Dual Damascene Patterning via Segmented Mask Layers
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Solution Overview
Problem
In semiconductor fabrication, the double patterning technique (DPT) can cause deformation and damage to the first pattern in the target layer during subsequent lithography processes, leading to incomplete patterns and reduced yield in dual damascene structures.
Innovation Solution
A method is developed where a dielectric mask layer and a metal mask layer are used to form trench and via openings, with the mask layers protecting the dielectric layer from etchants and photoresist effects, ensuring precise pattern transfer and maintaining material characteristics through multiple patterning processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the double patterning technique (DPT) is used to form complex patterns, then the patterning capability is improved, but the first pattern may be deformed or damaged by subsequent lithography processes
Solution Approach 1:
The patent segments the patterning process into two distinct stages: first forming trench openings through lithography and etching, then forming via openings through a second lithography and etching process. This segmentation allows each pattern type to be formed independently with optimized process parameters, preventing the degradation that would occur if both patterns were formed simultaneously or sequentially without protection.
Solution Approach 2:
The patent performs preliminary actions by first forming the trench openings and their associated mask structures before proceeding to form the via openings. The trench structure serves as a preliminary framework that guides subsequent via formation, ensuring that the first pattern is established and protected before the second patterning process begins.
2Adaptability or versatility
If multiple patterning processes are performed sequentially, then complex patterns are formed, but the dielectric layer may absorb etchants and lose material characteristics
Solution Approach 1:
The patent introduces mask layers as intermediary structures between the lithography/etching processes and the dielectric layer. These mask layers absorb the etchants and protect the dielectric layer from direct exposure to harmful chemicals, preventing material degradation while still allowing the pattern transfer to occur through the mask structures.
Solution Approach 2:
The patent applies beforehand cushioning by forming protective mask layers over the dielectric layer before performing the etching processes. These mask layers serve as a protective barrier that cushions the dielectric layer against the harmful effects of etchants, ensuring material characteristics are maintained throughout the multiple patterning processes.
3Ease of manufacture
If the first pattern is directly exposed to cleaning solutions and etchants in subsequent processes, then the patterning process is simplified, but the pattern correctness is reduced and yield decreases
Solution Approach 1:
The patent employs composite material structures consisting of multiple layers including the dielectric layer, mask layers, and conductive material layers. These composite structures provide both the pattern definition functionality and the protective functionality needed to maintain pattern correctness throughout the manufacturing process, while still allowing for relatively straightforward fabrication.
Data Source
AI summary
A method for fabricating a dual damascene structure includes the following steps. At first, a dielectric layer, a dielectric mask layer and a metal mask layer are sequentially formed on a substrate. A plurality of trench openings is formed in the metal mask layer, and a part of the metal mask layer is exposed in the bottom of each of the trench openings. Subsequently, a plurality of via openings are formed in the dielectric mask layer, and a part of the dielectric mask layer is exposed in a bottom of each of the via openings. Furthermore, the trench openings and the via openings are transferred to the dielectric layer to form a plurality of dual damascene openings.