Renesas Technology Corp.

Renesas Electronics Corporation

Norifumi Kameshiro

Tomoyuki Ishii

Toshiyuki Mine

Toshiaki Sano

Riichiro Takemura

To achieve a stable reading operation in a memory cell having a gain-cell structure, a write transistor is configured, which has a source and a drain that are formed on the insulating layer, a channel formed on the insulating layer and between the source and the drain and made of a semiconductor, and a gate formed on an upper portion of the insulating layer and between the source and the drain and electrically insulated from the channel by a gate insulating film and controlling the potential of the channel. The channel electrically connects the source and the drain on the side surfaces of the source and the drain.

Semiconductor device

In a two-transistor gain cell structure, a semiconductor memory device capable of stable reading without malfunction and having small-area memory cells is provided. In a two-transistor gain cell memory having a write transistor and a read transistor, a write word line, a read word line, a write bit line, and a read bit line are separately provided, and voltages to be applied are independently set. Furthermore, a memory cell is connected to the same read word line and write bit line as those of an adjacent memory cell.

Semiconductor memory device

After forming a source-drain material film on an insulator layer, an opening portion reaching the insulator layer is formed in the source-drain material film. Then, a channel having desired thickness and a gate insulator are sequentially formed on the insulator layer and the source-drain material film in the opening portion. Thereafter, a gate material film embedding the opening portion is formed on the gate insulator. Subsequently, a cap film is formed on the gate material film, thereby forming the gate made of the gate material film. Then, a mask layer is formed on the source-drain material film. Next, the source-drain material film not protected by the mask layer is removed while protecting the gate by the cap film, thereby leaving the source-drain material film on both sides of the gate. The source-drain material film on one side becomes the source and that on the other side becomes the drain.

Method for fabrication of semiconductor device

The present invention is a semiconductor memory device having a logic block and a memory block on the same chip. In the memory device, unit memory cells each include at least two transistors, one of which is a write transistor for storing an electric charge into and releasing it from an electric charge storage node, and the other is a read transistor whose conductance in a channel region provided between a source and drain of the read transistor is modulated dependently on the amount of electric charge stored into or released from the electric charge storage node by the write transistor. The read transistor has a gate-insulating film thicker than that of a transistor provided in the logic block, and uses the same diffusion layer structure as that of the logic block.

Growing community of inventors

Kokubunji, Japan

Norifumi Kameshiro