FA (Failure Analysis) sample preparation in semiconductor involves preparing a sample of a semiconductor device or component to identify the cause of its failure. This process is crucial to understanding how and why a semiconductor fails, allowing engineers to address potential design or manufacturing issues. The process typically involves several stages:
- Initial Inspection: Visual inspection using microscopes (optical, scanning electron microscope, etc.) to identify obvious damage or defects on the surface of the device.
- Cleaving or Sectioning: Cutting or cleaving the semiconductor to expose the internal layers and structures for further examination.
- Polishing or Lapping: Smoothing and polishing the cut surface to create a flat, clean area for detailed imaging and analysis. This often involves mechanical polishing followed by finer polishing to obtain a high-quality surface.
- Etching: Applying chemical treatments to remove layers of material and reveal the underlying structures. This could be used to examine the cross-sections of different layers within the semiconductor or expose certain defects.
- Scanning Electron Microscopy (SEM): After preparing the sample, SEM is often used to inspect the microstructures with high-resolution imaging to identify any faults or defects.
- Focused Ion Beam (FIB): FIB can be used to mill away specific areas of the sample for further analysis, or even to prepare ultra-thin cross-sections for transmission electron microscopy (TEM).
- X-ray Imaging: In some cases, X-ray imaging is used to identify internal defects like cracks or voids that may not be visible to optical or electron microscopes.
The goal is to gather as much information as possible regarding the failure mechanism, such as electrical shorts, open circuits, material degradation, or manufacturing defects, so that corrective actions can be taken to improve the design or fabrication process.
