Boosting Performance of Phase Change Devices by Hetero- and Nano-Structure Material Design

Project Information

BeforeHand

Grant agreement ID: 824957

DOI

10.3030/824957

Project closed

EC signature date 6 December 2018

Start date 1 January 2019

End date 30 June 2022

Funded under

• INDUSTRIAL LEADERSHIP - Leadership in enabling and industrial technologies - Information and Communication Technologies (ICT)

Total cost

€ 3 999 451,25

EU contribution

€ 3 999 451,25

Coordinated by

CONSIGLIO NAZIONALE DELLE RICERCHE
Italy

Periodic Reporting for period 2 - BeforeHand (Boosting Performance of Phase Change Devices by Hetero- and Nano-Structure Material Design)

Reporting period: 2020-07-01 to 2022-06-30

Summary of the context and overall objectives of the project

BeforeHand aims at establishing the foundations of a new technology, suitable for the implementation in networks of Electronic Smart Systems (ESS) exploiting the capability of phase-change materials (PCMs) to process and store data in the very same physical place, with particular focus on automotive applications. The ESS of the future should be able to sense its environment, locally store and process the information, as well as communicate with other objects in a network. We made use of a test vehicle to allow the comparison among different PCM materials. After successful evaluation of the best material combination, a demonstrator with processing/storage ability was implemented. At the end of the project a full evaluation of the demonstrator was performed.
To achieve such a target, the objectives of the project were:
1. Realization of PCM multilayers in thin films and nanostructures with improved physical properties;
Such Objective was achieved using three deposition techniques, all compatible with current device architectures and the implementation of complex crystalline heterostructures such as Ge-rich-GST/ GST, In-Sb-Te/ GST, In-Ge-Te/ GST and Ga-Sb-Te/ GST. Self-assembly of single and core-shell NWs was obtained as well.
2. Development of a single cell vehicle (SCV) and line cell vehicles (LCV) for electrical testing;
All three types of devices were developed and tested, thus objective 2 was achieved.
3. Complete understanding of the physical properties of PCM multilayers by detailed electrical, electronic, structural characterization and atomistic simulations;
Structural, electronic, electrical and thermal properties characterization on the materials and devices level, determined which materials system in combination with device architecture was the most promising to improve and boost device performance;
Furthermore, efforts were devoted to determine the physical mechanisms, such as thermal diffusion, phase separation and electromigration, affecting the endurance and the reliability properties of the devices. The experimental characterization was complemented in an integrated manner by theoretical modelling;
4. Technology transfer of the optimized best heterostructure for integration in a PCM device on complementary metal–oxide–semiconductor (CMOS) platform;
Technology transfer and thus the achievement of Objective 4 started on time and was concluded with the submission of D5.1 that reported several measurements of the structure and morphology of the integrated layers.
5. Demonstration of improved processing and storage performances achieved in a fully functional 1resistor-1transistor (1T1R) large size crossbar array on 200 mm large wafers;
Small (a few kbit) to medium size (1 Mbit) arrays were realized. The thermal stability of the multilayer was assessed using thermal stress experiments combined with electrical measurements and high-resolution physical analysis to detect possible intermixing or decomposition of the alloys.
6. Demonstration of the concept of integration in an automotive chip for IoT market through adequate benchmarking;
Benchmarking against state-of-the-art was performed to make sure that the project maintains its competitiveness.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

An extensive deposition work was carried out by the WP2 participants, aiming at the selection of the best performing phase change materials composing the expected heterostructures. The strength of the approach, using in parallel different deposition techniques, allowed the exploration of a common set of phase change materials both in the form of thin films and nanowires. The consortium worked incessantly to improve the control on the deposition of the most promising layers of phase change materials and their combination in multi-layered heterostructures and superlattices. A particularly interesting composition, named as golden Ge-rich GST, was identified and gave rise to a rich and intense stud. WP3 was taking care of the development of several vehicles suitable for electrical testing to allow for the evaluation of different stacks of multilayers. Several materials and heterostructures deposited by different methods within the Consortium were evaluated. The most promising material, among the investigated Ge-rich based alloys, was the golden Ge-rich GST composition, since it exhibits better retention and cyclability, and a very low resistance drift. At the beginning of the project, the primary focus of WP4 was on performing characterization and modeling activities required to optimize the materials development. This was done to check if the desired films were grown each time with the right composition and structure and to guide the growers towards optimized structures. Whereas, in the second half of the project, the characterization was performed with the aim of deep understanding of the various structural, electronic, electrical and thermal properties. Finally we generated an in-depth understanding of the properties and performances of the materials, with strong interlink with the other work packages.
WP5 was mainly devoted to the realization of a demonstrator able to prove the processing/storage concept of a device with the PCM multilayer as active layer. At first we developed multilayered stacks in a 200 mm PVD deposition. The chosen materials were integrated in a demonstrator (1Resistor) single cells, 1 transistor – 1 PCM (1T-1R) single cells and small arrays. The electrical characterization of single cells and arrays was carried out. Benchmarking, between the best PCM materials and GST-225 and Ge-GST:N, was performed to evaluate the possible integration of those materials in an automotive chip for the IoT market. We demonstrated that the golden Ge-rich GST composition used in heterostructures is of great interest, since it combines a good programming window, reduced programming currents, good endurance and data retention, but also could enable multilevel programming.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

BeforeHand innovation potential in terms of products is that of the field of embedded memories. In fact, such devices are at the heart of several systems within the automotive vehicles, and the number of those systems is increasing year by year, following the increasing “intelligence” requested by modern cars, not only for engine control, gasoline management, airbag, stability control and Global Positioning System functions, but also for future autonomous driving, electrification and battery control, telematics, inside and for vehicle-to-vehicle communication.
The industrial BeforeHand participant ST had a first-quarter report particularly positive.
Revenue increased in Automotive with Operating profit increased by 175.1% to $235 million. Such global economic scenario is positive for the general impact of BeforeHand on innovation in the automotive sector.
The dissemination and outreach actions undertaken were very rich (detail in D1.6 and D1.7). The consortium published 38 referred papers and had 51 conference contributions with 14 invited, 26 oral, 9 posters and 2 tutorials to be held. Several young researchers trained within the BeforeHand consortium got further working opportunities.

IOT for automotive within BeforeHand