Automated, high precision measurement of critical dimensions using the atomic force microscope

Abstract

We describe a computerized method to analyze the microstructure of optical disks. On digital versatile disks (DVDs), the smallest features are pits or bumps about 400 nm long, 320 nm wide, 120 nm high, with a track pitch of 740 nm. We measured the following parameters: track pitch, bump height, bump width and length (at various threshold levels), and four sidewall slope angles, in each case reporting the mean, standard deviation, and other statistics. In a single 10×10 μm image of a DVD stamper containing about 100 bumps, we tabulated about 1000 values. In a plot of bump width versus bump length, we found that the width at half height increased from 328 nm for the shortest bumps (440 nm long) to about 385 nm for bumps longer than 800 nm; this matches the increase seen for corresponding optical signals produced when a finished disk is played. Where a sidewall angle deviated from the norm, we were able to review the image data to identify the specific nature of the defect. This automated method yields statistically robust results, not only for mean values of structural parameters, but also for the standard deviations so that process windows can be determined. Thus, feature geometry will no longer be a hidden variable in the path between controlling production equipment and observing the good or bad electrical performance of a finished disk.

Roadmap for traceable calibration of a 5-nm pitch length standard

“…3 shows the AFM images used for the analysis of Run 2, Data Set 8. The measurements were made according to procedures described in detail elsewhere 11,12,13 and summarized here. The software computes an average height profile Z(x) by averaging all scan lines.…”

Multilaboratory comparison of traceable atomic force microscope measurements of a 70-nm grating pitch standard

“…The measurements were made according to procedures described in detail elsewhere [13][14][15] and summarized here. The software computes an average height profile Z(x) by averaging all scan lines.…”

Microstructure Measurement Method of Novel Multi-Level Run-Limited-Length Read Only Discs Using the Atomic Force Microscope

“…AFM has long been used for qualitative and quantitative analysis of the topography of compact discs and DVDs. 5) By measuring the parameters of track pitch and the pit geometry relating to the process position and noise of ML-RLL discs, we can improve the process control in optical disc manufacturing.…”