Anchor Structures for Uniform Wafer Planarization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in semiconductor image sensor devices is achieving uniform planarization and bonding of stacked dies to prevent structural weaknesses and device failures due to concave or convex surfaces formed during the planarization process, leading to the formation of bubbles or voids at the interface, which can cause device failure.
Innovation Solution
The introduction of anchor structures, including thin anchor layers and anchor pads on dielectric layers, which provide uniform planarization by matching the planarization selectivity of the interconnection material, promoting wafer bonding and reducing defects by ensuring coplanar surfaces and uniform pattern density across the device structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional planarization process is used on substrate surface, then planarization is achieved, but concave or convex surfaces form due to material removal rate variations, leading to bubbles or voids at bonding interface
Solution Approach 1:
An anchor layer is introduced as an intermediary between the interlayer dielectric layer and the substrate. This anchor layer acts as a mediator that receives the planarization process uniformly and transfers it to the underlying structure, preventing direct contact between the planarization tool and the interlayer dielectric material that would cause non-uniform material removal and surface deformation.
Solution Approach 2:
The bonding interface structure is segmented into multiple distinct layers: the substrate, the anchor layer, and the interlayer dielectric layer. This segmentation allows each layer to perform its specific function independently - the anchor layer handles planarization uniformly while the interlayer dielectric layer maintains its structural integrity, preventing the formation of concave or convex surfaces that would compromise bonding quality.
2Reliability
If anchor structures are introduced to improve planarization uniformity, then bonding interface quality improves, but device structure complexity increases
Solution Approach 1:
The anchor layer serves multiple functions simultaneously: it provides a uniform surface for planarization, acts as an adhesive promoter for bonding, and serves as a structural support layer. By combining these functions into a single layer, the design avoids the need for multiple separate components that would increase device complexity while still achieving improved bonding interface quality.
Data Source
AI summary
The present disclosure is directed to anchor structures and methods for forming anchor structures such that planarization and wafer bonding can be uniform. Anchor structures can include anchor layers formed on a dielectric layer surface and anchor pads formed in the anchor layer and on the dielectric layer surface. The anchor layer material can be selected such that the planarization selectivity of the anchor layer, anchor pads, and the interconnection material can be substantially the same as one another. Anchor pads can provide uniform density of structures that have the same or similar material.