Method and apparatus for separating fixture-induced error from measured object characteristics and for compensating the measured object characteristic with the error, and a bow/warp station implementing same

Measurement apparatus for separating fixture-induced errors from measurement data, comprising:

• a sensor;
• an object receiving fixture defined with respect to a fixture coordinate system;
• first signal processing means for obtaining first data representative jointly of an intended characteristic component and a fixture error component associated with determinable locations of an object received by the fixture determined by a first relative orientation of the object and the fixture coordinate system, and for obtaining second data representative jointly of the same intended characteristic component and the same fixture error component associated with the object received by the fixture but where the same determinable locations are determined by a second relative orientation of the object and the fixture coordinate system different from the first relative orientation;
• and
• second signal processing means responsive to the first and the second data for providing third data representative of the fixture related error component for each of the said locations of the object.

A bow and warp proofing station, comprising

• a capactive sensing head;
• an X, .theta., and Z moveable vacuum chuck assembly for receiving a semiconductor wafer to be profiled;
• a processing means operatively coupled to said capacitive sensing head and to said X, .theta., and Z moveable vacuum chuck assembly;
• first means connected to said capacitive sensing head and to said processing means for providing first input data representative of the distance to the median centerline of each of a plurality of identifiable locations of a right-sideup wafer controllably positioned successively in the capacitive sensing head by the X, .theta., and Z moveable vacuum chuck assembly;
• a memory;
• means connected to said first means for storing said first input data in the memory with each wafer location being uniquely identified by reference to the X and coordinates of the X, .theta., and Z assembly relative to a first home position;
• second means connected to said capacitive sensing head and to said processing means for providing second input data representative of the distance to the median centerline of each of a plurality of identifiable locations of the same but upside-down wafer controllably positioned successively in the capacitive sensing head by the X, .theta., and Z moveable vacuum chuck assembly;
• means for storing the second input data in memory with each wafer location of the upside-down wafer being uniquely identified with respect to its inverted position relative to the first home position of the X, .theta., and Z assembly;
• means connected to said memory and said processing means and responsive to the first and second data to separate an X-component error for each wafer location;
• and
• means for storing said X-component error data in memory.

A process for separating system components and element parameter components of an element measuring system, comprising:

• positioning said element in a first orientation at a station of said measuring system;
• measuring said element parameter by means of said measurement system to provide a first output indication of element parameter referenced to a selected location on said element;
• said first output indication being a first function of a component representative of the element parameter of said location and a component representative of unknown measurement system characteristics;
• positioning said element in a second orientation at said station of said measurement system;
• measuring said element parameter by means of said measurement system to provide a second output indication of element parameter referenced to said location;
• said second output indication being a second function of the component representative of the element parameter at said location and the component representative of unknown measurement system characteristics;
• and
• mathematically separating the components of said first and second functions from the component representative of the element parameter.