Three-dimensional scatterometry for measuring dielectric thickness
Methodologies and an apparatus for enabling three-dimensional scatterometry to be used to measure a thickness of dielectric layers in semiconductor devices are provided. Embodiments include initiating optical critical dimension (OCD) scatterometry on a three-dimensional test structure formed on a wafer, the three-dimensional test structure comprising patterned copper (Cu) trenches with an ultra-low k (ULK) dielectric film formed over the patterned Cu trenches; and obtaining, by a processor, a thickness of the ULK dielectric film based on results of the OCD scatterometry.
1. A method comprising:
initiating optical critical dimension (OCD) scatterometry on a three-dimensional test structure formed on a wafer, the three-dimensional test structure comprising patterned copper (Cu) trenches with an ultra-low k (ULK) dielectric film formed over the patterned Cu trenches; and
obtaining, by a processor, a thickness of the ULK dielectric film based on results of the OCD scatterometry.
2. The method according to claim 1 , wherein:
the OCD scatterometry is a three-dimensional OCD scatterometry, and
the thickness of the ULK dielectric film is obtained by way of light reflectivity.
3. The method according to claim 1 , wherein the patterned Cu trenches comprise:
first Cu trenches running in a first direction in the three-dimensional test structure, and
second Cu trenches, above the first Cu trenches, running in a second direction in the three-dimensional test structure.
4. The method according to claim 3 , wherein the first direction is perpendicular to the second direction.
5. The method according to claim 3 , wherein first direction is parallel to the second direction.
6. The method according to claim 1 , wherein the Cu trenches decrease in height near an edge of the wafer when compared to a center of the wafer according to normal process variation.
7. The method according to claim 1 , further comprising:
based on the results of the OCD scatterometry, automatically adjusting deposition time of a ULK dielectric film formed on a subsequent wafer, based on the results of the OCD scatterometry on the previously measured wafer.
8. The method according to claim 1 , further comprising:
prior to measuring the thickness of the ULK dielectric film, forming the ULK dielectric film over the Cu trenches.