Semiconductor Interconnect Structure With Hard Mask and Air Gaps
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Solution Overview
Problem
As semiconductor technology advances, the increased density and reduced spacing between conductive features lead to higher capacitive coupling, increased 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 features, which provides selective etch resistance during via formation, protecting the conductive features from damage and misalignment, and the use of air gaps to reduce capacitive coupling.
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 adjacent conductive features. This layer provides selective etch resistance that protects the conductive features during via formation processes, preventing damage and misalignment while allowing the conductive features to be positioned closer together, thereby increasing density without proportionally increasing capacitive coupling damage
Solution Approach 2:
The hard mask layer is formed on the conductive features before the via formation process begins. This preliminary protective action ensures that the conductive features are shielded from etch damage and misalignment issues that would otherwise occur during subsequent processing steps, enabling closer spacing
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 closer spacing of conductive features while controlling the via formation process to minimize damage. This allows the conductive features to be positioned closer together (reducing RC time constant) without suffering from etch damage that would increase resistance
3Quantity of substance
If the distance between conductive features is reduced to increase density, then the element density increases, but the power consumption increases
Solution Approach 1:
The hard mask layer protects conductive features from etch damage during via formation, preventing increases in resistive-capacitive time constants that would lead to higher power consumption. This enables closer spacing of conductive features without the penalty of increased power loss
4Manufacturing precision
If a hard mask layer is formed to protect conductive features, then the manufacturing precision improves, but the device complexity increases
Solution Approach 1:
The hard mask layer performs multiple functions: it provides selective etch resistance to protect conductive features, serves as a protective barrier during via formation, and enables precise via alignment. By consolidating these multiple protective and precision functions into a single layer, the complexity increase is minimized while achieving superior manufacturing precision
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 minimizes damage to conductive features during processing, maintains structural integrity, and reduces capacitive coupling, thereby improving device performance and efficiency.
Implementation Method 1
The implementation of a hard mask layer formed by materials different from the conductive features, which provides selective etch resistance during via formation, protecting the conductive features from damage and misalignment
Implementation Method 2
the use of air gaps to reduce capacitive coupling
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.