PUBLISHABLE EXECUTIVE SUMMARY The use of chalcogenide materials for electronic memory applications has gained much attention in recent years, due to their successful application as materials for optical data storage. Non volatile memories based on phase change materials are actually the most promising candidate to replace the actual Flash memory technology based on poly-silicon floating gate and on SiO2 as inter-poly-silicon dielectric. Phase change memories (PCM) have been demonstrated to be scalable beyond the limit of actual Flash memory technology. One of the main issues related to the introduction of chalcogenide materials is the choice of the deposition method. In particular, chalcogenides are now deposited by physical vapour deposition methods, but, with the down-scaling of the electronic device architectures, a more conformal deposition method is required. This project aims at the feasibility study of growing the main chalcogenide material, Ge2Sb2Te5 (GST), by metal organic chemical vapour deposition (MOCVD), with equal or superior thickness, stoichiometry and coverage control than those achieved by sputtering techniques. This requires the test and development of suitable precursors for MOCVD, together with the optimisation of process conditions, either by the development of a specific-designed MOCVD system, or by the optimisation of the deposition parameters. The in-depth investigation of structural, chemical and functional properties of MOCVD chalcogenide materials is also an aim of the project. Once the deposition process has been optimised, state of the art memory cells at the 90/65 nm node will be fabricated. The device perfomances will be compared with those of cells based on sputteringdeposited GST as benchmark. In parallel with the device optimisation, modified compounds will be investigated. The development of a research-size MOCVD reactor, and the demonstration of the feasibility to grow GST by MOCVD is the goal of the first year of the project. The process of MOCVD-GST based devices, together with the study of new compounds is the target of the second year. At the end, devices based on MOCVD-grown, optimised materials will be demonstrated. This project is coordinated by MDM laboratory, INFM-CNR (Agrate, Brianza, I), a National Laboratory situated inside the site of STMicroelectornics, one of the five main semiconductor manufactures worldwide and having one of the main Research and Development department devoted to the study of innovative non-volatile memories situated at the Agrate Brianza's site. The consortium gathers Europewide experts in the specific fields required for the success of the Chemaph project. The precursor development is assigned to Epichem (UK), the development of the new MOCVD reactor to Aixtron (G), the test of new precursor and preliminary MOCVD growth to Vilnius University (LT), the test of functionality of new materials to CSIC (Sp), and the device development, together with the exploitation and dissemination of results to STMicrolectronics (I). Despite the co-ordination activity, CNR takes also care of the MOCVD growth with the new reactor, and of the structural and chemical characterisation, as well as help in device manufacturing, based on compounds issued from the new reactor. During this first year of the project, the main effort was concentrated on the design and development of a new MOCVD system for the deposition of Ge2Sb2Te5, on the development of new precursors for the MOCVD growth and on the test with a research system of the deposition conditions of single elements, binary and ternary compounds of the GexSbyTez family. The design and fabrication of the new system, due to different restrictions and requirements presented in the Wp2 section, has absorbed more resources and time than expected in the DoW. The delivery date of the MOCVD system to CNR-MDM, scheduled for month 6, was shifted to month 11. The development, test and delivery of the new precursors were timely accomplished. The modification of the VU research system in order to fulfil the requirements necessary for the growth of GexSbyTez has been timely accomplished and a lot of work has been devoted to the test of different precursor combinations. Both structural (VU) and functional (CSIC) characterisation have been performed on well selected samples and switching properties has been demonstrated on the GexSby system. Up to now, although the growth of Ge2Sb2Te5 has not been demonstrated by liquid injection MOCVD, a large window of deposition parameters and precursor combinations has been tested. This preliminary work constitutes a very solid starting point for the growth of GexSbyTez . The new MOCVD reactor has been accepted on the Aixtron site at month 11 and promptly moved to the MDM Laboratory. The set up of the apparatus at the MDM 5 laboratory took place at the middle of month 12. Due to some delays of the installation team at ST site, the hook up and installation of the MOCVD reactor, started the end of month 12, is not accomplished at the time of this report. During month 7, the CHEMAPH coordinator, Dr. Andrew Teren, left CNR-MDM. Dr Claudia Wiemer, CNR-MDM, is the present coordinator of the CHEMAPH project and had the chance to meet all the partners and to become promptly involved and updated on the project achievements during the first Partner meeting held in Vilnius on the July 3th-14th 2006. After the first year, the exploitable results are mostly related to innovation in the field of precursor selection for chalcogenide material production. Due to the close relation between the new designed MOCVD system and a real industrial system, once the process will be accessed, STMicroelectronics will be able to easily industrialized it. However, due to the early stage of the project and to delay in the availability of the prototype equipment for the MOCVD deposition, it has not been yet possible to define a detailed exploitation plan and to assess the environmental, health and safety issues related to this equipment. As compared to the DoW, this project is delayed by at least 6 months, and a prolongation will probably be discussed during the review meeting.
CHEMAPH-2007-Periodic activity report
wiemer c
2007
Abstract
PUBLISHABLE EXECUTIVE SUMMARY The use of chalcogenide materials for electronic memory applications has gained much attention in recent years, due to their successful application as materials for optical data storage. Non volatile memories based on phase change materials are actually the most promising candidate to replace the actual Flash memory technology based on poly-silicon floating gate and on SiO2 as inter-poly-silicon dielectric. Phase change memories (PCM) have been demonstrated to be scalable beyond the limit of actual Flash memory technology. One of the main issues related to the introduction of chalcogenide materials is the choice of the deposition method. In particular, chalcogenides are now deposited by physical vapour deposition methods, but, with the down-scaling of the electronic device architectures, a more conformal deposition method is required. This project aims at the feasibility study of growing the main chalcogenide material, Ge2Sb2Te5 (GST), by metal organic chemical vapour deposition (MOCVD), with equal or superior thickness, stoichiometry and coverage control than those achieved by sputtering techniques. This requires the test and development of suitable precursors for MOCVD, together with the optimisation of process conditions, either by the development of a specific-designed MOCVD system, or by the optimisation of the deposition parameters. The in-depth investigation of structural, chemical and functional properties of MOCVD chalcogenide materials is also an aim of the project. Once the deposition process has been optimised, state of the art memory cells at the 90/65 nm node will be fabricated. The device perfomances will be compared with those of cells based on sputteringdeposited GST as benchmark. In parallel with the device optimisation, modified compounds will be investigated. The development of a research-size MOCVD reactor, and the demonstration of the feasibility to grow GST by MOCVD is the goal of the first year of the project. The process of MOCVD-GST based devices, together with the study of new compounds is the target of the second year. At the end, devices based on MOCVD-grown, optimised materials will be demonstrated. This project is coordinated by MDM laboratory, INFM-CNR (Agrate, Brianza, I), a National Laboratory situated inside the site of STMicroelectornics, one of the five main semiconductor manufactures worldwide and having one of the main Research and Development department devoted to the study of innovative non-volatile memories situated at the Agrate Brianza's site. The consortium gathers Europewide experts in the specific fields required for the success of the Chemaph project. The precursor development is assigned to Epichem (UK), the development of the new MOCVD reactor to Aixtron (G), the test of new precursor and preliminary MOCVD growth to Vilnius University (LT), the test of functionality of new materials to CSIC (Sp), and the device development, together with the exploitation and dissemination of results to STMicrolectronics (I). Despite the co-ordination activity, CNR takes also care of the MOCVD growth with the new reactor, and of the structural and chemical characterisation, as well as help in device manufacturing, based on compounds issued from the new reactor. During this first year of the project, the main effort was concentrated on the design and development of a new MOCVD system for the deposition of Ge2Sb2Te5, on the development of new precursors for the MOCVD growth and on the test with a research system of the deposition conditions of single elements, binary and ternary compounds of the GexSbyTez family. The design and fabrication of the new system, due to different restrictions and requirements presented in the Wp2 section, has absorbed more resources and time than expected in the DoW. The delivery date of the MOCVD system to CNR-MDM, scheduled for month 6, was shifted to month 11. The development, test and delivery of the new precursors were timely accomplished. The modification of the VU research system in order to fulfil the requirements necessary for the growth of GexSbyTez has been timely accomplished and a lot of work has been devoted to the test of different precursor combinations. Both structural (VU) and functional (CSIC) characterisation have been performed on well selected samples and switching properties has been demonstrated on the GexSby system. Up to now, although the growth of Ge2Sb2Te5 has not been demonstrated by liquid injection MOCVD, a large window of deposition parameters and precursor combinations has been tested. This preliminary work constitutes a very solid starting point for the growth of GexSbyTez . The new MOCVD reactor has been accepted on the Aixtron site at month 11 and promptly moved to the MDM Laboratory. The set up of the apparatus at the MDM 5 laboratory took place at the middle of month 12. Due to some delays of the installation team at ST site, the hook up and installation of the MOCVD reactor, started the end of month 12, is not accomplished at the time of this report. During month 7, the CHEMAPH coordinator, Dr. Andrew Teren, left CNR-MDM. Dr Claudia Wiemer, CNR-MDM, is the present coordinator of the CHEMAPH project and had the chance to meet all the partners and to become promptly involved and updated on the project achievements during the first Partner meeting held in Vilnius on the July 3th-14th 2006. After the first year, the exploitable results are mostly related to innovation in the field of precursor selection for chalcogenide material production. Due to the close relation between the new designed MOCVD system and a real industrial system, once the process will be accessed, STMicroelectronics will be able to easily industrialized it. However, due to the early stage of the project and to delay in the availability of the prototype equipment for the MOCVD deposition, it has not been yet possible to define a detailed exploitation plan and to assess the environmental, health and safety issues related to this equipment. As compared to the DoW, this project is delayed by at least 6 months, and a prolongation will probably be discussed during the review meeting.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
