Superior Quality Assurance Solutions for Advanced Packaging & Mini/Micro-LED Applications
Semiconductor packaging has become one of the most dynamic areas of electronics innovation. From system in package (SiP) and chiplet integration to fan out wafer level packaging (FOWLP) and 3D stacked architectures, new designs are demanding extreme precision in assembly and inspection. Deviations in coplanarity, surface contamination, voids in underfill, or tilted dies can jeopardize signal integrity and mechanical reliability.
To succeed in this environment, manufacturers need semiconductor metrology and inspection systems that deliver high resolution, high speed, and comprehensive 3D measurement capabilities, capable of analyzing everything from solder bumps to reflective silicon dies. Learn more about Semiconductor Metrology.
Koh Young’s Semiconductor Metrology is tailored for wafer and die inspection, detecting even the smallest irregularities to maintain the integrity of semiconductors at the foundational level. Complementing these inspection solutions, Koh Young’s Smart Factory Solutions embrace Industry 4.0 advancements, optimizing semiconductor manufacturing through data analytics, AI, and automation.
What Semiconductor Metrology Means in Advanced Packaging
In semiconductor packaging, metrology is dimensional measurement of the physical features that join a die to its package and the package to a board — printed bumps, solder balls, copper pillars, dies, underfill and flux deposits. It is measurement in microns, reported as height, diameter, volume, coplanarity and tilt, with a stated accuracy and repeatability attached to every number.
That is a different discipline from front-end fab metrology, which characterises features inside the die itself. Koh Young measures the packaging and assembly stages: from wafer-level bump inspection through die placement and substrate assembly to the finished board.
Metrology vs. Inspection: Why the Distinction Matters
In semiconductor manufacturing, metrology is distinct from inspection. Inspection answers a binary question: pass or fail. Metrology answers a quantitative one — how tall, how flat, how much volume, by how many microns. In advanced packaging, where the margin between a good joint and a reliability risk is measured in single-digit microns, that difference decides whether you can control a process or only sort its output.
An inspection system tells you a micro-bump is too short. A metrology system tells you it measured 62.3 μm against a 65 μm target, and that the standard deviation across the wafer is 0.8 μm. That second answer changes the engineering response: the trend is drifting, the drift is directional, and there is enough margin to correct the plating step before anything falls out of tolerance.
This is why measurement data, not defect counts, is what feeds statistical process control. A defect count tells you how often you failed. A measurement distribution tells you how close you are to failing next.
What Gets Measured in Advanced Packaging
Advanced packaging compresses more function into less space, which leaves less room for process drift. The dimensions that matter most are the ones 2D imaging cannot resolve:
- Bump and ball height — insufficient height risks an open after reflow; excess risks a bridge
- Coplanarity — the height distribution across a die or package, which determines whether every joint contacts
- Volume — the measurement that actually predicts joint strength, and one that area alone cannot infer
- Warpage — substrate and wafer distortion that shifts every feature on the part
- Die tilt — the angle of a placed die, which governs bond quality in stacked and hybrid-bonded assemblies
Each of these is a height measurement. None can be derived reliably from a top-down greyscale image, which is why metrology-grade 3D measurement is the baseline requirement rather than an upgrade. The systems below each cover a different stage of that flow.
Metrology Across the Packaging Workflow
No single measurement stage tells you where a problem started. Advanced packaging builds value across several steps, and a defect found at the end is usually the visible end of variation introduced earlier.
At wafer level, ZenStar establishes bump and pillar geometry before singulation — the reference every later stage is judged against, at 300 mm and 14 wafers per hour, with Z resolution to 0.1 μm and height accuracy under 1 μm. At die level, Meister D and D+ measure the singulated die: dimensional integrity, cracks and chipping from dicing, and the tilt that determines bond quality. At solder and bump level, Meister S and S+ measure the deposits that form the interconnect, the S+ resolving bumps to 50 μm diameter at 650 mm²/sec.
The value is in the sequence, not in any one station. When a bond fails final test, measurement data from each prior stage lets an engineer trace backward — was the bump already short at wafer level, did the die arrive tilted, or did the substrate paste volume run low? Without dimensional data at each step, that investigation is guesswork. With it, the answer is a query. Automotive, medical, and aerospace programmes increasingly expect exactly that: lot genealogy and retained measurement histories, not just a pass record.
Metrology-Grade Measurement for Substrate Assembly
Not all semiconductor metrology happens at wafer level. Advanced substrate assembly — placing passives, connectors, and interposers on organic or ceramic substrates — needs paste and component measurement held to the same standard. The aSPIre 3 measures deposits at 0.37 μm Z resolution with 1 μm height accuracy and a Gage R&R under 10% at 6 sigma, supporting components down to 03015 metric. That gauge capability is what makes the output usable as process data rather than just a screening result.
Making Metrology Data Actionable
Measurement is only worth its cost if something acts on it. Data from ZenStar, Meister, and aSPIre 3 systems flows into KSMART, where it drives process control rather than just reporting. Real-time SPC tracks stability across wafers and lots. KAP reduces programming time by up to 70%. Smart Review consolidates verification at twice the productivity of separate review stations. KPO closes the loop upstream — the printer module optimises parameters up to 12 times faster than manual tuning, with up to 47% higher productivity, and the mounter module corrects up to 90% of placement offsets automatically.
The result is a line where a drift detected at measurement becomes a correction at the process step that caused it.
What Makes Packaging Metrology Difficult
- The features are small, and the machine sets the floor. The Meister S measures bumps down to 70 µm in diameter at 5 µm XY resolution; the Meister S+ reaches 50 µm at 3.5 µm. Minimum pad gap follows the same split — 50 µm and 35 µm. Choosing the platform is choosing what the line can measure.
- Substrates warp. Thin packaging substrates move during processing, so a height reading is only meaningful with active warp compensation — up to ±5 mm on the Meister platform.
- Some surfaces defeat optics. Mirror-finish dies and transparent flux give an optical system almost no contrast to work with.
- Throughput cannot be traded away. Measurement has to keep line pace, which is why resolution and speed are specified together rather than separately.
From Measurement to Process Control
A measurement that only records what happened is a cost. The value appears when the number changes what the line does next. Koh Young systems feed measured height, volume, diameter, coplanarity and tilt into KSMART, which correlates readings across stages — wafer bump, die placement, substrate assembly and final board — so a drift at one step can be traced to its cause at another.
In practice that means a printer or dispenser can be adjusted from measured trend rather than from a scrap report, and a package that fails at final assembly can be traced back to the stage that introduced the variation. Repeatability is what makes this possible: on the Meister S and S+, height repeatability is under 0.30 µm at 3σ, so a change in the data is a change in the process rather than noise in the measurement.
Which System Measures What
| System | What it measures | Typical application |
|---|---|---|
| Meister S | 12 Mpix, 5 µm XY, 0.1 µm Z, 300 mm²/sec. Printed bumps and solder balls from 70 µm diameter, 20–150 µm tall. Warp compensation ±5 mm | Bump and solder-ball measurement in wafer-level packaging and SiP |
| Meister S+ | 25 Mpix, 3.5 µm XY, 0.1 µm Z, 650 mm²/sec. Adds ball-defect and flux inspection; reaches 50 µm bump diameter and 35 µm pad gap | Finer geometries and flux in advanced packaging and Mini/Micro-LED |
| Meister D / D+ | Post-placement die and component inspection down to 100 µm (0201 metric), 1 µm Z resolution, height accuracy Moiré ±1.5%. The D+ adds mirror-surface die measurement | SiP, MCM, chiplets, interposers, 2.5D stacking |
| ZenStar | Wafer-level 3D bump metrology on 300 mm wafers; 14 wafers/hour; 0.1–0.37 µm Z resolution; height accuracy <1 µm | Wafer bumps, solder balls, copper pillars, flip chip, BGA |
| Neptune C+ | 3D underfill and flux measurement by fluid tomography; voids, edge recession and coverage | Underfill and flux in advanced modules |
| Zenith series | True3D SMT AOI of the finished board — solder volume, bridging, skew | Board-level QA of packaged semiconductors |
Frequently Asked Questions
Is metrology the same as inspection?
No. Inspection returns a pass or fail against a tolerance. Metrology returns the measured value with a known accuracy and repeatability, which is what lets you see a process drifting before it produces a reject.
What is the smallest bump Koh Young can measure?
50 µm in diameter, on the Meister S+ at 3.5 µm XY resolution. The Meister S measures down to 70 µm at 5 µm. Both measure bump heights from 20 µm — up to 150 µm on the S and 100 µm on the S+ — with height accuracy under 1 µm.
Does Koh Young measure features inside the die?
No. Koh Young measures packaging and assembly features — bumps, balls, pillars, dies, underfill, flux and solder joints. Front-end characterisation of structures within the die is a separate discipline.
Can wafer-level measurement run inline?
Yes. ZenStar handles 300 mm wafers at 14 wafers per hour with an integrated EFEM and vacuum chuck, in a Class 1000 / ISO 6 environment.
How does measurement data get used?
Measurements feed KSMART, which is where the data becomes process control rather than a record of defects.
Semiconductor Metrology Solutions for Advanced Packaging
Dimensional accuracy, process control, and intelligent feedback are essential pillars of modern semiconductor metrology and inspection.