Backside Ground Plane for IC Inductance Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The design complexity of mobile RF transceivers at deep sub-micron process nodes is exacerbated by spacing considerations between passive devices and ground planes, affecting inductance values and performance, and the integration of shielding ground planes is challenging due to variations in substrate and flip-chip bump heights.
Innovation Solution
A backside conductive layer is deposited on the passive die to control the distance between the integrated passive device layer and the ground plane, integrating a shielding ground plane to avoid substrate ground plane usage, ensuring consistent performance by reducing electromagnetic coupling and interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If passive devices are placed close to the ground plane to reduce space, then area is reduced, but inductance values become unstable and performance degrades
Solution Approach 1:
The ground plane is moved from the traditional substrate level to the backside of the die, creating a new spatial dimension for the electromagnetic reference plane. This dimensional change allows the passive devices to maintain their position on the front side while achieving a controlled, consistent distance to the ground plane through the die thickness, thereby stabilizing inductance values without increasing area.
Solution Approach 2:
The invention changes the key parameter of ground plane location from substrate level to die backside, and controls the distance parameter through precise die thickness specification. This parameter change ensures consistent spacing between passive devices and ground plane, stabilizing inductance values while maintaining compact area.
2Reliability
If substrate ground plane is used for RF components, then ground reference is provided, but electromagnetic coupling and interference increase
Solution Approach 1:
Instead of placing the ground plane on the substrate below the passive devices, the invention inverts the approach by placing the ground plane on the backside of the die, directly behind the passive devices. This inversion provides a ground reference closer to the RF components while reducing the horizontal coupling paths through the substrate, thereby minimizing electromagnetic interference.
Solution Approach 2:
The die itself acts as an intermediary structure between the passive devices and the ground plane. By specifying the die thickness and material properties, the invention creates a controlled medium that provides electrical connection to ground while isolating the RF components from harmful electromagnetic coupling that would occur through the substrate.
3Productivity
If deep sub-micron process node is used to reduce cost and power consumption, then manufacturing cost and power usage are reduced, but design complexity increases
Solution Approach 1:
The backside ground plane structure serves multiple functions simultaneously: it provides the ground reference for RF components, acts as a shielding plane to reduce interference, establishes controlled impedance environments, and enables consistent inductance values. This multi-functionality reduces the need for additional separate components and structures, thereby managing design complexity while operating at deep sub-micron nodes.
4Manufacturing precision
If distance between passive devices and ground plane is increased to stabilize inductance, then inductance stability is improved, but area increases
Solution Approach 1:
The invention transitions the ground plane distance control from the horizontal plane (increasing area) to the vertical dimension (through die thickness). By establishing the ground plane on the die backside at a controlled distance equal to the die thickness, the design achieves stable inductance values without increasing the footprint area, as the separation is achieved in the third dimension rather than by expanding the planar dimensions.
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 approach allows for strict control over the distance between passive devices and ground planes, enhancing RF performance by stabilizing inductance values and reducing interference, while also optimizing space on the substrate for other components.
Implementation Method 1
integrating a shielding ground plane to avoid substrate ground plane usage, ensuring consistent performance by reducing electromagnetic coupling and interference
Implementation Method 2
a distance between passive devices (e.g., passive on glass (POG) devices or integrated passive devices (IPD) such as inductors) and a ground plane of a system board (e.g., a printed circuit broad (PCB)) affects inductance values
Data Source
AI summary
An integrated circuit (IC) device includes a die having an integrated passive device (IPD) layer. The integrated circuit device also includes a substrate supporting the die, a molding compound surrounding the die. The integrated circuit device further includes a backside conductive layer on a surface of the die that is distal from the IPD layer. The integrated circuit device also includes vias coupling the backside conductive layer to a ground plane through the molding compound.