Wet Etching Machine vs. Wet Cleaning Machine: A Battle Between “Precision” and “Cleanliness”

In the field of semiconductor wet-process technology, both wet etchers and wet strippers rely on chemical reagents to interact with the wafer surface; however, their underlying process principles are fundamentally different. The former is used for pattern transfer, while the latter is dedicated to ensuring surface cleanliness. A precise understanding of the fundamental differences between the two in terms of process objectives, chemical mechanisms, and evaluation metrics is a prerequisite for appropriate equipment selection and process optimization. This paper systematically elucidates these differences from these three perspectives.

I. The Fundamental Opposition Between the Core Purpose and the Essence of the Process

The primary objective of a wet etching machine is to selectively remove specific functional materials from the wafer surface, thereby transferring the pattern and defining the circuit structure or device profile. This process is inherently a “patterning process” and serves as a critical step following lithography, requiring precise control over etch depth and edge definition.

The primary objective of wet cleaning equipment is to uniformly remove all types of surface contaminants from wafers, restoring wafer cleanliness and providing a clean substrate for subsequent process steps. At its core, this process is a “pre- or post-processing step” that serves as a critical quality assurance element throughout the entire manufacturing flow; its fundamental focus is on cleaning, not pattern formation.

II. The Distinction Between Mechanism of Action and Chemical Mechanism

A wet etching machine exploits the specific chemical reactions between the etchant and the target materials—such as silicon dioxide, silicon nitride, polysilicon, and metals—to convert the solid materials into soluble species or gases. By using a mask to protect non-target areas, patterned removal is achieved. The process demands high selectivity: for example, when hydrofluoric acid is used to etch silicon dioxide, the etching rates for the silicon substrate and the photoresist are extremely low, thereby ensuring sharp pattern edges.

Wet cleaning machines utilize the dissolving, decomposing, complexing, and stripping actions of cleaning solutions to remove contaminants such as particles, organic matter, metal ions, and native oxide layers. Cleaning agents exhibit little selectivity toward the bulk material of the wafer; for example, SC-1 solution can simultaneously remove both particles and organic contaminants, but it does not target specific functional materials.

III. Direct Mapping of the Evaluation Indicator System

The evaluation metrics for the two types of equipment fully reflect the differences in their process objectives:

Conclusion

A wet etching machine is evaluated based on the “fidelity of pattern transfer,” while a wet cleaning machine is evaluated based on the “ultimate level of surface cleanliness.” The former prioritizes “accuracy”—precise selectivity, uniform etching, and well-defined feature boundaries—whereas the latter emphasizes “purity”—thorough contamination removal, minimal residue, and non-damaging treatment. This fundamental dichotomy dictates further divergence in their equipment architectures and process applications.

For more technical details, please contact our technical consultant at 13861996325!

▲Technical Consultation ▲Follow the Kechip Micro WeChat Official Account