Grounded Shielding Layer for FEOL and BEOL Process Protection
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Solution Overview
Problem
The miniaturization of CMOS-MEMS devices leads to increased susceptibility of FEOL and BEOL elements to process damage, resulting in low yield during fabrication due to electromigration and other damage mechanisms.
Innovation Solution
A conductive shielding layer is formed over the FEOL and BEOL elements and electrically connected to a ground contact, ensuring that accumulated charges are dissipated, thereby protecting the elements from damage during subsequent processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If device size decreases to advance technology, then integration density improves, but FEOL and BEOL elements become more susceptible to process damage and electromigration
Solution Approach 1:
A conductive shielding layer is introduced as an intermediary element between the FEOL/BEOL elements and the harmful charged particles generated during MEMS fabrication processes. This shielding layer intercepts and conducts away charged particles that would otherwise accumulate and cause electromigration damage to the sensitive FEOL and BEOL elements, thereby protecting them while allowing continued device miniaturization.
2Productivity
If continuous fabrication processes are used to increase productivity, then manufacturing efficiency improves, but charge accumulation and electromigration damage increase
Solution Approach 1:
The conductive shielding layer provides continuous protection throughout the entire fabrication process by maintaining a permanent conductive path to ground. This allows uninterrupted fabrication operations without periodic interruptions for charge dissipation, enabling continuous processing while preventing charge accumulation that would lead to electromigration damage.
3Reliability
If protective measures are added to prevent electromigration damage, then element reliability improves, but device complexity increases
Solution Approach 1:
The conductive shielding layer serves multiple functions simultaneously: it acts as an electromagnetic shield protecting FEOL and BEOL elements, provides a ground reference plane, facilitates heat dissipation, and serves as part of the interconnect structure. This multi-functionality reduces the need for separate protective structures, thereby limiting the increase in overall device complexity while achieving comprehensive protection.
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 implementation of a conductive shielding layer effectively reduces the risk of electromigration damage and other process-related damages to FEOL and BEOL elements, enhancing the yield and reliability of CMOS-MEMS device fabrication.
Implementation Method 1
the conductive shielding layer is grounded to the substrate through the interconnection structure... ensuring charges are conducted to the substrate
Data Source
AI summary
A method includes forming a front-end-of-the-line (FEOL) element over a substrate; forming a back-end-of-the-line (BEOL) element over the FEOL element; forming an interconnection structure over the substrate; forming a conductive shielding layer electrically connected to the interconnection structure and vertically overlapping the FEOL element and the BEOL element, wherein the conductive shielding layer is grounded to the substrate through the interconnection structure; and forming a dielectric layer covering the conductive shielding layer.