Air-based contactless wafer precision positioning system: Contactless sensing using charge coupled devices

Abstract

This paper presents the development of a contactless sensing system and the dynamic evaluation of an air-bearing based precision wafer positioning system. The contactless positioning stage is a response to the trend seen in the high-tech industry, where the substrates are becoming thinner and larger to reduce the cost and increase the yield. Using contactless handling it is possible to avoid damage and contamination. The system works by floating the substrate on a thin film of air. A viscous traction force is created on the substrate by steering the airflow. A cascaded control design structure has been implemented to the contactless positioning system, where the Inner Loop Controller (ILC) controls the actuator which steers the airflow and the Outer Loop Controller (OLC) controls the position of the substrate by controlling the reference of the ILC. The dynamics of the ILC are evaluated and optimized for the performance of the positioning of the substrate. The vibration disturbances are also handled by the ILC. The bandwidth of the system has been improved to 300 Hz. For the OLC a linear charge-coupled device has been implemented as a contactless sensor. The performance of the sensing system has been analyzed. During control in steady state, this resulted in a position error of the substrate of 12.9 $μ$ m RMS, which is a little more as two times the resolution. The bandwidth of the OLC is approaching 10 Hz.

Keywords

Air-bearing precision positioning,

Get full access to this article

View all access options for this article.

References

Fraunhofer, ISE: Photovoltaics report, February 2018.

Carey

, et al. Yield Impact of Backside Metal-Ion Contamination. Solid State Phenomena, vol. 187, Trans Tech Publications, 2012.

Wesselingh

. Contactless Positioning using an Active Air Film. PhD thesis, Delft University of Technology, 2011.

Vuong

. Air-Based Contactless Actuation System for Thin Substrates. PhD thesis, Delft University of Technology, 2016.

Verbruggen

. Air-Based Contactless Positioning of Thing Substrates, Master’s thesis, Delft University of Technology, 2018.

Vagher

. Contactless Passive Transport of Thin Solar Cells. Master’s thesis, Delft University of Technology, 2016.

Snieder

. Development of an Air-Based Contactless Transport Demonstrator. Master’s thesis, Delft University of Technology, 2017.

Voorrips

. The design of a distributed sensing system for contactless substrate transport. Master’s thesis, Delft University of Technology, 2017.

Jansen

. Actuation System for the FLowerbed, Master’s thesis, Delft University of Technology, 2018.

10.

Krijnen

. Control system design for a contactless actuation system. Master’s thesis, Delft University of Technology, 2016.

11.

Krijnen

, et al. The application of fractional order control for an air-based contactless actuation system. ISA Trans 2018; 82: 172–183.

12.

Katalenic

. Control of reluctance actuators for high-precision positioning. Eindhoven: Technische Universiteit Eindhoven, 2013.

13.

Chang-Ming

et al. Sub-pixel edge detection based on polynomial fitting for line-matrix CCD image. Weifang: Weifang University, 2009.

14.

Guo-Sheng

. Linear array CCD image sub-pixel edge detection based on wavelet transform. Weifang: Weifang University, 2009.

15.

Fischer

et al. Precise subpixel position measurement with linear interpolation of CMOS sensor image data. Prague: Czech Technical University, 2005.

16.

Hagara

Kulla

. Edge detection with sub-pixel accuracy based on approximation of edge with erf function. Radioengineering 2011: 516–524.

17.

Fischer

et al. Simple Methods of Edge Position Measurement Using Shadow Projected on CCD Sensor, Prague: Czech Technical University, 2003.

18.

12-2019, http://www.silicon-wafer.co.jp/semispec.htm.