Comparison of the Phase Metrics DFHT IV

This study compares the performance of the Phase Metrics DFHT IV and Zygo Pegasus 2000 fly height testers, focusing on their repeatabilities and measurement uncertainties. The objective was to assess which tester provided superior performance in measuring fly height, a critical factor in the design and quality control of hard disk drives. We conducted a series of measurements and evaluations under controlled conditions to gather comparative data. Our results indicated that the DFHT exhibited a repeatability of 0.25 nm, while the P2000 demonstrated a repeatability of 0.30 nm. At a fly height of 25 nm, the measurement uncertainty for the DFHT was 0.76 nm, compared to 1 nm for the P2000. Additionally, the P2000 showed limitations in recognizing small diamond-like carbon bumps, which could affect its accuracy. A consistent 3-nm offset was noted between the two testers' measurements, suggesting no clear advantage for either system. This research highlights the importance of selecting appropriate measurement tools in the increasingly vital field of near-contact recording, emphasizing that both testers have significant merits.