The gate electrode of a transistor includes at least one region with a p-type work function and at least one region with an n-type work function. The regions are located over corners formed between isolation regions and an active region. The double hump effect is reduced, which provides higher operational frequencies.

A high voltage semiconductor device isolation structure and a method of manufacturing the same prevent a silicon penetration region from being formed between a first STI region and the side wall of a DTI region so that the breakdown voltage characteristic of a device is prevented from being decreased due to electric field concentration on the penetration region, and a method of manufacturing the same.

Methods of forming high aspect ratio openings. The method comprises removing a portion of a dielectric material at a temperature less than about 0 C. to form at least one opening in the dielectric material. The at least one opening comprises an aspect ratio of greater than about 30:1. A protective material is formed in the at least one opening and on sidewalls of the dielectric material at a temperature less than about 0 C. Methods of forming high aspect ratio features are also disclosed, as are semiconductor devices.

An isolation structure, comprising: an isolation material layer, filled in a trench of a substrate; and a protection layer, having two portions extending from a topmost surface of the substrate to a top surface of the isolation material layer across boundaries of the trench, and covering opposite edges of the isolation material layer, wherein the two portions of the protection layer are laterally spaced apart from each other, and the protection layer has an etching selectivity with respect to the isolation material layer.