Dummy Passive Element Planarization in BEOL Fabrication
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Solution Overview
Problem
Current semiconductor fabrication methods for back-end-of-line (BEOL) processes face challenges in planarizing dielectric interlevel layers due to the destructive nature of chemical-mechanical polishing (CMP), which damages passive elements and introduces defects, and require duplicate equipment setups to prevent contamination, making it costly and inefficient.
Innovation Solution
The introduction of a dummy passive element adjacent to the actual passive element aids in planarization by forming a dielectric layer that is substantially planar between them, eliminating the need for CMP through the use of interconnects that overlap the dummy passive element, thus avoiding the need for planarization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chemical-mechanical polishing (CMP) is used to planarize dielectric interlevel layers in BEOL processes, then planarity is improved, but passive elements are damaged and defects are introduced
Solution Approach 1:
The patent applies preliminary action by forming dummy passive elements adjacent to actual passive elements before depositing the dielectric layer. These dummy elements create a planarized surface through their geometric configuration, eliminating the need for subsequent CMP processing that would damage the passive elements.
Solution Approach 2:
The dummy passive elements serve as intermediaries that mediate between the need for planarity and the protection of actual passive elements. By placing dummy elements next to real passive elements, the dielectric layer can be deposited over a planarized surface without requiring CMP, thus protecting the passive elements while achieving the desired planarity.
2Reliability
If duplicate equipment is provided for BEOL and FEOL processes to prevent contamination, then contamination is prevented, but equipment cost and complexity increase
Solution Approach 1:
The patent applies universality by designing FEOL equipment that can perform both FEOL dielectric planarization and BEOL dielectric planarization functions. The same equipment suite is used for both process stages, eliminating the need for separate BEOL CMP equipment and reducing overall equipment complexity while maintaining contamination prevention through proper process sequencing.
Solution Approach 2:
The patent merges the functions of FEOL and BEOL dielectric planarization equipment into a single equipment suite. By combining these functions, the patent reduces the total number of equipment pieces required while still preventing contamination through appropriate process ordering and dummy element usage.
3Temperature
If passive elements are positioned in later BEOL layers away from first metal layer, then thermal issues are reduced, but wiring layout efficiency decreases
Solution Approach 1:
The patent uses dummy passive elements as copies of actual passive elements to achieve planarity. This copying approach allows actual passive elements to be positioned in optimal locations for thermal management and wiring layout, while the dummy copies provide the necessary geometric configuration for planarized dielectric deposition without requiring CMP.
Data Source
AI summary
Methods of fabricating a passive element and a semiconductor device including the passive element are disclosed including the use of a dummy passive element. A dummy passive element is a passive element or wire which is added to the chip layout to aid in planarization but is not used in the active circuit. One embodiment of the method includes forming the passive element and a dummy passive element adjacent to the passive element; forming a dielectric layer over the passive element and the dummy passive element, wherein the dielectric layer is substantially planar between the passive element and the dummy passive element; and forming in the dielectric layer an interconnect to the passive element through the dielectric layer and a dummy interconnect portion overlapping at least a portion of the dummy passive element. The methods eliminate the need for planarizing.