Hard Mask Removal Sequence for Tungsten-Safe Interconnect Trenches
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Solution Overview
Problem
The removal of hard masks in semiconductor manufacturing poses challenges due to material interactions, leading to delamination and inconsistencies, particularly when conventional methods damage underlying tungsten structures.
Innovation Solution
A method involving partial etching of the base layer dielectric material, followed by sequential removal of titanium nitride and silicon oxynitride hard masks using an organic planarization layer (OPL) protection, and reactive ion etching to complete trench formation, ensuring underlying tungsten is protected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional hard mask removal methods are used, then the hard mask can be removed, but the underlying tungsten structures are damaged and delamination occurs
Solution Approach 1:
The base layer of dielectric material is partially etched before hard mask removal to create a protective cushion that prevents etchant from reaching and damaging the tungsten structures. This preliminary action establishes a safety barrier that allows subsequent hard mask removal without harmful effects to the underlying tungsten.
Solution Approach 2:
The partially etched base layer of dielectric material serves as an intermediary protective layer between the hard mask removal process and the tungsten structures. This intermediate layer absorbs the harmful effects of the removal process while allowing the hard mask to be completely removed.
2Manufacturing precision
If the base layer of dielectric material is fully etched during trench formation, then complete trench formation is achieved, but the hard mask cannot be completely removed
Solution Approach 1:
The trench formation and hard mask removal processes are segmented into separate sequential steps. First, trenches are etched partially into the base layer to a controlled depth. Then, the hard mask is completely removed. Finally, the base layer is fully etched to complete the trenches. This segmentation allows each process to be optimized independently without compromising the other.
Solution Approach 2:
The partial etching of the base layer is performed as a preliminary action before complete hard mask removal. This creates a controlled environment where the hard mask can be completely removed without exposing the tungsten structures to damaging etchants, while still progressing toward complete trench formation.
3Reliability
If sequential hard mask removal is performed with partial base layer etching, then delamination is reduced, but the process complexity increases
Solution Approach 1:
The fabrication process is segmented into distinct sequential steps: partial base layer etching, hard mask removal, and complete trench formation. While this increases the number of steps, each step is simpler and more controlled, allowing for better process optimization and reduced defects that would otherwise require complex remediation.
Solution Approach 2:
The partially etched base layer acts as an intermediary protective layer during hard mask removal. This intermediate state protects the tungsten structures from damage while allowing complete hard mask removal, thereby reducing delamination without requiring complex protective measures or process adjustments.
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 reduces delamination and voids in copper interconnects by reducing the aspect ratio of the hard masks, improving yield and reliability by enhancing the integration of titanium nitride and silicon oxynitride hard masks, and silicon oxynitride hard masks, and silicon oxynitride hard masks, while protecting underlying tungsten structures.
Implementation Method 1
The dielectric material of the base layer is opened with a reactive ion etch after the hard mask removal of the titanium nitride hard mask
Data Source
AI summary
Methods for full hard mask removal and a semiconductor structure are presented. A semiconductor structure comprises a base layer of dielectric material; a body layer of a low-k dielectric material over the base layer; a hard mask over the body layer; and a plurality of trenches etched through the hard mask and the body layer and only partially etched into the base layer.