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Inversion Van Der Pauw Structure for Direct Surface Mobility Measure-Ment

IP.com Disclosure Number: IPCOM000038380D
Original Publication Date: 1987-Jan-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

El-Kareh, B: AUTHOR [+2]

Abstract

A relatively easy measurement technique, independent of device dimensions and resistance outside the channel region, is reported using a novel semiconductor field-effect structure that allows direct measurement of surface mobility as a function of surface field. The structure used may be defined as an inversion Van der Pauw resistor, as shown in the figure. It consists of five terminals, i.e., two voltage sensing and two current forcing tabs centered preferably on the sides of a square-shaped metal-insulator-silicon (MIS) structure, and a gate electrode. When an appropriate gate voltage overdrive (VG - VT) is applied, an inversion layer of known carrier concentration is formed under the gate.

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Inversion Van Der Pauw Structure for Direct Surface Mobility Measure- Ment

A relatively easy measurement technique, independent of device dimensions and resistance outside the channel region, is reported using a novel semiconductor field-effect structure that allows direct measurement of surface mobility as a function of surface field. The structure used may be defined as an inversion Van der Pauw resistor, as shown in the figure. It consists of five terminals, i.e., two voltage sensing and two current forcing tabs centered preferably on the sides of a square-shaped metal-insulator-silicon (MIS) structure, and a gate electrode. When an appropriate gate voltage overdrive (VG - VT) is applied, an inversion layer of known carrier concentration is formed under the gate. Measurement of the inversion sheet resistance, Rs, yields the effective surface mobility as a function of surface field: (1) where meff is the field dependent effective surface mobility and Q' is the absolute value of the inversion charge

concentration in coulombs/cm2 .

Rs is measured by forcing a known current between pads 1-2 and measuring the voltage difference between pads 3-4, then forcing a known current between pads 1-4 and measuring the voltage between pads 2-3. Sheet resistance, Rs, is calculated as follows: (2) where

R34, 12 = V34 / I12 and R23, 14 = V23 / I14 . V34 and V23 are the voltages sensed between tabs 3-4 and

2-3, respectively. I12 and I14 is the current forced

between tabs 1-2 and...