David S. Kuo

Design of laser zone texture for low glide media

The design of laser zone texture on NiP/Aluminum substrates to create below-25 nm-glide-height media is described in this paper. A range of laser parameters such as beam size, pulse energy, and temporal pulse width of a pulsed Nd-YVO/sub 4/ laser are explored to reveal their relationship to the resulting bump topography. Depending on where the head contact is formed, four major categories of bump shapes are found to exist. The single-crater bump shape was selected to conduct the low glide texture design. Stiction and glide performance are shown to be in agreement with theoretical predictions, which constitute our major design guidelines. It is clearly demonstrated that with proper texture design below-25 nm-glide-height media with low stiction and minimal wear are readily achievable even in the landing zone with laser texture.

Fabrication of Silicon Oxide Nanodots with an Areal Density Beyond 1 Teradots Inch−2

The combination of solvent annealing, surface reconstruction, and a tone-reversal etching procedure provides an attractive approach to utilize block copolymer (BCP) lithography to fabricate highly ordered and densely packed silicon oxide nano-dots on a surface. The obtained silicon oxide nano-dots feature an areal density of 1.3 teradots inch(-2) .

Aligned nanowires and nanodots by directed block copolymer assembly.

The directed self-assembly of block copolymers (BCPs) is a promising route to generate highly ordered arrays of sub-10 nm features. Ultradense arrays of a monolayer of spherical microdomains or cylindrical microdomains oriented parallel to the surface have been produced where the lateral ordering is guided by surface patterning and the lattice defined by the patterning can be commensurate or incommensurate with the natural period of the BCP. Commensurability between the two can be used to elegantly manipulate the lateral ordering and orientation of the BCP microdomains so as to form well-aligned arrays of 1D nanowires or 2D addressable nanodots. No modification of the substrate surface, aside from the patterning, was used, making the influence of lattice mismatch and pattern amplification on the size, shape and pitch of the BCP microdomains more transparent. A skew angle between incommensurate lattices, defining a stretching or compression of the BCP chains to compensate for the lattice mismatch, is presented.

Directed Self‐Assembly of Poly(2‐vinylpyridine)‐b‐polystyrene‐b‐poly(2‐vinylpyridine) Triblock Copolymer with Sub‐15 nm Spacing Line Patterns Using a Nanoimprinted Photoresist Template

Low molecular weight P2VP-b-PS-b-P2VP triblock copolymer (poly(2-vinlypyridine)-block-polystyrene-block-poly(2-vinylpyridine)] is doped with copper chloride and microphase separated into lamellar line patterns with ultrahigh area density. Salt-doped P2VP-b-PS-b-P2VP triblock copolymer is self-assembled on the top of the nanoimprinted photoresist template, and metallic nanowires with long-range ordering are prepared with platinum-salt infiltration and plasma etching.

Advanced Lithography for Bit Patterned Media

For bit patterned media (BPM) applications, while significant progress has recently been made in demonstrating high-resolution dot patterning using e-beam direct writing, and followed by the successful imprint process, many serious issues in fabrication still remain. This paper will only discuss the key challenges in the BPM lithography, including (1) the commercial availability of a high-resolution rotating stage e-beam system; (2) the approach and limitation of directed polymer self-assembly for resist pattern quality improvement and resolution enhancement; (3) the difficulties and limitations in the fabrication and replication of a 1 times template with a density beyond 1 Tbit per square inch (Tb/in2), while the defectivity, lifetime, and damage of the template are still questionable; (4) the tight requirements of size uniformity and placement accuracy; and (5) the needs of advanced metrology associated with the very small dot size and defect characterization. In this paper, we will address the above challenges and present some experimental data along with possible solutions for the challenges.

Solvent‐Assisted Directed Self‐Assembly of Spherical Microdomain Block Copolymers to High Areal Density Arrays

The fabrication process for 5 Tb/in(2) bit patterns using solvent-assisted directed self-assembly is investigated. The N-methyl-2-pyrrolidone solvent vapor-annealing method was used to achieve good long-range lateral ordering of low-molecular-weight polystyrene-block-polydimethylsiloxane with a lattice spacing of 11 nm on flat Si substrates, PS modified substrates and lithographically patterned substrates, respectively.

Laser zone texturing on glass and glass-ceramic substrates

A RF driven CO/sub 2/ laser is used to create laser bumps on glass and glass-ceramic substrates. The resulting bump height is found to be a function of laser parameters such as pulse width, spot size, and pulse energy. Composition, structure and chemical strengthening of the substrates also affect the laser bump topography. Laser bumps on glass-ceramic, non-strengthened glass, or strengthened glass substrates, all exhibit net volume gain. Possible mechanisms for the volume increase include density change due to glass quenched to a subcooled state and/or due to phase transition from the crystalline phase to the glass phase. Stress release may play a role in the case of chemically strengthened glass substrates. The tribological performance of laser texture on glass and glass-ceramic substrates again shows low stiction and low friction build-up.

Effect of non-uniform lubricant distribution and de-wetting on head-disk dynamics

In this work, the effect of long-wavelength nonuniform lube distribution and lube de-wetting on head-disk dynamics is investigated by using disks with controlled within-disk nonuniformity in lubricant film thickness. Complex slider responses were observed, which were sensitive to lubricant film thickness and the extent of de-wetting. The effect of slider-assisted lubricant redistribution was also observed.

Disk shape and its effect on flyability

The static spacing loss of slider-disk interface is investigated through careful characterization of disk shape for disks of different form factors with different peak-to-valley flatness values. Measured radial profiles are normalized and found to be confined within a relatively narrow region. The representation of these shapes is reduced to a simple set of quadratic equations. Static flyability models associated with the disk radial slope (crown effect) and radial curvature (camber effect) are presented. Spacing loss is calculated for a negative pressure pico-slider and a positive pressure catamaran nano-slider. Results show that slider geometries and crown/camber sensitivity, as well as disk flatness and shape, all affect static slider-disk spacing loss. The analysis is focused on the effect of disk shape on the static spacing loss and its relationship to slider design.

Study of spin-coated resist coverage on nanoscale topography using spectroscopic ellipsometry

Using spectroscopic ellipsometry and rigorous coupled wave analysis, we studied the spin-coated resist coverage on 72.6 nm pitch line-and-space patterns of various depths (from ∼20 to ∼130 nm). Within the margin of measurement error, we find the tested nano-patterns have no apparent effect on the spin-coated resist thickness. The result suggests that, during the spinning, the resist ceased to flow at a critical thickness much larger than the pattern depth, and the resist thinning afterwards was dominated by solvent evaporation. The methods and results demonstrated in this work can improve the characterization and process control in a number of applications where spin coating on high-density nano-scale topographies is required.