In-line non-contact wafer boat inspection apparatus

An apparatus for automatic optical inspection of a wafer boat having a plurality of parallel slotted side rods and bottom rods, comprising:

• a frame;
• a cradle attached to the frame for supporting a wafer boat in a stationary horizontal position aligned to the frame;
• a carriage movably mounted upon the frame to permit linear motion of the carriage;
• a linear positioner mounted upon the frame and coupled to the carriage for moving the carriage in a direction parallel to the cradle;
• a plurality of first optical sensors mounted upon the carriage and projecting through the cradle so that when a wafer boat is supported in the cradle, each of the first optical sensors is in close proximity to a corresponding bottom rod of the wafer boat so as to permit non-contact detection of the slot edges within the corresponding bottom rod as the carriage is moved;
• a plurality of second optical sensors movably mounted upon the carriage, each positionable into either of first and second positions relative to the cradle, the first position being an operating position so that when a wafer boat is supported in the cradle, each of the second optical sensors is in close proximity to a corresponding side rod of the wafer boat so as to permit non-contact detection of the slot edges within the corresponding side rod as the carriage is moved, and the second position being a retracted position so that when a wafer boat is supported in the cradle, the second optical sensors are remote from the corresponding side rod in an outward direction to allow for removal of the wafer boat from the cradle;
• a plurality of actuators mounted upon the carriage and respectively coupled to the second optical sensors for moving the second optical sensors between their respective second and first positions;
• means coupled to each of the actuators for controlling the position of the second optical sensors;
• and
• means coupled to the linear positioner for controlling the position of the carriage.

An apparatus for automatic optical inspection of a wafer boat having parallel slotted first and second side rods and first and second bottom rods, comprising:

• a frame;
• a cradle attached to the frame for supporting a wafer boat in a stationary horizontal position aligned to the frame;
• a carriage movably mounted upon the frame to permit linear motion of the carriage;
• a linear positioner mounted upon the frame and coupled to the carriage for moving the carriage in a direction parallel to the cradle;
• a first stage movably mounted upon the carriage, being positionable into either of first and second positions;
• a first actuator mounted upon the carriage and coupled to the first stage, for moving the first stage between the first and second positions;
• a first optical sensor mounted upon the first stage, the first position of the first stage being an operating position so that when a wafer boat is supported in the cradle, the first optical sensor is in close proximity to the first side rod of the wafer boat so as to permit non-contact detection of the slot edges within the first side rod as the carriage is moved, and the second position of the first stage being a retracted position so that when a wafer boat is supported in the cradle, the first optical sensor is remote from the first side rod in an outward direction to allow for removal of the wafer boat from the cradle;
• a second stage movably mounted upon the carriage, being positionable into first and second positions;
• a second actuator mounted upon the carriage and coupled to the second stage, for moving the second stage between the first and second positions;
• a second optical sensor mounted upon the second stage, the first position of the second stage being an operating position so that when a wafer boat is supported in the cradle, the second optical sensor is in close proximity to the second side rod of the wafer boat so as to permit non-contact detection of the slot edges within the second side rod as the carriage is moved, and the second position of the second stage being a retracted position so that when a wafer boat is supported in the cradle, the second optical sensor is remote from the second side rod in an outward direction to allow for removal of the wafer boat from the cradle;
• a third optical sensor fixably mounted upon the carriage, so that when a wafer boat is supported in the cradle, the third optical sensor is in close proximity to the first bottom rod of the wafer boat so as to permit non-contact detection of the slot edges within the first bottom rod as the carriage is moved;
• a fourth optical sensor fixably mounted upon the carriage, so that when a wafer boat is supported in the cradle, the fourth optical sensor is in close proximity to the second bottom rod of the wafer boat so as to permit non-contact detection of the slot edges within the second bottom rod as the carriage is moved;
• means coupled to the first and second actuators for controlling the position of the first and second optical sensors;
• means coupled to the linear positioner for controlling the position of the carriage;
• and
• means coupled to the first, second, third, and fourth optical sensors for determining the slot edge locations within the respective first side rod, second side rod, first bottom rod, and second bottom rod, in accordance with the position of the carriage.