Failure Analysis

Failure Analysis

Failure analysis is a process of investigating and analyzing products that have failed in order to determine the failure mode and the root cause.
In addition to performing failure analysis on products with defects that have occurred during customer processes or in the field, we also analyze failures that have occurred during our manufacturing processes, inspection processes and reliability testing.
In all of these cases, AKM prevents recurrence of the problem by feeding back the failure analysis results to the source of the failure (design, wafer manufacturing, assembly, inspections, etc.).
In this way, the analysis results are used for continuous improvement of the quality and reliability that is built in to each process.

Failure Analysis Flow

Figure below illustrates AKM’s failure analysis flow. Defective products or intermediate products found in AKM’s processes are also analyzed in this flow with coordination with related departments.

Failure Analysis Flow

Root Cause Identification and Problem Solving Tools

As well as clarifying the failure mechanism of defective products by failure analysis, it is more important to check the correlation with the problem symptoms and identify the cause of the occurrence, based on the results of the analysis, and also to implement countermeasures to prevent occurrences.
Figure below illustrates the flow of action within AKM from the results of failure analysis to the implementation of measures to prevent reoccurrences.
These actions are carried out with consultation between engineers in each section (engineers in design, manufacturing, test, quality control, etc.). The 8D (8 Disciplines) process and other methods are also used as management tools for problem solving.

Actions for Problem Solving

Actions for Problem Solving

FA Systems Used for FA by AKM & FA Examples

Technologies for Analysis 

As semiconductor devices have been year by year developed to realize more shrinkage, higher integration and multilayer on the circuit and sensing part, there are also demands for shorter failure analysis periods and a customer service-oriented emphasis on faster identification of the cause of the failure.
Failure analysis of semiconductor devices requires highly precise, highly sensitive analytical instruments capable of enabling observation at the nanometer and micrometer level.
AKM has various types of failure analysis equipment to efficiently and comprehensively analyze the complex behavior of high integrated semiconductor devices.
In addition, AKM is reinforcing the tools and circumstances linked to design-related CAD data.

Analysis Equipment

AKM uses various types of equipment for failure analysis, as shown in Table below (We also use many measurement tools for electrical evaluations in addition to the equipment listed in the table).
AKM makes full use of all these systems to identify the causes of failures.

AKM's Main Analysis Equipment (Each photo below table)

Type

Equipment Name

Application

Equipment Photograph

 Non destructive  X-ray transmission system  Observes the inside of the package
 (condition of wire bonds, etc.).  

Photo-1

 Ultrasonic detection equipment   Observes the inside of the package
 (possible delamination, etc.).  

Photo-2

 (Scanning Acoustic Tomography)
 Semi destructive  Mold opener  Exposes the chip without electrically destroying it by melting the mold resin.

-

 Laser opener  Uses a laser to remove (open) the package resin.

-

 Circuit analysis  Emission microscope

 Identifies the location of abnormal current leakage, etc., by detecting the faint light emission in the chip.   

Photo-3

 EB tester

 Uses an electron beam to analyze the electrical operation of circuits (non-contact).

Photo-4

 Can obtain voltage contrast images and operation waveforms.

 Manual prober

 A probe needle is brought into direct contact with the product to analyze the electrical operation of the circuit.  

-

 OBIRCH analysis equipment

 Detects changes in the current when the sample is being lit by a laser (with local heating by a laser).  

Photo-5

 Used to identify the location of short circuits.
 Logic tester  Uses digital test patterns to evaluate digital function.

-

 FIB for circuit edit

 Corrects wiring in the circuits and creates probing pads, etc.

Photo-6

 Backside polishing system  Exposes and polishes the backside of the chip.  

-

 (Done as a preparatory treatment before emission or OBIRCH analysis, etc.)

 Nano-probing system

 SEM-based probing system.   MOS static characteristics measurement and interconnect analysis with the EBAC method.  

Photo-7

 Physical analysis

 Optical microscope  Optical observations of chips.

-

 RIE system

 Performs dry plasma etching for the removal of SiN and SiO2 films.   

-

 Draft chamber  Local exhaust system for wet etching processing.

-

 Scanning electron microscope  Detailed observation of the profile of the chip surface.

Photo-8

 (SEM)
 FIB/SEM dual system

 Inspecting chip cross-sections by processing using the FIB and then observation using the SEM.  

Photo-9

 EDX  Elemental analysis with characteristic X-ray detection.

-

 Scanning transmission electron microscope

Uses transmitted electrons to perform chip cross-section analysis.

-

  (STEM) (*1)
 Cutter

 Rough cutting for the observation of package cross-sections.

-

 Polisher  Polishing for the observation of package cross-sections.

-

(*1) Equipment at an affiliated company in the AKM Group.

 

       

Photo-1. X-ray Transmission System [Left side with CT function]             Photo-2. Scanning Acoustic Tomography (SAT)

 

 

        

 Photo-3. Emission Microscope                       Photo-4. EB Tester                     Photo-5. OBIRCH Analysis Equipment

 

 

   

                        Photo-6. FIB for Circuit Edit                                                   Photo-7. Nano-probing System

 

 

     

                  Photo-8. Scanning Electron Microscope (SEM)                                   Photo-9. Dual FIB/SEM System

Analysis Examples (Example using Nano-probing System)

The nano-probing system is a SEM-based probing system.  Using the SEM, it achieves nanometer-scale probing. A representative example is the measurement of static characteristics for a single MOS structure. Since probing is done directly onto an exposed contact, the static characteristics of a single MOS on a chip are measured.


Example of Analysis of MOS Static Characteristics Measurement using Nano-probing system
(left: probing, right: measurement results)

The nano-probing system also performs analysis using the absorbed current method (EBAC: Electron Beam Absorbed Current analysis). EBAC analysis is used to discover shorts and opens in the interconnects.


Example of EBAC Analysis

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