Working Distance Comparison of Inductive and Electromagnetic Couplings for Wireless and Passive Underwater Monitoring System of Rinsing Process in Semiconductor Facilities

This paper reports a side-by-side comparison of two wireless and passive sensing systems: inductive and electromagnetic (EM) couplings for an application of in-situ and real-time monitoring of wafer cleanliness in the rinsing process at semiconductor/microelectromechanical system (MEMS) manufacturing facilities. A MEMS sensor is designed to measure the resistivity of water, corresponding to the ionic concentration, to evaluate the rinsing process inside the micro-features. The transponder, containing the MEMS sensor, receives power from an external interrogator, modulates the resistivity data, and emits back the modulated signal to the interrogator, in all wireless and battery-free operation. Two wireless systems based on inductive and EM couplings have been implemented on 4-inch glass wafers, maintaining the wafer form factor. Inductive coupling system has parasitic electric field coupling. The working distance of the inductive coupling system is attenuated in water and is likely limited by signal-to-noise ratio (SNR), while that of the EM coupling is primarily limited by the coupled power. Hence, inductive coupling is suitable for a short distance measurement that allows more sophisticated functionality with sufficient power, whereas EM coupling could be optimized for long distance detection but has a tight power budget. The implemented on-wafer wireless monitoring units achieve a working distance of 6 and 25 cm with a concentration resolution of less than 2% (4 ppb for a 200 ppb solution) for inductive and EM couplings, respectively.

[1]  J. R. Torczynski,et al.  Evaluation of overflow wet rinsing efficiency , 1994 .

[2]  W. Marsden.  I and J , 2012 .

[3]  P.V. Nikitin,et al.  Theory and measurement of backscattering from RFID tags , 2006, IEEE Antennas and Propagation Magazine.

[4]  Bruce C. Towe,et al.  A FULLY-PASSIVE WIRELESS MICROFABRICATED NEURO-RECORDER , 2010 .

[5]  R. B. Standler,et al.  A frequency-dependent finite-difference time-domain formulation for dispersive materials , 1990 .

[6]  Jie Wu,et al.  A Fully Integrated 900-MHz Passive RFID Transponder Front End With Novel Zero-Threshold RF–DC Rectifier , 2009, IEEE Transactions on Industrial Electronics.

[7]  N. G. Alexopoulos,et al.  An analytic continuation method for the analysis and design of dispersive materials , 1997 .

[8]  Yi Jia,et al.  A Prototype RFID Humidity Sensor for Built Environment Monitoring , 2008, 2008 International Workshop on Education Technology and Training & 2008 International Workshop on Geoscience and Remote Sensing.

[9]  Bert Vermeire,et al.  In situ and real-time metrology during rinsing of micro- and nano-structures , 2009 .

[10]  Kin-Lu Wong,et al.  Planar Antennas for Wireless Communications , 2003 .

[11]  Moeness G. Amin,et al.  Localization and tracking of passive RFID tags , 2006, SPIE Defense + Commercial Sensing.

[12]  Constantine A. Balanis,et al.  Antenna Theory: Analysis and Design , 1982 .

[13]  F. Shadman,et al.  Passive Wireless Monitoring of Wafer Cleanliness During Rinsing of Semiconductor Wafers , 2010, IEEE Sensors Journal.

[14]  Steve Lazar,et al.  A RF to DC Voltage Conversion Model for Multi-Stage Rectifiers in UHF RFID Transponders , 2009, IEEE Journal of Solid-State Circuits.

[15]  Kurt Christenson.  Rinsing: A Critical Process in Contamination Removal , 2005 .

[16]  Soumyajit Mandal,et al.  Low-Power CMOS Rectifier Design for RFID Applications , 2007, IEEE Transactions on Circuits and Systems I: Regular Papers.