Mitsubishi Denki Kabushiki Kaisha

Yoshiki Kojima

Mitsunori Nakatani

Hiroyuki Minami

An alignment mark for fabricating a semiconductor device having a high density of circuit patterns and fine patterns using electron beam lithography techniques. No electrical charging of the alignment mark occurs during several scans by the electron beam. The area of a conductive layer and the area where the surface of a semiconductor substrate is exposed are reversed from those of the conventional alignment mark. The novel alignment mark includes a surface of the semiconductor substrate exposed through a conductive layer on the semiconductor substrate.

Alignment mark for electron beam lithography

A pattern transfer mask for use in an optical exposure process includes a transparent substrate having a surface; a light shielding film of a desired pattern disposed on the surface of the transparent substrate for shielding a part of a photoresist film from light transmitted through the mask and incident on the photoresist film and for transferring the desired pattern to the photoresist film; and a plurality of projections disposed at equal intervals on one side of and contacting the light shielding film pattern for reducing the intensity of light transmitted through the transparent substrate where the projections are present.

Pattern transfer mask

In a method for producing a field effect transistor, a positive photoresist is deposited on a surface of a semiconductor substrate, the positive photoresist is exposed to light having an asymmetric intensity profile where a gate electrode is to be formed, the positive photoresist is converted into a negative photoresist, the negative photoresist is developed to form a pattern having an aperture opposite the gate electrode formation region of the substrate and asymmetric overhanging portions at the aperture, the semiconductor substrate is wet etched using the photoresist pattern as a mask to form a recess in the semiconductor substrate, and a gate metal is deposited using the photoresist pattern as a mask to form a gate electrode in the recess. Therefore, only one exposure process provides a photoresist pattern having asymmetric overhanging portions at the aperture of the pattern.

Growing community of inventors

Itami, Japan

Yoshiki Kojima