Metal-nitride-oxide-silicon /MNOS/ capacitors act like metal-nitride-silicon /MNS/ capacitors with extra interface where sheet of charge can be stored in slow states. Flatband voltage shifts over a wide range by adjusting store charge density

Raburn, W. D.

English

NASA Technical Reports Server

September 1971
	 Brief 7 1- 10350 
NASA TECH BRIEF 
Marshall Space Flight Center
	 -4:v 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the. Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
A Study of Nitride Devices for Computer Memory Applications 
The voltage-current and voltage-capacitance 
characteristics of metal-nitride-oxide-silicon (MNOS) 
capacitors were investigated over a wide range of 
temperatures to determine the effects of fast and 
slow interface states on their performance. The 
MNOS samples were fabricated with nitride thick-
nesses of 500 A and 2000 A and a thermally grown 
oxide of 50 A thickness. Both n-type 3.2 to 4.8l-
cm and p-type 0.4 to 0.6-cm silicon substrates 
were used, with the orientation in the (111) direc-
tion. An aluminum contact with a radius of 0.102 
cm was deposited on the nitride surface. 
A detailed analysis of the data was based on the 
assumptions that the modes of charge flow within 
the device included conduction due to tunneling 
from the silicon into the oxide conduction band, 
then drifting to the nitride, and finally conduction 
in the silicon nitride due to repeated excitations 
from traps into the nitride conduction band. 
Conclusions derived from the analysis of the 
experimental measurements indicate that the MNOS 
capacitor acts like an MNS capacitor with an extra 
interface where a sheet of charge can be stored 
in slow states. In addition, the flatband voltage 
can be shifted any desired amount, over a wide 
tange of voltages, by adjusting the stored charge 
density. The conduction mechanism in the nitride 
layer appears to be primarily the Frenkel-Poole 
effect with an ohmic contribution at low fields. At
high fields, the shape of the curves for the field 
emission and Frenkel-Poole are similar, indicating 
that field emission may possibly occur. Field 
emission could also be related to the onset of break-
down. The nitride conduction mechanisms so 
completely overshadowed those of the thin oxide 
layer that nothing definitive could be said about 
the latter. The C-V hysteresis loop exhibited none 
of the predicted distortions due to fast surface or 
interface states, indicating that these would not be 
a problem if the devices were to be used in computer 
memory applications. 
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
Code A&TS-TU 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: B71-10350 
Patent status: 
No patent action is contemplated by NASA. 
Source: W. D. Raburn of

The University of Alabama

under contract to

Marshall Space Flight Center

(MFS-20971) 
Category 03 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19710000348 2020-03-17T02:28:16+00:00Z


A study of nitride devices for computer memory applications

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