Simultaneous multi-bandwidth optical inspection of semiconductor devices

An optical inspection apparatus for qualifying semiconductor wafer processing, said apparatus comprising:

• an illumination module producing source light illuminating a semiconductor wafer, said illumination module including:
• a common light source that emits light having wavelengths in a first waveband and a second waveband, wherein the first waveband and the second waveband partially overlap;
• a first optical element comprising a first aperture wheel having multiple apertures arranged along a first optical path of the first waveband, said first aperture wheel regulating a first optical parameter of the first waveband;
• and
• a second optical element comprising a second aperture wheel having multiple apertures arranged along a second optical path of the second waveband, and said second aperture wheel regulating a second optical parameter of the second waveband;
• a collection module including a first image sensor and a second image sensor, said first image sensor receiving reflected light in the first waveband from the semiconductor wafer and said second image sensor receiving reflected light in the second waveband from the semiconductor wafer;
• and
• an image processor that processes a first image of the semiconductor wafer generated in accordance with data obtained from the first image sensor, and processes a second image of the semiconductor wafer generated in accordance with data obtained from the second image sensor to qualify the semiconductor wafer based on a predetermined value of a defect count.

An inspection method for qualifying semiconductor wafer processing, said method comprising:

• illuminating a semiconductor wafer with source light having wavelengths in a plurality of wavebands, including at least a first waveband and a second waveband, said second waveband partially overlapping the first waveband;
• prior to the illuminating, conditioning the source light having wavelengths in the first waveband including regulating one of an aperture provided for the source light having wavelengths in the first waveband and a polarization of the source light having wavelengths in the first waveband, and conditioning the source light having wavelengths in the second waveband including regulating one of an aperture provided for the source light having wavelengths in the second waveband and a polarization of the source light having wavelengths in the second waveband, wherein said conditioning of the source light having wavelengths in the second waveband is carried out independently of said conditioning of the source light having wavelengths in the first waveband;
• separating light reflected from the semiconductor device as a result of said illuminating, said separating dividing the reflected light according to waveband such that reflected light in the first waveband is directed to a first image sensor, while reflected light in the second waveband is directed to a second image sensor;
• generating a first image of the semiconductor wafer in accordance with data produced from the first image sensor;
• generating a second image of the semiconductor wafer in accordance with data produced from the second image sensor;
• and
• applying a convolution neural network (CNN) to the first and second images to simultaneously detect and classify defects.