Etching Composition for High Si/Dielectric Selectivity
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Solution Overview
Problem
The semiconductor industry faces challenges in selectively etching silicon in the presence of other materials like metal conductors, gate materials, and low-k dielectric layers, which is crucial for advanced integrated circuit production due to shrinking feature sizes and increasing density of electronic components.
Innovation Solution
The development of etching compositions comprising quaternary ammonium hydroxide, specific amines, organophosphorus compounds, and organic solvents, which are designed to selectively remove silicon while minimizing the removal of other materials, such as silicon oxide and silicon nitride, by controlling the pH and solvent composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching compositions are used to remove silicon, then silicon removal is achieved, but other materials such as metal conductors, gate materials, and low-k dielectric layers are also removed or damaged
Solution Approach 1:
The patent applies parameter changes by carefully controlling the pH of the etching composition within a specific range (pH 10-14) and selecting specific quaternary ammonium hydroxide compounds. These parameter adjustments enable the etching solution to selectively attack silicon while being substantially non-reactive toward other materials such as copper, tungsten, titanium nitride, silicon oxide, and low-k dielectric layers, thereby achieving high selectivity without damaging other components.
Solution Approach 2:
The patent employs composite etching compositions that combine quaternary ammonium hydroxides with specific additives and co-etchants. This composite formulation creates a synergistic effect where the base quaternary ammonium hydroxide provides selective silicon etching capability, while additional components enhance the selectivity and control the etching rate, ensuring that silicon is removed while other materials remain intact.
2Productivity
If feature sizes are decreased to increase device density, then device capacity increases, but etching selectivity becomes more difficult to maintain
Solution Approach 1:
The patent maintains etching selectivity at smaller feature sizes by optimizing the pH parameter within a narrow range (pH 10-14) and selecting specific quaternary ammonium hydroxide compounds with appropriate molecular weights and structures. These parameter controls ensure that even as feature dimensions shrink, the etching process remains selective to silicon without affecting adjacent materials, thereby enabling continued scaling for higher device density.
3Reliability
If high selectivity etching is achieved through composition optimization, then device yield improves, but composition complexity increases
Solution Approach 1:
The patent achieves high device yield through selectivity by optimizing key parameters such as pH (maintained at 10-14) and the concentration of quaternary ammonium hydroxide (1-10% by weight). By focusing control on these critical parameters rather than using complex multi-component formulations, the patent achieves high selectivity and device yield while keeping the composition relatively simple and manageable in terms of preparation and process control.
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 compositions achieve high selectivity and efficiency in removing silicon relative to dielectric materials, ensuring high device yield and performance by maintaining a high Si/dielectric material removal rate selectivity, thereby addressing the challenges of miniaturization in semiconductor manufacturing.
Implementation Method 1
etching compositions that can selectively etch silicon in the presence of other exposed or underlying materials
Implementation Method 2
compositions and processes for selectively etching Si (e.g., polysilicon) relative to hard mask layers, gate materials
Implementation Method 3
at least one organic solvent selected from water soluble alcohols, water soluble ketones, water soluble esters, and water soluble ethers; and water
Data Source
AI summary
The present disclosure is directed to etching compositions that are useful for, e.g., selectively removing silicon from a semiconductor substrate as an intermediate step in a multistep semiconductor manufacturing process.