Semicon Wet Processes

Understanding Wet Processes in Semiconductor Manufacturing: Applications & Materials

As the demand for smaller, faster, and more powerful electronic devices continues to grow, the semiconductor industry constantly seeks more precise, efficient, and contamination-free manufacturing techniques. Among the critical steps in chip fabrication are wet processes, which play a central role in preparing, cleaning, etching, and treating wafers. 

Table of Contents

What Are Wet Processes?

Applications of Wet Processing

Materials Used in Wet Processing Equipment and Systems

Challenges and Trends

Conclusion

What Are Wet Processes?

Wet processes refer to the use of liquid chemicals, typically acids, bases, solvents, or water for treating semiconductor wafers. These processes are essential at various stages of semiconductor device manufacturing, from wafer cleaning to etching and surface modification. The goal is to remove contaminants, oxidize layers, or etch patterns into the wafer with high precision.

Key Types of Wet Processes:

1. Wet Cleaning

Removes organic residues, particles, and metallic contaminants from wafer surfaces.

Common cleaning chemistries include:

  • RCA clean (a mix of hydrogen peroxide, ammonium hydroxide, and hydrochloric acid)
  • Piranha solution (sulfuric acid and hydrogen peroxide)
  • DI water rinses and megasonic cleaning

2. Wet Etching

Selectively removes layers from the wafer surface using chemicals.

There are two types:

  • Isotropic etching (uniform in all directions)
  • Anisotropic etching (directional etching for defined patterns)

Common materials removed via wet etching include silicon dioxide (SiO₂), silicon nitride (Si₃N₄), and various metal films.

3. Electroplating & Electropolishing

  • Used in interconnect formation, especially for copper metallization.
  • Wet chemistry enables controlled deposition or smoothing of metal films.

4. Oxidation and Surface Treatments

  • Chemical oxidation layers may be grown or removed to prepare the wafer for lithography or doping.

 

Applications of Wet Processing

Wet processing is integrated into multiple steps across semiconductor manufacturing, including:

  • Front-End-of-Line (FEOL) – During transistor formation, wet cleaning ensures surface purity before ion implantation or oxide growth.
  • Back-End-of-Line (BEOL) – In interconnect formation, wet etching and plating are used to shape and fill vias and trenches.
  • Photolithography – Pre- and post-exposure cleans help ensure adhesion and prevent defects.
  • Packaging and final assembly – Surface treatment and residue removal are necessary for wire bonding and die attach processes.

 

Materials Used in Wet Processing Equipment and Systems

The aggressive chemicals used in wet processes require specialised materials that can withstand high purity standards, resist corrosion, and maintain dimensional stability.

Common High-Performance Materials:

  • PTFE (Polytetrafluoroethylene)

Excellent chemical resistance and low surface energy make it ideal for tubing, wafer handling components, and seals in wet benches.

  • PFA (Perfluoroalkoxy alkane)

Offers similar resistance to PTFE but with improved clarity and processability. Common in piping, fittings, and chemical delivery systems.

  • PVDF (Polyvinylidene fluoride)

Good chemical resistance and mechanical strength. Used in fluid handling components.

  • PCTFE (Polychlorotrifluoroethylene)

Ultra-low permeability, excellent chemical resistance, dimensional stability under vacuum. Common in valve seats, gas delivery seals, load lock chamber components.

  • ETFE / ECTFE (Ethylene-Tetrafluoroethylene / Ethylene-Chlorotrifluoroethylene)

Excellent resistance to strong acids, durability, and easy to process into complex geometries. Used in wet process tanks, pipe linings, chemical delivery systems.

  • Quartz and Borosilicate Glass

Used in tanks and carriers for high-temperature or HF-based chemistries.

  • Ceramics (e.g., alumina, silicon carbide)

Used in high-wear areas and where contamination control is critical.

  • High-purity silicon carbide and graphite composites

Employed in wafer carriers and susceptors in aggressive chemical environments.

 

Challenges and Trends

As semiconductor nodes shrink below 5nm and 3nm, the margin for error becomes continues to tighten. This puts greater pressure on wet process control and innovation. Some emerging challenges and trends include:

  • Micro-contamination control

With increasingly sensitive devices, even sub-micron particles or residual films can cause yield loss. Advanced filtration, inline monitoring, and real-time analytics are being adopted to detect and eliminate these threats.

  • Tool miniaturisation and footprint optimisation

As fab space becomes more valuable, equipment designers are focusing on more compact, modular wet benches and systems to maximise throughput per square foot.

  • Automation and robotics integration

Automation is reducing human handling and improving consistency in wet processing steps. From wafer transfer to chemical dosing, robotic systems are enhancing safety, precision, and productivity.

  • Chemical waste reduction and recycling

With sustainability goals rising across the industry, fabs are investing in chemical reclamation systems and closed-loop recycling to reduce hazardous waste and overall operating costs.

 

Conclusion

Wet processes may not grab headlines like EUV lithography or AI chip architecture, but they are a foundational element of semiconductor fabrication. Selecting the right materials for tools and handling equipment is just as crucial as the chemistries themselves. As device architectures evolve and complexity increases, so too must the precision and reliability of wet processing technologies.

Let’s talk about how Fluorocarbon’s high performance materials can enhance the performance and reliability of your wet processing tools. Contact Us.

Similar Articles