Post Passivation Interconnect Inductor with Dummy Pad Shielding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for creating spiral-shaped inductors in semiconductor devices result in limited performance, particularly due to the complexity of ultra-thick metal processes and constraints on achieving high quality factors.
Innovation Solution
The design incorporates a post passivation interconnect (PPI) layer and an under bump metallization (UBM) layer with a dual-passivation structure, including polymeric material layers and dummy pads to enhance shielding from electromagnetic interference and improve the quality factor, allowing for the formation of inductors with high quality factors and efficient electromagnetic interference shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional spiral-shaped inductor fabrication methods are used, then inductors can be created on the substrate surface, but the quality factor is limited and performance is constrained
Solution Approach 1:
The patent transitions from planar spiral inductors to three-dimensional vertical inductors by utilizing the thickness dimension of the substrate. The inductor coils are formed as vertical structures extending through the substrate thickness, enabling higher inductance values and quality factors without increasing planar footprint or fabrication complexity
Solution Approach 2:
The invention changes the geometric parameters of the inductor from two-dimensional spiral patterns to three-dimensional vertical coils. By adjusting the number of turns, coil diameter, and vertical positioning within the substrate, the patent achieves high quality factors while maintaining compatibility with standard semiconductor fabrication processes
2Reliability
If ultra-thick metal process is used to fabricate inductors, then inductor structures can be formed, but the process is complex and requires large chip area
Solution Approach 1:
The patent divides the inductor structure into multiple segments: vertical coils formed in the substrate, through-substrate vias for electrical connection, and separate contact pads. This segmentation allows each component to be formed using standard fabrication techniques while achieving high-performance three-dimensional inductor structures without requiring complex ultra-thick metal processes
Solution Approach 2:
The vertical coil structures serve multiple functions: they provide the inductive element, act as current pathways, and utilize the substrate thickness dimension for electromagnetic field confinement. This multi-functionality eliminates the need for separate ultra-thick metal layers while achieving high inductance and quality factor
3Object-affected harmful factors
If conventional inductor structures are used, then fabrication is simpler, but electromagnetic interference shielding is insufficient
Solution Approach 1:
The patent embeds the inductor coils within the substrate volume, nesting them between the top surface and bottom contact layer. This nested configuration provides natural electromagnetic shielding by containing the magnetic fields within the substrate, reducing interference with external circuits while maintaining a compact form factor
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
The solution achieves good shielding from electromagnetic interference and high quality factors in inductor devices, overcoming the limitations of conventional methods by optimizing the structure and materials used in inductor fabrication.
Implementation Method 1
the dummy pads disposed around a substantial portion of the coil to shield the coil from electromagnetic interference
Data Source
AI summary
An inductor device and method of forming the inductor device are provided. In some embodiments the inductor device includes a post passivation interconnect (PPI) layer disposed and an under bump metallization (UBM) layer, each disposed over a substrate. The PPI layer forms a coil and dummy pads. The dummy pads are disposed around a substantial portion of the coil to shield the coil from electromagnetic interference. A first portion of the UBM layer is electrically coupled to the coil and configured to interface with an electrical coupling member.