Ruthenium Circularity for the Semiconductor Industry
In this article, we discuss the use of ruthenium as an interconnect material, present our ruthenium precursor for ALD & CVD and explain why the concept of circularity is key to ruthenium affordability. For further discussion and exchange, we offer a contact detals at the bottom of the page.
Closing the Ruthenium Loop in Leading Edge Chip Technology Nodes
The semiconductor industry has achieved wondrous things in recent decades, fitting hundreds of billions of transistors on a space the size of a postage stamp. Challenges have been overcome in ways that for the layman seem to derive from a science fiction novel (see EUV lithography for example). Miniaturization continues to be key for improving performance. Accordingly, the industry is geared towards smaller and smaller technology node designations.
While Apple enthusiasts get excited about the new high-end M2 Pro processor produced with 3 nm chip manufacturing technology, the semiconductor industry is already preparing to start the 2 nm technology production in high volumes by 2024/25. A major challenge on this path is a phenomenon called electromigration, which takes place within the interconnects that link transistors to each other. Today, interconnects are mainly made of copper. Unfortunately, the thinner the copper structure becomes, the more likely electromigration occurs. Copper’s resistive properties just can’t keep up with the ultra-tiny interconnect sizes required nowadays.
Faster chips require new materials
A new material with low resistivity will be needed if miniaturizing continues. The trend in technology points to the precious metal ruthenium which could be used in the thinnest interconnect layers thanks to its superior immunity to electromigration.
Heraeus Precious Metals offers the chemistry needed for depositing ruthenium on a wafer: a selection of ruthenium intermediates and volatile ruthenium precursors which may be applied via atomic layer deposition or chemical vapor deposition.
| Ruthenium Compound | CAS Number | Formula | Availability |
|---|---|---|---|
|
Bis(ethylcyclopentadienyl)ruthenium(II) |
32992-96-4 | Ru(EtCp)2 | Send Inquiry |
|
Bis(cyclopentadienyl)ruthenium(II) |
1287-13-4 | Ru(Cp)2 | Send Inquiry |
|
Dicarbonylcyclopentadienylruthenium dimer |
12132-87-5 |
[Ru(Cp)CO2]2 |
Send Inquiry |
|
Bis(2,4-dimethylpentadienyl)ruthenium |
85908-78-7 | Ru(DMPD)2 | Send Inquiry |
|
(toluene)(1,5-cyclooctadiene)ruthenium |
63395-20-0 | Ru(COD)(Tol) | Send Inquiry |
|
Triruthenium Dodecacarbonyl |
15243-33-1 | Ru3(CO)12 | Request Quote |
| Dichloro(p-cymene)ruthenium(II) dimer | 52462-29-0 | [Ru(p-cymene)(Cl2)]2 | Request Quote |
| (p-Cymene)(N,N′-diisopropyl-1,2-ethanediimine)ruthenium | 1638669-96-1 | Ru(p-Cymene)(iPrDAD) | Send Inquiry |
Ruthenium - a precious challenge
While ruthenium has excellent material properties, its high price has previously prevented it from being introduced in semiconductor manufacturing. To illustrate the value of this precious metal, the average price per kilogram ruthenium metal was around 10 000 USD in 2020 and has been quite volatile in recent years.
So, does this mean it will be impossible to use such a valuable material in industrial scale processes?
Closing the loop – a circular solution
Needless to say, it isn’t. Precious metal specialists like Heraeus, offer hedging and financing solutions , which help clients with planning stability. While this tackles the issue of price volatility, precious metal recycling is what actually mitigates the high prices of platinum group metals (PGMs).
PGMs have been employed globally for decades in numerous industrial scale processes, mainly in the chemical industry. They are often used in their chemical compound form, mostly as process catalysts. When these catalysts are depleted, they are sent back to a precious metal recycler like Heraeus where the metal is recovered, purified and used to synthesize new chemical compounds - thereby closing the precious metal recycling loop. The metal content of the returned waste stream is largely refunded to the customer making the precious metal much more affordable.
This circular business model can be applied within the semiconductor industry as well. Ruthenium is also used in the form of a chemical compound – as a precursor for the deposition on wafers. In this process a waste stream is formed, containing most of the precious metal used. Only a small fraction of the metal ends up on the microchip. Thus, recycling and refunding the wasted ruthenium along the production chain will be the key to its affordability.
Closing the Ruthenium loop for semiconductor deposition processes seems plausible and feasible. It might require coordination between multiple players along the value chain, but it will enhance the business case for everyone involved.
In short
For the next generation of interconnect materials at the 2 nm node, ruthenium is on the semiconductor industry’s agenda. However, it is a rare precious metal with high and volatile prices. Furthermore, wafer deposition processes create unnecessary waste and much more ruthenium is needed up front compared to the small amounts that end up on the chips. Fortunately, Heraeus offers solutions to these challenges: CVD/ALD precursor materials and their raw materials, precious metal recycling and refunding as well as risk management to mitigate price volatility.
Contact us
Get in touch with us and discuss how Heraeus can facilitate your sustainable use of ruthenium within the microchip manufacturing chain.
