UltrasonicScanning Microscope: The "Micro-Inspector" of Semiconductor ChipPackaging
Amid the trend of increasing semiconductor chip packagingdensity and the widespread application of heterogeneous integrationtechnologies, Ultrasonic Scanning Microscopy is becoming a core inspection toolfor ensuring chip packaging quality. This technology transmits high-frequencyultrasonic waves into the chip's interior. By utilizing the differences inacoustic impedance at various material interfaces to reflect signals, itconstructs high-resolution images of the chip's internal microstructure,providing a reliable solution for detecting hidden defects within chippackages.
Technical Principle
The Ultrasonic Scanning Microscope uses high-frequencyultrasonic waves (typically ranging from 10 MHz to 1 GHz) as the detectionmedium. As these waves penetrate the chip's packaging structure, they encounterdifferent interfaces—such as those between the chip and substrate, bond wiresand pads, or underfill and chip—resulting in reflected waves of varyingintensities. By receiving and analyzing parameters like the time-of-flight andamplitude of these reflected signals, a computer processes the data toreconstruct two-dimensional or three-dimensional images of the chip's interior.This clearly reveals micro-defects such as delamination, voids, cracks, andcold solder joints, with detection precision reaching the micron level. It caneven identify minute voids with diameters smaller than 5 μm.
Quality Advantages
•Non-Destructive Testing: Causes no damage tothe chip's circuit structure or performance, making it suitable for inspectionthroughout the chip's entire lifecycle.
•D Imaging Capability: Provides intuitivevisualization of defect distribution across the chip's multi-layer internalstructure, avoiding the information loss inherent in traditional 2D inspectionmethods.
•High Degree of Automation: Supports batchscanning inspection of chip arrays, increasing detection speed by over 500%compared to manual microscopic observation.
•Quantifiable Results: Enables precisemeasurement of defect parameters such as size, location, and quantity,providing a data basis for optimizing packaging processes.
Application Fields
This technology has become a key inspection method in thefield of high-reliability semiconductor chip packaging:
•Inspection of flip-chip packages for advancedprocess nodes (e.g., 7nm and below).
•Quality inspection of bond wires and solderballs in RF chips and power semiconductor devices.
•Structural integrity inspection for MEMS(Micro-Electro-Mechanical Systems) chip packaging.
•Sampling and full inspection of packagingquality in high-reliability sectors such as automotive electronics andindustrial control chips.
As semiconductor chips evolve towards the "More thanMoore" paradigm, packaging structures are becoming increasingly complex,rendering traditional optical inspection inadequate for detectingmicro-defects. Ultrasonic Scanning Microscopy not only addresses the challengeof identifying hidden defects in chip packages but also empowers packagingprocess optimization through micro-level data analysis. It facilitates theindustry's transition from "extensive production" to "precisioncontrol," thereby providing a solid guarantee for the stable operation ofhigh-end chips.