Patent ID: 7472579
Filing Date: 2009-01-06
Classification: G03F,G05D

Abstract:
1. A liquid flow lithography proximity sensor, comprising: a junction that divides liquid input into the liquid flow proximity sensor into a reference channel and a measurement channel; a first porous flow restrictor placed along the reference channel, wherein said first porous flow restrictor evenly restricts liquid flow through the reference channel; a second porous flow restrictor placed along the measurement channel, wherein said second porous flow restrictor evenly restricts liquid flow through the measurement channel; a reference probe at an end of the reference channel, whereby liquid exits the reference channel through the reference probe and travels across a reference standoff to impinge upon a reference surface; a measurement probe at an end of the measurement channel, whereby liquid exits the measurement channel through the measurement probe and travels across a measurement standoff to impinge upon a lithographic measurement surface; and a liquid mass flow sensor coupled between the reference and measurement channels for sensing the flow of liquid therebetween, whereby, the difference in standoffs between the reference and measurement surfaces can be sensed; wherein the liquid flow sensed by said liquid mass flow sensor is indicative of a difference between the measurement standoff and the reference standoff in a nanometer range.