In the field of biochemical deposition, the use of organic molecules to modify the interface between metal and high-permittivity (K) material is a recent development with a wealth of applications. Generally, there have been two main approaches to molecular control over electronic device properties: 1) control of the electrical potential at the interface (electrostatics), 2) control of charge transport across the interface (electron dynamics). For purposes of stability and reliability, the electrostatic approach may be more favorable. Methods, while complicated, do exist for tuning complementary metal-oxide-semiconductor (CMOS) devices integrating high permittivity (K) gate dielectric films; however, effective integration of such materials into future devices, specifically dual-metal MOSFETs, will require alternative solutions to tuning specific metals. Meanwhile, an alternative to the use of dual metals in CMOS with high K dielectrics would also be desirable.

Researchers at Arizona State University have developed such an alternative method to tune the properties of solid surfaces through deposition of self-assembled monolayers (SAM) or organic molecules yielding hybrid, multifunctional systems that combine both the molecular and non-molecular worlds. Specifically, the method applies systematic substitutions of different functional groups within an organic molecule to tailor both the magnitude of the dipole moment and its direction on a solid surface. Subsequently, a molecularly based system can potentially tune the electrical characteristics (e.g. equivalent oxide thickness (EOT), flat band voltage (VFB), work-function, and leakage current) of CMOS gate-stacks with a simplified production technology.

Potential Applications

• Microelectronics (e.g. CMOS devices)
• Optoelectronics
• Molecular Electronics and Bio-Nanodevices

Benefits and Advantages

• Eliminates the Use of Dual Metal Gates in CMOS – alleviates complications from deposition/etching and issues of yield, etc.
• Significantly Reduces Cost – reduces cost of metallization in advanced semiconductor devices by simplifying the technology
• Enhanced Tuning Capability – potential to tune EOT, VFB, work-function, and leakage current
• Novel Bio-sensor Fabrication – soft-mode hardening may allow for changes to eigen-frequency of the transverse optical phonon mode

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