Reflectometric method for measuring residual oxides in through-silicon vias for 3D chip integration

Area of Science:

• Semiconductor Manufacturing
• Optical Metrology
• 3D Chip Architectures

Background:

• Ensuring inter-layer contact in 3D chip fabrication is critical.
• Current methods like scanning electron microscopy are destructive and time-consuming.
• Accurate metrology is essential for process control in microelectronics.

Purpose of the Study:

• To develop a rapid, non-destructive optical technique for metrology in 3D chip fabrication.
• To simultaneously measure through-silicon via (TSV) depths, silicon wafer thickness, and residual oxide thickness.
• To provide a feasible alternative to current destructive metrology methods.

Main Methods:

• Utilized Fourier peak shift analysis (FPSA).
• Employed reflectance measurements in the near-infrared (1200 nm-2200 nm) spectral regions.
• Applied FPSA to samples from a commercial TSV integration process for MEMS and CMOS.

Main Results:

• Demonstrated good agreement between FPSA measurements and reference scanning electron microscopy data.
• Confirmed the feasibility of FPSA for in-line and in-situ metrology in semiconductor fabrication.
• Showcased the potential for simultaneous measurement of TSV depth, wafer thickness, and residual oxide.

Conclusions:

• FPSA is a viable non-destructive optical technique for 3D chip metrology.
• The method offers accurate and simultaneous measurements crucial for process control.
• FPSA holds significant potential for real-time monitoring in advanced semiconductor manufacturing.