Equivalent circuit for ion implanted counterdoped layers as determined by MOS admittance and crosstalk measurements

Abstract

Counterdoping ion implantation of doses above loll cm-2 into MOS structures leads to the formation of a p-n junction close to the Si0,-Si-phase boundary. The hf-C( V ) curves of this structure show an additional frequency dispersion in the implanted layer accumulation regime. This dispersion is caused by the two-dimensional current propagation into the lateral channel and into the bulk of the silicon across the p -n junction underneath the gate electrode. The lateral current spread is described by an infinitely distributed equivalent network. The voltage and current along its components are calculated for a linear geometry of finite dimensions. The model is checked by the measurement of the input accumulation admittance and the measurement of the complex dot-to-dot crosstalk voltage. Identical values of sheet resistance, junction capacitance, and effective junction conductance are found for either method.Gegendotierende Ionenimplantation bei Dosen oberhalb loll cm-2 in MOS-Strukturen fuhrt zur Bildung eines p-n-ubergangs in der Nahe der Si0,-Si-Phasengrenze. Die HF-C( V)-Kurven dieser Struktur zeigen eine zusatzliche Frequenzdispersion im Akkumulationsbereich der implantierten Schicht. Diese Dispersion wird verursacht durch die zweidimensionale Stromausbreitung in den lateralen Kana1 und in das Silizium-Volumen uber den p-n-ubergang unter der Gate-Elektrode. Die laterale Stromausbreitung wird durch ein unendlich verteiltes aquivalentes Netzwerk bescbrieben. Die Spannung und der Strom entlang seiner Komponenten werden fur eine linewe Geometrie mit endlichen Abmessungen berechnet. Das Modell wird durch Messung der Anreicherungs-Eingangsadmittanz sowie der Messung der komplexen Ubersprechspannung von Punkt-zu-Punkt iiberpruft. Mit jeder Methode werden identische IVerte fur den Schichtwiderstand, die p-n-Kapazitat und den effektiven p-n-Leitwert gefunden. l )

Metal‐Oxide‐Semiconductor Capacitance Measurements on Amorphous Silicon

“…This resistance can be converted to the resistivity of the layer using the geometrical data for AG and d~_s~. This resistivity might be converted in turn to a free-carrier density using the generally accepted data for the mobility, p~ = 1 cmZ/Vs: the relation i/p = q -n 9 #~ [2] yields the electron concentration. The resistivities of the intrinsic layers of the samples used for the investigations cover values ranging from 1.7 9 107 t2 9 cm to 1.0.10 ~~ 12. cm and even more, too high to be determined with our experimental setup.…”

Implantation Profiles of Buried Layers (MOS pn) from HF or LFC(U) Curves

“…The C( U ) measurements were carried out by the means of two HP-bridges 42748 and 42758, a simultaneous HF/LF set-up, and pulsed C( U ) measurement set-up. The block diagram and details of the set-ups might be found in [3].…”

“…11. From crosstalk and admittance measurements [3] we know that the nominal fluence a t which the implant operator aimed was not reached. From the fit of Fig.…”