Capacitor Element Flatness on Protruding Wiring
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Solution Overview
Problem
The reliability of capacitor elements in semiconductor devices is reduced due to protrusions such as hillocks on the upper surface of wiring, which can lead to leakage and poor film formation, despite existing technologies like JP 11-87650 A and JP 2007-49089 A, which are ineffective in addressing local steps and protrusions effectively.
Innovation Solution
A semiconductor device structure is developed with a first wiring layer, a second insulating film, and a third insulating film, where the capacitor element is formed on the third insulating film, ensuring its flatness and preventing the capacitor from being affected by protrusions on the wiring, with the third insulating film's thickness set equal to or less than the second insulating film's thickness to avoid excessive thickness and facilitate plug formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the capacitor element is formed directly over the wiring with protrusions, then the manufacturing process is simplified, but the reliability of the capacitor element is reduced due to leakage and poor film formation
Solution Approach 1:
A planarization insulating film is introduced as an intermediary layer between the wiring layer with protrusions and the capacitor element. This mediator absorbs the surface unevenness caused by protrusions while providing a flat upper surface for reliable capacitor film formation, thus preventing leakage without significantly complicating the manufacturing process
Solution Approach 2:
The planarization insulating film is formed in advance before the capacitor element is fabricated. This preliminary action pre-compensates for the protrusion-induced unevenness, ensuring that subsequent capacitor films can be formed uniformly without being affected by the underlying wiring surface irregularities
2Reliability
If a thick insulating film is used to cover protrusions, then the capacitor element is protected from protrusion effects, but the total film thickness becomes excessive and plug formation becomes difficult
Solution Approach 1:
The planarization insulating film provides localized protection only where protrusions exist, rather than requiring a uniformly thick insulating layer across the entire structure. This allows the film thickness to be optimized locally - thick enough to cover protrusions and provide a flat surface, but not excessively thick to complicate plug formation in areas where protrusions are absent
Data Source
AI summary
A semiconductor device includes a first wiring layer which is provided above a semiconductor substrate and includes a first insulating film and a wiring buried in the first insulating film, a second insulating film provided above the first wiring layer, a third insulating film provided on the second insulating film, and a capacitor element provided on the third insulating film. The wiring includes an upper surface having a protruding portion. The capacitor element includes a lower electrode provided on the third insulating film, a capacitor insulating film provided on the lower electrode, and an upper electrode provided on the capacitor insulating film.