Hi there! 👋
When we think of semiconductor photolithography, our minds often go straight to exposure and etching—the “cool” stuff. But have you ever stopped to consider what happens after all that patterning is done?
Let me tell you: there’s one more essential step that often gets overlooked—the strip process. And believe me, it’s more than just cleanup.
What Is the Photoresist Strip Process?
In the simplest terms, the strip (or de-scum) process removes the photoresist (PR) layer that’s no longer needed after etching or ion implantation.
Think of it as the final sweep after all the core lithography work is done.
Leaving photoresist residue on the wafer can lead to:
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Contamination
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Pattern misalignment in the next layer
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Increased particle defects
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Reduced process yield
So, even though strip happens at the end, it’s foundational to the success of everything that follows.
Types of Strip Processes
Depending on the process node, throughput, and environmental constraints, engineers choose between two main types of stripping methods:
1. Wet Strip
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Uses chemical solvents (like NMP or DMSO) to dissolve and wash away the PR.
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Typically involves a batch process with heated chemicals and DI water rinse.
Pros:
✅ Cost-effective
✅ Simple system design
Cons:
❌ Environmental concerns
❌ Chemical handling risks
2. Dry Strip
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Uses plasma (O₂, CF₄, or other gases) to break down and ash the PR without liquids.
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Conducted in plasma ashing systems or downstream plasma tools.
Pros:
✅ High precision
✅ Cleaner surface with minimal residues
✅ Environmentally safer
Cons:
❌ Higher equipment cost
❌ Slower throughput than wet methods
Today, as semiconductor geometries shrink below 10nm, dry strip has become the industry standard due to its superior control and cleanliness.
Post-Strip Inspection: How Do You Know It Worked?
Stripping is only useful if you’re sure it’s complete. That’s where metrology and inspection come in. These tools help detect residues, damage, or surface alterations left behind.
Ellipsometer
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Measures changes in surface thickness and optical properties
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Useful for detecting residual films or changes in oxide thickness
Why the Strip Process Matters More Than Ever
As devices scale down and multilayer stacks get more complex, clean interfaces between layers are non-negotiable. Even a thin residue of PR can throw off alignment, cause defects, or contaminate deposition layers.
The strip process isn’t just about removal—it’s about ensuring that the wafer is truly ready for what’s next.
In other words, strip is not cleanup—it’s completion.
We’re Here to Help
We warmly welcome any inquiries regarding product specifications or pricing.
With English-speaking staff on our team, we’re well-prepared to assist you efficiently and clearly.
Please don’t hesitate to contact me directly — I will personally respond to your email.
You can reach me at: hy.kang@kovistek.com