System and method for controlling chemical mechanical planarization

A method, comprising:

• performing a chemical mechanical planarization process on a first semiconductor wafer held by a chemical mechanical planarization head;
• unloading the first semiconductor wafer from the chemical mechanical planarization head to a wafer load and unload unit, wherein the wafer load and unload unit includes a shelf configured to support the first semiconductor wafer when the first semiconductor wafer is unloaded to the wafer load and unload unit, wherein the wafer load and unload unit includes a recess in a bottom interior surface such that when the first semiconductor wafer is supported on the shelf the recess is directly below the first semiconductor wafer;
• placing a camera in the recess of the wafer loading and unloading unit such that the camera is positioned at an angle θ relative to a vertical line, wherein θ is greater than 0° and less than 90°, wherein the recess is located in the wafer loading and unloading unit such that when a wafer is held by the loading and unloading unit the camera is directly below the wafer;
• capturing an image, with the camera positioned at the angle θ, of a retainer ring of the chemical mechanical planarization head after unloading the first semiconductor wafer;
• detecting, with a control system, that the retainer ring is damaged based on the image;
• and
• stopping, with the control system, operation of the chemical mechanical planarization head responsive to detecting that the retainer ring is damaged.

A method, comprising:

• receiving a semiconductor wafer with a wafer load and unload unit of a chemical mechanical planarization system, wherein the wafer load and unload unit includes a shelf configured to support the semiconductor wafer when the semiconductor wafer is received with the wafer load and unload unit, wherein the wafer load and unload unit includes a recess in a bottom interior surface such that when the semiconductor wafer is supported on the shelf the recess is directly below the semiconductor wafer;
• receiving the semiconductor wafer from the wafer load and unload unit with a chemical mechanical planarization head;
• performing a chemical mechanical planarization process on the semiconductor wafer while holding the semiconductor wafer with the chemical mechanical planarization head;
• returning the chemical mechanical planarization head to a position above the wafer load and unload unit after performing the chemical mechanical planarization process;
• positioning a camera in the recess of the wafer loading and unloading unit such that the camera is positioned at an angle θ relative to a vertical line, wherein θ is greater than 0° and less than 90°;
• determining, with a control system, whether the retainer ring has been used more than a threshold number of uses;
• if the retainer ring has not been used more than the threshold number of uses, preventing activation of the camera;
• if the retainer ring has been used more than the threshold number of uses, after returning the first semiconductor wafer to the wafer handling unit, using the control system to activate the camera and pivot the camera through a plurality of positions to capture a plurality of images over an entire inner circumference of a retainer ring of the chemical mechanical planarization head;
• analyzing, with the control system, the plurality of images with an image analysis process;
• generating, with the control system, a classification of the plurality of images;
• and
• controlling, with the control system, the chemical mechanical planarization head responsive to the classification.