Semiconductor device and mfg. method thereof

Abstract

A semiconductor device of the present invention includes a MISFET provided in an element formation region Re of a semiconductor substrate 11 and a trench isolation 13 surrounding the sides of the element formation region Re. An oxygen-passage-suppression film 23 is provided from the top of the trench isolation 13 to the top of a portion of the element formation region Re adjacent to the trench isolation 13. The oxygen-passage-suppression film 23 is made of a silicon nitride film or the like through which oxygen is less likely to permeate. Therefore, since it becomes hard that the upper edge of the element formation region Re of the semiconductor substrate 11 is oxidized, an expansion of the volume of the upper edge is suppressed, thereby reducing a stress.

Description

technical field [0001] The present invention relates to a semiconductor device and its manufacturing method, and more particularly to a semiconductor device having a trench element isolation structure and its manufacturing method. Background technique [0002] As one of methods for electrically isolating elements on a semiconductor substrate, there is a trench element isolation method. The so-called trench device isolation method is a method of digging trenches of appropriate depth in the region between devices and embedding insulators therein to separate devices from each other (for example, refer to Patent Document 1). [0003] Next, a method of manufacturing a trench device isolation structure in a conventional semiconductor device will be described with reference to FIGS. 5( a )-( f ). 5( a )-( f ) are cross-sectional views showing the manufacturing process of the trench device isolation structure of the conventional semiconductor device. [0004] First, in the process...

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Problems solved by technology

Since when the excess oxidation region 61 is formed, the volume of this part will expand and stress will be generated, so crystal defects are likely to occur on the semiconductor substrate.

Therefore, leakage current is easily generated through crystal defects, which will lead to a decrease in the element separation effect

[0015] In addition, when the element formed in the element formation region of the semiconductor substrate 51 is an N-type MISFET, the mobility of electrons is reduced due to the influence of stress in the excess oxidation region, thereby causing a problem that the driving force of the transistor is reduced.

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