Application of STM Nanometer-Size Oxidation Process to Planar-Type MIM Diode

Abstract

Ultra fine oxidized titanium (Ti) lines 18 nm wide and 3 nm high have been formed on the surface of a 4 nm Ti layer on a SiO2/Si substrate using the scanning tunneling microscope [STM] tip as a selective anodization electrode. The dependence of the size of the oxidized titanium line on the various parameters is investigated. The formed oxidized titanium line has resistivity of 2×104 ohm cm, which is a value seven orders of magnitude higher than that of the deposited Ti layer. The oxidized Ti line is used in the planar type metal-insulator-metal [MIM] diode, and works as an energy barrier for the electron. The energy barrier height of the oxidized Ti line is found to be δE g=0.25 eV.

Organosilane Monolayer Resists for Scanning Probe Lithography.

“…In addition to surface imaging, marked progress has been made employing SPM as a surface modification tool. For example, there have been several recent reports describing the fabrication of nanometer-scale electronic devices where SPM-directed surface anodization was used to make insulating parts [1][2][3][4][5]. In order to apply SPM more generally to nano-device fabrication, SPM-based nanolithographic processes must be developed.…”

Nanofabrication with proximal probes

“…It has also been used to fabricate lateral metal-oxide-metal tunnel junctions by introducing thin regions of oxide in an otherwise continuous metal film [9], [10]. Such lateral metaloxide-metal junctions can be made very small and thus have correspondingly small junction capacitance.…”

“…When an electrical bias is applied to such a system, the sample surface is locally oxidized over lateral dimensions of 10-100 nm and to a depth of 1-10 nm, the size depending on the type of sample, the shape of the tip, and the exposure conditions. This and other more recently developed AFM/STM lithographic processes can be used for a variety of applications such as fabricating masks for selective etching [7], patterning growth templates by using self-assembling monolayer films (SAM's) [8], directly patterning the conduction path through thin conducting films [9], [10], and mechanically machining thin resist layers [11]. In all such applications the fine resolution and unique imaging properties of proximal probes can be utilized to achieve a unique lithographic tool that is well suited for device fabrication [12]- [15].…”

Metal point contacts and metal-oxide tunnel barriers fabricated with an AFM

“…AFM/STM anodization of metal films has been reported by a number of research groups [5][6][7][8][9], and the process is similar to conventional electrochemical anodization except that an AFM/STM tip is used as the cathode and water from the ambient humidity is used as the electrolyte. Conventional electrochemical anodization requires a threshold field ∼ 10 7 V cm −1 for anodization [10].…”

“…These oxide patterns have been used for a variety of purposes that include etch masks [3], templates for metalization [4] and insulating layers used to pattern thin metal films [5]. With the aid of in situ electrical measurements this last process can be used to fabricate sub-10 nm metal/oxide devices with precisely controlled electrical properties [6].…”