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Dumbbell Type Resistance Testing Structure

IP.com Disclosure Number: IPCOM000076939D
Original Publication Date: 1972-May-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Baker, TH: AUTHOR [+5]

Abstract

In integrated circuits, it is customary to incorporate test structures either in the kerf between the chips on the wafer or at selected sites in the wafer. One known structure is the dumbbell-type resistor shown in Fig. 1. The purpose of this dumbbell resistor structure is to minimize all undesirable resistances, in order to obtain a measurement as close as possible to the base resistivity. In utilizing this structure to measure resistivity of the P-type base region power is applied across the base by pads 11 and 11', while the resistivity of the base is sensed by sensing pads 12 and 12'. With this approach, as shown in the electrical schematic representation of the structure in Fig. 1A, the contact resistances RC of contacts 11 and 11', which would adversely affect the resistivity measurements are eliminated.

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Dumbbell Type Resistance Testing Structure

In integrated circuits, it is customary to incorporate test structures either in the kerf between the chips on the wafer or at selected sites in the wafer. One known structure is the dumbbell-type resistor shown in Fig. 1. The purpose of this dumbbell resistor structure is to minimize all undesirable resistances, in order to obtain a measurement as close as possible to the base resistivity. In utilizing this structure to measure resistivity of the P-type base region power is applied across the base by pads 11 and 11', while the resistivity of the base is sensed by sensing pads 12 and 12'. With this approach, as shown in the electrical schematic representation of the structure in Fig. 1A, the contact resistances RC of contacts 11 and 11', which would adversely affect the resistivity measurements are eliminated.

However, it has been found that parasitic resistances which are associated with the regions between the ends of the N+ emitter overlay region 13 and points 14 and 14', at which sensing contact is made with the base region 10, arise and, as shown schematically in Fig. 1A, interfere with the true value of base resistivity RB. The structure shown in Fig. 2, and schematically shown in Fig. 2A, solves the problem. By enlarging the lateral dimensions of the N+ emitter overlay 13 so that it covers points 14 and 14', the effects of the parasitic resistances RP on the sensing of base resistivity RB through contacts 12 and 1...