Semiconductor Substrate Warping Mitigation via Segmented Buried Insulators
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Solution Overview
Problem
The semiconductor substrate tends to warp during the manufacturing process of semiconductor devices with a super junction structure due to the shrinkage of insulating films formed within deep trenches, leading to errors in later processes and potential failure in forming p-type column layers along the trench walls.
Innovation Solution
The formation of buried insulators in island shapes within the terminal region, rather than a continuous ring or linear shape, helps to mitigate substrate warping and ensures proper formation of p-type column layers by maintaining trench dimensions and reducing silicon oxide film shrinkage during thermal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If insulating films are formed within deep trenches to protect the substrate during dopant injection, then the substrate is protected from damage, but the insulating films shrink during thermal oxidation processing causing substrate warping
Solution Approach 1:
The continuous insulating film within the deep trench is segmented into multiple discrete insulating films formed at different depths. This segmentation reduces the overall shrinkage stress on the substrate during thermal oxidation, preventing warping while maintaining protective functionality. The first insulating film is formed at a first depth and the second insulating film is formed at a second depth greater than the first depth, creating a distributed stress profile rather than a concentrated one.
Solution Approach 2:
Different regions of the deep trench are assigned different insulating film properties based on their specific functional requirements. The upper portion contains the first insulating film with specific dielectric properties, while the lower portion contains the second insulating film with different properties optimized for that depth. This local differentiation allows each film to contribute differently to stress management and substrate protection.
2Reliability
If deep trenches are formed in the terminal region to create super junction structure, then lower conductive resistance and higher junction withstand voltage are achieved, but substrate warping occurs due to insulating film shrinkage
Solution Approach 1:
The insulating film structure within the deep trenches of the terminal region is divided into multiple segments at different depths. This segmentation reduces the cumulative shrinkage stress that would otherwise cause substrate warping, while the deep trenches themselves remain intact to provide the necessary super junction structure for high voltage withstand capability.
Solution Approach 2:
The multi-level insulating film structure acts as a counterbalancing mechanism against the shrinkage forces. By distributing the insulating material at different depths, the structure creates a balanced stress profile that counteracts the warping tendency, allowing the deep trenches to maintain their depth and structural integrity for voltage blocking while preventing substrate deformation.
3Reliability
If thermal oxidation processing is used to form protective insulating films, then substrate protection during dopant injection is improved, but insulating film shrinkage causes carrying errors in manufacturing devices
Solution Approach 1:
The protective insulating film is segmented into multiple films at different depths within the deep trenches. This segmentation reduces the overall shrinkage magnitude during thermal oxidation, minimizing substrate warping and the resulting carrying errors in manufacturing devices. Each segmented film contributes less to total shrinkage stress while maintaining the protective function.
4Reliability
If continuous insulating films are formed within deep trenches, then complete substrate protection is achieved, but substrate warping and chipping during dicing occur
Solution Approach 1:
The continuous insulating film is divided into multiple discrete insulating films at different depths. This segmentation reduces the stress concentration that causes warping and subsequent chipping during dicing, while still providing complete protective coverage. The distributed structure maintains protection functionality without the mechanical constraints of a continuous film.
Solution Approach 2:
The deep trench structure becomes a composite system with multiple insulating film layers at different depths, each contributing different mechanical and electrical properties. This composite structure provides both protection and structural integrity, resisting warping and chipping forces better than a single continuous film while maintaining the necessary electrical insulation properties.
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 effectively suppresses substrate warping and ensures reliable formation of p-type column layers, enhancing the withstand voltage and reducing the risk of carrying errors in semiconductor manufacturing, while also preventing chipping during dicing.
Implementation Method 1
The insulating film formed within the deep trench tends to shrink according to the thermal oxidation processing
Data Source
AI summary
A semiconductor substrate is easily warped by the shrink of the insulating film formed within the deep trench according to the thermal processing in the super junction structure. In order to solve the above problem, in a semiconductor device, an element region and a terminal region are defined on one main surface of the semiconductor substrate. The terminal region is arranged to surround the element region. In the terminal region, a plurality of buried insulators are formed from the main surface of the semiconductor substrate in a way of penetrating an n-type diffusion layer and an n-type column layer and arriving at an n-type epitaxial layer. The buried insulator is formed within a deep trench. The plural buried insulators are arranged in island shapes mutually at a distance from each other.