Patterned wafer inspection using spatial filtering for the cluster environment.

Area of Science:

• Semiconductor Manufacturing
• Optical Inspection Technologies
• Advanced Materials Science

Background:

• Automated-process tool clusters are essential in modern semiconductor fabrication.
• Integrated inspection of patterned semiconductor wafers for defects and particulates is critical.
• Existing inspection tools face challenges in size, sensitivity, cost, and speed for cluster compatibility.

Purpose of the Study:

• To demonstrate an effective method for integrated wafer inspection compatible with automated cluster environments.
• To present a novel approach using intensity spatial filtering for enhanced defect and particulate detection.
• To develop a small, sensitive, and inexpensive inspection solution for semiconductor manufacturing.

Main Methods:

• Utilizing intensity spatial filtering with refined techniques.
• Employing dark-field illumination.
• Implementing a nonrectangular azimuthal orientation (e.g., 45 degrees) relative to the wafer pattern.

Main Results:

• The proposed method achieves the required sensitivity and speed for integrated inspection.
• Strongest diffraction from the wafer pattern is successfully bypassed, simplifying optical system requirements.
• The technique allows for the use of readily available, off-the-shelf optical components.

Conclusions:

• Intensity spatial filtering, when refined and combined with specific illumination and orientation strategies, provides a viable solution for wafer inspection in automated clusters.
• This approach overcomes limitations of existing inspection tools by being small, sensitive, inexpensive, and fast.
• The method reduces the need for specialized optical components, making it more practical for semiconductor manufacturing.