ILLUMINATION MONITORING APPARATUS FOR USE IN SEMICONDUCTOR DEVICE FABRICATION EQUIPMENT

摘要

An apparatus for maintaining quantity of light of a lamp in semiconductor device fabrication equipment is provided to enhance accuracy of measurement in overlay equipment by maintaining a constant value of quantity of light at a reference position. A voltage controller(30) applies a voltage from a power supply unit to a lamp(10) according to a voltage control signal to turn on the lamp. A light detection sensor is installed around an optic part for receiving and transmitting the quality of light to sense the quantity of light. A control unit(100) compares a sensing signal applied through the light detection sensor with a predetermined reference signal to determine an abnormal state of the lamp. The control unit applies the voltage control signal for changing the quantity of light to the voltage controller when the compared value belongs to the allowable limit.