Friday, June 12, 2015

Samsung and SNU identifies the next Super High-k

Here is another publication from Samsung on high-k screening in collaboration with Academia. This time in collaboration with researchers from the home base at Seoul National University. This is somehow a new behavior of Samsung who actually withdrew talks in front of ALD 2012 in Dresden on anything realting to high-k and DRAM development and I have not seen that much publishing from Samsung since then on these topics. Calculated results do usually not tend to interest me but this one is very, very interesting and I think it will take me some time to go there it - fully understand I will not.

"Except for c-BeO, we could not find any outstanding high-κ dielectrics with eitherEg or κ larger than those of the HfO2 thin films currently used in CPU or DRAM (Eg~6.0 eV and κ~20–25; see t-HfO2)"

Cubic BeO will probably be a hot ALD topic for the rest of 2015 and I do wonder if Prof. Wang will mention BeO in Portland at the AVS ALD 2015 in Portland when he gives his invited talk: 

Cheol Seong Hwang, Seoul National University
“Capacitor Dielectric and Electrodes for DRAM with sub-20 nm Design Rule”

Check out the paper - it is Open Access - thank you Samsung!

Novel high-κ dielectrics for next-generation electronic devices screened by automated ab initio calculations (Open Access)

Kanghoon Yim, Youn Yong, Joohee Lee, Kyuhyun Lee, Ho-Hyun Nahm, Jiho Yoo, Chanhee Lee, Cheol Seong Hwang and Seungwu Han

NPG Asia Materials (2015) 7, e190; doi:10.1038/am.2015.57
Published online 12 June 2015

The experimental band gap and dielectric constant for well-known oxides. The property region ideal for dielectrics is also shown.

As the scale of transistors and capacitors in electronics is reduced to less than a few nanometers, leakage currents pose a serious problem to the device’s reliability. To overcome this dilemma, high-κ materials that exhibit a larger permittivity and band gap are introduced as gate dielectrics to enhance both the capacitance and block leakage simultaneously. Currently, HfO2 is widely used as a high-κ dielectric; however, a higher-κ material remains desired for further enhancement. To find new high-κ materials, we conduct a high-throughput ab initiocalculation for band gap and permittivity. The accurate and efficient calculation is enabled by newly developed automation codes that fully automate a series of delicate methods in a highly optimized manner. We can, thus, calculate >1800 structures of binary and ternary oxides from the Inorganic Crystal Structure Database and obtain a total property map. We confirm that the inverse correlation relationship between the band gap and permittivity is roughly valid for most oxides. However, new candidate materials exhibit interesting properties, such as large permittivity, despite their large band gaps. Analyzing these materials, we discuss the origin of large κ values and suggest design rules to find new high-κ materials that have not yet been discovered.

Eg vs κ plot for computed structures for 1158 oxides. Each point is color coded according to the figure of merit (Eg·κ). The candidate oxides that have not yet been tested are indicated by the chemical formula. The rough boundary of material properties that are adequate for each device type is marked by dashed lines. CPU, central processing unit.

Worth to mention also in this context is that Han Jin Lim from Samsung Semiconductor R&D Center will give a tutorial at the AVS ALD2015 conference at the end of June in Portland.

Han Jin Lim, Samsung Electronics, “ALD Technologies and Applications in Semiconductor Device Fabrication”

As semiconductor devices of both memory and logic have been smaller than 20nm feature size and beyond, it is most important to acquire the conformal high-quality thin films that effect on the electrical performance enhancement in the three dimensional patterned scheme. ALD technology has been required in such critical steps as transistor and capacitor and also increased its applications including DPT (double patterning technology).

This talk consists of two parts. The first part covers the ALD in general. Those introduce the general ALD technologies including processes, precursors, reactants and equipment. The second part deals with its applications in semiconductor device fabrication. Major applications include oxide for transistor gate and DPT pattrening, nitide for transistor spacer, high-k dielectrics for transistor as well as capacitor, and metal electrode.

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