Self-Aligned Interconnect Structure for Overlay Shift Spacing
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Solution Overview
Problem
The semiconductor industry faces challenges in achieving low resistance structures and improved thermal performance due to reduced spacing between conductive structures caused by overlay alignment shift defects, leading to issues like short circuits and breakdown voltage degradation.
Innovation Solution
The implementation of inverted trapezoidal trenches in metal lines, combined with a conformal dielectric layer and self-aligned vias, enhances spacing and alignment precision, reducing the risk of misalignment and improving electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If photolithography and etching processes are used to form dual damascene openings, then conductive structures can be formed to interconnect semiconductor structures, but overlay alignment shift defects cause reduced spacing between conductive structures leading to short circuits and breakdown voltage degradation
Solution Approach 1:
The patent applies preliminary action by forming a mandrel structure before the actual conductive structure formation. The mandrel is deposited and patterned first, then used as a template to define the precise location and shape of subsequent dielectric recesses and conductive structures. This preliminary mandrel formation establishes the geometric framework that ensures proper spacing and alignment, preventing overlay shift defects from compromising the final structure integrity.
Solution Approach 2:
The mandrel structure serves as an intermediary element between the photolithography patterning process and the final conductive structure formation. It mediates the transfer of the desired pattern geometry through the dielectric layer, ensuring that the conductive structures are formed with precise spacing and alignment. The mandrel acts as a temporary template that guides the formation of dielectric recesses and subsequent conductive material deposition, thereby preventing short circuits and breakdown voltage issues.
2Productivity
If minimum feature size is reduced to increase integration density, then more components can be integrated into a given area, but spacing between conductive structures decreases causing alignment sensitivity and electrical failures
Solution Approach 1:
The mandrel structure is formed in advance with the precise dimensions and pattern geometry required for the final high-density interconnect structure. By establishing this preliminary template, the patent enables the formation of closely-spaced conductive structures with controlled dimensions, achieving high integration density while maintaining manufacturing precision. The mandrel's pre-defined geometry ensures that even at reduced feature sizes, the spacing between conductive structures remains sufficient to prevent alignment-related failures.
3Ease of manufacture
If conventional planar metal lines are used, then fabrication is simpler, but spacing control between adjacent conductive structures is insufficient leading to short circuits
Solution Approach 1:
The patent replaces conventional planar metal lines with inverted trapezoidal trenches that feature curved sidewalls. This geometric modification improves spacing control between adjacent conductive structures by creating a self-aligning profile during the etching and deposition processes. The curved sidewalls of the inverted trapezoidal shape provide better mechanical interlocking and electrical isolation, preventing short circuits while maintaining fabrication feasibility through standard semiconductor processing techniques.
Solution Approach 2:
The inverted trapezoidal trench geometry introduces asymmetry in the vertical profile of conductive structures, with wider openings at the top and narrower bases. This asymmetric shape improves spacing control by providing better lateral separation between adjacent structures while allowing for effective bottom coverage by conductive materials. The asymmetric profile enhances reliability by preventing bridging and short circuits, while still being compatible with conventional fabrication processes.
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
The solution effectively increases spacing between conductive structures, mitigating short circuits and breakdown voltage issues, thereby enhancing the reliability and performance of semiconductor devices.
Implementation Method 1
photolithography involves depositing a photoresist material and then irradiating (exposing) and developing in accordance with a specified pattern to remove a portion of the photoresist material
Implementation Method 2
an electroplating process may be applied to the dual damascene opening. As a result, the dual damascene opening is filled with a conductive material
Data Source
AI summary
An apparatus comprises a first metal feature in a first dielectric layer over a substrate, wherein a sidewall portion of the first dielectric layer is over a top surface of the first metal feature, a second dielectric layer over the first dielectric layer and a second metal feature extending through the second dielectric layer, wherein a bottom of a first portion of the second metal feature is in contact with the top surface of the first metal feature and a bottom of a second portion of the second metal feature is in contact with the sidewall portion of the first dielectric layer.