ISSN 10637397, Russian Microelectronics, 2012, Vol. 41, No. 7, pp. 370–375. © Pleiades Publishing, Ltd., 2012.
Original Russian Text © V.A. Galperin, 2011, published in Izvestiya Vysshikh Uchebnykh Zavedenii. Elektronika, 2011, No. 3, pp. 26–34.
During the commercial production of uptodate
verylargescale and ultralargescale integration cir
cuits, and products of power electronics, the highly
selective anisotropic silicon etching process with a
controlled profile refers to fundamental processes.
Understanding mechanisms, determining the process
flowing condition, enables us to efficiently control the
main process characteristics.
The purpose of this work is to study the physical–
chemical parameters of the reactiveion etching (RIE)
process of silicon in an HBr/SF
mixture and to
apply numerical and experimental simulation for opti
mizing the process, taking into account the require
ments of micro and nanoelectronics designers.
An attempt at reaching qualitatively new results of
the silicon etching process was made by combining the
numerical and experimental simulations, and the data
on plasma diagnostics. Experimentally inaccessible
kinetic parameters, required for the numerical simula
tion, were determined by the designed procedure,
which compares experimentally obtained etching pro
files and numerical calculations in accordance with
the etching process model.
Plasma etching experi
ments were performed on the “Karolina 15” plant
(“ESTOvacuum” Co.), equipped with a lock speci
men loading and highdensity induction plasma
source with a possibility of the additional magnetic
retention of a highdensity gas discharge. Highfre
quency (HF) power with a frequency of 13.56 MHz is
applied through the matching unit to the flat induction
electrode, inserted in the working chamber and pro
tected by a quartz screen. The wafers are placed on the
temperaturecompensated waferholder (5–50
with a He supply under the plate and maintaining the
plates by the mechanical ring clamp. The walls of the
chamber are heated up to a temperature of 60
following diagnostic methods are used for obtaining
the internal parameters of the performed processes:
mass spectrometry; probe method for determining the
plasma density in the volume; optical emission spec
troscopy (OES); and the probe method for measuring
the ion flux to the wafer with the probe positioning on
The mass spectrometry is used for monitoring con
centrations of stable particles. Relative concentrations
of known neutrals, such as F and O, are estimated by the
OES in combination with actionometry  For this
purpose, up to 5 vol % of Ar is added with respect to the
whole working mixture. The following wavelengths
(704 nm (F*), 844 nm (O*), and 750 nm (Ar*)) are
observed. The probe for measuring the ion flux has a
small area (no more than 1 mm
) to exclude the influ
ence on the distribution of the total flux, and the nega
tive potential with respect to the “earth” potential is
applied to it through the highfrequency filterplug.
Silicon wafers with a diameter of 150 mm with
a topology of grooves of different linear sizes and a
800nm thick SiO
mask are used for the experiments.
mask is formed by etching on the LAM 4500
plant with a RIE reactor and split HF power source
(applied alternately to the upper and lower electrodes)
with a 400kHz frequency in the CHF
ture through a photoresist mask with its further
removal in O
plasma. The area of the Si opening does
not exceed 3%; the groove etching profile is estimated
on the REM. The average etching rate in the center of
the groove, selectivity, and value of the drift under a
mask is determined from test specimens at specified
process parameters. In addition, parameters such as
the ion flux value, HF bias voltage, F concentration,
and F/O ratio are fixed by diagnostic methods.
Procedure for estimating kinetic parameters.
determine kinetic parameters, three specimens were
etched (each within 120 s) on the assumption of the
dry chemical etching run at different pressures of 10,
25, and 75 mTorr (the HF power applied to the
antenna was 800 W; the power to the waferholder was
Application of Experimental and Numerical Simulation Methods
for Studies of the Dry Groove Silicon Etching Process
V. A. Galperin
Moscow State Institute of Electronic Engineering (Technical University), Moscow, Russia
Received October 21, 2010
—A physical–chemical silicon etching model is described; an etching profile is calculated by the
string method; and model adequacy is considered. The simulation results of the groove etching process as
function of process optimization parameter variations are analyzed.