Mass Metrology for controlling and understanding processes

Abstract

In this paper we report on mass metrology used for the characterization of different process steps (etch, clean, cavity etch, HARP deposition and CMP) of shallow trench isolation (STI) module in conventional CMOS technology. We also report on mass metrology for the characterization of plasma doping and on HfO2 high k gate dielectric deposition process. The performance of the mass balance metrology is benchmarked against state of the art metrology, including ellipsometery and Rutherford Backscattering (RBS).

Metrology for Monitoring and Detecting Process Issues in a TSV Module

“…Of Line (FEOL) steps, a first mass measurement was done at the position [Pre Litho], which serves as the mass measurement reference point, thereby implicitly correcting for any deviations that have occurred up to that point in the process flow, which can be due to non-critical process fluctuations or intentional splits on any layer thickness in the preceding FEOL module(s) all of which cause mass differences. 15 In the TSV module, measurements were done in between all process steps, to keep track of deviations and mass changes for each step. By taking the difference in mass between the position [Post Strip] and this reference point at [Pre Litho], one can calculate the amount of silicon etched (see Figure 1 and 2b), results of which are shown in Figure 3 for a wide range of TSV depth using the 5 μm diameter TSV reticle.…”