Stacked Semiconductor Die RF Shielding via Inter-Die Conductive Ground
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Solution Overview
Problem
In semiconductor devices with stacked dies, radio frequency (RF) interference occurs when both dies operate at high frequencies, making it difficult to eliminate interference without modifying the circuit design or adjusting operation frequencies.
Innovation Solution
A conductive layer is introduced between the dies to act as a reference ground, surrounded by a redistribution structure, which effectively shields the first die from RF interference from the second die, using a via to couple the conductive layers and maintaining the original circuit design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If both dies operate at high frequencies simultaneously, then system functionality is maintained, but RF interference occurs between the dies
Solution Approach 1:
A conductive layer is introduced as an intermediary element between the first die and second die. This conductive layer serves as a reference ground that mediates the electromagnetic interaction between the two high-frequency operating dies, absorbing or redirecting RF energy and preventing interference while allowing both dies to maintain their high-frequency operation.
Solution Approach 2:
The conductive layer is segmented into a first conductive layer on the first die and a second conductive layer on the second die, connected through vias. This segmentation allows the reference ground to be distributed across multiple locations, effectively creating shield zones around each die without requiring a single continuous ground plane that would complicate the stacked architecture.
2Object-affected harmful factors
If a conductive layer is added to shield RF interference, then RF interference is eliminated, but device complexity increases
Solution Approach 1:
The conductive layer serves multiple functions simultaneously: it acts as a reference ground for signal stability, provides RF shielding between dies, and serves as an electrical connection path through the stacked structure. By combining these functions into a single structural element, the design avoids adding separate components for each function, thereby limiting the increase in device complexity.
Solution Approach 2:
The reference ground function and RF shielding function are merged into the same conductive layer structure. Instead of adding a separate shielding layer on top of the reference ground, the conductive layer itself is configured to perform both roles, simplifying the overall device architecture while achieving both objectives.
3Object-affected harmful factors
If the conductive layer is extended beyond the projection area, then RF shielding is improved, but manufacturing precision requirements increase
Solution Approach 1:
The conductive layer is configured with different extension characteristics in different areas: within the projection area, it provides dense reference ground coverage for signal integrity, while extending beyond the projection area, it provides RF shielding. This local quality variation optimizes the shielding effectiveness without requiring uniform extension throughout the entire device area, thereby moderating the manufacturing precision requirements.
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 conductive layer shields the first die from RF interference, allowing both dies to operate at high frequencies simultaneously without modifying the circuit design, reducing the burden on circuit designers and eliminating RF interference.
Implementation Method 1
the conductive layer is able to effectively shield the first die from the second die
Implementation Method 2
The second conductive layer provides the reference ground to the first conductive layer via the via
Data Source
AI summary
The present disclosure provides a semiconductor device. The semiconductor device includes a first die and a conductive layer. The first die is to be bonded with, in a direction, a second die external to the semiconductor device. The conductive layer, between the first die and the second die in the direction, has a reference ground.