Mosel Vitelic Corporation

Su-Wen Chang

Mao-Song Tseng

Chiao-Shun Chuang

Hsin-Huang Hsieh

Rong-ching Chen

Chin-lin Lin

Embodiments of the present invention are directed to a termination structure provided for a trench DMOS device to reduce occurrence of current leakage resulting from electric field crowding at the border of the active area and a method of manufacturing the same. In one embodiment, the termination structure for the trench DMOS device comprises a substrate of a first type conductivity and an epitaxial layer of the first type conductivity over the substrate. The epitaxial layer has a lower doping concentration than the substrate. A body region of a second type conductivity is provided within the epitaxial layer. A trench extends through the body region between an active area and an edge of the substrate. A gate oxide layer lines the trench and extends to the upper surface of the body region between the trench and the active area. A passivation layer is formed on the gate oxide layer, including sidewalls and a bottom surface of the trench. A metal layer covers portions of the passivation layer on the side walls of the trench to expose a part of the passivation layer over the bottom surface of the trench.

Termination structure for trench DMOS device and method of making the same

In the invention, a photoresist layer is first spread on a semiconductor structure, and then using a photomask with a specially designed pattern exposes the photoresist layer. Next, the photoresist layer is developed to form a patterned photoresist layer. Thereafter, using the patterned photoresist layer as a mask, a trench is formed in the semiconductor structure by selective etching. The pattern of the photomask according to the invention is formed as in the following steps. At first, a first pattern extending in a first direction and having a first side and a second side that is opposite to the first side is formed. Next, a second pattern extending in a second direction that is perpendicular to the first direction is formed in such a way that an end of the second pattern is connected with the first side of the first pattern. Thereafter, a concave edge is formed on the second side to substantially face the second pattern. The distance between the first side and the second side is shortened due to the presence of the concave edge. As a result, the depth of the dimples developed at the intersection points of the dimple lines is greatly reduced when a polysilicon layer is deposited on the trench formed according to the invention.

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Hsinchu, Taiwan

Su-Wen Chang