High-Aspect-Ratio Metal Lines With Dielectric Support
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Solution Overview
Problem
The challenge in semiconductor manufacturing is the collapse or deformation of high aspect ratio features during the formation of metal lines, leading to poor insulation and reduced reliability of semiconductor components due to voids in insulating layers and potential short circuits.
Innovation Solution
A method involving two photolithography stages and chemical-mechanical polishing to form first and second metal lines within a dielectric layer, providing mechanical support to high aspect ratio metal lines and preventing collapse or deformation, while ensuring reliable insulation between semiconductor components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography resolution is increased to reduce line width and line space, then metal line dimensions are reduced, but photoresist thickness must be reduced which limits IC integration increase
Solution Approach 1:
The patent divides the single photolithography process into two sequential photolithography stages. The first stage forms a preliminary pattern with sufficient photoresist thickness, and the second stage refines the pattern to achieve the final narrow line width and line space. This segmentation allows each stage to use optimized photoresist thickness, avoiding the limitation of reducing photoresist thickness while maintaining manufacturing precision.
2Manufacturing precision
If hard mask is used to form metal lines, then gap aspect ratio increases, but voids are easily formed in insulating layer during deposition
Solution Approach 1:
The patent performs preliminary actions by forming a preliminary pattern first, then using it as a basis for the second photolithography process. This preliminary structure provides mechanical support that prevents collapse during subsequent processing, and the two-stage approach allows for better control of gap dimensions, reducing the aspect ratio and preventing void formation in the insulating layer.
3Reliability
If second interlayer insulating layer is deposited after metal line formation, then insulation is provided, but voids occur in the second interlayer insulating layer
Solution Approach 1:
By segmenting the metal line formation into two photolithography stages, the patent creates a more gradual and controlled structure. The preliminary pattern formed in the first stage provides a foundation that, when combined with the second stage pattern, results in metal lines with better dimensional control. This reduces the gap aspect ratio, allowing the second interlayer insulating layer to be deposited without forming voids, thus maintaining both insulation reliability and layer integrity.
4Length of moving object
If high aspect ratio trenches are formed, then deep metal line trenches are created, but collapse or deformation of semiconductor structures occurs
Solution Approach 1:
The patent segments the trench formation process into two stages corresponding to the two photolithography processes. The first stage creates a preliminary pattern with shallower trenches, and the second stage completes the deep trench formation. This segmentation allows the structure to be built progressively with better mechanical support at each stage, preventing collapse or deformation that would occur if the full depth trench were formed in a single step.
Solution Approach 2:
The preliminary pattern formed in the first photolithography stage serves as a structural foundation before the second stage deepens the trenches. This preliminary action provides mechanical support that prevents collapse during the formation of high aspect ratio trenches, enabling deep metal line trenches to be created while maintaining structure stability.
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 significantly reduces or eliminates the collapse of high aspect ratio metal lines, enhancing the reliability of semiconductor structures and increasing yield by maintaining insulation integrity between components.
Implementation Method 1
forming a first hard mask pattern over the dielectric layer to define a dense pattern in the dielectric layer covering the pattern-dense area and a loose pattern in the dielectric layer covering the pattern-loose area
Implementation Method 2
performing chemical-mechanical polishing (CMP) to remove the first metal over the dielectric layer
Data Source
AI summary
The present disclosure provides to a method for preparing metal lines with a high aspect ratio comprising two photolithography stages. According to the design of the method of the present disclosure, first metal lines with high aspect ratio are formed in a dielectric layer, which provides a mechanical support to the first metal lines, thereby preventing the first metal lines from collapsing or deforming. Because of a significant reduction or elimination of collapse or deformation phenomenon in the semiconductor structure, a problem associated with short circuits due to direct contact between the semiconductor components can be mitigated, and reliability of the semiconductor structures can be enhanced. As a result, a yield of the semiconductor structure is increased.