Thermal Oxidation Via Insulation for High-Density TSV Alignment
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Solution Overview
Problem
Existing through silicon via (TSV) formation methods result in poor-quality insulation due to low-temperature silicon oxide deposition, leading to degraded electric performance and reduced via integration density, as well as alignment issues when forming vias after electronic components are created.
Innovation Solution
The method involves forming openings in the substrate, thermally oxidizing the walls, filling with a sacrificial material, forming electronic components, etching the sacrificial material, and then filling with metal, allowing for high-quality thermal oxide insulation and closer via placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If low-temperature CVD is used to deposit silicon oxide insulation layer, then the deposition temperature is kept below 200°C, but the insulation quality is poor and non-conformal
Solution Approach 1:
The patent changes the deposition temperature parameter from low-temperature CVD (<200°C) to high-temperature thermal oxidation (>1000°C). This parameter change transforms the deposition process into a thermal oxidation process that produces high-quality conformal silicon oxide insulation layers, resolving the contradiction between temperature control and insulation quality.
2Measurement precision
If vias are formed after electronic components are made, then alignment references are available, but the distance between vias must be increased for sufficient insulation
Solution Approach 1:
The patent applies preliminary action by forming the via openings and applying the insulation layer before the electronic components are fabricated. This sequence allows components to be formed over the via structures using the via openings as alignment references, eliminating the need for increased spacing while maintaining precise alignment. The insulation layer is deposited conformally on the via walls before component formation, ensuring sufficient insulation without increasing via distance.
3Manufacturing precision
If thermal oxidation is used to form insulation, then high-quality conformal insulation is achieved, but the process temperature reaches 1000°C which causes metal diffusion into substrate
Solution Approach 1:
The patent performs the thermal oxidation process to form high-quality conformal insulation layers before fabricating the electronic components. By completing the insulation formation early in the process sequence, the high-temperature thermal oxidation (1000°C+) is executed when no metal layers are present that could diffuse into the substrate. Subsequent component fabrication occurs at lower temperatures that do not cause diffusion, thus achieving both high insulation quality and preventing metal contamination.
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 provides high-quality insulation suitable for high-voltage applications, increases via integration density, and ensures accurate positioning by forming vias before electronic components, resulting in improved electric performance and increased via density.
Implementation Method 1
b) thermally oxidizing walls of the openings
Data Source
AI summary
A method for forming through vias connecting the front surface to the rear surface of a semiconductor substrate, including the steps of: forming openings in the substrate, thermally oxidizing walls of the openings, filling the openings with a sacrificial material, forming electronic components in the substrate, etching the sacrificial material, filling the openings with a metal, and etching the rear surface of the substrate all the way to the bottom of the openings.