Semiconductor Interconnect Structure With Hard Mask Alignment Control
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Solution Overview
Problem
As semiconductor industry advances, the increased density and reduced dimensions of integrated circuits lead to increased capacitive coupling between conductive features, resulting in higher power consumption and longer RC time constants, posing challenges in device performance and efficiency.
Innovation Solution
The implementation of a hard mask layer formed by materials different from the conductive feature and glue layer, which provides selective etch selectivity to protect the conductive feature during the formation of openings and prevents damage, allowing for precise alignment and minimizing misalignment issues such as edge placement errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the distance between conductive features is reduced to increase density, then the element density increases, but the capacitive coupling between conductive features increases
Solution Approach 1:
A hard mask layer is introduced as an intermediary between the conductive features and the etching process. This layer provides selective etch selectivity that protects the conductive features during opening formation, enabling precise alignment and reduced spacing between features while maintaining protection against damage. The hard mask layer acts as a mediator that allows closer feature placement without increasing harmful capacitive coupling effects.
Solution Approach 2:
The patent changes the material parameter of the mask layer to have different etch selectivity characteristics. By using a hard mask layer with specific etch selectivity properties that differ from both the conductive feature material and the glue layer, the process enables precise control over feature spacing and alignment, allowing reduced distance between features while protecting against damage during fabrication.
2Quantity of substance
If the distance between conductive features is reduced to increase density, then the element density increases, but the RC time constant increases
Solution Approach 1:
The hard mask layer serves as a protective intermediary that enables reduced spacing between conductive features through precise alignment control. By protecting the conductive features during etching and enabling more accurate feature placement, the layer allows for reduced inter-feature distance that directly reduces the RC time constant while maintaining high element density.
3Reliability
If a hard mask layer with different material is used to protect conductive features, then the protection against damage and alignment precision improve, but the device complexity increases
Solution Approach 1:
The hard mask layer performs multiple functions simultaneously: it protects the conductive features from damage during etching, provides selective etch selectivity for precise alignment, and serves as a structural layer in the interconnect formation process. By consolidating these multiple functions into a single layer with appropriate material properties, the patent reduces overall process complexity compared to using separate protection and alignment layers.
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 effectively reduces capacitive coupling and protects the conductive features during the interconnect structure formation, enhancing device performance by minimizing power consumption and RC time constants while maintaining precise alignment and preventing damage.
Implementation Method 1
The hard mask layer and the conductive layer are formed by different materials and have different selectivity to the etchants used to remove the portions of the conductive layer
Data Source
AI summary
An interconnect structure includes a dielectric layer, a first conductive feature, a hard mask layer, a conductive layer, and a capping layer. The first conductive feature is disposed in the dielectric layer. The hard mask layer is disposed on the first conductive feature. The conductive layer includes a first portion and a second portion, the first portion of the conductive layer is disposed over at least a first portion of the hard mask layer, and the second portion of the conductive layer is disposed over the dielectric layer. The hard mask layer and the conductive layer are formed by different materials. The capping layer is disposed on the dielectric layer and the conductive layer.