Process-Dependent Charges and Traps in Dielectrics on SiC

Dielectric charges and charge stability were compared in different dielectrics formed on SiC by different processing techniques. The concentration and transient behavior of the interface and trapped charges were investigated. Strong hysteresis and flat-band voltage drift under applied bias were observed in some of the samples. They are attributed to the trapping of the charge injected in the dielectrics. Differences in charge injection, charge trapping, and capture/emission of carriers by interface traps were pronounced for the investigated SiO2 and Si3N4 dielectrics.

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Electrical Characterization of High-k Dielectrics by Means of Flat-Band Voltage Transient Recording

MRS Proceedings ◽

10.1557/proc-0996-h07-11 ◽

2007 ◽

Vol 996 ◽

Author(s):

Salvador Duenas ◽

Helena Castán ◽

Héctor García ◽

Luis Bailón ◽

Kaupo Kukli ◽

...

Keyword(s):

Electric Fields ◽

Electrical Characterization ◽

Charge Trapping ◽

Atomic Layer ◽

Localized States ◽

Oxide Semiconductor ◽

Flat Band ◽

Flat Band Voltage ◽

High K ◽

Mos Structures

AbstractWe have carried out a comparison between flat-band transients displayed in metal-oxide-semiconductor (MOS) structures fabricated on several atomic layer deposited (ALD) high-k dielectric films: HfO2, ZrO2, Al2O3, Ta2O5, TiO2, and Gd2O3. The gate voltage as a function of time is recorded while keeping constant the capacitance at the initial flat band condition (CFB). Since samples are in darkness, under no electric fields and no charge-injection conditions, transients must be due to charge trapping of localized states produced by electrons (holes) coming from the semiconductor by tunnelling. The process is assisted by phonons and it is therefore thermally activated. The temperature-transient amplitude relation follows an Arrhenius plot which provides the thermal activation energy of soft-optical phonons. Finally, we describe the dependencies of the flat-band voltage on the setup bias history (accumulation or inversion) and the hysteresis sign (clockwise or counter-clockwise) of the capacitance-voltage (C-V) characteristics of MOS structures.

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Electrical charge injection and storage in off-stoichiometric SiO2 films

Journal of Materials Research ◽

10.1557/jmr.1989.1233 ◽

1989 ◽

Vol 4 (5) ◽

pp. 1233-1237 ◽

Cited By ~ 7

Author(s):

M. López ◽

C. Falcony

Keyword(s):

Applied Voltage ◽

Charge Injection ◽

Opposite Polarity ◽

Electrical Contacts ◽

Electrical Charge ◽

Flat Band ◽

Flat Band Voltage ◽

Si Substrate ◽

And Storage

The injection and storage characteristics of electrical charge in off-stoichiometric SiO2 films have been studied using two types of capacitor structures: (A) a simple capacitor formed with an off-stoichiometric SiO2 film deposited on either p- or n-type silicon substrate and a metallic (Al) contact, and (B) a structure similar to (A) but with a thin (100 Å or 500 Å) SiO2 layer between the Si substrate and the off-stoichiometric SiO2. The flat band voltage shifts measured from high frequency capacitance versus voltage curves of these devices were used to study the accumulation of charge in the off-stoichiometric SiO2 layer induced by applied voltage pulses. The width of these pulses was in the range of 10 ms to 100 μs and the amplitude was in the range of 0 to 80 volts. The role of the SiO2 layer in the (B) type structures is to inhibit or reduce charge injection to or from the Si substrate at low applied voltage amplitudes. This effect originates initial shifts of the flat band voltage of opposite polarity to those observed in the case of (A) type structures. The relaxation of the stored charges was monitored by measuring the shifts of the flat band voltage as a function of time when both electrical contacts were connected to ground potential.

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