Highly Reliable Contacts to Silicon Enabled by Low Temperature Sputtered Graphenic Carbon

Max Stelzer,Alexander Holleitner,Ursula Wurstbauer,Moritz Jung,Franz Kreupl

doi:10.1109/jeds.2019.2894975

Max Stelzer, Alexander Holleitner + Show 3 more

Open Access

https://doi.org/10.1109/jeds.2019.2894975

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Abstract

Titanium silicide (TiSi) contacts are frequently used metal-silicon contacts but are known to diffuse into the active region under high current density stress pulses. Recently, we demonstrated that graphenic carbon (GC) deposited by CVD at 1000 °C on silicon has the same low Schottky barrier as TiSi, but a much improved reliability against high current density stress pulses. In this paper, we demonstrate now that the deposition of GC is possible at 100 °C – 400 °C by a sputter process. We show that the sputtered carbon-silicon contact is over 1 billion times more stable against high current density pulses than the conventionally used TiSi–Si junction, while it has the same or even a lower Schottky barrier. SC can be doped by nitrogen (CN) and this results in an even lower resistivity and improved stability. Scalability of the CN thickness down to 5 nm is demonstrated. The finding that there is a low temperature approach for using the excellent carbon properties has important consequences for the reliability of contacts to silicon and opens up the use of GC in a vast number of other applications.

Highlights

Metal to semiconductor contacts are essential elements in integrated and discrete electronic devices
Common source and drain contacts in state-of-the-art FinFETs rely on the formation of titanium silicide (TiSi) [1]–[3]
We reported earlier [10], [11] that a CVD-deposited graphenic carbon (GC) contact to silicon (CVD-C-Si) has similar electrical properties as TiSi-Si but a much higher temperature stability and a more than 100 million times improved stability against electrostatic discharge (ESD) current pulses

Summary

Introduction

Metal to semiconductor contacts are essential elements in integrated and discrete electronic devices. We reported earlier [10], [11] that a CVD-deposited GC contact to silicon (CVD-C-Si) has similar electrical properties as TiSi-Si but a much higher temperature stability and a more than 100 million times improved stability against ESD current pulses.

Results

Conclusion