Stepped Sidewall Contact Aperture for Semiconductor Alignment
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Solution Overview
Problem
Misalignment of contact vias with respect to contact regions in semiconductor structures leads to compromised performance of semiconductor devices, as existing methods fail to ensure precise alignment and optimal interconnection within dielectric layers.
Innovation Solution
The development of semiconductor structures with narrow bottomed stepped sidewall contact apertures and vias, fabricated using a method involving a passivation layer, mask layer, and reacted material layer to form coaxial stepped sidewall portions, ensuring precise alignment and improved electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional contact aperture fabrication methods are used, then the fabrication process is simple, but the alignment precision between contact vias and contact regions deteriorates
Solution Approach 1:
The contact aperture formation process is segmented into multiple etching steps with different etch masks, allowing precise control of the aperture profile. The first etch step creates an initial aperture, followed by a second etch step that refines the shape to achieve the desired narrow bottom and stepped sidewalls for improved alignment precision.
Solution Approach 2:
The invention introduces a vertical dimension to the aperture profile by creating stepped sidewalls with different slopes at different heights. This three-dimensional aperture shape provides mechanical interlocking and chemical bonding surfaces that enhance via-to-aperture alignment while maintaining fabrication control.
2Reliability
If contact vias are made with standard sidewall profile, then the fabrication is easier, but the electrical performance deteriorates due to misalignment and increased parasitic capacitance
Solution Approach 1:
The contact aperture is designed with non-uniform sidewall properties, featuring stepped profiles with different slopes at different heights. The narrower bottom portion provides precise alignment with the contact region, while the wider upper portion facilitates easier via formation and reduces parasitic capacitance, optimizing both electrical performance and manufacturability.
Solution Approach 2:
The invention changes the geometric parameters of the contact aperture by creating a profile with varying width at different heights. The narrow bottom width ensures precise alignment for optimal electrical contact, while the wider top width reduces parasitic capacitance and improves via filling, thereby enhancing overall electrical performance.
3Ease of manufacture
If contact apertures with wide opening are used, then the via formation is easier, but the alignment precision with contact region deteriorates
Solution Approach 1:
The aperture formation is divided into sequential etching steps that first create a wider opening for easy via formation, then refine the shape to achieve narrow bottom walls for precise alignment. This segmented approach allows each step to optimize for its specific function while achieving both ease of manufacture and high precision.
Data Source
AI summary
A semiconductor structure includes a semiconductor device including a contact region. The semiconductor structure also includes a passivation layer passivating the semiconductor device including the contact region. A narrow bottomed stepped sidewall contact aperture is located within the passivation layer to expose the contact region. A corresponding narrow bottomed stepped sidewall contact via is located within the narrow bottomed stepped sidewall contact aperture to contact the contact region. The narrow bottomed stepped sidewall contact aperture and contact via provide for improved contact to the contact region and reduced parasitic capacitance with respect to the semiconductor device. Methods for fabricating the narrow bottomed stepped sidewall contact aperture use a mask layer (either dimensionally diminished or dimensionally augmented) in conjunction with a two step etch method.