Semiconductor device and method for manufacturing the same

Abstract

At least a laminate of a gate insulating film 6 and a gate electrode 7 and an active region 13 are formed on a silicon substrate 1, and an underlying interlayer insulating film 10 is further formed. Then, a conductor 11a connected to the gate electrode 7, and a conductor 11b that is a dummy conductor and is connected to the active region 13 are formed simultaneously on the underlying interlayer insulating film 10. Thereafter, an interlayer insulating film 12 is formed on the underlying interlayer insulating film 10 by a plasma process. At this time, charging current from a plasma 14 is emitted through the conductor 11b, which is a dummy conductor.

Description

TECHNICAL FIELD [0001] The present invention relates to a semiconductor device and a method for manufacturing the same. BACKGROUND ART [0002] In recent years, in a semiconductor device constituted by semiconductor integrated circuits, high integration has undergone great development. In particular, in semiconductor devices of MIS (metal insulated semiconductor) type, miniaturization and high performance of elements such as transistors have been promoted in order to cope with high integration, and there is a demand for further miniaturization and high performance. [0003] In a process for forming conductors of such a semiconductor device, plasma processing including plasma CVD or plasma etching has been increasingly utilized. This is because in the process for forming conductors of a semiconductor device, there is a limitation regarding the amount to be subjected to heat treatment because of diffusion of impurities, the heat resistance of a metal material for conductors and the like, ...

AI Technical Summary

Benefits of technology

[0037] It is a first object of the present invention to solve the above-described problem and provide a semiconductor device that can suppress plasma charging damage in a plasma process and a method for manufacturing the same.

[0042] It is a second object of the present invention to solve the above-described problem and provide a semiconductor device that can suppress plasma charging damage without being influenced by the application direction of an electric field at the time of a plasma process and a method for manufacturing the same.

[0044] When the second semiconductor device is used, compared with the example of FIG. 13 shown in “Background Art”, more rays in the ultraviolet region are incident on the active region serving as a diode, so that the rectification property of the diode is reduced significantly and the leakage current in the forward direction in the active region is increased. Therefore, even if the electric field by plasma is applied in the reverse direction, the charging current from the plasma can flow off to the ground potential via the diode, and electrical stress applied to the gate insulating film during a plasma process can be reduced.

[0046] Also when the third semiconductor device is used, as in the second semiconductor device, compared with the example of FIG. 13 shown in “Background Art”, more rays in the ultraviolet region are incident to the active region serving as a diode, so that the rectification property of the diode is significantly lost and the leak current in the forward direction in the active region is increased. Therefore, electrical stress applied to the gate insulating film during a plasma process can be reduced also in the third semiconductor device.

[0048] When the second method for manufacturing a semiconductor device is used, compared with the example of FIG. 13 shown in “Background Art”, more rays in the ultraviolet region are incident on the active region serving as a diode when forming the second insulating layer by a plasma process. Therefore, the rectification property of the diode is reduced significantly and the leakage current in the forward direction in the active region is increased. Therefore, even if the electric field by plasma is applied in the reverse direction, the charging current from the plasma can flow off to the ground potential via the diode, and a semiconductor device can be produced while electrical stress applied to the gate insulating film during a plasma process is reduced.

[0050] When the third method for manufacturing a semiconductor device is used, compared with the example of FIG. 13 shown in “Background Art”, more rays in the ultraviolet region are incident on the active region serving as a diode when forming another insulating layer on the insulating layer obtained in the step (c) by a plasma process. Therefore, also in the third method for manufacturing a semiconductor device, the rectification property of the diode is reduced significantly and the leakage current in the forward direction in the active region is increased, and a semiconductor device can be produced while electrical stress applied to the gate insulating film during a plasma process is reduced.

Problems solved by technology

This is because in the process for forming conductors of a semiconductor device, there is a limitation regarding the amount to be subjected to heat treatment because of diffusion of impurities, the heat resistance of a metal material for conductors and the like, and the amount to be subjected to heat treatment can be reduced by the plasma process.

However, with the increased utilization of the plasma process, device damage due to the plasma process tends to occur.

In a semiconductor device that is subjected to such plasma charging damage, the device characteristics are deteriorated, so that the semiconductor device is defective.

In the problem of plasma charging damage, in particular, deterioration in the reliability of gate insulating films constitutes a serious problem.

Therefore, the gate insulating film 26 is damaged and thus the device characteristics are damaged.

However, higher integration of the semiconductor device has been making the gate insulating film thinner year by year, and consequently the breakdown voltage of the gate insulating film has become smaller than the junction breakdown voltage of the protection diode.

The effect of suppressing the plasma charging damage by the protection diode becomes smaller as the gate insulating film becomes thinner, and although the protection diode is provided, the device characteristics are deteriorated by the plasma charging damage.

Furthermore, when the semiconductor substrate on which the protection diode is formed is subjected to the plasma process, a problem as described below may be caused.

Therefore, when an electric field is applied in the reverse direction, a part of the charging current from the plasma does not flow through the protection diode, and is directed to the gate insulating film 136, which applies electrical stress to the gate insulating film 136, and thus the device characteristics are damaged.

Therefore, it is pointed out that there is a limitation regarding the role of the protection diode.

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