Two-Step Plasma Etch for Hard Mask Removal
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Solution Overview
Problem
In semiconductor manufacturing, sub-lithographic techniques introduce processing complexity and reduce device yield due to incomplete removal of film layers, particularly the overlying hard mask layer, which interferes with pattern transfer to the underlying organic layer.
Innovation Solution
A two-step plasma etch process is used to remove the overlying organic layer remnants and the hard mask layer, employing specific gas mixtures and power settings to ensure complete removal and minimize surface damage, allowing for precise pattern transfer in microelectronic substrate processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If sub-lithographic techniques are used for patterning, then smaller device features can be manufactured, but processing complexity increases and device yield decreases due to incomplete removal of film layers
Solution Approach 1:
The patent segments the hard mask removal process into two distinct plasma etch steps: a first selective etch step that removes organic layer remnants while preserving the hard mask layer, and a second etch step that removes the hard mask layer. This segmentation resolves the technical contradiction by breaking down the complex multi-layer removal problem into manageable sequential steps, thereby reducing processing complexity while maintaining the ability to manufacture smaller device features using sub-lithographic techniques
2Length of moving object
If sub-lithographic techniques are used for patterning, then smaller device features can be manufactured, but device yield decreases due to incomplete removal of film layers
Solution Approach 1:
The patent applies preliminary action by performing the first selective etch step before the second etch step. The first step preliminarily removes organic layer remnants that would otherwise interfere with complete hard mask layer removal in subsequent steps. This preliminary action ensures complete film layer removal and improves device yield while maintaining the capability to manufacture smaller device features through sub-lithographic patterning techniques
3Ease of manufacture
If a single plasma etch step is used to remove the hard mask layer, then the process is simpler, but incomplete removal occurs due to interference from organic layer remnants
Solution Approach 1:
The patent segments the etch process into two specialized steps: a first selective etch step using a plasma chemistry that selectively removes organic layer remnants while preserving the hard mask layer, followed by a second etch step that removes the hard mask layer. This segmentation resolves the contradiction by ensuring complete removal of both organic and inorganic layers with high pattern transfer accuracy, while keeping each individual step relatively simple and specialized in its function
4Productivity
If the overlying hard mask layer is not completely removed, then fewer processing steps are needed, but pattern transfer to the underlying organic layer is interfered with
Solution Approach 1:
The patent implements preliminary action through the first selective etch step that removes organic layer remnants before the hard mask layer removal. This preliminary action prevents interference with subsequent pattern transfer operations, ensuring high manufacturing precision. The two-step process maintains productivity by efficiently removing both layers in sequence without requiring additional corrective steps
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 two-step plasma etch process effectively removes residual organic layer remnants and hard mask layers, improving pattern transfer accuracy and reducing processing complexity, thereby enhancing device yield and manufacturing efficiency in sub-lithographic patterning.
Implementation Method 1
a two-step plasma etch process
Implementation Method 2
gas mixture comprising a chlorine-containing gas and a carbon-containing gas
Data Source
AI summary
The disclosure relates to methods for a multi-step plasma process to remove metal hard mask layer from an underlying hard mask layer that may be used to implement a sub-lithographic integration scheme. The sub-lithographic integration scheme may include iteratively patterning several features into the metal hard mask layer that may be transferred to the hard mask layer. However, the iterative process may leave remnants of previous films on top of the metal hard mask that may act as mini-masks that may interfere with the pattern transfer to the hard mask layer. One approach to remove the mini-masks may be to use a two-step plasma process that removes the mini-mask using a first gas mixture ratio of a carbon-containing gas and a chlorine-containing gas. The remaining metal hard mask layer may be removed using a second gas mixture ratio of the carbon-containing gas and the chlorine-containing gas.