by Debra Vogler, senior technical editor, Solid State Technology
September 3, 2009 - Molecular Imprints Inc. (MII) has introduced the Perfecta TR1100 template replication system for patterned media applications. In combination with the company’s jet-and-flash imprint lithography (J-FIL) technology, the new system enables the mass-replication of master imprint templates with high fidelity at a cost that the company says is orders of magnitude lower than that of fabricating the original master template.
Maintaining the historical 40% annual growth in hard-disk drive (HDD) areal density to 1Tb/in2 and beyond will require patterned media with critical dimensions under 20nm, at less than one-tenth the cost of current semiconductor patterning (see figure), company CEO Mark Melliar-Smith explained to SST. “Until recently, the industry stayed on the roadmap by writing finer magnetic domains on a spinning magnetic disk by improving the read/write head,” he said, but approaching that 1Tb/in2 density mark means that “the dimensions of the magnetic domain being written are so small that it is unstable at room temperature — hence, unreliable.” To fix the problem, HDD manufacturers have had to physically separate magnetic material through patterning (e.g., discrete track recording). But as Melliar-Smith notes, ultimately (in about two or three years) the industry will have to undergo a significant change to higher densities using bit-patterned media — i.e., etching in two dimensions, and every bit on the disk drive will be a single <20nm column of magnetic material. This, he says, will "bring them into the 20nm lithography business -- and at the same time, they have to find a way to do that inexpensively."
According to Molecular Imprints, today’s unpatterned media cost is $4-$6/disk; the HDD industry is targeting patterned media cost at $1-$2/disk on top of that due to additional process steps required (e.g., imprinting, etch, stripper/planarization, etc.). HDD manufacturers will need to start working at tighter dimensions, such as 50nm pitch with a CD of ~20nm, Melliar-Smith told SST, “and they’ll head down from that point fairly quickly as they get to bit-patterned media where they will approach 10nm in the middle of the next decade.”
In addition to nanopatterning systems that support the HDD industry’s resolution and cost requirements, manufacturers also must have a ready supply of affordable imprint templates to transfer the nanometer-scale patterns onto the disk substrates. However, as Melliar-Smith notes, producing master templates using traditional e-beam technology in the volume needed to support patterned media production is cost-prohibitive.
The new approach to template fabrication being promulgated by the company is its J-FIL technology, which it says can deliver the resolution of e-beam technologies at a much lower cost. Once a master template is initially created using traditional e-beam technologies, the new template system can replicate it thousands of times. Each of the subsequent template replicas or “daughter” templates that are produced can then be used to produce thousands of disks.
The company has already sold two Perfecta TR1100 systems, with one formally accepted and installed by merchant mask and HDD disk manufacturer Hoya Corp., which will facilitate the commercial availability of imprint templates for advanced patterned media development and pilot production. – D.V.
Development template (~100nm pitch; 20nm minimum critical dimension) showing the variable pattern across the field of view. Current development templates are ~50nm pitch. (Source: Molecular Imprints Inc.)