Plasma Surface Treatment in Semiconductor Packaging
Plasma cleans and activates surfaces quickly and in a controlled manner. In semiconductor packaging, this supports highly particle-free process control, helping to reduce waste and improve quality. Surface treatment can be tailored to the specific application, using Openair-Plasma® at atmospheric pressure or AURORA-Plasma in a low-pressure environment. Improved adhesion and wettability can contribute to greater product stability and help minimize interface failures such as Interface Delamination Mode (IDM) or Cohesive Cracking Mode (CCM).
Interface quality is crucial
Plasma cleans and activates surfaces quickly and in a controlled manner, either inline at atmospheric pressure or in a controlled low-pressure environment. In the semiconductor industry in particular, this enables highly particle-free process control, which reduces waste and increases quality. Improved adhesion and wettability can also contribute to service life and product stability by helping to minimize interface failures such as Interface Delamination Mode (IDM) or Cohesive Cracking Mode (CCM).
Modern semiconductor products consist of complex multi-material systems, from metal/metal and metal/polymer interfaces to various polymer combinations. Their reliability depends crucially on clean, durable bonds at these interfaces. Even small defects can lead to delamination, cracks or unexpected failures.
Four main factors can compromise interface quality. Oxides in undesired areas can hinder bonding and electrical contact. Poor surface wettability can prevent uniform adhesion and reliable material flow during joining. Particles and residues may create defects that weaken the connection or cause premature failure. Differences in the coefficients of thermal expansion (CTE mismatch) can generate mechanical stress and microcracks during temperature changes, reducing long-term reliability.
Plasma technology offers different ways to address these challenges. Openair-Plasma® enables targeted treatment at atmospheric pressure, while AURORA-Plasma provides low-pressure plasma treatment in a controlled chamber environment.
Wafer Cleaning – Plasma Solutions for Pristine Surfaces
Advanced semiconductor devices start with the purest wafer surfaces, since every process step depends on them. Silicon wafers, chips, and high-performance semiconductors are extremely sensitive – even the smallest contamination can affect performance and yield. Depending on the application and process requirements, both atmospheric-pressure and low-pressure plasma provide effective solutions for cleaning and activating these sensitive surfaces.
For inline processing, Openair-Plasma® enables surface cleaning directly at atmospheric pressure, eliminating the need for an additional vacuum step and supporting automated production workflows. AURORA-Plasma extends the range of treatment options with controlled low-pressure plasma for homogeneous treatment of larger surfaces, complex geometries or multiple components.
Wafers can move directly from slicing and polishing into Openair-Plasma® treatment, where organic contamination and particles are effectively removed. The result: fewer defects, efficient processing and reproducible surface preparation.
Where chamber processing is better suited to the application, AURORA-Plasma provides uniform treatment under defined low-pressure conditions. This gives manufacturers the flexibility to select the plasma process that best matches the component geometry and production setup.
Result: Clean and reproducibly prepared surfaces provide the basis for subsequent processes such as wire bonding, die attach and encapsulation.
Die Attachment and Interconnection
A reliable connection is at the heart of semiconductor packaging. Contaminated or poorly prepared surfaces can lead to bonding errors, delamination, “non-stick on pad” and premature failure.
In processes such as wire bonding, die bonding (flip chip) and adhesive bonding, surface quality has a direct influence on reliability and performance. Critical surfaces such as substrates, bond pads and chips/dies can be prepared with Openair-Plasma® in an inline process or treated with AURORA-Plasma under controlled low-pressure conditions. Plasma cleaning and activation improve surface wettability and adhesion and create defined conditions for subsequent bonding processes.
Lead Frame—Oxide Reduction
Oxide layers on metal lead frames can weaken or prevent strong, reliable connections in semiconductor devices. With Openair-Plasma® and REDOX®, these unwanted oxide layers are removed inline, dry and without vacuum chambers, allowing seamless integration into the production process. The result is improved electrical and mechanical bond quality, along with higher production yields, reduced waste and consistent, repeatable surface conditions for reliable processes.
Die Bonding—Why is plasma indispensable before the die attach process?
The quality of the die attach process is crucial for the reliability and performance of semiconductor devices. Uneven bonding, voids or poorly adhering dies can compromise functionality and long-term reliability.
Surface preparation can follow different process routes. Openair-Plasma® cleans and activates dies and substrates inline at atmospheric pressure, while AURORA-Plasma offers treatment in a controlled low-pressure environment. Both approaches create defined surface conditions for subsequent bonding processes. Organic residues can be removed and surface properties modified to improve wettability and adhesion.
The benefits include reliable and reproducible surface preparation, improved adhesion for adhesives and epoxies, and better wettability. This helps reduce voids, delamination and adhesion-related defects, contributing to higher yields, less waste and consistent product quality.
Wire bonding—Maximum reliability through plasma activation
A reliable wire bond starts with a clean, activated surface. Even small amounts of contamination, such as oxides or organic residues, can contribute to “non-stick on pad,” reduced shear strength or premature bond failure.
For wire bonding, plasma treatment can be adapted to the production environment. Openair-Plasma® prepares critical surfaces directly within the production line, whereas AURORA-Plasma enables uniform low-pressure treatment in a controlled chamber process. Both technologies can create defined surface conditions prior to bonding and improve the wettability and adhesion characteristics of critical surfaces.
This helps reduce defects such as weak bonds and bond lift while supporting stable, repeatable bond quality and higher production yields.
Thermo-Compression Bonding (TCB)—Plasma ensures perfect flux-free connections
With the Openair-Plasma® and REDOX® processes, you create the ideal conditions for even the most demanding bonding applications—ensuring reliable advanced packaging and high-end performance. These innovative surface treatment technologies enable stable, void-free connections without the need for flux, providing maximum process reliability and repeatability. At the same time, they support environmentally friendly and cost-efficient production, while delivering superior electrical and mechanical reliability for long-term performance and product quality.
Plasma before fluxing
In Thermo-Compression Bonding (TCB), the quality of the surface determines the reliability and performance of the entire connection. Plasma treatment prior to fluxing creates a uniform, high-energy surface and ensures optimal wetting behavior. This significantly reduces the amount of flux required, making bonding more reliable and measurably increasing the reliability of the device.
Fluxless TCB
The removal of metal oxides is particularly important in flux-free TCB processes. Here, Plasmatreat's REDOX® technology offers automated, inline-capable plasma reduction: metal surfaces are completely cleaned and activated during the ongoing production process, and oxide layers are removed—without the use of chemicals or wet processes.
Encapsulation Preparation
Reliable protective encapsulation depends on well-prepared surfaces. Residues, oxides or insufficient wettability can contribute to delamination, voids and other defects, affecting the electrical performance and long-term stability of the package.
For surface preparation prior to encapsulation, Openair-Plasma® enables inline treatment at atmospheric pressure, while AURORA-Plasma provides controlled low-pressure plasma treatment. Plasma treatment improves surface wettability and adhesion, supporting uniform encapsulant flow and reliable bonding to the substrate.
Activation Before Underfill
High and uniform surface energy supports reliable wetting and flow of underfill materials. Openair-Plasma® activates substrate surfaces directly within the inline process, while AURORA-Plasma enables uniform treatment under controlled low-pressure conditions. Plasma treatment removes particles and organic residues from preceding process steps and improves surface wettability and adhesion.
This supports uniform underfill distribution and fillet formation while helping to reduce voids and delamination, contributing to reliable encapsulation and long-term package stability.
Surface Preparation for Molding and Encapsulation
The surface quality of the substrate plays a critical role in reliable molding and protective encapsulation. Materials such as lead frames, wires and other package components require well-defined surface conditions to support material flow, adhesion and long-term stability.
Different plasma processes can be selected according to the specific surface and process requirements. Openair-Plasma® provides inline cleaning, activation and, in combination with REDOX®, targeted oxide reduction. AURORA-Plasma enables uniform low-pressure treatment of components in a controlled chamber environment. PlasmaPlus® adds another option by applying thin functional coatings to modify and protect surfaces.
Together, these processes can improve wettability and adhesion, support uniform material flow and help reduce voids and delamination, contributing to reliable molding and encapsulation processes.
Nano coatings for optimum EMC adhesion
For particularly demanding packaging applications, nanoscale plasma coatings ensure optimum bonding between epoxy mold compounds (EMCs) and the prepared substrates or dies. The result: superior adhesion, maximum reliability, and consistent performance—even under the highest thermal and mechanical loads. These nano-coatings create precisely tailored, highly active surfaces that effectively prevent delamination and cracking. This keeps the package stable and durable—from the first functional test to years of field use. Fewer defects, more output—and consistently high quality.
Barrier Coatings—Protection at the atomic level for sensitive ICs
Modern barrier coatings such as PlasmaPlus® provide sensitive semiconductor components with reliable protection against moisture, migration, and a wide range of environmental influences. The atmospheric, ultra-thin protective layer—typically only 700 to 1,000 nanometers thick—forms an effective shield around internal components. This advanced coating technology offers reliable protection against water and ionic contamination, ensures electrical insulation and long-term performance, and maintains high resilience under thermal and mechanical stress. As a result, every IC package remains fully functional and electrically stable, even under the most demanding environmental conditions.
Final Assembly Cleaning & Marking
The advantages of this approach become immediately clear: end products remain completely free of particles and residues all the way to the delivery point, ensuring the highest standards of cleanliness and precision.
At the same time, secure and permanent marking can be applied to any surface, guaranteeing traceability and durability. By minimizing scrap, you achieve maximum yield, making processes both efficient and cost-effective.
Throughout production, process reliability and comprehensive quality assurance are maintained,right up to the final step. Only with clean, optimally prepared end products can true production reliability be ensured, allowing you to consistently deliver perfection and exceed customer expectations from start to finish.