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Written by Dr Amit Pratap Singh
Reviewed By Dr Alidad Amirfazli
Reviewed: 28
This is a practical guide to Surface Science for researchers working in the Semiconductors Industry.
In this all-new guide you’ll learn all about:
Let’s dive right in.
Semiconductor manufacturers face the constant challenge of maximizing performance and refining processes. Often underestimated, surface properties play a crucial role in optimizing these performances. By measuring these properties, we gain valuable insights into material properties, processes, and device performance, ultimately leading to:
We use the important surface properties below to understand the behavior of Semiconductors products and improve their quality.
Young – Laplace Method
Polynomial Method
Dynamic Contact Angle
Ideally, when we place a drop on a solid surface, a unique angle exists between the liquid and the solid surface. We can calculate the value of this ideal contact angle (the so-called Young’s contact angle) using Young’s equation. In practice, due to surface geometry, roughness, heterogeneity, contamination, and deformation, the contact angle value on a surface is not necessarily unique but falls within a range. We call this range’s upper and lower limits the advancing contact angle and the receding contact angle, respectively. The values of advancing and receding contact angles for a solid surface are also very sensitive. They can be affected by many parameters, such as temperature, humidity, homogeneity, and minute contamination of the surface and liquid. For example, the advancing and receding contact angles of a surface can differ at different locations.
Practical surfaces and coatings naturally show contact angle hysteresis, indicating a range of equilibrium values. When we measure static contact angles, we get a single value within this range. Solely relying on static measurements poses problems, like poor repeatability and incomplete surface assessment regarding adhesion, cleanliness, roughness, and homogeneity.
In practical applications, we need to understand a surface’s liquid spreading ease (advancing angle) and removal ease (receding angle), such as in painting and cleaning. Measuring advancing and receding angles offers a holistic view of liquid-solid interaction, unlike static measurements, which yield an arbitrary value within the range.
This insight is crucial for real-world surfaces with variations, roughness, and dynamics, aiding industries like cosmetics, materials science, and biotechnology in designing effective surfaces and optimizing processes.
Learn how Contact Angle measurement is done on our Tensiometer
For a more complete understanding of Contact Angle measurement, read our Contact Angle measurement: The Definitive Guide
This property measures the force that acts on the surface of a liquid, aiming to minimize its surface area.
Dynamic Surface Tension
Dynamic surface tension differs from static surface tension, which refers to the surface energy per unit area (or force acting per unit length along the edge of a liquid surface).
Static surface tension characterizes the equilibrium state of the liquid interface, while dynamic surface tension accounts for the kinetics of changes at the interface. These changes could involve the presence of surfactants, additives, or variations in temperature, pressure, and composition at the interface.
Dynamic surface tension is essential for processes that involve rapid changes at the liquid-gas or liquid-liquid interface, such as droplet and bubble formation or coalescence (change of surface area), behavior of foams, and drying of paints (change of composition, e.g., evaporation of solvent). We measure it by analyzing the shape of a hanging droplet over time.
Dynamic surface tension applies to various industries, including cosmetics, coatings, pharmaceuticals, paint, food and beverage, and industrial processes, where understanding and controlling the behavior of liquid interfaces is essential for product quality and process efficiency.
Learn how Surface Tension measurement is done on our Tensiometer
For a more complete understanding of Surface Energy measurement, read our Surface Tension measurement: The Definitive Guide
Learn how Surface Energy measurement is done on our Tensiometer
For a more complete understanding of Surface Energy measurement, read our Surface Energy measurement: The Definitive Guide
The sliding angle measures the angle at which a liquid film slides over a solid surface. It is commonly employed to assess the slip resistance of a surface.
Learn how Sliding Angle measurement is done on our Tensiometer
For a more complete understanding of Sliding Angle measurement, read our Sliding Angle Measurement: The Definitive Guide
Within the Semiconductors industry, several case studies exemplify the advantages of conducting surface property measurements.
In photolithography, meticulous pattern creation is key to manufacturing complex semiconductor devices. This process relies heavily on the delicate interplay between the photoresist and the substrate. Photoresist adhesion to the substrate acts as a linchpin, directly determining the sharpness and precision of the resulting patterns. To achieve optimal results, manufacturers delve into the surface science of these properties. By examining the substrate’s surface energy and analyzing the contact angle exhibited by the photoresist, they gain valuable insights to fine-tune adjustments.
This refining process enhances adhesion properties, ultimately leading to a seamless pattern transfer. The benefits are manifold, including increased yields, sharper results, and a significant reduction in defects throughout the lithography process.
Chip packaging relies heavily on adhesives to securely bind the delicate semiconductor die to its protective casing. However, a major challenge arises from leftover adhesive residue, which can negatively impact device reliability.
To combat this issue, manufacturers meticulously measure and manage the sliding angle of the packaging material during application. This precise control ensures that the liquid adhesive smoothly glides away, leaving no unwanted residue behind. This optimization delivers two key benefits: firstly, it significantly reduces the risk of electrical shorts or unintended connections, and secondly, it effectively boosts the overall electrical performance of the device.
To achieve successful immersion lithography, meticulous management of the immersion fluid is crucial. A major failure point is the receding meniscus event, which leaves residual liquid behind on the wafer as a thin film or droplets. Ideally, the immersion fluid should be confined near the lens, allowing the wafer to scan smoothly during exposure.
For a semiconductor manufacturer, the meniscus failure mechanism remained a significant hurdle, hindering the successful implementation of immersion lithography. Recognizing the critical role of surface forces in drainage and pattern collapse during lithography, they sought a solution from a laboratory. The scientists, understanding the importance, developed a new fluid formulation with precisely tailored surface tension characteristics that facilitated proper liquid drainage, eliminating the meniscus issue.
If you are interested in implementing these or any other applications, please contact us.
In an industry where precision reigns supreme, where do Semiconductors manufacturers turn to ensure their products can survive scrutiny? The answer lies in standards and guidelines: the compass that guides cosmetics manufacturers through the complex maze of quality and performance.
In ULSI fabrication the particle contamination on silicon wafer can impact the final yield badly. To suppress particle surfactants can be added. In this regard, D1331-14 covers the guidelines to evaluate the effectiveness of surface active agents in reducing surface tension. This method also helps in predicting the interactions between liquids and solid surfaces that can be used to establish wetting properties.
Silicon wafers with hydrophobic surfaces can be bonded at room temperature (RT) with the help of a dip in diluted HF and that becomes possible due to Dispersion van der Waals forces. D7490-13 standard takes the help the concept that total free energy at a surface is the sum of contributions from different intermolecular forces, such as dispersion, polar and hydrogen bonding. This test method provides a procedure to calculate the surface properties like surface tension and its dispersion and polar components of the solid.
We hope this guide showed you how to apply surface science in cosmetics industry.
Now we’d like to turn it over to you:
Droplet Lab was founded in 2016 by Dr. Alidad Amirfazli, faculty member at York University, and two of his researchers, Dr. Huanchen Chen and Dr. Jesus L. Muros-Cobos.
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