Siconnex

Wet Etching Processes for Semiconductor Manufacturing

In modern semiconductor fabrication, the quality of the etching process dictates the yield. Our wet etching processes focus on the precise control of chemical reactions to ensure maximum uniformity and process stability – from complex metal layers to micro-structuring for MEMS.

The core challenge in wet etching is maintaining uniformity while managing chemical efficiency. A highly controlled etching process minimizes uniformity variation and guarantees excellent repeatability across all wafer batches, whether utilizing HF, KOH, or complex acid mixtures.

Possible FEOL & BEOL Process Applications

Metal Etching

Highly selective etching of alloys such as AlCu, AlSi, or AlSiCu.

Freckle & Barrier Etch

Complete removal of silicon residues (freckles) and precise barrier structuring (Ti, TiN, TiW).

Oxide Etching

Implementation of BOE, BHF, or HF-based mixtures, often achieving < 1% in-wafer uniformity.

Si Patterning

Targeted structuring for MEMS utilizing KOH or TMAH under strict temperature control.

Glass Etching

Creation of micro-channels and flow cells through highly concentrated HF processes.

Multi-Process Integration

Tri-Metal-Etch and Photoresist Removal

A typical tri-metal-etch process requires maximum configuration. Our system utilizes up to four chemical tanks to process complex stacks. Often consisting of silver, nickel, and titanium—without manual transfer steps.

Incoming wafer
Tank 1
Silver etch
Tank 2
Nickel etch
Tank 3
Titanium etch
Tank 1
Second silver etch
(pull back)
Tank 4
Organic-based PR strip

Proven Efficiency Gains

By replacing 4x semi-automated wet benches and 2x spin-rinse-dryers with a single BATCHSPRAY® Acid system, fabs achieve significant operational improvements:

0%
Less handling time*
0%
Maintenance cost savings*

Reduction in exhaust consumption comparing 4x semi-automated wet benches with 1x BATCHSPRAY® Acid.

0%
Reduction in exhaust consumption*

*Compared to conventional processes. Numbers vary based on application.

Multi-Process Integration Example

Al Etch

Etching of any kind of metal types is easily achieved through wet processing. To ensure precise etching, it is essential to use a BATCHSPRAY® approach. This method is particularly common with aluminum and its alloys, such as AlCu, AlSi, or AlSiCu. By optimizing chemical exchange homogeneity between the wafer and from wafer to wafer, non-uniformities of less than 3% can be achieved.

Multi-Process Integration Example

Freckle Etch

Performing an AlSi etch means that silicon (Si) grains from the alloy remain on the etched area. To remove these Si residues, a freckle etch is conducted.

Multi-Process Integration Example

Barrier Etch

Barrier layers protect the silicon or underneath layers from diffusing aluminum. They can be etched as a follow-up step following the AlSi and Freckle etch processes.

Multi-Process Integration Example

PR Strip

Finally, the photoresist is stripped either via SicOzone process or by solvent based medias.

Suitable Equipment

Equipment for etching applications

BATCHSPRAY® Acid

BATCHSPRAY® Autoload Acid

BATCHSPRAY® Autoload Multi

BATCHSPRAY® Autoload Multi

FAQs

High uniformity is achieved by optimizing the chemical exchange rate across the wafer surface. Controlling fluid dynamics and temperature minimizes non-linear etch rates, consistently delivering uniformity below 3% (and often < 1% for oxide etches).

The processes accommodate a wide range of chemistries, including H₂SO₄, HF, NH₄OH, KOH, HNO₃, BHF, BOE, KOH, TMAH, and various metal-etching acid mixtures, tailored to specific selectivity requirements.

In many applications, yes. With advanced process control, wet etching offers a highly selective, cost-effective alternative to dry etching, particularly when combined with post-etch residue cleaning to ensure defect-free surfaces.

Any questions?

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