System and Method for Detecting Cracks in a Wafer

An inspection tool equipped with crack detection capabilities comprising:

• a light source configured to illuminate an area of a surface of a wafer disposed on a rotational wafer stage assembly configured to secure a wafer and selectively rotate the wafer;
• a detector configured to detect light reflected or scattered from the illuminated area of the wafer;
• a crack detection light source positioned on a first side of a surface of the wafer and configured direct at least a portion of a light beam through the wafer, wherein the light beam is at least partially transmittable through the wafer;
• a crack detection sensor positioned on a second side of the wafer opposite the first side and configured to monitor one or more characteristics of light transmitted through the wafer as the rotational wafer stage assembly rotates the wafer, wherein the rotational wafer stage assembly and the light source are configured to cause the light beam to trace a pattern across the wafer;
• a controller communicatively coupled to the sensor and a portion of the rotational wafer stage assembly, the controller configured to:
• determine the presence of one or more cracks in the wafer based on the monitored one or more characteristics of light transmitted through the wafer;
• and
• responsive to the determination of the presence of one or more cracks in the wafer, direct the rotational stage assembly to adjust the rotational condition of the wafer.

A method for detecting cracks in a wafer comprising:

• generating a light beam at least partially transmittable through the wafer;
• selectively rotating a wafer disposed on a rotational wafer stage assembly in order to trace the light beam across the surface of the wafer;
• monitoring one or more characteristics of light transmitted through the wafer;
• determining the presence of one or more cracks in the wafer based on the monitored one or more characteristics of light transmitted through the wafer;
• and
• responsive to the determination of the presence of one or more cracks in the wafer, directing the rotational stage assembly to adjust the rotational condition of the wafer.

A system for monitoring centering of wafer on a rotational wafer stage comprising:

• a rotational wafer stage assembly configured to secure a wafer and selectively rotate the wafer;
• a light source positioned on a first side of a surface of the wafer and configured direct at least a portion of a light beam through the wafer, wherein the light beam is at least partially transmittable through the wafer;
• a sensor positioned on a second side of the wafer opposite the first side and configured to monitor an edge bevel location of the wafer based on one or more characteristics of light transmitted through the wafer as the rotational wafer stage assembly rotates the wafer, wherein the rotational wafer stage and the light source are configured to cause the light beam to trace a pattern across the wafer proximate to the bevel of the wafer;
• a controller communicatively coupled to the sensor and a portion of the rotational wafer stage assembly, the controller configured to:
• determine a centering condition of the wafer based on the monitored one or more characteristics of light transmitted through the wafer;
• and
• responsive to the determination an off-center condition, direct the rotational stage assembly to adjust the rotational condition of the wafer.

A system for monitoring wafer slippage on a rotational wafer stage comprising:

• a rotational wafer stage assembly configured to secure a wafer and selectively rotate the wafer;
• a light source positioned on a first side of a surface of the wafer and configured direct at least a portion of a light beam through the wafer, wherein the light beam is at least partially transmittable through the wafer;
• a sensor positioned on a second side of the wafer opposite the first side and configured to monitor changes in at least one of a wafer notch location and a spindle axis location as the rotational wafer stage assembly rotates the wafer;
• a controller communicatively coupled to the sensor and a portion of the rotational wafer stage assembly, the controller configured to:
• determine a slippage condition of the wafer based on the monitored changes in at least one of the wafer notch location and the spindle axis location;
• and
• responsive to the determination of a slippage condition exceeding a selected slippage threshold, direct the rotational stage assembly to adjust the rotational condition of the wafer.