Semiconductor device

This application is based on Japanese patent applications No. 2003-183369 and No. 2004-168131, the content of which are incorporated herein by reference.

1. Field of the Invention

The present invention relates to a semiconductor device, and more particularly to a semiconductor device including a fuse.

2. Description of the Related Art

When a semiconductor device includes fuses, it is possible to adjust the resistance value by opening some of the fuses, or alternating a defective element to a functional element by opening one of the fuses connected to the defective element. This method of alternating the defective element to the functional element is applied to a semiconductor device having redundancy. Conventionally, it is common to open the fuses by laser irradiation. However, there are some problems in opening the fuses by the laser irradiation.

Firstly, in order to avoid damage to elements other than the fuse when the fuse is opened, the portion to be opened in the fuse has to be placed with a predetermined space from the elements. Thus, the size of the semiconductor device is increased.

In addition, in order to form a fuse to be opened by the laser irradiation, additional photolithography processes are necessary. Usually, an insulating layer is formed on a fuse. Thus, an additional step to adjust the thickness of the insulating layer to form an opening above the fuse for laser irradiation is necessary. In addition, when the semiconductor device including a fuse is examined, the following three steps are necessary. Firstly, electrical properties of the device are examined, then, the fuse is opened, and finally, electrical properties are examined again. Thus the manufacturing processes for the semiconductor device are increased and makes the cost of manufacturing the semiconductor device is greater.

In order to solve the problem caused by the laser irradiation, there have been attempts to open the fuses by current flow. For example, Japanese patent application No. 2002-197884 discloses a fuse that is opened by current flow. In this application, a part of the fuse is made narrow, or the fuse includes an angled portion to promote blowout of the fuse.

However, the inventor of the present invention found that the fuse disclosed in the above application still has a problem in that a large amount of current or voltage is required to open the fuse.

The present invention has been conceived in view of the foregoing situation, with the object of providing a semiconductor device including a fuse which needs less current or voltage to be opened compared with a conventional fuse.

According to the present invention, there is provided a semiconductor device comprising: a semiconductor substrate; and a conductive element formed on the semiconductor substrate and capable of being opened when a predetermined current flows, wherein the conductive element turns plurality of times.

Here, “a conductive element capable of being opened when a predetermined current flows” is a fuse. The word “turn” or the word “turning” means that at which the conductive line rotates more than 90 degrees.

As the conductive element turns plurality of times, the conductive element can be formed such that the center portion of the conductive element is surrounded by the rest portions of the conductive element. With this structure, the center portion of the conductive element is heated by the rest portions thereof. Thus, the center portion of the conductive element can be kept relatively high temperature so that the conductive element is easily opened when a predetermined current flows therethrough.

The conductive element may include a first one way linear portion which extends in a first direction, an another way linear portion which extends in a second direction which is substantially opposite direction to the first direction, and a second one way linear portion which extends in the first direction. The first one way linear portion, the another way linear portion, and the second one way linear portion may be positioned parallel to each other and electrically connected with each other.

With this structure, either one of the first one way linear portion, the another way linear portion, and the second one way linear portion is placed to be surrounded by the other portions. Thus, the portion surrounded by the other portions can be kept relatively high temperature. Therefore, the conductive element is easily opened when a predetermined current flows therethrough.

The conductive element may include a first one way linear portion which extends in a first direction, a another way linear portion which extends in a second direction which is substantially opposite direction to the first direction, an second one way linear portion which extends in the first direction, a first connecting portion which connects one of the edges of the first one way linear portion and one of the edges of the another way linear portion, and a second connecting portion which connects the other of the edges of the another way linear portion and one of the edges of the second one way linear portion. The first one way linear portion, the another way linear portion, the second one way linear portion, the first connecting portion, and the second connecting portion may be electrically connected with each other.

The conductive element may include a plurality of first linear portions positioned parallel to each other and each of which extends in a first direction, and a plurality of second linear portions positioned parallel to each other and each of which extends in a second direction which is different from the first direction. The plurality of first linear portions and the plurality of second linear portions may be placed such that at least one of the plurality of first linear portions or at least one of the plurality of second linear portions is surrounded at four sides by the rest of the plurality of first linear portions and the plurality of second linear portions.

With this structure, the linear portion which is surrounded by the other linear portions at four sides can be kept relatively high temperature. Thus, the conductive element is easily opened at the linear portion which is surrounded by the other linear portions when a predetermined current flows therethrough.

The plurality of first linear portions and the plurality of second linear portions may be placed such that the current respectively flow toward different directions in the first linear portions adjacent to each other, and the current respectively flow toward different directions in the second linear portions adjacent to each other, when the current flows from one of the edges of the conductive element to the other edge of the conductive element.

With this structure, magnetic field generation is avoided even when the current flows through the conductive element.

The conductive element may include a plurality of first linear portions positioned parallel to each other and each of which extends in a first direction, a plurality of second linear portions positioned parallel to each other and each of which extends in a second direction which is different from the first direction, a current input terminal, and a current output terminal electrically connected with the current input terminal. The plurality of first linear portions and the plurality of second linear portions may be placed such that the current respectively flow toward different directions in the first linear portions adjacent to each other, and the current respectively flow toward different directions in the second linear portions adjacent to each other, when the current flows from the current input terminal to the current output terminal.