Why It Matters

In semiconductor manufacturing, wafer grinding and polishing are essential post-processing steps that reduce wafer thickness, improve flatness, and prepare the surface for packaging. Precise thickness control is critical—especially as wafers become thinner—to avoid issues such as cracking, warping, or over-grinding.

Advanced packaging technologies, such as 3D IC and fan-out wafer-level packaging (FOWLP), require wafers with highly consistent thickness. Any deviation can lead to device failure, poor bonding quality, or low production yield. Therefore, real-time, high-precision thickness monitoring during the grinding and polishing process is vital for quality assurance and production efficiency.

Common Measurement Methods

Measurement Principle and Process

The dual-head chromatic confocal thickness sensor operates based on the principle of spectral focus separation. A pair of optical probes—positioned on both sides of the wafer—simultaneously capture the distance to the top and bottom surfaces of the wafer without making contact.

Measurement steps:

1. Probe Alignment: The upper and lower confocal probes are aligned vertically across the wafer, mounted on a precision fixture.

2. Real-Time Scanning: As the wafer moves through the grinding or polishing stage, the system continuously collects distance data from both sides.

3. Thickness Calculation: The total wafer thickness is calculated as the difference between the top and bottom surface positions in real time.

4. Monitoring and Feedback: The system can send feedback to grinding equipment to adjust pressure or speed dynamically.

This non-contact, real-time method ensures consistent monitoring and control without interrupting the process.

Tronsight Solution



Recommended Product: TS-C2600←Click for more details 

The TS-C2600 series chromatic confocal sensor system is specially designed for dual-probe thickness measurements with sub-micron accuracy and outstanding stability.

Key features:

• Dual-probe configuration for through-thickness measurements

• Submicron thickness resolution

• Excellent performance on transparent, polished, or semi-transparent wafers

• Robust industrial design for in-line process integration

Whether used in 300 mm wafer grinding stations or advanced CMP (Chemical Mechanical Planarization) lines, the TS-C2600 ensures ultra-precise, real-time thickness control.

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