Microdiffraction
A method of X-ray diffraction illuminates a beam ( 4 ) of X-rays along an illuminated strip ( 16 ) on a surface ( 14 ) of a sample ( 10 ). The X-rays are diffracted by the sample ( 10 ) and pass through a mask ( 20 ) having a slit extending essentially perpendicularly to the strip ( 16 ). The X-rays are detected by a two-dimensional X-ray detector to measure the diffracted X-rays at different positions along the strip ( 16 ).
1. A method of X-ray diffraction for measuring a sample having a sample surface, the method comprising:
illuminating a beam of X-rays along an illuminated strip extending along the surface of the sample in a y direction;
passing X-rays diffracted by the sample along the illuminated strip through a mask between the sample and a two-dimensional detector, wherein the mask has a slit extending substantially perpendicularly to the y direction and the mask is placed at a distance from the illuminated strip of between 20% and 80% of the distance between the illuminated strip and the X-ray detector so that X-rays diffracted from different positions along the illuminated strip are received at different positions along the y direction on the two-dimensional X-ray detector;
detecting X-rays diffracted by the sample at the two-dimensional X-ray detector, so that different positions along the y direction at the two-dimensional detector correspond to different positions along the illuminated strip and different positions in the perpendicular direction, z′, to the line direction on the two-dimensional X-ray detector correspond to different diffraction angles 2θ.
2. The method according to claim 1 , wherein the step of illuminating a beam comprises generating X-rays using an X-ray source and passing the generated X-rays through a source slit to illuminate the sample.
3. The method according to claim 2 further comprising moving the source slit to move the location of the illuminated strip on the surface of the sample.
4. The method according to claim 1 further comprising passing the beam through additional conditioning optics.
5. The method according to claim 1 , wherein the sample is a sample with an inhomogeneous surface.
6. The method according to claim 1 further comprising adjusting the position of the mask to vary the length of the illuminated strip imaged by the two-dimensional X-ray detector.
7. The method according to claim 1 wherein the width of the illuminated strip ( 16 ) is 0.05 mm to 2 mm.
8. X-ray diffraction apparatus for measuring a sample having a sample surface, the apparatus comprising:
an X-ray source for generating a beam of X-rays;
a sample stage for supporting the sample;
an X-ray optic between the X-ray source and the sample stage arranged to restrict the beam to illuminate an illuminated strip extending along the surface of the sample in a y direction;
a two-dimensional X-ray detector for detecting X-rays diffracted by the sample; and
a mask between the sample and the two-dimensional detector, wherein the mask has a slit extending substantially perpendicularly to the y direction and the mask is placed at a distance from the illuminated strip of between 20% and 80% of the distance between the illuminated strip and the X-ray detector so that X-rays diffracted from different positions along the illuminated strip are received at different positions along the y direction on the two-dimensional X-ray detector.
9. The X-ray diffraction apparatus according to claim 8 wherein the X-ray optic comprises a source slit ( 6 ).
10. A method of operation of X-ray diffraction apparatus:
illuminating a beam of X-rays from an X-ray source passing through an X-ray optic along an illuminated strip extending along the surface of the sample in a y direction;
passing X-rays diffracted by the sample along the illuminated strip through a slit in a mask so that X-rays diffracted from different positions along the illuminated strip are received at different positions along the y direction on a two-dimensional X-ray detector wherein the mask is placed at a distance from the illuminated strip of between 20% and 80% of the distance between the illuminated strip and the X-ray detector;
detecting X-rays diffracted by the sample at the two-dimensional X-ray detector, so that different positions along the y direction at the two-dimensional detector correspond to different positions along the illuminated strip and different positions in the perpendicular direction, z′, to the line direction on the two-dimensional X-ray detector correspond to different diffraction angles 2θ.