Development of World’s First 2-gigabit DRAM based on High-K Metal Gate Technology
Elpida Memory has announced the development of industry’s first DRAM based on high-k metal gate (HKMG) technology. The new DRAM is a 2-gigabit DDR2 Mobile RAM (LPDDR2) at the 40nm-class. HKMG is a technology that was developed to reduce current leakage and improving transistor performance. The technology uses insulator film with a high dielectric constant in the transistor gate. In addition to this, metal gate electrodes which are required in high-k dielectric process are used.
There have been attempts to use HKMG by makers of logic semiconductor but higher heat treatment temperatures after HKMG formation plus complicated DRAM structural characteristics have hampered the effort in DRAM fabrication process. Use of HKMG technology in development of new DRR2 Mobile RAM has contributed in reduction of electrical thickness of the gate dielectric in the transistor by around 30% in comparison to silicon oxide dielectric, plus it has increased the DRAM performance by increasing transistor-on current by as much as 1.7 times in comparison with silicon oxide film. Furthermore, the employment of the HKMG technology can drastically reduce energy consumption in standby mode for DRR2 Mobile RAM.