US 7,472,580 B2
Pressure sensor
Joseph H. Lyons, Wilton, Conn. (US); Peter C. Kochersperger, Easton, Conn. (US); James Walsh, Newtown, Conn. (US); and Rajan Mali, Shelton, Conn. (US)
Assigned to ASML Holding N.V., Veldhoven (Netherlands)
Filed on Dec. 29, 2006, as Appl. No. 11/647,575.
Application 11/647575 is a continuation in part of application No. 11/321651, filed on Dec. 30, 2005, abandoned.
Prior Publication US 2007/0176121 A1, Aug. 02, 2007
Int. Cl. G01B 13/08 (2006.01); G01L 7/00 (2006.01)
U.S. Cl. 73—37.5  [73/700] 16 Claims
OG exemplary drawing
 
13. A proximity sensor for sensing a difference between a reference surface standoff and a measurement surface standoff surrounded by conditioned ambient fluid, comprising:
a flow device that evacuates the conditioned ambient fluid, wherein the flow device is configured to maintain a downstream pressure that is lower than a predetermined pressure;
a junction that combines fluid flow into a channel coupled to a vacuum in the proximity sensor, wherein the junction combines a reference channel and a measurement channel;
a first resistive element located in the reference channel, wherein said first resistive element restricts fluid flow through the reference channel;
a second resistive element located in the measurement channel, wherein said second resistive element restricts fluid flow through the measurement channel;
a reference probe at an end of the reference channel, whereby fluid enters the reference channel through the reference probe having traveled across the reference surface standoff;
a measurement probe at an end of the measurement channel, whereby fluid enters the measurement channel through the measurement probe having traveled across a measurement surface standoff; and
a sensor coupled between the reference and measurement channels that senses the mass of fluid flow therebetween, whereby, the difference in standoffs between the reference and measurement surfaces can be sensed.