Patent ID: 6268639
Filing Date: 2001-07-31
Classification: H01L,Y10S

Abstract:
A protection circuit formed in a semiconductor substrate, the protection circuit comprising:a. a bipolar transistor having emitter, base, and collector regions within the semiconductor substrate;b. a resistor formed within the semiconductor substrate and extending between the base and emitter regions of the bipolar transistor; andc. a zener diode having:i. a cathode diffusion connected to the collector region of the bipolar transistor, the cathode diffusion extending a first diffusion depth into the semiconductor substrate in a direction perpendicular to the substrate; andii. an anode diffusion connected to the base region of the bipolar transistor, the anode diffusion extending through the cathode diffusion a second diffusion depth into the semiconductor substrate in the direction perpendicular to the substrate;iii. wherein the second diffusion depth is greater than the first diffusion depth.