Mastering the Role of Photoresist Stripping Agents in Semiconductor Manufacturing

The Critical Role of Stripping Agents in Microfabrication

In the world of semiconductor and electronics manufacturing, precision is non-negotiable. One of the most intricate steps in this high-stakes process is photolithography, which involves applying a photoresist to define microscopic circuit patterns on a silicon wafer. But once the etching or ion implantation is done, the residual photoresist must be completely removed. This is where photoresist stripping agents become indispensable.

A high-performance photoresist stripping agent ensures clean surfaces, prevents contamination, and protects the integrity of wafer substrates. Without an effective stripping solution, defects and residues can compromise the final product’s functionality, especially in advanced node semiconductor technologies.

Composition and Chemistry Behind Modern Stripping Agents

Tailored Formulations for Diverse Requirements

Not all photoresist materials are created equal — nor are the stripping agents. Advanced formulations combine a variety of active chemicals including amines, hydroxylamine, solvents, chelating agents, and corrosion inhibitors to balance performance with substrate safety. Yuanan’s proprietary stripping agents, for example, are engineered to:

• Dissolve hardened or cross-linked resists,

• Minimize metal corrosion on aluminum, copper, and gold layers,

• Ensure compatibility with sensitive dielectric materials like low-k films.

Some stripping agents are aqueous-based, while others rely on solvent-heavy formulas, depending on the resist type and underlying materials. The trick lies in formulating a product that strips completely while leaving no ionic or metallic residues behind.

Why Choosing the Right Stripping Agent Matters

Process Compatibility Is Key

A misaligned photoresist removal step can lead to catastrophic yield loss. Therefore, compatibility with specific etch processes, implant steps, or low-k materials is critical. Yuanan’s solutions are extensively tested for compatibility across a wide range of wafer fabrication steps — from traditional CMOS lines to cutting-edge EUV lithography.

Performance Metrics That Define Excellence

The best photoresist stripping agents perform strongly in several areas:

• Removal Efficiency: Strips even deeply hardened resists quickly.

• Material Selectivity: Leaves underlying films intact.

• Surface Cleanliness: Prevents metal redeposition and residue formation.

• Thermal Stability: Performs at varied process temperatures.

• Environmental Compliance: Low VOCs and biodegradable formulations when possible.

Key Applications Across the Semiconductor Industry

From logic chips and memory devices to MEMS and compound semiconductors, photoresist stripping agents serve vital roles. Their use is not confined to a single lithography stage. They’re applied after:

• Ion implantation (where resist becomes highly carbonized),

• Plasma etching (which can lead to sidewall hardening),

• Dual damascene processes (requiring selective removal without disturbing dielectric stacks).

In advanced packaging, particularly fan-out wafer-level packaging (FOWLP), the stripping chemistry must protect ultra-thin wafers and high-density redistribution layers. Yuanan has developed formulas specifically tuned for these modern challenges.

Common Challenges in Photoresist Stripping—and How to Overcome Them

Residue Problems in Advanced Nodes

As device geometries shrink below 5nm, resist films become thinner but more complex in chemistry, often undergoing hardening due to plasma exposure. These changes can cause traditional solvents to underperform. Yuanan’s high-activity agents target these residues through a dual-action mechanism—swelling and dissolving—followed by thorough rinsing.

Corrosion and Material Degradation

Stripping agents that contain aggressive amines or strong acids can damage metals like copper or aluminum. Yuanan’s corrosion-inhibited formulations preserve sensitive layers, even under extended soak conditions, helping maintain electrical performance and surface planarity.

Throughput and Cost Efficiency

With semiconductor fabs aiming for higher throughput, batch and single-wafer wet benches must be optimized. Yuanan’s solutions feature fast removal times, reducing soak durations and allowing fabs to maintain high-volume output without compromising quality.

Wet Stripping vs. Plasma Ashing: A Strategic Choice

While dry plasma ashing is another method for resist removal, it often falls short with hard-baked or implant-hardened films. Wet chemical stripping using high-performance agents like those developed by Yuanan is:

• More efficient for thick or crosslinked layers

• Less damaging to sensitive low-k or porous substrates

• Better at clearing residues in high aspect ratio features

Many fabs adopt a hybrid approach: initial plasma ashing followed by a wet strip, ensuring total removal with minimal material damage.

Conclusion

In the rapidly evolving semiconductor industry, choosing the right photoresist stripping agent is no longer just a technical decision — it's a strategic one. With over a decade of experience in precision chemistry and close collaboration with fab engineers worldwide, Yuanan delivers unmatched reliability, safety, and performance.

Whether you're handling deep-UV hardened resists or tackling next-gen EUV photoresist residues, Yuanan’s advanced formulations are built to meet the challenge. Reach out today to explore how we can optimize your resist removal process — and elevate your yield, performance, and environmental footprint.