Imaging Sensor Strain Monitoring for CSP Stress Defect Screening
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Solution Overview
Problem
Semiconductor packages face challenges in detecting mechanical and thermal stresses during assembly, which lead to late-coming defects such as cracks or peeling off, making it difficult to identify defects before shipment, resulting in non-defective products being provided to users.
Innovation Solution
Incorporating a strain sensor on the same layer as the photoelectric converter in the semiconductor element, which is connected to conductive electrodes and an adhesive layer, allowing for real-time strain monitoring during manufacturing and inspection processes, enabling detection of residual stresses that could cause late-coming defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a wafer level chip size package (CSP) is used to increase semiconductor element density, then productivity and miniaturization are improved, but mechanical stress and thermal stress concentrate on the support board or adhesive layer, causing late-coming defects
Solution Approach 1:
The patent applies preliminary action by incorporating strain sensors during the semiconductor element manufacturing process, before the element is shipped to the user. This allows residual stress to be detected and problematic elements to be identified in advance, preventing late-coming defects from occurring after the element is mounted in a CSP package. The strain sensors are integrated into the semiconductor element structure itself, enabling proactive quality control rather than reactive defect management.
2Manufacturing precision
If electrical inspection or optical characteristic inspection is performed before shipment, then manufacturing precision is improved, but strain defects remain undetected, resulting in non-defective products being provided to users
Solution Approach 1:
The patent applies universality by designing the strain sensor to work within the existing semiconductor element structure, serving multiple functions: it acts as part of the normal device architecture while simultaneously providing stress detection capability. The strain sensor is integrated alongside other functional elements (such as microlenses and photoelectric converters) and can be read through existing conductive electrode pathways, making the inspection system universal and applicable to standard manufacturing workflows without requiring separate specialized equipment.
3Reliability
If strain sensors are added to detect residual stress, then reliability is improved by detecting defects early, but device complexity increases
Solution Approach 1:
The patent applies merging by combining the strain sensor functionality with existing semiconductor element structures. The strain sensor is integrated on the same layer as other functional components (such as the photoelectric converter), and its electrical connections are made through the same conductive electrode system that is already present for normal device operation. This merging approach allows stress detection capability to be added without creating separate independent systems, thereby limiting the increase in overall device complexity.
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
Enables the detection of defects that would otherwise occur post-shipment due to secondary mounting or module assembly, ensuring that defective products are identified and addressed before delivery, thereby improving product reliability and reducing late-coming defects.
Implementation Method 1
a strain sensor provided on the same layer as the photoelectric converter to detect a strain
Implementation Method 2
a plurality of microlenses provided on a main surface to collect light, a photoelectric converter to which the light collected by the plurality of microlenses is guided
Data Source
AI summary
A semiconductor element includes a plurality of microlenses provided on a main surface to collect light, a plurality of conductive electrodes provided on a back surface of the main surface, a photoelectric converter to which the light collected by the plurality of microlenses is guided, and a strain sensor provided on the same layer as the photoelectric converter to detect a strain. A solid-state imaging apparatus includes the semiconductor element, a transparent member, an adhesive layer that covers the plurality of microlenses and adheres to the transparent member, and a plurality of external connection electrodes electrically connected to the plurality of conductive electrodes, respectively.