Multi-Damascene Cavity Formation via Single Exposure
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Solution Overview
Problem
Conventional semiconductor manufacturing methods, such as the damascene process, face challenges in reducing production complexity and costs, especially at the sub-micron level, due to the need for multiple lithography steps and etch processes, which drive up costs and complexity.
Innovation Solution
A multi-damascene structure is formed using a single exposure process with a precursor structure comprising a semiconductor substrate and multiple dielectric layers, where the layers have different removal rates and are in direct contact without an intermediate etch stop layer, allowing for the creation of cavities with varying widths and shapes using a single lithography step.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple lithography steps and etch processes are used to create multi-damascene structures, then manufacturing precision and cavity control are improved, but production complexity and costs increase
Solution Approach 1:
The patent segments the dielectric layer into multiple portions with different etch selectivities, allowing each segment to be removed at different rates during a single etch process. This enables precise control of cavity widths at different levels without requiring multiple lithography steps, thus maintaining manufacturing precision while reducing production complexity
Solution Approach 2:
The patent applies local quality by creating regions within the dielectric layer that have different local properties (etch selectivity). By modifying specific portions of the dielectric layer to have different etch resistance, the process achieves differential removal rates in different locations, enabling precise cavity formation with varying widths using a single exposure step
2Manufacturing precision
If multiple lithography exposure steps are used to pattern multiple layers, then cavity width variation and shape control are improved, but production costs increase
Solution Approach 1:
The dielectric layer is segmented into portions with different etch selectivities, enabling a single lithography exposure to define patterns that result in cavities with varying widths and shapes after differential etching. This maintains cavity shape fidelity while reducing production costs by eliminating multiple exposure steps
Solution Approach 2:
The patent changes the etch selectivity parameter of different dielectric portions, allowing them to respond differently to the same etch process. This parameter variation enables complex cavity shapes to be formed from a single lithographic pattern, maintaining shape fidelity while reducing the number of expensive lithography steps required
3Reliability
If intermediate etch stop layers are used between dielectric layers, then process control is improved, but device complexity increases
Solution Approach 1:
The patent extracts or removes the intermediate etch stop layer from the structure, relying instead on the inherent etch selectivity differences between portions of the dielectric layer. This eliminates the need for additional layers while maintaining process control through the selective etching of different dielectric regions
Solution Approach 2:
The dielectric layer portions serve their own function as selective etch stops through their intrinsic etch selectivity differences. Each portion self-regulates the etching process based on its material properties, eliminating the need for external etch stop layers and reducing structural complexity while maintaining reliable process control
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 the number of lithography exposure steps, decreases production complexity, and lowers costs by enabling the formation of multi-damascene patterns with different sized cavity structures, improving the accuracy and fidelity of semiconductor device fabrication.
Implementation Method 1
the second layer has a different removal rate than the first layer for a given material removal process. In various embodiments, the given removal process is reactive ion etching.
Data Source
AI summary
Cavities of possibly different widths can be etched in a stack of conductive layers (such as metal) using the same lithographic mask. Dielectric can be formed in the cavities. The cavities may contain voids. Other embodiments are also provided.