Defect detection in packaging application

An optical inspection system for pre-bonding inspection, comprising:

• a stage having a surface on which a sample to be inspected is placed, the surface of the sample having a two dimensional (2D) periodic pattern and defects;
• an optical fiber;
• a reflective spatial light modulator (SLM);
• a measurement lens configured to transmit a beam of light reflected at the reflective SLM;
• a camera configured to detect the transmitted beam of light from the measurement lens;
• and
• a measuring beam path through which a beam of light from the optical fiber is incident on and reflected at the surface of the sample on the stage, and transmitted to the reflective SLM,
• wherein the reflective SLM is configured to block the beam of light reflected by the 2D periodic pattern on the surface of the sample.

A method of chip-to-substrate hybrid bonding, comprising:

• performing a pre-bonding inspection process on a substrate die having metallic bond pads, and a chiplet having metallic bond pads, comprising:
• generating an optical image of point defects on a surface of the substrate die by an optical inspection system having an optical fiber illumination and a spatial light modulator (SLM);
• and
• inspecting the generated optical image, wherein inspecting the generated optical image comprises at least one of:
• determining a location of at least one of the point defects on the surface of the substrate die based on the optical image of the point defects on the surface of the substrate die;
• and
• determining a location of at least one of the point defects on the surface of the chiplet based on the optical image of the point defects on the surface of the chiplet.