Wafer Level Package S-Shaped Contact for Adhesion
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Solution Overview
Problem
Conventional CMOS image sensor wafer level packages face issues with weak spots and low reliability due to small contact areas between T-shaped connections and contact pads, leading to poor conductivity and adhesion.
Innovation Solution
The introduction of contact area ladder structures and an S-shaped connection formed by a conductive layer contacting exposed vertical and horizontal portions of contact pads, increasing the contact area and enhancing conductivity and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a T-shaped connection is used between the substrate bonding contact and die bonding contacts, then the chip scale package can be assembled, but the contact area is too small causing weak spots and low reliability
Solution Approach 1:
The contact area structure is transformed from a simple T-shaped planar connection to a multi-dimensional ladder structure that extends vertically and horizontally. The conductive layer is deposited to form multiple tiers (first, second, third conductive portions) that create additional contact surfaces, effectively increasing the contact area from a single plane to a three-dimensional structure with enhanced surface area for bonding.
Solution Approach 2:
The contact area is divided into multiple segmented conductive portions (first, second, third conductive portions) arranged in a ladder configuration. Each segment provides additional bonding surface and creates multiple parallel conduction paths, distributing the electrical and mechanical stress across several discrete contact regions rather than relying on a single large contact area.
2Device complexity
If the contact area between T-shaped connection and contact pads is small, then the structure remains simple, but conductivity and adhesion are poor
Solution Approach 1:
The connection structure evolves from a simple two-dimensional T-shape to a multi-dimensional ladder structure by adding vertical layers (first, second, third conductive portions at different heights). This dimensional expansion increases conductivity and adhesion without requiring a proportionally large increase in planar footprint, maintaining relative structural compactness while enhancing performance.
Solution Approach 2:
The contact area structure combines multiple materials including the conductive layer (metal), inter-layered dielectric layers (insulating material), and underlying contact pads. This composite construction provides both electrical conductivity through the metal portions and mechanical adhesion through the layered structure, achieving superior conductivity and adhesion properties compared to single-material designs.
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
This solution improves the reliability and conductivity between the T-shaped connection and contact pads, addressing the weak spots and low reliability issues in conventional designs, resulting in a more robust chip scale package.
Implementation Method 1
conformably depositing a conductive layer on the back of the semiconductor wafer
Data Source
AI summary
Electronic device wafer level scale packages and fabrication methods thereof. A semiconductor wafer with a plurality of electronic devices formed thereon is provided. The semiconductor wafer is bonded with a supporting substrate. The back of the semiconductor substrate is thinned. A first trench is formed by etching the semiconductor exposing an inter-layered dielectric layer. An insulating layer is conformably deposited on the back of the semiconductor substrate. The insulating layer on the bottom of the first trench is removed to create a second trench. The insulating layer and the ILD layer are sequentially removed exposing part of a pair of contact pads. A conductive layer is conformably formed on the back of the semiconductor. After the conductive layer is patterned, the conductive layer and the contact pads construct an S-shaped connection. Next, an exterior connection and terminal contact pads are subsequently formed.