Fujitsu Corporation

Kabushiki Kaisha Toshiba

Sumio Yamamoto

Yoshimi Yamashita

Kinjiro Kosemura

Shigeru Kuroda

Hidetoshi Ishiwari

Noriaki Nakayama

Takeshi Kondou

In a method of diagnosing deterioration of a paint film, a probe is applied to the surface of a paint film. A voltage having a predetermined waveform is applied by a preamplifier across the probe and a base metal on which the paint film is formed. A current flowing through the paint film is measured by the preamplifier. An analog signal indicative of a measured current value is converted to a corresponding digital signal by an analog-to-digital converter. A personal computer operates to analyze the digital signal in accordance with a predetermined analyzing procedure so that the degree of deterioration of the paint film is determined. The resultant determination is displayed on the display.

Method and device for diagnosis of paint film deterioration

Disclosed is a method of producing a compound semiconductor device comprising an enhancement-mode transistor and a depletion-mode transistor, each of which has a heterojunction and utilizes a two-dimensional electron gas. The method of producing the device comprises the steps of: forming an undoped GaAs channel layer on a semi-insulating GaAs substrate; forming an N-type AlGaAs electron-supply layer so as to form the heterojunction; forming an N-type GaAs layer; forming an AlGaAs layer; selectively etching the AlGaAs layer to form a recess; performing an etching treatment using an etchant which can etch rapidly GaAs and etch slowly AlGaAs to form simultaneously grooves for gate electrodes of the enhancement-mode transistor and the depletion-mode transistor, the bottoms of the grooves being in the N-type AlGaAs layer and the distance between the bottoms being equal to the thickness of the AlGaAs layer; and forming simultaneously the gate electrodes in the grooves.

Method of producing a two-dimensional electron gas semiconductor device

A compound semiconductor device comprises an enhancement-mode transistor and a depletion-mode transistor, each of which has a heterojunction and utilizes a two-dimensional electron gas. The method of producing the device comprises the steps of: forming an undoped GaAs channel layer on a semi-insulating GaAs substrate; forming an N-type AlGaAs electron-supply layer so as to form the heterojunction; forming an N-type GaAs layer; forming an AlGaAs layer; selectively etching the AlGaAs layer to form a recess; performing an etching treatment using an etchant which can etch rapidly GaAs and etch slowly AlGaAs to form simultaneously grooves for gate electrodes of the enhancement-mode transistor and the depletion-mode transistor, the bottoms of the grooves being in the N-type AlGaAs layer and the distance between the bottoms being equal to the thickness of the AlGaAs layer; and forming simultaneously the gate electrodes in the grooves.

HEMT with etch-stop

A method for producing a field effect type semiconductor device includes the steps of forming a semiconductor active layer on a substrate, forming a resist layer on the semiconductor active layer, exposing a first portion of the resist layer in accordance with a gate electrode pattern, carrying out auxiliary exposure of a second portion near the first portion after or before the exposure of the first portion. The method further includes developing the exposed resist layer, forming a recess in the semiconductor active layer by etching the exposed semiconductor active layer using the resist layer as a mask and forming a gate electrode on the surface of the recess using the resist layer as a mask. This method improves the series resistance between the source electrode and the gate electrode, and also improves the Schottky withstand voltage between the drain electrode and the gate electrode.

Method for producing field effect type semiconductor device

A method of electron beam exposure in which a plurality of sets of reference values for setting the conditions for electron beam exposure are found in relation to a plurality of sizing marks which are successively arrayed at positions in the vicinity of the pattern area of a specimen, and the exposure condition values corresponding to registration marks on the surface of the specimen are derived from these said reference values for setting the exposure conditions.

Growing community of inventors

Yokohama, Japan

Sumio Yamamoto