ISSN 1063-7397, Russian Microelectronics, 2007, Vol. 36, No. 1, pp. 53–55. © Pleiades Publishing, Ltd., 2007.
Original Russian Text © A.B. Simakov, A.Yu. Bashin, 2007, published in Mikroelektronika, 2007, Vol. 36, No. 1, pp. 62–65.
The design and production of radiation-resistant
electronic components for space, military, and particle-
physics applications constitute a key area of microelec-
tronics. The issue of radiation hardness is often
addressed in the context of metal–oxide–semiconduc-
tor (MOS) circuits, the most popular technology. In
integrated MOS transistors, the most radiation-suscep-
tible part is the ﬁeld oxide; with power discrete MOS
transistors, ionizing radiation mainly affects the gate
oxide. (The latter type of MOS transistor accounts for
over 30% of all the MOS structures available.) Note
that the radiation response of gate oxides is primarily
determined by interface traps, whereas that of ﬁeld
oxides is governed by oxide-trapped charge.
Although the topic of making radiation-resistant sil-
icon dioxide ﬁlms is extensively discussed in the litera-
ture, most techniques are designed to impart radiation
hardness to an as-grown ﬁlm (usually by repeated
application of irradiation–heating–cooling cycles).
This paper is concerned with ensuring radiation hard-
ness of oxide ﬁlms
their growth. We propose an
approach that takes less time and is less laborious com-
pared with postoxidation treatment. It can be imple-
mented with minimal effort on almost any oxidizing
machine in current use. On the other hand, the new oxi-
dation process essentially employs a linear accelerator
(linac) of electrons, which is an expensive piece of
The approach proposed is to treat a growing ﬁlm of
thermal oxide with gamma-ray photons of mean energy
The electron linac is a very promising tool for
microelectronics manufacturing as it provides a versa-
tile source of pulsed ionizing radiation with widely
adjustable parameters. In addition to electrons, differ-
ent ionizing species (neutrons, gamma-ray photons,
etc.) can be obtained as secondary emission from suit-
In our approach, a 34-MeV electron beam from a
linac strikes a metal target to generate gamma-ray pho-
tons that act on molecules of deionized water to yield
O + n. (1)
The unstable isotope
O (half-life about 3 min) is
fed into an oxidizing chamber by pumping the water.
As a result, the thermal oxidation of silicon is accom-
panied by the decay of
N + e
The positrons are immediately annihilated by elec-
trons to produce two desired gamma-ray photons of
mean energy 511 keV:
As it grows, the oxide ﬁlm thus experiences low-
intensity continuous gamma radiation.
Figure 1 is a photograph of the linac (U-17,
designed at the Institute) employed in our experiment.
Figure 2 is a block diagram of the 511-keV gamma-ray
source. Its main constituents are an electron linac (
tungsten target (
); an activation tank (
) for deionized
water, which is forced along a circuit (
) by a pump (
and a gamma irradiator (
), which is part of the circuit.
The rate of water circulation is adjusted with a valve (
The activation tank and the irradiator are located in the
high-radiation section (
) and the low-radiation section
), respectively, separated by a shield
shield is used to absorb unwanted gamma rays in the
low-radiation section. Note that one linac can serve a
number of oxidizing machines simultaneously.
Radiation-Enhanced Thermal Oxidation of Silicon
A. B. Simakov and A. Yu. Bashin
Moscow Engineering Physics Institute (State University), Moscow, Russia
Received November 3, 2005
—A technique of radiation-enhanced thermal oxidation of silicon is developed and implemented in
process equipment. Test SiO
ﬁlms are grown under exposure to 511-keV gamma-ray photons. Their electrical
and radiation performance are evaluated. Basic mechanisms of radiation-enhanced oxide growth are proposed.
PACS numbers: 81.40.Wx