Milton Russell Latta

Excimer laser projection lithography on a full-field scanning projection system

Optical projection lithography using an excimer laser light source is demonstrated on a commercial state-of-the-art full-wafer scanning 1x projection system. Images are printed on 125-mm-diameter wafers on a Perkin-Elmer Model 500 projection printer using an XeCl laser operating at 308 nm. Near-vertical image profiles and 1-µm resolution are experimentally demonstrated. The anamorphic optical transformation system necessary to transform the collimated, nearly rectangular excimer laser beam into the arc-shaped, effectively self-luminous illumination required by the projection system is also described.

Optical recording in the blue using a frequency-doubled diode laser

We have developed a 428 nm blue laser source based on resonator-enhanced frequency doubling of a GaAlAs diode laser and have used this source to demonstrate writing and reading on an MO disk. The power, beam quality, and noise of the blue laser are sufficient for high-density optical recording.

Measuring and modeling optical diffraction from subwavelength features

We describe a technique for studying scattering from subwavelength features. A simple scatterometer was developed to measure the scattering from the single-submicrometer, subwavelength features generated with a focused ion beam system. A model that can describe diffraction from subwavelength features with arbitrary profiles is also presented and shown to agree quite well with the experimental measurements. The model is used to demonstrate ways in which the aspect ratios of subwavelength ridges and trenches can be obtained from scattering data and how ridges can be distinguished from trenches over a wide range of aspect ratios. We show that some earlier results of studies on distinguishing pits from particles do not extend to low-aspect-ratio features.

Effect of track crossing on focus servo signals: feedthrough

We discuss the origin of focus servo feedthrough in optical storage drives and show modeling and experimental feedthrough results for various aberrations.