Semiconductor device and method of fabricating the same

Abstract

A semiconductor device includes a semiconductor substrate and first and second trenches. The first trench with a high aspect ratio is formed in a surface of the semiconductor substrate and has a bottom, two sidewalls and an open end. The first trench is formed so that at the bottom side, an inclination of each sidewall relative to the bottom has a first angle approximate to a right angle and at the bottom side, the inclination of each sidewall relative to the bottom has a second angle smaller than the first angle. The second trench has a lower aspect ratio than the first trench. The second trench has a bottom, two sidewalls and an open end and is formed so that an inclination of each sidewall relative to the bottom is substantially uniform from the bottom side to the open end side and has a third angle which is approximate to the second angle.

Description

CROSS-REFERENCE TO RELATED APPLICATION [0001] This application claims priority from Japanese patent application No. 2004-85051, filed Mar. 23, 2004, the content of which is incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a semiconductor device provided with trenches having high and low aspect ratios respectively and a method of fabricating the same. [0004] 2. Description of the Related Art [0005] Semiconductor devices employ a shallow trench isolation (STI) structure in order that elements may be isolated from each other. A trench is formed in a semiconductor substrate and filled with an insulating material such as silicon oxide (SiO2), whereby the element isolating STI structure is formed. [0006] In forming a trench, a semiconductor substrate with an etching pattern is disposed in a vacuum process chamber of a processing apparatus. A reactive gas is then introduced into the chamber and a discharg...

AI Technical Summary

Benefits of technology

[0011] Therefore, an object of the present invention is to provide a semiconductor device in which a desirable trench fill capability of the insulating film in the trench with high aspect ration can be maintained even if the miniaturization of the device progresses, and a method of fabricating the same.

Problems solved by technology

As a result, the trench cannot completely be filled with the insulating film material, whereupon voids are formed in the trench.

The voids further result in a new failure such as short circuit between the elements with an increasing frequency of occurrence.

However, this method has the following inconvenience.

Accordingly, limitations of a lower limit value of the taper angle become strict according to an opening width of the trench such that the limitations are difficult to cope with.

Under these conditions, the trench fill capability is hard to maintain at the level of the previous design rules.

In this case, however, the productivity cannot be improved even if the trench fill capability can be satisfied.

Additionally, it is difficult to reduce the costs.

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