Many semiconductor failure-analysis techniques require direct access to structures that are hidden inside an IC package. The semiconductor die, bond pads, bond wires and other critical components may be completely covered by epoxy molding compound or other packaging materials. Before these structures can be examined using techniques such as optical microscopy, emission microscopy, SEM or electrical probing, part of the package may need to be carefully removed.
This process is known as IC decapsulation, often shortened to IC decap or decapping. IC decapsulation is an important sample-preparation step in semiconductor failure analysis. The goal is not simply to remove packaging material. The package must be opened while preserving the structures and evidence needed for the subsequent investigation. This distinction is critical.
If decapsulation damages a bond wire, attacks a bond pad, removes contamination or alters the original failure site, the preparation process can create new artifacts and potentially compromise the root-cause investigation. Semiconductor decapsulation methods are therefore selected according to the package construction, materials, failure being investigated and analytical technique that will follow.
For an overview of the complete failure-analysis process, see:
Semiconductor Failure Analysis: The Complete Guide to IC Failure Analysis
For the physical-analysis workflow, see:
Physical Failure Analysis (PFA) of Semiconductor Devices
IC decapsulation is the controlled removal of semiconductor package material to expose the die or other internal components for inspection, testing or failure analysis.
Depending on the objective, decapsulation may expose:
The amount of material removed depends on what needs to be analyzed. In some investigations, only a small window needs to be opened above part of the die. In others, most of the molding compound may need to be removed.
The overriding objective is to expose the necessary structure without altering the evidence associated with the original failure.
Decapsulation is used when the package prevents access to the region requiring analysis. After the die has been exposed, engineers may perform techniques such as:
Decapsulation may be required during:
It may also be required before more specialized sample preparation.
For example:
Electrical failure
↓
Fault localization
↓
IC decapsulation
↓
Die-level inspection
↓
FIB / SEM / further analysis
↓
Failure mechanism
↓
Root cause
Decapsulation therefore provides physical access. It does not by itself establish why the semiconductor failed.
The best decapsulation process is not necessarily the method that removes package material fastest. The more important question is:
What must remain unchanged after the package is opened?
Depending on the investigation, this may include:
This creates one of the major challenges in semiconductor decapsulation.
The encapsulant must be removed selectively while minimizing damage to the components underneath it. Research into advanced-package decapsulation emphasizes preservation of the original die, bond wires, bond pads, contamination and other potential failure evidence because altering these features can reduce confidence in the subsequent root-cause analysis.
There is no single decapsulation method suitable for every semiconductor package. The main approaches include:
Each method has advantages and limitations.
| Decapsulation Method | Typical Purpose | Main Advantages | Main Considerations |
|---|---|---|---|
| Wet Chemical Decapsulation | Removal of epoxy molding compound to expose the semiconductor die and internal structures | Established process; selective package removal can be achieved; suitable for many conventional plastic packages | Chemical compatibility with bond wires, bond pads, die metallization and failure evidence must be considered |
| Plasma Decapsulation | Selective removal of organic package materials using reactive plasma species | Can preserve sensitive metal structures and contamination evidence; useful for some Cu and PdCu wire packages | Plasma chemistry and process conditions must be matched to the package materials and structures |
| Laser-Assisted Decapsulation | Rapid and localized removal of bulk package material | Fast, precise and useful for creating a cavity before final chemical or plasma processing | Laser energy, thermal effects, removal depth and proximity to sensitive structures must be carefully controlled |
| Mechanical Decapsulation | Bulk package removal, thinning or pre-cavitation before final decapsulation | Controlled physical removal without chemical attack; useful for reducing the amount of encapsulant remaining | Mechanical stress, die cracking, bond-wire damage and depth control must be carefully managed |
| Hybrid Decapsulation | Complex packages where more than one removal technique is beneficial | Combines the speed or bulk-removal capability of one method with the selectivity of another | Requires careful sequencing to avoid introducing artifacts or damaging the failure site |
The choice depends heavily on package materials and the feature that must survive the process. Research and commercial FA systems use combinations of chemical, laser, mechanical and plasma approaches rather than treating one method as
universally superior.
Wet chemical decapsulation removes molding compound using a chemical etchant that attacks the encapsulating polymer while attempting to preserve the semiconductor die and internal metal structures. It is one of the traditional methods used for plastic semiconductor packages.
A controlled process may selectively expose:
Chemical decapsulation can be highly effective, but material compatibility is critical. The chemicals used to remove the package may also interact with metals or other structures that the failure analyst wants to preserve.
This has become particularly important as semiconductor packaging has moved from traditional gold bond wires toward copper and palladium-coated copper structures. Research into copper-wire package decapsulation has specifically focused on developing processes that remove molding compound while minimizing bond-wire attack.
Potential concerns include:
Some wire materials may be more sensitive to a particular chemical environment than others.
A preparation process that works well for one package may therefore be inappropriate for another.
The die’s bond-pad metallurgy must remain intact if electrical probing, microscopy or bond analysis will follow.
If the failure investigation concerns contamination or corrosion, aggressive chemistry could potentially modify the very evidence being investigated.
Package-removal processes should avoid leaving material that interferes with subsequent inspection.
Once the required region has been exposed, unnecessary additional processing can increase the risk of sample damage.
This is why the failure-analysis laboratory should understand the package construction before selecting a chemical decapsulation process.
Plasma decapsulation uses reactive species generated in a plasma to remove organic packaging materials. Unlike liquid chemical decapsulation, the package material is removed through a dry or gas-phase process. Plasma-based decapsulation has become particularly relevant where analysts need to preserve metal structures or sensitive failure evidence.
Atmospheric microwave-induced plasma systems, for example, are used to selectively remove organic molding materials while preserving inorganic structures. Published work on complex stacked-die packages has demonstrated the use of plasma decapsulation to preserve contamination sites and internal structures that were important to the failure investigation.
Potential applications include cases where the laboratory needs to preserve:
Plasma is therefore particularly interesting for packages where conventional chemical preparation could alter sensitive metallic structures. However, the appropriate process still depends on the package materials and analytical objective.
Neither method should automatically be considered the best approach for every device.
The decision depends on what needs to be preserved.
For example, if the purpose of the investigation is simply to expose a robust die surface, a conventional wet process may be entirely suitable.
If investigators need to preserve:
a more selective plasma approach may offer advantages.
The decision should therefore be based on failure-analysis requirements rather than habit.
A laser can remove molding material from a controlled area of a semiconductor package. Laser-assisted decapsulation is particularly useful for removing substantial amounts of package material or creating a cavity before a more selective finishing process. Research on laser decapsulation describes it as a fast and accurate pre-decapsulation method for preparing plastic packages for failure analysis.
A laser can be programmed to remove material only from a selected area.
This can help:
Laser processing does not always need to perform the complete decapsulation.
One approach is:
Laser removes most of the molding compound
↓
A controlled chemical process removes the remaining material near sensitive structures
Research on copper-wire devices has demonstrated combined laser-ablation and chemical-etch approaches designed to expose dies and bond structures while minimizing wire thinning and pad damage.
This illustrates an important principle:
The best decapsulation process may use several methods rather than one.
Because the laser removes material by delivering concentrated energy, the process must be carefully controlled near sensitive structures.
Important factors can include:
The purpose is normally to remove enough material efficiently while leaving a safe margin for the final exposure process.
Mechanical decapsulation uses physical material removal to create access to the semiconductor package. Methods may include precision milling or other controlled machining processes.
Mechanical techniques can be useful for:
Commercial decapsulation systems use controlled mechanical pre-cavitation before final chemical or plasma processing. Mechanical approaches can also accommodate variations in package dimensions that may complicate processes that rely on a fixed removal depth.
A common strategy is:
Mechanical removal of bulk material
↓
Stop before reaching sensitive structures
↓
Final chemical or plasma decapsulation
This reduces the amount of encapsulant that must be removed by the final process.
As with laser pre-decapsulation, the objective is to combine efficiency with preservation of the device.
Physical material removal introduces its own potential risks.
These can include:
Accurate alignment and depth control are therefore important.
Complex semiconductor packages increasingly require hybrid decapsulation workflows.
A hybrid process might combine:
Mechanical milling removes bulk material.
Plasma completes the exposure near sensitive structures.
Laser ablation creates the cavity.
Chemical decapsulation removes the final encapsulation layer.
Mechanical pre-cavitation reduces package thickness.
Chemical processing exposes the die.
The advantage of a hybrid process is that each technique performs the task for which it is best suited.
Published work on copper-wire devices, for example, has used laser ablation followed by a lower-temperature chemical step to expose die and bond structures while reducing damage to sensitive metal features.
Not every investigation requires complete exposure of the semiconductor die.
Only a selected area is opened.
This may be useful when:
A larger portion of the die and internal package structures is exposed.
This may be useful for:
The appropriate approach should be decided before material removal begins.
Traditional plastic wire-bond packages can contain:
The decapsulation process must remove enough molding compound to expose the required structures without damaging the wires or die surface.
The choice of bond-wire material is important because different metallurgies respond differently to preparation processes. The transition toward Cu and PdCu wires has been one reason alternative decapsulation approaches have received increased attention.
Stacked-die packages create additional challenges.
The package may contain:
Removing material from such packages while keeping each layer intact can be significantly more difficult than exposing a single die.
Published work on complex 3D stacked-die packages has shown that preservation of bond wires, contamination and original failure sites becomes particularly important because damage during package opening can compromise the entire root-cause investigation.
Semiconductor packaging is becoming increasingly heterogeneous.
Modern devices may contain:
At the same time, modern semiconductor FA increasingly needs to identify extremely small defects. NIST notes that the complexity of advanced semiconductor structures makes failure analysis increasingly challenging, with reliability sometimes depending on defects at extremely small dimensions.
This makes sample preparation increasingly important.
If the sample is damaged before high-resolution analysis begins, even the most advanced analytical instrument may not recover the lost evidence.
Decapsulation and delayering are not the same process.
Removes package material to expose the semiconductor die or internal package structures.
Removes layers from the semiconductor device itself to access deeper interconnect or transistor structures.
A typical sequence might therefore be:
Package
↓
Decapsulation
↓
Die exposed
↓
Electrical / optical analysis
↓
Delayering
↓
Deeper circuitry exposed
↓
SEM / nanoprobing / other analysis
Keeping the terms distinct helps clarify the failure-analysis workflow.
These processes also serve different purposes.
Provides relatively broad access through the semiconductor package.
Removes extremely localized material from a specific region of the die.
A typical investigation could therefore involve:
Decapsulation
↓
EMMI identifies suspected region
↓
FIB creates site-specific cross-section
↓
SEM examines the defect
For more information, see:
Emission Microscopy (EMMI) detects weak photon emission from electrically active semiconductor defects. For some packaged devices, the molding compound blocks optical access to the die.
Decapsulation may therefore be necessary before front-side EMMI can be performed. The workflow could be:
Electrical characterization
↓
Controlled decapsulation
↓
Device electrically biased
↓
EMMI
↓
Emission location identified
↓
Physical analysis
However, modern thermal and optical localization techniques can sometimes localize packaged defects before decapsulation, allowing analysts to target the subsequent package opening more precisely. This is preferable where practical because it helps avoid unnecessary package removal.
One of the biggest risks in any sample-preparation process is introducing an artifact. An artifact is a feature created by the analysis process rather than by the original semiconductor failure.
Examples might include:
The analyst may then face an important question:
Was this feature present before decapsulation, or did decapsulation create it?
This is why the original device should be documented before destructive preparation.
Useful pre-decapsulation records can include:
Maintaining this chain of evidence improves confidence in the final conclusion.
There is no universal decision tree, but several questions should be answered.
The package construction determines what material must be removed.
Gold, copper, palladium-coated copper and other structures can respond differently to preparation methods.
A corrosion investigation may require different preparation from an investigation of a transistor-level electrical defect.
If additional electrical testing is required after decapsulation, the die, wires and electrical connections must remain usable.
Decapsulation for optical inspection may have different requirements from sample preparation for EMMI, probing or SEM.
If so, partial decapsulation may be possible.
If only one failed device exists, minimizing sample-preparation risk becomes especially important.
Consider a packaged IC that exhibits excessive leakage current.
The leakage is reproduced.
A non-destructive technique identifies a suspected area within the package.
Only the relevant die region is exposed.
Photon emission localizes the electrically active defect more precisely.
A cross-section is prepared through the region.
The physical defect is characterized.
The physical and electrical evidence is correlated. In this workflow, decapsulation serves as a bridge between package-level localization and die-level physical analysis.
Consider an IC showing an open connection on one pin.
Electrical continuity testing confirms the open.
X-ray examination indicates an abnormality near a bond wire.
The package is selectively decapsulated.
Optical microscopy or SEM examines the exposed bond structure.
The analyst determines whether the wire is:
Further investigation is then needed to establish why the bond failed. The decapsulation step should expose the bond structure without creating a new break that could be mistaken for the original failure.
Contamination investigations require particular care. Suppose electrical analysis indicates leakage and investigators suspect foreign material. If the decapsulation process removes or chemically changes the contamination, valuable root-cause evidence may be lost. The preparation technique should therefore be selected specifically to preserve the suspected material. Research into complex stacked-die decapsulation has demonstrated this principle by deliberately evaluating whether contamination sites survived the package-opening process.
Once exposed, the region might be analyzed using:
The package materials should determine the preparation process, not simply the equipment that happens to be available.
If the failure is localized, partial access may preserve more evidence.
A process suitable for one bond-wire material may damage another.
Once the package is opened, the original condition cannot be fully reconstructed.
Any abnormal structure found after preparation should be evaluated for the possibility that it was introduced during decapsulation.
The preparation method itself may alter residues or corrosion products that are critical to root-cause analysis.
Decapsulation exposes the device. Further Electrical Failure Analysis and Physical Failure Analysis are normally required to determine what actually failed.
Once the relevant structures have been successfully exposed, the next analytical step depends on the failure. Possible paths include:
→ Optical microscopy / SEM
→ EMMI / OBIRCH / electrical probing
→ SEM + EDS/EDX
→ FIB cross-section + SEM
→ Nanoprobing → FIB → TEM
→ Optical microscopy / SEM / mechanical bond analysis
The decapsulation strategy should therefore be planned backward from the analytical technique that will follow.
IC decapsulation is the controlled removal of semiconductor package material to expose the die, bond wires, bond pads or other internal structures for failure analysis, reliability analysis or inspection.
IC decapping is another term for IC decapsulation.
Both describe opening a semiconductor package so internal structures can be accessed.
Decapsulation provides physical or optical access to internal semiconductor structures that are otherwise hidden by package material.
After decapsulation, techniques such as optical microscopy, EMMI, SEM and electrical probing may be performed.
Common approaches include:
Research and commercial FA practice include combined laser/chemical, mechanical/final-etch and plasma approaches.
Decapsulation removes part of the package and is therefore an invasive sample-preparation technique.
The goal is usually to preserve the die and whatever internal structures are required for subsequent analysis.
In some cases, yes.
A carefully controlled decapsulation may preserve electrical connectivity so additional electrical analysis can be performed. Plasma-decapsulation studies have specifically demonstrated preservation of copper-wire connectivity for continued FA workflows.
Whether continued operation is possible depends on the package, device, method and amount of material removed.
Copper-based wire structures can be vulnerable to attack or alteration during some conventional package-removal processes. This has led to development of specialized chemical, hybrid and plasma decapsulation techniques intended to preserve copper-wire structures.
Plasma decapsulation uses reactive plasma species to remove organic encapsulation materials while aiming to preserve underlying semiconductor and metal structures.
Atmospheric plasma approaches have been developed specifically for semiconductor package decapsulation and complex failure-analysis applications.
Laser-assisted decapsulation uses controlled laser ablation to remove package material from a selected area.
It is often useful as a pre-decapsulation technique before final package removal closer to sensitive semiconductor structures.
Decapsulation removes the semiconductor package.
Delayering removes layers of the semiconductor die itself to access buried circuitry.
IC decapsulation may appear to be a relatively simple objective:
Remove the package and expose the chip.
In failure analysis, however, that is not sufficient.
The real objective is:
Expose the structures required for analysis while preserving the original condition of the failure site.
A poor preparation process can destroy evidence before the real investigation even begins.
A successful process should therefore be selected according to:
The semiconductor failure-analysis sequence then becomes:
Failure identified
↓
Failure electrically characterized
↓
Defect localized
↓
Correct decapsulation method selected
↓
Die or package structure exposed
↓
Electrical / optical / physical analysis
↓
Failure mechanism identified
↓
Root cause determined
Decapsulation is therefore much more than simply opening an IC package. It is a critical sample-preparation step that can determine whether the subsequent failure analysis succeeds.
If you have a failed semiconductor device that needs IC decapsulation or further failure analysis, AnySilicon can help connect you with companies and laboratories providing the appropriate capabilities.
Typical services may include:
Find a Semiconductor Failure Analysis Company
When requesting support, provide the package type, semiconductor technology, observed failure, number of samples available, bond-wire material if known, previous analysis and what analysis needs to be performed after decapsulation. This information helps the laboratory select the appropriate package-opening method.
