1. Field of the Invention
This invention relates to a method of manufacturing a semiconductor device, and particularly to the formation of an embedded portion such as a device separation region or the like.
2. Description of the Related Art
Attention has been focused on a device separation technique using trenches as a technique for forming device separation regions employed in a semiconductor device.
A conventional process for forming device separation regions using trenches has been disclosed in Japanese Patent Application Laid-Open No. Hei 9-102539.
In the conventional device separation region forming method, resists are left above portions where the trenches are defined, regardless of the widths of device separation regions to be formed. A silicon oxide film has been etched with the resists as masks.
With advances in miniaturization of a semiconductor element or chip, leaving resists on trenches extremely narrow in width is becoming extremely difficult.
The formation of resist patterns over a silicon oxide film encounters difficulties in accurately aligning masks over the pre-formed trenches in regions above the trenches narrow in width. There is a possibility that when a displacement in alignment occurs even slightly, the resists and trenches will be shifted in position from each other on the trenches extremely narrow in width.
An object of the present invention is to solve the above-described problems.
According to one aspect of this invention, for achieving the above object, there is provided a method for forming a device separation region, comprising the following steps:
a step for forming a plurality of trenches each serving as the device separation region over a semiconductor substrate;
a step for forming an insulating film over the plurality of trenches and the semiconductor substrate;
a step for forming resists over the insulating film;
a step for leaving only the resists formed above the trenches each having a width larger than a predetermined width, of the plurality of trenches;
a step for removing the insulating film by etching with the remaining resists as masks; and
a step for removing the remaining insulating film by chemical machine polishing after the removal of the remaining resists and forming the trenches buried by the insulating film.
Typical ones of various inventions of the present application have been shown in brief. However, the various inventions of the present application and specific configurations of these inventions will be understood from the following description.