Patent ID: 7940391
Filing Date: 2011-05-10
Classification: G01B,G03F

Abstract:
1. A method for aligning a Metrology Assembly comprising: coupling a non-aligned Metrology Assembly to a test chamber, wherein a first pre-aligned output wall of a source chamber is coupled to a first alignment wall of the test chamber and a second pre-aligned input wall of a receiver chamber is coupled to a second alignment wall of the test chamber, wherein the first pre-aligned output wall has a first pre-aligned angle, and the first alignment wall has a first alignment angle substantially equal to the first pre-aligned angle, the second pre-aligned input wall having a second pre-aligned angle, the second alignment wall having a second alignment angle substantially equal to the second pre-aligned angle; coupling a optical test source to a first pre-aligned input wall of the source chamber using one or more first coupling elements and one or more first alignment devices, the first pre-aligned input wall comprising a first input optical element having an illumination pinhole; establishing one or more aligned internal source beams in the source chamber using a test beam from the optical test source; establishing a test incident beam, wherein a first output optical element is mounted and aligned in the first pre-aligned output wall of the source chamber and is configured to receive at least one aligned internal source beam and to establish the test incident beam; establishing a test reflection beam using the test incident beam and a test wafer in the test chamber; establishing one or more aligned internal received beams in the receiver chamber, wherein a second input optical element is mounted and aligned in the second pre-aligned input wall of the receiver chamber and is configured to receive the test incident beam and to establish at least one aligned internal received beam; establishing a measurement beam from the receiver chamber, wherein a second output optical element is mounted and aligned in a second pre-aligned output wall of the receiver chamber, the second output optical element having an output pinhole configured to establish the measurement beam using at least one aligned internal received beam; obtaining measurement data for the Metrology Assembly using the measurement beam and a measurement subsystem, the measurement subsystem being coupled to the second pre-aligned output wall of the receiver chamber using one or more second coupling elements and one or more second alignment devices; determining an alignment error between the test incident beam and the test reflection beam; identifying the test incident beam and the test reflection beam as pre-aligned beams and identifying the non-aligned Metrology Assembly as a Pre-Aligned Metrology Assembly when the alignment error is less than a first error limit; and performing a corrective action when the alignment error is not less than the first error limit.