Backside sample preparation of semiconductor chips is a process used in semiconductor manufacturing and failure analysis. It involves preparing the underside (or backside) of a semiconductor wafer or chip for various analyses, such as imaging, inspection, and testing. This technique is commonly used when it’s important to examine the inner structures or layers of the chip, especially for applications like probing or failure analysis.
The key steps involved in backside sample preparation typically include:
- Wafer Thinning: The wafer is thinned to a specific thickness using mechanical grinding or chemical etching. This step is done to make the backside of the chip more accessible for analysis or to allow light to pass through if optical analysis is involved.
- Polishing: After thinning, the wafer is often polished to a mirror-like finish to minimize surface defects and prepare it for high-resolution imaging, such as scanning electron microscopy (SEM) or optical inspection.
- Backside grinding and Lapping: These are additional steps where the back surface is ground or lapped to achieve the desired flatness and smoothness, ensuring accurate results during subsequent analysis.
- Etching and Cleaning: Once the wafer is thinned and polished, it may undergo etching to remove any unwanted layers or residues. The sample is then cleaned to ensure no particles are left that could interfere with the analysis.
Backside preparation is crucial for various purposes:
- Failure Analysis: Investigating issues like electrical shorts, layer delamination, or other defects in the chip.
- Probing: Accessing internal circuit nodes for testing without damaging the chip.
- Failure Root Cause Identification: Understanding how specific parts of the chip fail under stress or use conditions.
This process is widely used in research and development, as well as in quality control and troubleshooting for semiconductor devices.
