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Posted on January 23, 2012 by  & 

Tanaka Precious Metals develops ruthenium material for DRAM

Tanaka Kikinzoku Kogyo K.K. has unveiled a ruthenium material able to form a film up to six times the normal depth for capacitor electrodes used in semiconductor memory DRAM (Dynamic Random Access Memory).
The company part of Tanaka Precious Metals developed the material with Professor Seiji Ogo of the Graduate School of Engineering Department of Applied Chemistry at Kyushu University.
With the full-scale introduction of MOCVD (Metalorganic Chemical Vapor Deposition) used in technology for the miniaturization of next-generation DRAM, the Company aims to commercialize the material in 2012.
This ruthenium material is a MOCVD film formation material (precursor) used in next-generation DRAM with a circuit with of 20 nanometers (1 billionth of a meter) or later, and can form a uniform ruthenium film inside fine pores with a high aspect ratio (ratio of the depth and diameter of pores) of 40:1. This enables the manufacture of capacitor electrodes with six times the normal depth. Semiconductor manufacturers are considering the mass production of next-generation semiconductors in the 20-nanometer range during 2012, and by using this ruthenium precursor the manufacture of capacitor electrodes able to support miniaturization in the 20-nanometer generation and later.
With the increase in capacity of semiconductor memory, semiconductor manufacturers plan to adopt manufacturing methods that deeply carve memory cells to give capacitor electrodes a 3-dimensional structure, and MOCVD is expected to be used as a method for manufacturing 3-dimensioonal electrodes. However, the largest aspect ratio of pores making up electrode film that could be formed by conventional MOCVD ruthenium precursors was 6:1, and the inability to manufacture capacitor electrodes with the high aspect ratio required for the 20-nanometer generation and later has become a technical challenge.
Metallo-organic complexes that evaporate easier than normal metal are used in MOCVD film materials. The ruthenium precursor successfully developed for the first time by Tanaka Kikinzoku Kogyo is a metallo-organic complex made up of organic compounds (Cyclooctatetraene and Carbonyl) and a metallic element (Ruthenium). Because it has properties of high vapor pressure (tendency to evaporate when forming a film) and easy precipitation of metal by heating, it is possible to form a ruthenium film with a coverage factor of 70% within pores with the high aspect ratio of 40:1 at the low temperature of 165 degrees Celsius.
The results of development of this ruthenium precursor are scheduled to be published in Dalton Transactions published by the United Kingdom's Royal Society of Chemistry. Tanaka Kikinzoku Kogyo will continue to strive to make technical improvements to ruthenium precursors able to form films in electrode pores with higher aspect ratios.
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