Benjamin W. Mooring

Accuracy Analysis of Dynamic-Wafer-Handling Robotic System in Semiconductor Manufacturing

Wafer-handling robots are widely used to transfer wafers in semiconductor manufacturing. To improve the wafer transfer efficiency, optic sensors are installed at each station to estimate the wafer eccentricity on the fly. However, due to nonideal factors such as light beam radius, robot motion error, and system nonlinearity and uncertainties, it is difficult to achieve high-accuracy eccentricity estimation to satisfy the demanding requirements in semiconductor manufacturing. To further improve the eccentricity estimation accuracy, the relationship among the robot kinematic error, sensor calibration error, and eccentricity identification error is analyzed. The analytic results show that both the error modeling method and the global data sampling method can greatly improve the wafer eccentricity estimation accuracy. The proposed eccentricity estimation techniques are verified by experiments performed on a wafer-handling robotic system. The results demonstrate that the developed methods can be used to improve the wafer-handling accuracy and reduce the wafer-handling cycle time in semiconductor manufacturing.

Dynamic wafer handling process in semiconductor manufacturing

In semiconductor manufacturing, wafers are transferred using wafer handling robots. Typically a pick-measure-place method is used to transfer wafers accurately between stations. The measurement step is performed using an aligner, which is time-consuming. To increase wafer transfer efficiency, it is desirable to speed up the measurement or place it in parallel with other operations. Hence two optic sensors are installed at each station to estimate the wafer eccentricity on the fly. The eccentricity values are then used to control the robot to place the wafer directly onto another station accurately without using the aligner. In this paper, the kinematic model of a wafer handling robot is developed. A sensor position calibration is proposed to identify the sensor positions. A wafer eccentricity identification method is then derived. Experiments were performed to validate the proposed methods. The computed wafer eccentricity values are compared with those measured using an aliger. The results demonstrated that the developed methods can be applied to estimate the wafer eccentricity on-the-fly, thus reduce the wafer transfer cycle time and increase productivity.

Error modeling and analysis in dynamic wafer handling

Wafer handling robots are used to transfer wafers in semiconductor manufacturing. A pick-measure-place method is typically used to transfer wafers accurately between stations. The measurement step is performed by an aligner, which is time-consuming. To improve the wafer transfer efficiency, it is necessary to speed up the measurement process or place it in parallel with other operations. Thus optic sensors are installed at each station to estimate the wafer eccentricity on-the-fly. The estimation process is consist of two stages: sensor calibration and wafer eccentricity estimation. Theoretical analysis and numerical optimization methods are used to accomplish these tasks. Based on the wafer handling robot kinematics model, robot kinematics error, sensor calibration error and eccentricity identification error are analyzed in this paper. The proposed error model based method is verified by both theoritical analysis and real experiment performed on a wafer handling robot system. Experiment results demonstrate that the error modeling methods can greatly reduce the wafer eccentricity estimation error on-the-fly. Hence the developed methods can be used to improve the wafer handling accuracy and reduce the wafer handling cycle time in semiconductor manufacturing.

Improving wafer handling performance in semiconductor manufacturing

Purpose – The electronics industries are relying increasingly on robotics for their production. Wafer handling robots are used to transfer wafers between wafer processing stations. A pick‐measure‐place method is typically utilized to transfer wafers accurately. The measurement step is performed using an aligner, which is time‐consuming. To increase wafer transfer efficiency, it is desirable to speed up the measurement process or place it in parallel with other operations. To solve the problem, optic sensors are installed at each station to estimate the wafer eccentricity on‐the‐fly. The eccentricity values are then applied to control the robot to place the wafer directly onto another station accurately without using the aligner. However, current methods face problems to achieve high accuracy requirements to meet the electronic manufacturing needs. The purpose of this paper is to develop a technique to improve the wafer handling performance in semiconductor manufacturing.Design/methodology/approach – The k...