Custom electrodes for molecular memory and logic devices

Abstract

A method is provided for fabricating molecular electronic devices comprising at least a bottom electrode and a molecular switch film on the bottom electrode. The method includes forming the bottom electrode by a process including: cleaning portions of the substrate where the bottom electrode is to be deposited; pre-sputtering the portions; depositing a conductive layer on at least the portions; and cleaning the top surface of the conductive layer. Advantageously, the conductive electrode properties include: low or controlled oxide formation (or possibly passivated), high melting point, high bulk modulus, and low diffusion. Smooth deposited film surfaces are compatible with Langmuir-Blodgett molecular film deposition. Tailored surfaces are further useful for SAM deposition. The metallic nature gives high conductivity connection to molecules. Barrier layers may be added to the device stack, i.e., Al2O3 over the conductive layer.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] The present application is related to U.S. Pat. No. 6,459,095, issued Oct. 1, 2002, entitled “Chemically Synthesized and Assembled Electronic Devices”, which is directed to the formation of nanowires used for nanoscale computing and memory circuits. The present application is also related to U.S. Pat. No. 6,314,019, issued Nov. 6, 2001, entitled “Molecular Wire Crossbar Interconnect (MWCI) for Signal Routing and Communications”, and to U.S. Pat. No. 6,128,214, entitled “Molecular Wire Crossbar Memory”, issued on Oct. 3, 2000, as well as to applications Ser. No. 09 / 280,045, entitled “Molecular Wire Crossbar Logic (MWCL)”, and Ser. No. 09 / 280,188, entitled “Molecular Wire Transistor (MWT)”, both filed on Mar. 29, 1999, which are all directed to various aspects of memory and logic circuits utilized in nanocomputing. The present application is also related to application Ser. No. 09 / 823,195, filed Mar. 29, 2001, entitled “Bistable Molecular...

AI Technical Summary

Benefits of technology

[0036] Advantageously, conductive electrode properties include: a controlled oxide formation (under certain circumstances), a high melting point, high bulk modulus, low diffusion, some degree of stability (which depends on surface preparation). Smooth deposited film surfaces are compatible with Langmuir-Blodgett molecular film deposition. The metallic nature gives high conductivity connection to molecules. Barrier layers may be added to the device stack, i.e., Al2O3 over the conductive layer.

Problems solved by technology

As feature sizes of integrated-circuit devices continue to decrease, it becomes increasingly difficult to design well-behaved devices.

The fabrication is also becoming increasingly difficult and expensive.

In addition, the number of electrons either accessed or utilized within a device is decreasing, which produces increased statistical fluctuations in the electrical properties.

Aluminum forms a poorly controlled native oxide that acts as a natural barrier to electronic transport.

Platinum is difficult to maintain in a stable form.

Working with a just-deposited-film (perhaps the “cleanest” way) is difficult and impractical.

Shadow masks avoid lithographic process, but are dimensionally limited (to large micron-sized dimensions, sparsely placed).

Even nano-imprinting exposes surfaces to organic chemicals that are potentially incompatible with the use of organic active layers.

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