The definition is simple.

Analysis technology that identifies the causes of defects and failures that have occurred and leads to recurrence prevention.

Its targets are diverse.

● Manufacturing defects

● Material defects

● Design deficiencies

● Assembly problems

● Causes in the usage environment

It is technology that pinpoints the true cause of how things fail.

There are three reasons.

① The starting point for yield improvement

② The basis for reliability assurance

③ Responding to customer complaints

Especially in volume production, a single defect → losses of millions of units.

Failure analysis is the last bastion protecting the factory’s profits.

Analysis is systematized.

① Reproducing the failure

② Electrical localization

③ Physical localization

④ Estimating the cause

⑤ Planning recurrence prevention measures

The key point is: do not destroy things blindly. If the order is wrong, the evidence disappears.

The first step is electrical analysis.

Typical techniques:

● I-V measurement → judging leakage / disconnection

● OBIRCH → locating points of current concentration

● TIVA → detecting leakage locations

● Emission microscopy → detecting abnormal light emission

Purpose: to identify the coordinates of the failure.

Once the electrical location has been identified, the work moves to physical analysis.

Typical techniques:

● Optical microscope → surface observation

● SEM (scanning electron microscope) → high-resolution observation

● TEM → atomic-level observation

● FIB → cross-section preparation

● X-ray / CT → non-destructive internal observation

Only at this point is the failure structure visualized.

Commonly found failures:

● Wiring disconnection → EM, processing defects

● Short circuits → residues, foreign matter

● Gate oxide breakdown → TDDB, ESD

● Voids → solder / wiring

● Cracks → caused by thermal stress

Classification of failure modes becomes basic data for recurrence prevention.

These have been increasing in recent years.

● Bump cracks

● RDL disconnections

● Delamination

● TSV defects

With 3D and fan-out, the difficulty of analysis is rising sharply.

Isolating the cause is important.

● Manufacturing-induced: early defects, process variation

● Usage-induced: overvoltage, thermal runaway, humid environments

This is also directly linked to where responsibility lies.

It is becoming harder at advanced nodes.

① Wiring cannot be seen (nm scale)

② More layers

③ 3D stacking

④ Diversification of materials

Even when something fails, it is hard to find.

Recent evolution:

● AI classification of defect images

● Automatic estimation of failure modes

● Big data correlation analysis

● Shorter analysis times

FA is also becoming data science.

FA is not only about technology.

● Writing reports

● Explaining causes

● Proposing recurrence prevention

● Restoring trust

From the customer’s point of view, it is an area where a company’s integrity shows.

Typical composition:

● Device engineers

● Analysis equipment engineers

● Materials analysts

● Process engineers

● Quality assurance

Comprehensive knowledge is required.

Directions of evolution:

● Non-destructive 3D analysis (higher-resolution X-ray CT)

● AI defect classification

● In-line FA

● Wafer-level failure analysis

● Isolating failures between chiplets

It is evolving, led by packaging.

・Failure analysis is the science of determining causes

・It is the starting point for yield improvement and reliability assurance

・The basic order is electrical localization → physical analysis

・SEM / FIB / TEM are the main tools

・The difficulty of analysis is rising sharply with 3D

・AI analysis is at the core of next-generation FA

1.Explain the basic flow of failure analysis.

2.Why is electrical analysis performed first?

3.Name one reason why failure analysis is difficult for advanced devices.

4.Why is FA important in responding to customers?

 

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.