Backside Pad Electrode for RF Semiconductor Inspection
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Solution Overview
Problem
Existing radiofrequency-band semiconductor devices, such as MMICs, face challenges in characterizing their performance when mounted on a substrate due to the exposure of only the front surface, making it difficult to inspect their characteristics.
Innovation Solution
The semiconductor device incorporates a through hole and a pad electrode on the lower surface, allowing for the detection circuit or coupler circuit outputs to be connected to the back surface, enabling inspection of characteristics without increasing the substrate size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the semiconductor device is mounted face-down on a substrate with solder bumps on the front surface, then the device can be securely fixed and miniaturized, but the back surface becomes exposed and inaccessible for characteristic inspection
Solution Approach 1:
The pad electrode extends from the front surface through a through-hole to the back surface of the semiconductor substrate, creating a three-dimensional structure that allows electrical connection and inspection access from both surfaces. This dimensional transition enables the inspection function to be performed on the back surface while maintaining the front surface mounting configuration.
Solution Approach 2:
The pad electrode acts as an intermediary element that bridges the detection circuit on the front surface and the external inspection equipment on the back surface. It provides a conductive path through the semiconductor substrate, enabling signal transmission for characteristic inspection without interfering with the mounting function.
2Difficulty of detecting and measuring
If a through-hole and pad electrode are added to enable back surface inspection, then inspection accessibility is improved, but the device structure becomes more complex
Solution Approach 1:
The pad electrode serves multiple functions: it provides electrical connection for the detection circuit, enables back surface inspection access, and maintains structural integrity of the semiconductor device. By combining multiple functions into a single element, the overall device complexity is minimized while achieving inspection capability.
Solution Approach 2:
The pad electrode is divided into two functional portions: a first portion on the front surface connected to the detection circuit, and a second portion on the back surface for external connection. This segmentation allows each portion to be optimized for its specific function while maintaining overall simplicity.
Data Source
AI summary
A semiconductor device includes a semiconductor substrate in which a through hole is formed, a transistor formed on the upper surface side of the semiconductor substrate, a detection circuit formed on the upper surface side of the semiconductor substrate and connected to the transistor, a dielectric film covering the transistor and the detection circuit, a solder bump formed on the dielectric film, and a pad electrode having a first portion connected to an output of the detection circuit in the through hole, and a second portion connected to the first portion and provided on a lower surface of the semiconductor substrate.