Method of forming four layer overvoltage protection device
AssigneeTeccor Electronics, Inc.
InventorsMonty F. Webb, Elmer L. Turner
Life of this patent
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Abstract
An overvoltage protection device having multiple shorting dots in the emitter region and multiple buried regions substantially aligned with these shorting dots. The placement, number, and area of these buried regions reduce and more accurately set the overshoot voltage value of the device while maintaining the high surge capacities of the device. Further, doping types and concentrations have been modified from that known in the prior art to reduce overshoot providing a more accurate and sensitive overvoltage protection device than that known previously in the prior art.
Claims33
A method of making a multiple layer overvoltage protection device comprising the steps of:
- providing a mid-region layer having a first type of conductivity;
- forming a plurality of discrete first buried regions having a first type of conductivity in an upper surface of said mid-region layer;
- forming an upper base region having a second type of conductivity on the upper surface of said mid-region layer;
- forming a lower base region layer having a second type of conductivity on a lower surface of said mid-region layer;
- forming a first emitter region having a first type of conductivity on a surface of said upper base region layer;
- providing a plurality of discrete first shorting dot regions in said first emitter region wherein at least one of said plurality of discrete first buried regions in said mid-region layer is substantially vertically aligned with at least one of said plurality of discrete first shorting dot regions;
- coupling a first metal contact to said upper base region layer;
- and
- coupling a second metal contact to said lower base region layer.
A method of making a multiple layer overvoltage protection device comprising the steps of:
- providing a mid-region layer having a first type of conductivity;
- forming a first buried region having a first type of conductivity in an upper surface of said mid-region layer;
- forming an upper base region having a second type of conductivity on the upper surface of said mid-region layer;
- forming a lower base region layer having a second type of conductivity on a lower surface of said mid-region layer;
- forming a first emitter region having a first type of conductivity on a surface of said upper base region layer;
- forming a first getter region having the same type of conductivity as said lower base region in said lower base region;
- providing a first shorting dot region in said first emitter region;
- coupling a first metal contact to said upper base region layer;
- and
- coupling a second metal contact to said lower base region layer.
Dependencies are inferred from the claim text.