Semiconductor memory device

Details Semiconductor memory device Semiconductor memory device

2007-03-21

2010-06-01

Smith, Zandra (Department: 2822)

Active solid-state devices (e.g., transistors, solid-state diode

Field effect device

Having insulated electrode

C257S296000, C257S298000, C257S300000, C257S306000, C257SE27034, C257SE21648, C257SE21649, C438S239000, C438S240000

Reexamination Certificate

active

07728376

ABSTRACT:
HfO2films and ZrO2films are currently being developed for use as capacitor dielectric films in 85 nm technology node DRAM. However, these films will be difficult to use in 65 nm technology node or later DRAM, since they have a relative dielectric constant of only 20-25. The dielectric constant of such films may be increased by stabilizing their cubic phase. However, this results in an increase in the leakage current along the crystal grain boundaries, which makes it difficult to use these films as capacitor dielectric films. To overcome this problem, the present invention dopes a base material of HfO2or ZrO2with an oxide of an element having a large ion radius, such as Y or La, to increase the oxygen coordination number of the base material and thereby increase its relative dielectric constant to 30 or higher even when the base material is in its amorphous state. Thus, the present invention provides dielectric films that can be used to form DRAM capacitors that meet the 65 nm technology node or later.

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Zhao, Xinyuan, et al., “First-principles study of structural, vibrational, and lattice dielectric properties of hafnium oxide”, The American Physical Society, Physical Review B, vol. 65, 2002, pp. 2332106-1-233106-4.
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Kita, Koji, et al., “Permittivity increase of yttrium-doped HfO2through structural phase transformation”, American Institute of Physica, Applied Physics Letters 86, 2005, pp. 1-3.

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