Biopolar/Darlington transistor having enhanced comprehensive electricity characteristics

A Darlington transistor comprising

• a first bipolar transistor formed on a first semiconductor substrate;
• and
• a second bipolar transistor formed on a second semiconductor substrate;
• said first and second bipolar transistors being arranged in Darlington connection, having a front stage of said first bipolar transistor and a rear stage of said second bipolar transistor;
• said first bipolar transistor including a first collector low resistivity layer, a first collector high resistivity layer formed on said first collector low resistivity layer and having its resistivity set higher than a resistivity of said first collector low resistivity layer, a first base region formed in a surface of said first collector high resistivity layer, and a first emitter region formed in a surface of said first base region;
• said second bipolar transistor including a second collector low resistivity layer, a second collector high resistivity layer formed on said second collector low resistivity layer and having its resistivity set higher than a resistivity of said second collector low resistivity layer, a second base region formed in a surface of said second collector high resistivity layer, and a second emitter region formed in a surface of said second base region;
• characterized in that
• a resistivity of said first collector high resistivity layer is set higher than a resistivity of said second collector high resistivity layer.