Semiconductor device having protection diode

A semiconductor device comprising:

• a semiconductor element;
• a protection diode for protecting the semiconductor element from a first reverse voltage applied to the semiconductor element;
• a capacitor;
• and
• a SOI substrate having an isolated region, a trench and an insulation layer, wherein
• the protection diode is coupled in parallel to the semiconductor element,
• the protection diode has a forward direction, which is equal to a first applying direction of the first reverse voltage,
• the capacitor is coupled in parallel to the protection diode,
• the capacitor is capable of absorbing a second reverse voltage applied to the protection diode,
• the second reverse voltage is larger than a breakdown voltage of the protection diode, and has a second applying direction opposite to the first applying direction,
• the semiconductor element, the protection diode and the capacitor are disposed in the SOI substrate,
• the isolated region is electrically separated from other regions of the SOI substrate with an insulation film in the trench and the insulation layer, and
• the protection diode is disposed in the isolated region.

A semiconductor device comprising:

• a semiconductor element;
• a protection diode for protecting the semiconductor element from a first reverse voltage applied to the semiconductor element;
• a capacitor;
• and
• a substrate having an insulation layer and a poly crystalline silicon layer, wherein
• the protection diode is coupled in parallel to the semiconductor element,
• the protection diode has a forward direction, which is equal to a first applying direction of the first reverse voltage,
• the capacitor is coupled in parallel to the protection diode,
• the capacitor is capable of absorbing a second reverse voltage applied to the protection diode,
• the second reverse voltage is larger than a breakdown voltage of the protection diode, and has a second applying direction opposite to the first applying direction,
• the poly crystalline silicon layer is disposed on the insulation layer, and
• the protection diode is formed in the poly crystalline silicon layer by a selective impurity implantation method.

A semiconductor device comprising:

• a semiconductor element;
• a protection diode for protecting the semiconductor element from a first reverse voltage applied to the semiconductor element;
• and
• a capacitor, wherein
• the protection diode is coupled in parallel to the semiconductor element,
• the protection diode has a forward direction, which is equal to a first applying direction of the first reverse voltage,
• the capacitor is coupled in parallel to the protection diode,
• the capacitor is capable of absorbing a second reverse voltage applied to the protection diode,
• the second reverse voltage is larger than a breakdown voltage of the protection diode, and has a second applying direction opposite to the first applying direction,
• the semiconductor element is a temperature sensitive diode having a predetermined relationship between a current and a voltage flowing and applying in a forward direction of the temperature sensitive diode, and
• the predetermined relationship is changeable based on a temperature around the temperature sensitive diode.