Nec Corporation

Nec Electronics Corporation

Takeshi Nakura

Seiichi Takahashi

Hidemitsu Mori

Tohru Miwa

There is provided a semiconductor memory device for preventing an increase of a cell area of a Shadow RAM comprising a portion of an SRAM memory cell and a ferroelectric capacitor connected to a storage node of the portion of the SRAM memory cell and achieving high capacitance formation of a storage capacitor. The Shadow RAM is provided with a relay wiring layer between a wiring layer corresponding to the storage node and a lower electrode of the ferroelectric capacitor, a wiring corresponding to the storage node is connected to a relay wiring via a first and a second opening portion arranged at a first interval and the lower electrode of the ferroelectric capacitor is connected to a relay wiring via a third and a fourth opening portion arranged at a second interval narrower than the first interval.

Semiconductor memory device including Shadow RAM

An interlayer insulating film, contacts, and wirings are formed on a MOS transistor formed on a silicon substrate. Another interlayer insulating film and contacts are formed thereon. Subsequently, as a first heat treatment, a heat treatment is performed in a hydrogen atmosphere or a nitrogen- or otherwise-diluted hydrogen atmosphere at a temperature of the order of 300-500&deg; C. for about 5-60 minutes, thereby recovering defects that occur in the MOS transistor and insulating film forming steps and the like. Then, a ferroelectric capacitor connected to either diffusion layer of the MOS transistor is formed along with wirings, electrodes, and the like. Thereafter, as a second heat treatment, a heat treatment is performed in nitrogen at a temperature of the order of 300-500&deg; C. for about 5-60 minutes. This recovers defects that occur after the first heat treatment step.

Method of fabricating semiconductor device having ferroelectric capacitor

A consolidated LSI including a logic circuit section and a FeRAM section formed on a single chip has a hydrogen barrier layer covering the cell array of the FeRAM section. The hydrogen barrier layer is made of plasma CVD SiON and has an excellent hydrogen barrier function. The hydrogen barrier layer protects the ferroelectric film of a ferroelectric capacitor an against the hydrogen-annealing process in the fabrication a process for the consolidated LSI.

Growing community of inventors

Tokyo, Japan

Takeshi Nakura