Apparatuses and methods for detecting defects in semiconductor workpieces
Non-contact methods and apparatuses for detecting defects such as pile-ups in semiconductor wafers are disclosed herein. An embodiment of one such method includes irradiating a portion of a semiconductor workpiece, measuring photoluminescence from the irradiated portion of the semiconductor workpiece, and estimating a density of defects in the irradiated portion of the semiconductor workpiece based on the measured photoluminescence.
1 . A non-contact method of detecting defects in a semiconductor workpiece, the method comprising:
irradiating a portion of a semiconductor workpiece;
measuring photoluminescence from the irradiated portion of the semiconductor workpiece; and
estimating a density of defects in the irradiated portion of the semiconductor workpiece based on the measured photoluminescence.
2 . The method of claim 1 wherein estimating the density of defects comprises determining the density of defects based on an area of the irradiated portion of the semiconductor workpiece and a dimension of the individual defects in a plane generally parallel to a surface of the semiconductor workpiece.
3 . The method of claim 1 wherein estimating the density of defects comprises:
determining a length of the individual defects in a plane generally parallel to a surface of the semiconductor workpiece;
summing the lengths of the individual defects;
estimating an area of the irradiated portion of the semiconductor workpiece;
and
dividing the summed length of the individual defects by the estimated area.
4 . The method of claim 1 wherein estimating the density of defects comprises detecting a defect pile-up in the irradiated portion of the semiconductor workpiece.
5 . The method of claim 1 wherein estimating the density of defects comprises detecting a plurality of threading arms in the semiconductor workpiece.
6 . The method of claim 1 wherein estimating the density of defects comprises:
filtering the photoluminescence data to detect pile-ups in the semiconductor workpiece;
generating a mask based on the filtered photoluminescence data; and
determining a dimension of at least one pile-up based on the mask.
7 . The method of claim 1 wherein the individual defects extend in a direction generally transverse to a surface of the semiconductor workpiece.
8 . The method of claim 1 wherein estimating the density of defects comprises filtering the photoluminescence data to detect pile-ups in the semiconductor workpiece.
9 . The method of claim 1 wherein the individual defects extend from a dislocation within the semiconductor workpiece to a surface of the workpiece.
10 . The method of claim 1 , further comprising comparing the estimated density of defects with a predetermined range of acceptable defect densities for the semiconductor workpiece.
11 . The method of claim 1 wherein estimating the density of defects comprises determining the density of defects without analyzing a reflectance of light from the semiconductor workpiece.
12 . The method of claim 1 wherein irradiating the portion of the semiconductor workpiece comprises directing a laser beam toward the portion of the workpiece.
13 . A non-contact method of detecting defects in a semiconductor workpiece, the method comprising:
measuring photoluminescence from a portion of a semiconductor workpiece; and
detecting a defect pile-up in the semiconductor workpiece based on the measured photoluminescence.
14 . The method of claim 13 wherein detecting the defect pile-up comprises filtering the photoluminescence data to detect the defect pile-up.
15 . The method of claim 13 , further comprising estimating a density of defects in the semiconductor workpiece based detected defect pile-up.
16 . The method of claim 13 wherein detecting the defect pile-up comprises:
filtering the photoluminescence data; and
generating a mask based on the filtered photoluminescence data.
17 . The method of claim 13 wherein detecting the defect pile-up comprises detecting a dislocation pile-up extending in a direction generally transverse to a surface of the semiconductor workpiece.
18 . The method of claim 13 wherein:
measuring photoluminescence comprises generating an image with a plurality of pixels; and
detecting the defect pile-up comprises determining a photoluminescence gradient between at least one pixel and neighboring pixels of the at least one pixel.
19 . A non-contact method of detecting defects in a semiconductor workpiece, the method comprising:
irradiating a portion of a semiconductor workpiece;
measuring photoluminescence emitted from the irradiated portion of the workpiece; and
filtering the photoluminescence data to detect a defect extending generally transverse to a surface of the semiconductor workpiece.
20 . The method of claim 19 wherein:
measuring photoluminescence comprises generating an image with a plurality of pixels; and
filtering the photoluminescence data comprises determining a photoluminescence gradient between at least one pixel and neighboring pixels of the at least one pixel.
21 . The method of claim 19 , further comprising generating a mask based on the filtered photoluminescence data.
22 . The method of claim 19 , further comprising estimating a density of defects in the semiconductor workpiece based on the filtered photoluminescence data.
23 . The method of claim 19 , further comprising:
determining a length of the defect in a plane generally parallel to the surface of the workpiece;
estimating an area of the irradiated portion of the semiconductor workpiece; and
calculating a density of defects in the semiconductor workpiece based on the area of the irradiated portion and the length of the defect.
24 . A non-contact method of detecting defects in a semiconductor workpiece, the method comprising:
measuring photoluminescence from a semiconductor workpiece; and
detecting a threading arm in the semiconductor workpiece by comparing the measured photoluminescence from a first section of the semiconductor workpiece to at least one of (a) the measured photoluminescence from a second section of the workpiece, or (b) a predetermined range of photoluminescence values.
25 . The method of claim 24 , further comprising estimating a density of defects in the semiconductor workpiece based on the measured photoluminescence.
26 . The method of claim 24 , further comprising determining a dimension of a defect pile-up in a plane generally parallel to a surface of the semiconductor workpiece, wherein the defect pile-up comprises the threading arm.
27 . The method of claim 24 wherein detecting a threading arm comprises detecting a dislocation pile-up extending in a direction generally transverse to a surface of the semiconductor workpiece.
28 . An apparatus for detecting defects in a semiconductor workpiece, the apparatus comprising:
a radiation source configured to irradiate a portion of the semiconductor workpiece;
a detector configured to measure photoluminescence from the semiconductor workpiece; and
a controller operably coupled to the detector, the controller having a computer-readable medium containing instructions to perform a method comprising—
irradiating a portion of the semiconductor workpiece;
measuring photoluminescence from the irradiated portion of the semiconductor workpiece; and
estimating a density of defects in the irradiated portion of the semiconductor workpiece based on the measured photoluminescence.
29 . The apparatus of claim 28 wherein the radiation source comprises a laser configured to direct a laser beam toward the semiconductor workpiece.
30 . The apparatus of claim 28 wherein the instructions for estimating the density of defects comprise determining the density of defects based on an area of the irradiated portion and a dimension of the individual defects in a plane generally parallel to a surface of the semiconductor workpiece.
31 . The apparatus of claim 28 wherein the instructions for estimating the density of defects comprise detecting a defect pile-up in the irradiated portion of the semiconductor workpiece.
32 . An apparatus for detecting defects in a semiconductor workpiece, the apparatus comprising:
a radiation source configured to irradiate a portion of the semiconductor workpiece;
a detector configured to measure photoluminescence from the semiconductor workpiece; and
a controller operably coupled to the detector, the controller having a computer-readable medium containing instructions to perform a method comprising—
measuring photoluminescence from the semiconductor workpiece; and
detecting a defect pile-up in the semiconductor workpiece based on the measured photoluminescence.
33 . The apparatus of claim 32 wherein the radiation source comprises a laser configured to direct a laser beam toward the semiconductor workpiece.
34 . The apparatus of claim 32 wherein the instructions for detecting the defect pile-up comprise filtering the photoluminescence data to detect the defect pile-up.
35 . An apparatus for detecting defects in a semiconductor workpiece, the apparatus comprising:
a radiation source configured to irradiate a portion of the semiconductor workpiece;
a detector configured to measure photoluminescence from the semiconductor workpiece; and
a controller operably coupled to the detector, the controller having a computer-readable medium containing instructions to perform a method comprising—
irradiating the portion of the semiconductor workpiece;
measuring photoluminescence emitted from the irradiated portion of the workpiece; and
filtering the photoluminescence data to detect a defect extending generally transverse to a surface of the semiconductor workpiece.
36 . The apparatus of claim 35 wherein the radiation source comprises a laser configured to direct a laser beam toward the semiconductor workpiece.
37 . The apparatus of claim 35 wherein:
the instructions for measuring photoluminescence comprise instructions for generating an image with a plurality of pixels; and
the instructions for filtering the photoluminescence data comprise instructions for determining a photoluminescence gradient between at least one pixel and neighboring pixels of the at least one pixel.
38 . An apparatus for detecting defects in a semiconductor workpiece, the apparatus comprising:
means for measuring photoluminescence from a portion of a semiconductor workpiece; and
means for detecting a threading arm in the semiconductor workpiece based on measured photoluminescence.
39 . The apparatus of claim 38 wherein the means for detecting the threading arm comprise a controller having a computer-readable medium containing instructions to perform a method including filtering the photoluminescence data to detect the threading arm.
40 . The apparatus of claim 38 , further comprising means for irradiating the portion of the semiconductor workpiece.