1. Field of the Invention
The present invention relates to a method for fabricating a semiconductor device and, more particularly, to a mask for evaluating a selective epitaxial growth process.
2. Description of the Related Art
Semiconductor devices have become more highly-integrated and have higher performance capabilities and accordingly, new methods have been developed to improve device properties. A selective epitaxial growth (xe2x80x9cSEGxe2x80x9d) process is one of the methods.
The SEG process has been applied to shallow junction formation and the isolation process in memory devices and recently, it has been applied to contact plug formation. And, it is expected that the SEG process will be widely used for simplifying processes and for improving of electric properties.
As is generally known, in the SEG process, single crystal silicon is selectively grown on the exposed silicon region of the semiconductor and is not grown on insulating layers such as oxide layers and nitride layers. As a result, the SEG process is completely different from a general CVD process and therefore, development of the SEG process is also different from that of CVD process.
That is, according to the SEG process, single crystal silicon is grown by supplying silicon growth sources to an exposed silicon region using activation of a gas phase reaction. Therefore, single crystal silicon growth differs according to the exposed silicon region. The exposed silicon region effects the growth speed, facet, selectivity and uniformity in the single crystal silicon.
Therefore, in order to develop the SEG process, the above items need to be evaluated. In a conventional method, test patterns corresponding to the items are formed and then evaluation thereof is performed.
However, there is difficulty in technological development of the conventional SEG process since it evaluates specific test patterns. That is, different test patterns are required for each development item, therefore, significant time and cost is required to get data on each test pattern.
Moreover, due to a lack of test items, there is a limitation in understanding the mechanism of single crystal silicon growth with the conventional SEG process.
Therefore, an object of the present invention is to provide a mask for evaluating the SEG process, possessing most suitable patterns therein.
Another object of the present invention is to provide a mask for evaluating the SEG process capable of reducing time and cost for SEG technological development.
And, still another object of the present invention is to provide a mask for evaluating the SEG process capable of being advantageously applied to development of SEG process equipment.
In order to achieve the above objects, in the present invention, a mask for evaluating the selective epitaxial growth process to evaluate the growth mode of single crystal silicon grown with the selective epitaxial growth process according to an exposed silicon region comprises a mask pattern with four distinct areas. First there is a mask pattern for measuring the sheet resistance of grown single crystal silicon in a first area. The second is a mask pattern for selectivity evaluation to evaluate selectivity of single crystal silicon growth in a second area diagonal to the first area. Third, there is a mask pattern for facet generation evaluation to evaluate facet generation of grown single crystal silicon, having different shapes in a third area. Next, is a mask pattern for loading effect evaluation to evaluate a growth mode of single crystal silicon by loading effect in the upper part of a fourth area Lastly, is a mask pattern for uniformity evaluation to evaluate uniformity of grown single crystal silicon in the lower part of the fourth area.
The above objects, and other features and advantages of the present invention will become more apparent after reading the following detailed description when taken in conjunction with the drawings.