Thermal Oxidation Insulation for High-Aspect-Ratio Through Electrodes
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Solution Overview
Problem
In three-dimensional mounting packages, fine through electrodes of high aspect ratio face challenges in forming a resin insulating layer with sufficient thickness, leading to compromised insulation function and potential leakage currents.
Innovation Solution
A device-mounted substrate configuration featuring a thermal oxidation layer on both the surface and internal surfaces of via holes, with a conductive body surrounded by an insulating layer, ensuring uniform thickness and enhanced insulation characteristics, along with a method that separates the formation of the via hole and insulating layer from the device circuit, allowing for plating of the conductive body without migration issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fine through electrodes of high aspect ratio are formed using a resin insulating layer, then the insulation function is improved, but it becomes difficult to form the resin insulating layer with sufficient thickness
Solution Approach 1:
The patent changes the material parameter from resin insulating layer to thermal oxidation layer, which enables formation of uniform thick insulation on vertical surfaces. The thermal oxidation process naturally conforms to the high aspect ratio via hole geometry, achieving sufficient thickness (50-200nm) that resin cannot provide without compromising uniformity.
Solution Approach 2:
The patent replaces the mechanical deposition process (resin coating) with a chemical/thermal process (thermal oxidation). This substitution allows the insulating layer to form uniformly on complex three-dimensional surfaces including the vertical walls of high aspect ratio via holes, where mechanical methods fail to achieve sufficient and uniform thickness.
2Object-affected harmful factors
If resin insulating layer is formed between through electrode and substrate, then leakage current is prevented, but the insulation function is compromised due to insufficient thickness
Solution Approach 1:
The patent changes the insulating material from resin to thermal oxidation layer, which provides superior insulation characteristics. The thermal oxidation layer achieves sufficient thickness (50-200nm) that effectively blocks leakage current while maintaining uniformity, thereby simultaneously improving both leakage prevention and overall insulation reliability.
3Ease of manufacture
If via hole and insulating layer are formed before device circuit, then plating of conductive body can be performed, but migration issues occur
Solution Approach 1:
The patent performs preliminary thermal oxidation to form the insulating layer on the via hole walls before device circuit fabrication and plating. This preliminary action creates a stable, migration-resistant insulating barrier that prevents metal diffusion during subsequent high-temperature plating and device fabrication processes, thereby eliminating migration issues while enabling the plating process.
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 configuration achieves superior insulation characteristics and prevents leakage currents, enabling the manufacture of high-aspect-ratio through electrodes with improved reliability and density, suitable for infrared light sensors and three-dimensional stacked packages.
Implementation Method 1
a first insulating layer including a thermal oxidation layer, the thermal oxidation layer being formed on the first surface and the internal surface
Data Source
AI summary
A via hole is formed on a base substrate before a device circuit is formed, and thermal oxidation is performed to form a thermal oxidation layer on a surface of the base substrate on which the device circuit is formed and a surface in the via hole. The device circuit having a conductive section is formed on the base substrate after the thermal oxidation, and then, a conductive body is embedded in the via hole.