Meaning
Structural coefficient measures the change in the total volume of a solid when a single point defect is introduced. The relaxation volume accounts for the displacement of surrounding atoms as they adjust to the presence of a vacancy or an interstitial. This value is critical for calculating the internal pressure and mechanical stability of semiconductor thin films.
It applies to crystalline materials where the lattice period is well-defined. Variations in these values influence the macroscopic strain observed in bulk samples after ion implantation.
Lattice Distortion
Displacement occurs because the electronic bonds around the defect site are either stretched or compressed. A negative relaxation volume indicates that the nearby atoms have moved inward toward a vacancy. This contraction creates a localized tensile stress field that interacts with other defects in the material.
Yield Engineering
Manufacturing processes for advanced integrated circuits must account for these micro-strains to prevent wafer breakage. High relaxation volume in dopant atoms leads to unexpected shifts in the electrical properties of the transistor channel. Engineers use this data to calibrate the deposition parameters for multilayer metal stacks.
Metrological Standard
Quantifying these effects requires advanced X-ray diffraction techniques according to the GB/T standards for silicon wafers. Precise measurement of relaxation volume allows for the simulation of long-term material aging under thermal load. The National Institute of Metrology provides the reference samples used to calibrate the testing equipment for semiconductor foundries.
