1. Technical Field
The present invention relates to a semiconductor device and a semiconductor device manufacturing method.
2. Related Art
A conventional semiconductor device is known in which electrodes such as source electrodes are formed of aluminum and a barrier metal is provided between these aluminum electrodes and the semiconductor substrate, as shown in Patent Document 1, for example.
Patent Document 1: Japanese Patent Application Publication No. 2012-129503
When an electrode formed of aluminum is placed in a high-temperature environment, there are cases where hydrogen is generated. For example, hydrogen is generated when aluminum reacts with water. When the hydrogen enters into a region near a boundary plane between a gate insulating film and a semiconductor layer, a positive charge is generated at this boundary plane and the threshold voltage fluctuates.
In contrast, there is an idea of forming a hydrogen absorbing metal layer made of titanium, for example, below an aluminum electrode. By having the hydrogen absorbing metal absorb the hydrogen, it is possible to restrict the hydrogen from entering into the region near the boundary plane of the gate insulating film. However, when aluminum and the hydrogen absorbing metal form an alloy, the hydrogen absorption effect is weakened.