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. An apparatus comprising:
a processor; and
memory including computer program code for a program,
the memory and the computer program code configured to, with the processor, cause the apparatus to perform at least the following:
initiate 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 a ultra-low k (ULK) dielectric film formed over the patterned Cu trenches; and
measure, by the processor, a thickness of the ULK dielectric film based on results of the OCD scatterometry.
2. The apparatus according to claim 1 , wherein the OCD scatterometry is a three-dimensional OCD scatterometry.
3. The apparatus according to claim 1 , wherein the patterned Cu trenches comprise:
a first Cu trenches running in a first direction in the three-dimensional test structure, and
a second Cu trenches, above the first Cu trenches, running in a second direction in the three-dimensional test structure.
4. The apparatus according to claim 3 , wherein the first direction is perpendicular to the second direction.
5. The apparatus according to claim 3 , wherein the first direction is parallel to the second direction.
6. The apparatus according to claim 1 , wherein the Cu trenches decrease in thickness near an edge of the wafer when compared to a center of the wafer.
7. The apparatus according to claim 1 , wherein the apparatus further performs:
based on the results of the OCD scatterometry on the wafer, an automatic adjustment of deposition time of ULK dielectric film formed on the next wafer, based on the results of the OCD scatterometry on the previously measured wafer.
8. The apparatus according to claim 1 , wherein the apparatus further performs:
prior to measuring the thickness of the ULK dielectric film, forming the ULK dielectric film over the Cu trenches having upper surfaces subjected to chemical mechanical polishing (CMP).