Most notably, the capability to create huge amounts of data, often stored only in electronic format, has led to a crisis not only in the need for preservation standards for digital documents, but as well has resulted in impossible demands upon the physical storage capabilities of microfilm storage vaults. With the limited lifespan of organic-based microfilms, particularly older films, the need to replace microfilm with a more durable and dense storage medium is acute. Readback of this data is direct, requiring no intermediate bitstream interpreter. Of particular interest to data storage is ion implantation. Because of fast write rates, implantation and subsequent etch-stop techniques have developed as the method by which data can be efficiently and rapidly written.
Ions are well suited to write data by implantation and etching techniques.
By adjusting the ion beam current and the dwell time per spot, the size of the data spot and the dose of implanted ions can be carefully controlled. Under these conditions, gallium serves as an etch-enhancement dopant, with etchant exposure times as short as 1 minute. Figure 1 is a schematic of the ion implantation process. In this case, the spatial resolution is governed by the beam current, which is a function of the selected aperture. Typical spot sizes, which determine the pixel size of the written data, are about 50 nm.