Nondestructive imaging and surface quality inspection of structured plates

Abstract

A system includes a stage, a detector and a measuring device. The stage is configured to hold a substrate. The substrate includes a plurality of tapered structures, and each of the plurality of tapered structures includes a tapered wall between first and second openings at opposite ends of the plurality of tapered structures. The detector is tilted at a first angle and configured to measure light reflected from the tapered wall at about 90 degrees to the tapered wall. The first angle depends at least in part a second angle between the tapered wall and a longitudinal axis running through the tapered structure. The measuring device is configured to determine a characteristic of the tapered wall and whether the characteristic of the tapered wall is above or below a threshold.

What is claimed is: 
     
         1 . A system, comprising:
 a stage;   a light source;   a detector positioned to measure light from the light source that has been reflected from a tapered wall of a substrate disposed on the stage, wherein a first angle between the detector and a longitudinal axis of a tapered structure of the substrate comprising the tapered wall depends at least in part on a second angle between the tapered wall and the longitudinal axis; and   a measuring device configured to determine a presence of a surface defect on the tapered wall.   
     
     
         2 . The system of  claim 1 , wherein the surface defect includes at least one of surface roughness, linearity, and shape. 
     
     
         3 . The system of  claim 1 , wherein the stage comprises a rotation stage and a translation stage. 
     
     
         4 . The system of  claim 3 , wherein the rotation stage is configured to be rotated about an axis relative to the translation stage. 
     
     
         5 . The system of  claim 3 , wherein the translation stage is configured to move up and down relative to the rotation stage. 
     
     
         6 . The system of  claim 3 , wherein the translation stage is configured to move laterally relative to the rotation stage. 
     
     
         7 . The system of  claim 6 , wherein the rotation stage is configured to be rotated about an axis relative to the translation stage and the translation stage and the rotation stage are configured to be moved independently. 
     
     
         8 . The system of  claim 7 , wherein the measuring device is configured to effectuate movement of at least one of the translation stage and the rotation stage based at least in part on the presence of the surface defect. 
     
     
         9 . The system of  claim 6 , wherein the substrate is located on the rotation stage. 
     
     
         10 . The system of  claim 6 , wherein the substrate is located on the translation stage. 
     
     
         11 . The system of  claim 1 , wherein the detector is further configured to capture an image of the light source that has been reflected from the tapered wall and the measuring device is further configured to determine the presence of the surface defect based on the image. 
     
     
         12 . The system of  claim 11 , wherein the surface defect includes features having a height of nanometer scale over a micrometer measurement range, and the measuring device determines whether the surface defect of the tapered wall is above or below a threshold based on the image. 
     
     
         13 . The system of  claim 1 , wherein the detector includes a fold mirror and a third angle is formed between an axis of the detector and the fold mirror, such that the fold mirror directs the light source that has been reflected to the detector. 
     
     
         14 . The system of  claim 1 , wherein the substrate is disposed on the stage at about 90 degrees to the tapered wall. 
     
     
         15 . A system, comprising:
 a translation stage and a rotation stage, at least one of the translation stage and the rotation stage being moveable;   a light source;   a detector positioned to measure light from the light source that has been reflected from a tapered wall of a substrate disposed on one of the translation stage and the rotation stage, wherein a first angle between the detector and a longitudinal axis of a tapered structure of the substrate comprising the tapered wall depends at least in part on a second angle between the tapered wall and the longitudinal axis; and   a measuring device configured to determine a presence of a characteristic on the tapered wall.   
     
     
         16 . The system of  claim 15 , wherein the substrate is disposed on the stage at about 90 degrees to the tapered wall. 
     
     
         17 . The system of  claim 15 , wherein the rotation stage is configured to be rotated about an axis relative to the translation stage. 
     
     
         18 . The system of  claim 17 , wherein the translation stage is configured to move linearly relative to the rotation stage. 
     
     
         19 . The system of  claim 18 , wherein the substrate is located on the rotation stage. 
     
     
         20 . The system of  claim 18 , wherein the substrate is located on the translation stage.