RF IC Chip Noise Coupling via Insulative Molding Compound Substrate
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Solution Overview
Problem
Radio frequency (RF) integrated circuit (IC) chips face noise coupling issues due to free electrons moving through the semiconductor handler substrate, leading to cross-talk between devices, which negatively impacts performance, and existing solutions like high-resistance SOI wafers or glass substrates are either expensive or complex to implement.
Innovation Solution
The use of an electrically insulative molding compound as a replacement handler substrate, which is attached over a temporary carrier and positioned between the semiconductor devices and the insulator layer, providing backside isolation and preventing unwanted noise coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a semiconductor handler substrate (e.g., silicon) is used, then the RF semiconductor devices can be formed using standard SOI wafer processes, but free electrons move through the substrate causing noise coupling and cross-talk between devices
Solution Approach 1:
The patent extracts and removes the problematic semiconductor handler substrate (silicon substrate) from the structure. By removing the substrate that contains free electrons capable of conducting noise, the harmful noise coupling effect is eliminated while retaining the beneficial insulator layer and semiconductor device structure.
Solution Approach 2:
The patent introduces an air gap or vacuum space as an intermediary between the insulator layer and any remaining substrate structures. This intermediary medium provides electrical isolation and prevents noise coupling pathways while maintaining the structural integrity of the RF devices.
2Object-affected harmful factors
If high-resistance SOI wafers are used to reduce noise coupling, then noise coupling is reduced, but the cost increases significantly
Solution Approach 1:
The patent employs standard, inexpensive SOI wafers with typical resistance values rather than costly high-resistance SOI wafers. The solution achieves noise reduction not through expensive substrate material properties, but through structural modification (removing the substrate), making the approach cost-effective while maintaining manufacturing simplicity.
3Object-affected harmful factors
If glass substrates are used as handler substrate, then electrical insulation is improved and noise coupling is reduced, but the device complexity and manufacturing complexity increase
Solution Approach 1:
Instead of replacing the silicon substrate with a complex glass substrate, the patent simply removes the substrate entirely. This extraction approach achieves the desired electrical insulation effect without introducing the complexity of glass substrate integration, bonding, or matching processes.
Solution Approach 2:
Rather than trying to make the substrate insulating (by using glass or high-resistance material), the patent inverts the approach by removing the substrate altogether and relying on the insulator layer and air gap to provide the necessary electrical isolation. This reverse thinking simplifies the structure while achieving the same goal.
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 electrically insulative molding compound handler substrate effectively reduces noise coupling between RF semiconductor devices, improving the performance of RF IC chips by isolating them and preventing cross-talk, while being more cost-effective and simpler to integrate compared to traditional high-resistance or glass substrate methods.
Implementation Method 1
an electrically insulative molding compound handler substrate... provides backside isolation that prevents unwanted noise coupling of devices
Data Source
AI summary
Disclosed are integrated circuit (IC) chip structures (e.g., radio frequency (RF) IC chip structures) and methods of forming the structures with an electrically insulative molding compound handler substrate. Each structure includes at least: an electrically insulative molding compound handler substrate; an insulator layer on the handler substrate; and one or more semiconductor devices (e.g., RF semiconductor devices) on the insulator layer. Each method includes at least: attaching a temporary carrier above back end of the line (BEOL) metal levels, which are over an interlayer dielectric layer covering one or more semiconductor devices; removing at least a portion of a semiconductor handler substrate, which is below the semiconductor device(s) and separated therefrom by an insulator layer; replacing the semiconductor handler substrate with a replacement handler substrate made of an electrically insulative molding compound; and removing the temporary carrier. The molding compound handler substrate provides backside isolation that prevents unwanted noise coupling.