Research On Driving Control System Of Three Dimensional Motion Air-floatation Platform

Lithography is one of the most important equipment in microelectronics IC manufacturing. As one of the key subsystems of lithography tool, stage and the control system has been becoming one of the cores in lithography technology.Separating demand of accuracy and speed, currently the platform in lithography tool is gradually adopting high precision linear motor with floating support, coarseto-fine construction and closed loop technology with interferometer, to achieve a higher level of resolution, overlay accuracy and yield in lithography tool day by day, and give consideration to high precision, high speed and high stability. This work requires a kind of control system with high level of integration, efficiency, real-time, and variety of interfaces.Existing domestic control systems of precision workpiece mainly output pulse signal for control or perform by independent movement control module, which has no enough in type and quantity of the interfaces, signal precision, and system integration. Encoders and gratings are used widely as position sensor in closed loop, and few can directly communication with few interferometer acquisition system. Studies the structure of control system for high accuracy motion platform, analyzes the control principle of linear motor, servo motor and piezoelectric actuator in corarse/fine stage. Furthermore, developed a kind of motion control system based on FPGA and DSP, which includes two parts, the movement control CARDS and piezoelectric drive controller with high degree of integration, each has algorithm, software hardware design.Control algorithm of position loop is completed. A method based on quadratic function is used for compensating the nonlinear error of piezoelectric actuator. Comprehensive analysis of polynomial curve planning for speed of the linear motors, and in addition, the algorithm is optimized to improve the efficiency. For engineering, in one hand, the MC CARD is designed to output 3 channels of 14 effective resolution of the analog signal for the linear motor, 3 channels of the pulse signal with speed curve for servo motor and a CAN port used to transceiver control data of piezoelectric actuators(fastest speed 8.2 k Hz). In the other hand, the MC CARD based on PCI bus can communicates with PC in the form of interruption, and has direct communication with interferometer acquisition card by PCI initial mode with the fastest speed 138 k Hz. The piezoelectric drive controller is designed to quickly complete decoding of the CAN message data, output 6 channels of as high as 18 effective resolution of analog signals.