Mitsubishi Denki Kabushiki Kaisha

Shinichi Sakamoto

Takuji Sonoda

Nobuyuki Kasai

Tetsuya Yagi

Kazuo Hayashi

A field effect transistor has an active layer containing a multi-step recess that becomes narrower as it approaches the substrate. A gate electrode is produced at the deepest portion of the recess section. The transistor may be produced by successively selectively etching the active layer and an overlying semiconductor surface protection film to produce a multi-step configuration recess, depositing a gate electrode at the bottom of the recess, and depositing source and drain electrodes on the active layer.

Method for producing a field effect transistor with a gate recess

A mushroom-shaped gate electrode has a lower end in a recess in a semiconductor active layer on a semiconductor substrate. The gate electrode has an enlarged head. A metallic side wall is disposed on a portion of the leg of the gate electrode adjacent the head. Thus, the gate length of a semiconductor device, such as a field effect transistor, is reduced while the effective cross-sectional area of the gate electrode is increased whereby the noise characteristics of the semiconductor device are improved.

Method of making a mushroom-shaped gate electrode of semiconductor device

A field effect transistor includes a GaAs substrate on which an undoped GaAs layer is disposed. A doped electron supply layer is disposed on the undoped GaAs layer and has a negligible deep dopant level. A channel layer disposed on the electron supply layer has a larger electron affinity than the electron supply layer. The electron supply layer and the channel layer form a heterojunction. A third semiconductor layer having the same conductivity type as the electron supply layer is disposed on the electron supply layer. Gate, drain, and source electrodes are disposed on the third semiconductor layer. The dopant concentration of the third layer is smaller than the dopant concentration of the electron supply layer.

Field effect transistor

Semiconductor device with a mushroom-shaped gate electrode

At least two unit transistor groups, each including unit transistors arranged along a straight line, are disposed on a substrate parallel to and facing each other. Each transistor in one group and a facing transistor in the other group have integral first, second, and control electrodes. The first, second, and control electrodes of the unit transistors are connected to associated respective electrode pads.

Monolithic parallel connected transistor structure

A method of producing a semiconductor device includes etching a recessed aperture in a substrate, forming a gate electrode in the aperture, burying the gate electrode with resist, etching the resist to expose the gate electrode, depositing a high conductivity metal on the gate electrode, and forming ohmic electrodes on opposite sides of the gate electrode by a series of processing steps.

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Itami, Japan

Shinichi Sakamoto