Inspection is often misunderstood as:

・A process that rejects defects at the end

・A confirmation task before shipping

In reality, however, inspection is a feedback mechanism that affects the entire manufacturing process, and it plays the role of connecting the front-end, back-end, design, and quality.

The more a factory thinks of inspection as “work at the exit,” the more likely it is to fall into a state where:

・The same defects recur

・Identifying causes is delayed

・Yield does not improve

Inspection tends to be given lower priority because:

・It does not directly make products

・Its contribution to sales is hard to see

・It tends to be regarded as a cost

On the shop floor, however, when inspection is weak, problems surface later and larger.

Specifically:

・Defective products escaping

・Customer complaints

・Massive losses after volume production

・Emergency analysis in the middle of the night

・Recurrence with unknown causes

Inspection is also a mechanism for stopping problems early, while they are still small.

The roles of inspection and characterization fall into three main categories.

(1) Separating Good from Bad

Pass/fail judgment of electrical characteristics, appearance, and functions.

This is the easiest role to understand, but the value of inspection does not end here.

(2) Identifying the “Cause” of Defects

・In which process

・What

・How

something deviated.

Unless this can be identified, yield will never improve.

Inspection is also a technology for putting defects into a state where they can be explained.

(3) Determining the Next Decision

Inspection data is used for:

・Correcting process conditions

・Equipment maintenance decisions

・Revising design rules

In other words, inspection is a data source that supports decision-making in manufacturing, design, and quality.

What matters is that inspection is not confined to a specific process.

・Front-end: in-line inspection

・Back-end: final test

・Development: characterization

・Volume production: SPC and yield analysis

It is involved in all of them.

If any one of them is weak, the accuracy of decisions across the entire factory declines.

Inspection is the eye that oversees the entire manufacturing line.

Although we simply call it “inspection,” its content spans completely different specialized fields.

Examples:

・Electrical characteristic testing

・Visual inspection

・Failure analysis (FA)

・Reliability evaluation

・Data analysis

The required knowledge, thinking, and skills differ greatly.

This is why Chapter 7 is divided into detailed sections.

Lumping inspection together erases the reality of the shop floor.

There are clear changes behind this:

・Narrower tolerances due to scaling

・More stochastic defects due to EUV

・Internal defects becoming invisible due to 3D structures

・High current and high heat density in AI chips

・Compound yield problems due to chiplets

“Invisible defects” are increasing rapidly, and conventional inspection can no longer keep up.

As a result, we have entered an era in which inspection × data analysis × AI is indispensable.

In Chapter 7, we will organize, role by role:

・What kinds of inspections

・In which processes

・For what purpose they are performed

・How they are used in decision-making

The goal is one thing:

to turn inspection from a passive task into an offensive weapon.

・Inspection and characterization are not processes for rejecting defects

・They are a central function that supports the factory’s very ability to make decisions

・Their importance only continues to grow in the era of scaling, 3D, and AI

1.Why is it dangerous to think of inspection as the final process?

2.What kinds of decisions is inspection data used for?

3.Why do problems arise when inspection is lumped together?

4.Name one reason why inspection is becoming more difficult in leading-edge processes.

 

Column Supervisor: Koji Kakumoto (President, OTIS Co., Ltd.)

After studying abroad and working in planning and development at a trading company, he joined OTIS Co., Ltd. in 2011. While primarily working in the Corporate Planning Department, he has also served concurrently in manufacturing and technical divisions, and since 2018 has served as President, working to drive business growth and strengthen the organization.

 

This article is a general technical explanation intended for educational purposes and does not refer to any specific company, product, or technology.