Semiconductor Mask Patterning With Merged Spacers Against Sub-Trenches
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Solution Overview
Problem
The existing semiconductor manufacturing processes, particularly those using self-alignment double patterning (SADP), often result in sub-trench formation and damage or disconnection of patterned mask layers due to differential etching rates, leading to reduced yield and reliability of semiconductor devices.
Innovation Solution
A semiconductor structure and manufacturing method involving a trunk and branch portion design, where the handle portion has a greater line width than the two-pronged portion, and a spacer structure with merged and non-merged spacers, allowing the patterned mask layer to cover and expose specific spacer portions to prevent sub-trench formation during etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the patterned photoresist layer is used as a mask to define the rail pattern and array pattern, then the pattern definition is achieved, but the patterned mask layer is damaged or broken due to sub-trench formation from differential etching rates
Solution Approach 1:
The patent introduces a mandrel structure as an intermediary element between the photoresist mask and the underlying layers. The mandrel serves as a sacrificial support that prevents sub-trench formation during etching, thereby protecting the patterned mask layer from damage while maintaining pattern definition accuracy.
Solution Approach 2:
The patent applies beforehand cushioning by designing the mandrel structure to extend beyond the patterned mask layer boundaries, providing protective support in advance before the etching process occurs. This pre-positioned cushioning prevents the mask layer from being damaged during subsequent etching operations.
2Adaptability or versatility
If the patterned mask layer and patterned photoresist layer are used together as masks, then both rail pattern and array pattern can be defined, but the structure becomes complex and prone to disconnection
Solution Approach 1:
The patent merges the mandrel structure with the patterned mask layer to form an integrated composite mask structure. This merging allows both the rail pattern and array pattern to be defined using a unified mask system, reducing structural complexity while maintaining versatility.
Solution Approach 2:
The mandrel structure serves multiple functions: it acts as a support structure during etching, defines pattern boundaries, and provides mechanical reinforcement to prevent disconnection. This multi-functionality reduces the need for separate protective structures, simplifying the overall mask system.
3Productivity
If the etching process is performed with the patterned photoresist layer covering the patterned mask layer, then the rail pattern is etched, but the array pattern mask layer is damaged due to faster etching rate at the boundary
Solution Approach 1:
The mandrel structure acts as an intermediary protective barrier at the boundary between rail and array patterns. It absorbs the differential etching stress and prevents the formation of sub-trenches that would compromise mask layer dimensional accuracy, while allowing the etching process to proceed efficiently.
Solution Approach 2:
The mandrel structure is formed in advance before the etching process, pre-positioning protective support at critical boundaries. This preliminary action ensures that when etching occurs, the mask layer is already protected from differential etching rates, maintaining dimensional accuracy throughout the high-efficiency etching process.
Data Source
AI summary
A method manufacturing of a semiconductor structure including following steps is provided. A material layer is provided. A first mask layer is formed on the material layer. Core patterns are formed on the first mask layer. A spacer material layer is conformally formed on the core patterns. An etch-back process is performed on the spacer material layer. A portion of the spacer material layer located on two ends of the core pattern is removed, then spacer structures are formed. Each spacer structure includes a merged spacer and a non-merged spacer. The core patterns are removed. The first patterned mask layer is formed to cover a portion of the merged spacer and expose another portion of the merged spacer and the non-merged spacer. The first patterned mask layer and the spacer structure are used as a mask, and the first mask layer is patterned into a second patterned mask layer.