The present invention relates, in general, to a new and unique method of fine line patterning, and more particularly to a technique based on the selective surface oxidation of aluminum for producing pattern lines in the range of 1500 .ANG. in width for use in making submicron device structures or etching masks.
Pattern definition and pattern transfer are among the most important activities in the fabrication of semiconductor devices and integrated circuits. The production of micro-miniature electronic components requires the formation of very accurately dimensioned component patterns in layers on a substrate or in a semiconductor body. A standard production method is to irradiate portions of a radiation-sensitive layer overlaid on a component layer or body to define a pattern of differential solubility. The pattern definition typically involves the use of optical, X-ray or electron beam lithography, followed by development of the sensitive layer to remove either the radiated region, in the case of a positive resist material, for example, or the non-irradiated region, in the case of a negative resist material, for example, and in each case to leave the remainder of the sensitive layer to define the desired pattern. The pattern is then transferred to the underlying substrate by, for example, etching or deposition through the openings or windows defined in the radiation sensing layer.
Radiation sensitive materials with the high resolution capabilities required to obtain high accuracy in the fabrication of electronic components are available with positive sensitivity to allow the transfer of original patterns to substrates. But is is often important to be able to produce the negative of the original pattern in the substrate. This may be accomplished by means of a negative resist or by the liftoff of a deposited film, but for dimensions below one micrometer (1 .mu.m), as required in the fabrication of micro-miniature devices, both of these latter processes have limitations. High resolution negative resists with sufficient sensitivity and with reproducable characteristics have not yet been developed, despite major research efforts, and the use of lift-off techniques to produce pattern inversion produces lines with triangularly-shaped cross-sections, a feature which is generally undesirable and is difficult to control precisely.