Galvanic Isolation Transformer on Quartz Substrate
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Solution Overview
Problem
Existing galvanic isolation methods for integrated circuits face challenges in achieving high target isolation voltages, such as 5kV, due to dielectric breakdown and increased processing costs, particularly when using silicon substrates, which require significant distance between transformer windings and substrates to prevent leakage.
Innovation Solution
The formation of a galvanic isolation transformer on a quartz substrate, which acts as a dielectric isolator, allowing for closer winding-to-substrate separation without dielectric breakdown, and enabling the use of a single die attach paddle and local copper interconnects for simplified and cost-effective packaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transformer is formed on a silicon substrate to provide galvanic isolation, then galvanic isolation between integrated circuits is achieved, but the distance between transformer windings and substrate must be significantly increased to prevent dielectric breakdown
Solution Approach 1:
The patent changes the substrate material parameter from silicon to quartz. Quartz has superior dielectric properties with higher breakdown voltage and lower loss tangent, especially at high frequencies. This material substitution allows the transformer windings to be positioned closer to the substrate while maintaining the required 5kV isolation voltage, thus resolving the contradiction between achieving reliable galvanic isolation and minimizing winding-to-substrate distance
Solution Approach 2:
The patent employs a composite structure combining quartz substrate with specific dielectric materials (such as BCB or silicon dioxide) in the transformer winding structure. This composite approach leverages the excellent dielectric properties of quartz combined with the advantageous characteristics of other dielectric materials to achieve both high voltage isolation and compact winding-to-substrate spacing
2Reliability
If significant distance is maintained between transformer windings and substrate to prevent dielectric breakdown, then isolation voltage is maintained, but processing complexity and costs increase
Solution Approach 1:
By changing the substrate material parameter to quartz, the patent inherently provides superior dielectric strength and electrical properties. This eliminates the need for complex multi-layer dielectric structures and excessive spacing, thereby simplifying the overall device structure and reducing processing complexity while maintaining 5kV isolation voltage
3Reliability
If significant distance is maintained between transformer windings and substrate, then dielectric breakdown is prevented, but device area and packaging size increase
Solution Approach 1:
The patent changes the substrate material to quartz, which provides superior dielectric strength and electrical properties. This allows the transformer windings to be positioned much closer to the substrate surface while still preventing dielectric breakdown at 5kV isolation voltage. Consequently, the overall device footprint and packaging size are reduced compared to silicon substrate implementations that require larger spacing
4Ease of manufacture
If silicon substrate is used for transformer formation, then standard semiconductor processing is utilized, but eddy currents increase and frequency response deteriorates
Solution Approach 1:
The patent changes the substrate material from silicon to quartz. Quartz is an electrically insulating material with no free electrons, thereby completely eliminating eddy current losses that occur in conductive silicon substrates. This results in dramatically improved frequency response and higher Q factors for the transformer, especially at high frequencies, while the quartz substrate can still be integrated into standard semiconductor processing workflows
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 eliminates dielectric breakdown to the substrate, reduces processing complexity and costs, and enhances frequency response by minimizing eddy currents, achieving higher Q factors and tighter packaging with improved data transmission efficiency.
Implementation Method 1
a transformer formed on a quartz substrate, which acts as a dielectric isolator, allowing for closer winding-to-substrate separation without dielectric breakdown
Implementation Method 2
enhances frequency response by minimizing eddy currents, achieving higher Q factors
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
An integrated circuit die system comprises a first integrated circuit die, a second integrated circuit die and a transformer formed on a dielectric (e.g., quartz) substrate and electrically connected between the first integrated circuit die and the second integrated circuit die to provide galvanic isolation therebetween.