Patent ID: 8073316

Claim:
An apparatus for heating a semiconductor wafer, comprising: a heating surface including a first heating zone configured to provide a first amount of heat and a second heating zone configured to provide a second amount of heat; a first sensor configured to generate a first signal based on a proximity of the wafer to the first sensor; a second sensor configured to generate a second signal based on a proximity of the wafer to the second sensor; and a controller configured to control the first amount of heat provided by the first heating zone based on the first signal and to control the second amount of heat provided by the second heating zone based on the second signal, wherein the heating surface further includes a third heating zone configured to provide a third amount of heat and a fourth heating zone configured to provide a fourth amount of heat, wherein the controller is further configured to control the third amount of heat based on the first signal and to control the fourth amount of heat based on the second signal, and wherein the third amount of heat is different from the first amount of heat and the fourth amount of heat is different from the second amount of heat.