Semiconductor Substrate Groove Stress Relief Thinning
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Solution Overview
Problem
Conventional methods for manufacturing semiconductor devices for millimeter-wave applications face challenges due to residual stress during substrate thinning, leading to variations in chip thickness and accuracy issues, which affect high-frequency operation stability.
Innovation Solution
A method involving forming a groove around the chip region on the substrate and thinning from the back surface to reduce stress and maintain uniformity, allowing the groove to serve as a scribe line for precise substrate separation, thereby minimizing thickness deviations and enhancing high-frequency signal blocking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the semiconductor substrate is thinned to block excitation in the substrate-thickness direction, then high-frequency signal propagation is improved, but stress-induced thickness variations and deformation occur
Solution Approach 1:
The groove is formed in advance before the substrate thinning process. This preliminary action creates a stress relief structure that prevents stress-induced deformation during subsequent thinning operations, thereby maintaining thickness uniformity while achieving the required thin substrate for high-frequency operation stability
Solution Approach 2:
The substrate is segmented by forming grooves that divide the continuous substrate into regions separated by these grooves. This segmentation allows stress to be localized and relieved at the groove locations, preventing widespread deformation and thickness variations across the entire substrate during the thinning process
2Length of stationary object
If mechanical grinding is applied to thin the substrate, then substrate thickness is reduced for blocking excitation, but stress-induced deformation and thickness variation occur
Solution Approach 1:
The groove formation is performed as a preliminary action before mechanical grinding. This pre-formed groove structure serves as a stress relief mechanism that prevents stress accumulation during the mechanical grinding process, enabling uniform thickness reduction without inducing deformation or thickness variations
Solution Approach 2:
The groove acts as an intermediary stress relief structure between the mechanical grinding process and the substrate material. It provides a controlled pathway for stress dissipation during grinding, mediating the interaction between the grinding force and the substrate to prevent unwanted deformation
3Reliability
If the substrate is thinned to several tens of μm, then excitation blocking is improved, but adhesive agent residual stress causes deformation
Solution Approach 1:
The groove is formed in advance before the substrate is thinned to several tens of micrometers. This preliminary groove structure prevents residual stress from the adhesive agent from causing deformation in the ultra-thin substrate, maintaining planarity while achieving the necessary thickness for excitation blocking
Solution Approach 2:
The groove introduces local structural variation at specific locations (around chip regions) without affecting the overall substrate thinness. This local quality change provides stress relief precisely where needed, preventing global deformation while maintaining the ultra-thin profile required for millimeter wave operation stability
Data Source
AI summary
A groove is formed around a chip region of a principal surface of a substrate by an etching process or cutting with a dicing blade (a second step). Next, the substrate is thinned from a back-surface side of the substrate to cause a bottom of the groove to reach a backside of the substrate to serve as a space, thus cutting out a portion that is to be a chip of the chip region (a third step).