Nitrogen-Free ARC Layer Cap for Sputter Etch Defect Reduction
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Solution Overview
Problem
The patterning of dielectric materials in semiconductor devices using anti-reflective coating (ARC) layers faces challenges such as resist poisoning and increased defect rates due to nitrogen contamination, especially at shorter exposure wavelengths, which affects the precision and yield of the lithography process.
Innovation Solution
Incorporating a substantially nitrogen-free cap layer and an intermediate adhesion layer with high adhesion properties within the ARC stack to reduce flaking during sputter etch processes, allowing for efficient patterning and reduced defect rates by providing an internal source of adhesion material that compensates for materials with reduced adhesion characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If nitrogen-enriched silicon dioxide is used as ARC material to adjust optical characteristics, then the optical performance is improved, but the flaking tendency during sputter etch increases
Solution Approach 1:
The ARC layer is segmented into multiple sub-layers with different nitrogen concentrations. The lower portion contains higher nitrogen content for optimal optical performance, while the upper portion has reduced nitrogen content to minimize flaking during sputter etch. This segmentation allows each layer to fulfill its specific function without compromising the other.
Solution Approach 2:
Different regions of the ARC layer are assigned different material compositions tailored to their specific functional requirements. The lower ARC layer near the resist interface has optimized nitrogen content for anti-reflective properties, while the upper ARC layer has modified composition to reduce adhesion to chamber walls and prevent flaking. This local quality variation resolves the contradiction between optical performance and reliability.
2Manufacturing precision
If shorter exposure wavelength is used to reduce feature size, then the resolution is improved, but the resist poisoning effect increases
Solution Approach 1:
The nitrogen concentration parameter in the ARC layer is changed as a function of depth from the resist interface. By reducing nitrogen content in the upper ARC layer, the harmful interaction with resist at shorter wavelengths is minimized, thereby reducing resist poisoning while maintaining the benefits of short-wavelength lithography for high-resolution patterning.
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
This approach maintains the optical and etch performance of the ARC layer while significantly reducing the defect rate during sputter etch processes, enhancing process throughput and yield by ensuring a stable adhesion material release, thus improving the overall production efficiency.
Implementation Method 1
During the manufacturing process for forming respective wiring layers of semiconductor devices, frequently respective dielectric materials may have to be patterned to receive appropriate openings
Implementation Method 2
The adhesion layer has a higher adhesion on a surface when sputtered off during a sputter cleaning process compared to other materials contained in the anti-reflective layer stack
Data Source
AI summary
By incorporating a material exhibiting a high adhesion on chamber walls of a process chamber during sputter etching, the defect rate in a patterning sequence on the basis of an ARC layer may be significantly reduced, since the adhesion material may be reliably exposed during a sputter preclean process. The corresponding adhesion layer may be positioned within the ARC layer stack so as to be reliably consumed, at least partially, while nevertheless providing the required optical characteristics. Hence, a low defect rate in combination with a high process efficiency may be achieved.