Layered Isolator Insulation for Breakdown Voltage and Low Wafer Warping
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Solution Overview
Problem
The use of thick insulating films in isolators to maintain breakdown voltage leads to increased internal stress and warping of wafers during manufacturing, causing manufacturing process issues.
Innovation Solution
Employing a layered insulating film structure comprising a silicon oxynitride film with controlled nitrogen composition as the first insulating film, a silicon oxide film as the second insulating film, and a silicon nitride film as the third insulating film, with specific thickness ratios to manage stress and prevent warping while maintaining high breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick insulating film is used to maintain breakdown voltage, then dielectric breakdown is prevented, but internal stress increases and wafer warping occurs
Solution Approach 1:
The thick insulating film is divided into multiple layers with different materials (first insulating film with silicon oxynitride, second insulating film with silicon oxide, third insulating film with silicon nitride). Each layer has different stress characteristics that can be balanced to reduce overall wafer warping while maintaining the required total thickness for breakdown voltage protection.
Solution Approach 2:
The patent specifies precise thickness ratios between layers (first insulating film thickness ≥ 50 nm, second insulating film thickness ≥ 200 nm, third insulating film thickness ≥ 50 nm, with specific ratio relationships). By controlling these dimensional parameters and material composition ratios, the stress distribution is optimized to prevent warping while ensuring adequate insulation.
2Reliability
If a thick insulating film is used to prevent dielectric breakdown, then reliability is improved, but manufacturing process difficulty increases
Solution Approach 1:
The patent employs a composite insulating film structure combining three different materials (silicon oxynitride, silicon oxide, silicon nitride) in specific layers. This composite approach allows each material to contribute its beneficial properties while the combined structure achieves stress balance, making the manufacturing process feasible despite the requirement for high breakdown voltage.
Solution Approach 2:
Different regions of the insulating film structure have different material compositions and thicknesses tailored to specific functions. The first layer provides baseline insulation, the second layer contributes to stress management, and the third layer enhances dielectric strength. This localized optimization of material properties enables manufacturing while maintaining reliability.
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 layered insulating film structure effectively reduces stress and suppresses wafer warping, enhancing manufacturing efficiency and reliability of isolators by optimizing film thickness and composition.
Implementation Method 1
When the insulating film is made thick, however, the internal stress increases, and warp occurs in the wafer on which the insulating film is formed
Data Source
AI summary
An isolator includes first and second conductors, and first to third insulating film. The first insulating film is provided between the first and second conductors. The first insulating film has a first film thickness, and includes silicon, oxygen, and nitrogen. The second insulating film is provided between the first conductor and the first insulating film. The second insulating film includes silicon and oxygen. The second insulating film includes no nitrogen, or further includes nitrogen of a smaller composition ratio than a nitrogen composition ratio in the first insulating film. The third insulating film is provided between the first conductor and the second insulating film. The second and third insulating films has second and third film thicknesses, respectively. The second and third film thickness are less than the first film thickness. The third insulating film having a different composition from the compositions of the first and second insulating films.